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Brain Sci. 2017, 7(2), 20; https://doi.org/10.3390/brainsci7020020

Article
The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline
Research & Development Department, Skin Biology, 4122 Factoria Boulevard SE Suite No. 200 Bellevue, WA 98006, USA
*
Author to whom correspondence should be addressed.
Academic Editor: Kamen Tsvetanov
Received: 30 November 2016 / Accepted: 8 February 2017 / Published: 15 February 2017

Abstract

:
Neurodegeneration, the progressive death of neurons, loss of brain function, and cognitive decline is an increasing problem for senior populations. Its causes are poorly understood and therapies are largely ineffective. Neurons, with high energy and oxygen requirements, are especially vulnerable to detrimental factors, including age-related dysregulation of biochemical pathways caused by altered expression of multiple genes. GHK (glycyl-l-histidyl-l-lysine) is a human copper-binding peptide with biological actions that appear to counter aging-associated diseases and conditions. GHK, which declines with age, has health promoting effects on many tissues such as chondrocytes, liver cells and human fibroblasts, improves wound healing and tissue regeneration (skin, hair follicles, stomach and intestinal linings, boney tissue), increases collagen, decorin, angiogenesis, and nerve outgrowth, possesses anti-oxidant, anti-inflammatory, anti-pain and anti-anxiety effects, increases cellular stemness and the secretion of trophic factors by mesenchymal stem cells. Studies using the Broad Institute Connectivity Map show that GHK peptide modulates expression of multiple genes, resetting pathological gene expression patterns back to health. GHK has been recommended as a treatment for metastatic cancer, Chronic Obstructive Lung Disease, inflammation, acute lung injury, activating stem cells, pain, and anxiety. Here, we present GHK’s effects on gene expression relevant to the nervous system health and function.
Keywords:
GHK; copper; dementia; Alzheimer’s disease; Parkinson’s disease; neurons; glial cells; DNA repair; anti-oxidant; anti-anxiety; anti-pain

1. Introduction

Age-related cognitive decline is a common problem for many elderly people, yet its cause is poorly understood. Over 99% of investigational drugs, participating in over 200 clinical trials, failed to receive approval for the treatment of Alzheimer’s disease [1]. Even the success of a few approved drugs provides only minimal patient improvement. There is a need for new, safe, and effective therapeutics with extensive safety and efficacy data that can be developed for use in humans within the next few years.
GHK (glycyl-l-histidyl-l-lysine) is a human plasma copper-binding peptide with a stunning array of actions that appear to counter aging-associated diseases and conditions. GHK was isolated in 1973 as an activity bound to human albumin that caused aged human liver tissue to synthesize proteins like younger tissue [2]. It has a strong affinity for copper and readily forms the complex GHK-Cu. It was first proposed that GHK-Cu functions by modulating copper intake into cells [3]. Since then, it has been established that the GHK peptide has stimulating and growth-promoting effects on many cells and tissues such as chondrocytes [4], liver cells and human fibroblasts [5]. It increases stemness and stimulates integrin secretion in human epidermal basal keratinocytes [6], as well as has a strong wound-healing and tissue-repairing effect [7]. GHK has also been shown to improve wound healing in controlled experiments using animals, such as rats, dogs, and rabbits [8,9,10].
In 2010, Hong et al. using the Broad Institute’s Connectivity Map (cMap), a compendium of transcriptional responses to compounds, identified GHK as the most active of 1309 bioactive substances, uniquely capable of reversing the expression of 54 genes in a metastatic-prone signature for aggressive early stage mismatch-repair colorectal cancer. GHK was active at a very low concentration of 1 µM [11].
Another study, which also used the cMap to identify genes affected by GHK, was conducted in 2012 when Campbell et al. identified 127 genes whose expression levels were associated with regional severity of chronic obstructive pulmonary disease (COPD). Emphysema and chronic bronchitis, the two main conditions of COPD, cause both small airway obstruction and significant loss of lung function over time. The cMap predicted that GHK would reverse the aberrant gene-expression signature associated with emphysematous destruction and induce expression patterns consistent with healing and repair. These finding were supported by laboratory experiments. GHK, at 10 nM, added to cultured fibroblasts from the affected lung areas of patients, changed gene expression patterns from tissue destruction to tissue repair. This led to the organization of the actin cytoskeleton, elevated the expression of integrin beta 1, and restored collagen contraction [12].
In addition to topping the list of 1309 biologically active molecules as the computer-recommended treatment for both human COPD (chronic obstructive pulmonary disease) and aggressive metastatic colon cancer, GHK has been recommended as a treatment for inflammations, acute lung injury, activation of stem cells, regeneration of aged skin, wound healing and tissue regeneration (skin, hair follicles, stomach and intestinal linings, hair growth, and boney tissue). It is also widely used in anti-aging skin products [13].
Even though it is not always possible to link gene expression data to biological actions, it is important to notice that GHK is highest in very healthy young people. Unfortunately, GHK declines with age. In studies at the University of California at San Francisco, young (age 20–25), male medical students were found to have about 200 nanograms/mL of GHK in their blood plasma, while the healthy, male medical school faculty (average age of 60) had only 80 nanograms/mL [7].
Our previous publication reviewed the biological effects of GHK relevant to neurodegeneration and cognitive health [14]. This paper will discuss the effect of GHK on gene expression relevant to nervous system functions and cognitive decline as well as review genetic and laboratory data relevant to nerve outgrowth, copper transport into cells, anxiety and pain, DNA repair, the ubiquitin proteasome system, the anti-oxidant system, changes in gene expression for glial cells, astrocytes, brain cells, dendrites, ganglia, motor neurons, Schwann cells, and sensory cells. It will also present possible methods for the use of therapeutic GHK in the treatment of nerve diseases.

2. Materials and Methods

The cMap was used to acquire the gene expression data. It is a large database that contains more than 7000 gene expression profiles of 5 human cell lines treated with 1309 distinct small molecules. Three GHK profiles are contained in this repository. The profiles are the result of cell lines treated with GHK at 1 micromolar which is around the concentration where many of GHK’s cellular effects occur [15]. These profiles were created using the GeneChip HT Human Genome U133A Array. Among the 5 cell lines used by the Connectivity Map only 2 were treated with GHK. Two of the profiles were created using the PC3 cell line - human prostate cancer cells, while the third used the MCF7 cell line – human breast cancer cells. Our studies utilized all three gene expression profiles.
GenePattern, a publicly available computational biology open-source software package developed for the analysis of genomic data, was used to analyze the gene data obtained from the cMap. The CEL files (data files used by Affymetrix software, used by the Broad Institute) were processed with MAS5 (Microarray Analysis Suite 5 software, Affymetrix, Santa Clara, CA, USA) and background correction. Files were then uploaded to the ComparativeMarkerSelectionViewer module in order to view fold changes for each probe set. Gene abbreviations appearing throughout the paper are consistent with the NCBI Gene database [16].
Due to multiple probe sets mapping to the same gene, the fold changes in m-RNA production produced by GenePattern were converted to percentages, and then all probe sets representing the same gene were averaged. It was determined that the 22,277 probe sets in the Broad data represent 13,424 genes. This ratio (1.66) was used to calculate the overall number of genes that affect GHK at various cutoff points (rather than probe sets).
The percentage of genes stimulated or suppressed by GHK with a change greater than or equal to 50% was estimated to be 31.2% [17]. Listed in the article are the gene expression effects of GHK on over 700 human genes associated with various nerve cell types. For well-defined systems where animal and cell cultures exist, such as anti-pain and anti-oxidation, relevant genes were manually chosen. For other systems, each gene’s Gene Ontology description was searched, using terms such as “neuron” or “glial”. The Gene Ontology consortium provides controlled vocabularies for the description of the molecular function, biological process, and cellular component of gene products. [18]. For most systems, gene expression numbers were given from 100% + or − and larger.
The cMap data was proven to be predictive of biological actions in most cases. In 2010, cMap predicted the anti-cancer actions of GHK. Subsequent work found GHK at 1 to 10 nanomolar reset the programmed cell death system on human nerve cancer cells and inhibited their growth in culture, while having the same effect on sarcoma cell growth in mice; it changed the gene expression of over 80 genes in an anti-growth manner [17]. Data from cMap also led to experiments that found GHK at 10 nanomolar caused human COPD-afflicted lung cells to switch cell expression from tissue destruction to repair and remodeling. For anti-oxidant actions, cMap has been very predictive of actions in mammals. However, gene expression numbers can vary widely at times and are not always predictable. For example, the cMap gives NGF (nerve growth factor) as a −243% decrease, yet in vivo rat studies have found NGF to be increased and two in vitro cell culture studies have found GHK to increase nerve outgrowth, an effect usually attributed to NGF.
Below, we cover GHK’s relationship with the following.
  • Nerve Outgrowth
  • Copper Lack in Nerve Diseases
  • Anti-Anxiety and Anti-Pain
  • Anti-Oxidant Biological and Gene Expression Data
  • DNA Repair Data and Gene Expression DNA Repair
  • Restoring Regeneration after Cortisone Treatment
  • Gene Expression—Clearing Damaged Protein with the Ubiquitin Proteasome System (UPS)
  • Gene Expression—Neurons
  • Gene Expression—Motor neurons
  • Gene Expression—Glial cells
  • Gene Expression—Astrocytes
  • Gene Expression—Schwann
  • Gene Expression—Myelin
  • Gene Expression—Dendrite
  • Gene Expression—Oligodendrocyte cells
  • Gene Expression—Schwann cells
  • Gene Expression—Spinal
  • Possible methods of therapeutic use of GHK for nerve disease

3. Results

3.1. Nerve Outgrowth

The lack of nerve outgrowth growth is considered a major factor in dementia [19,20,21].
GHK was discovered in 1973 as a growth factor for cultured hepatocytes. In 1975, Sensenbrenner and colleagues reported that GHK induced the formation chick embryonic neurons while suppressing glial cells. See Figure 1 [22].
Lindner and colleagues found that explants from chick embryo PNS (ganglion trigeminale) and from CNS of embryonal rats (hippocampus) and dissociated cells from chick embryo cerebral hemispheres that 0.01 microgram GHK per ml of medium stimulated the outgrowth of neuronal processes. Again, GHK promoted neuronal growth but not glial cells [23].
In studies of rats, severed sciatic nerves (axotomy) were inserted into a collagen prosthesis to which GHK was bonded. These were re-inserted into the rat, then removed after 10 days. GHK enhanced the production of trophic factors (Nerve Growth Factor, Neurotrophins 3 and 4) and recruited hematogenous cells and Schwann cells, which in turn help in the secretion of certain vital trophic and tropic factors essential for early regeneration. This improved nerve regeneration following axotomy [24]. Surprisingly, GHK’s gene expression data gives suppression of NGF (−243%) and NGFR (nerve growth factor receptor) (−132%). Thus, the biological system within wounded rat’s nervous tissue is more complex and probably due to other nerve stimulatory molecules.

3.2. Copper Deficiency, Dementia, and Nerve Dysfunction

Copper is an essential component of important anti-oxidant proteins such as SOD (copper zinc superoxide dismutase), ceruloplasmin, and Atox1 (human antioxidant protein 1). Copper deficiency has been postulated as a causative factor in a variety of gene diseases such as Alzheimer’s [25,26,27,28,29,30], myelopathy [31], motor neuron diseases and amyotrophic lateral sclerosis [32], Huntington’s [33], Lewy bodies and Creutzfeldt Jakob diseases [34].
More importantly, analysis of actual human brains from deceased patients with dementia has found the damaged areas to have very little cellular copper. In plaques from persons with Alzheimer’s disease, iron and aluminum appear to cause plaque formation while copper and zinc may be protective [26,27,28,35,36,37].
Copper deficiency caused by bariatric surgery or gastrointestinal bleeding led to myelopathy (human swayback), paralysis, blindness and behavioral and cognitive changes. Mice born and maintained on a copper deficient diet had 80% reduction in brain copper level at 6-8 weeks and had neuronal and glial changes typical for neurodegenerative disorders [25,31,38,39].

3.2.1. Supplying Copper to Nerve Cells

Though copper deficiency appears linked to major nerve diseases, the use of copper supplements as a treatment has been disappointing. A placebo-controlled study of 68 Alzheimer’s patients (34 control, 34 copper) with a treatment of 8 mgs of daily copper (a high level) for 1 year produced no negative findings. This seems to rule out excessive copper levels as a causative agent for the development of Alzheimer’s. The predictive protein marker, CSF Abeta42, is lower in persons developing Alzheimer’s. Subjects given extra copper supplementation maintained this protein at a higher level, a possible positive effect, but there was minimal improvement in the disease [40].
One small copper complex chelator, CuATSM (diacetyl-bis(4-methylthiosemicarbazonato)copper 2+), has given indications of ameliorating the effects of ALS (familial amyotrophic lateral sclerosis) in a strain of genetically modified mice that develop a form of ALS. CuATSM extends life in such mice by up to 25%. The motor neuron disease can be restarted and then stopped by controlling CuATSM treatment. The treatment increases the amount of active superoxide dismutase in the mice [41]. The safety of CuATSM is largely unknown. The safety data sheet states the following: “Material may be irritating to the mucous membranes and upper respiratory tract. May be harmful by inhalation, ingestion, or skin absorption. May cause eye, skin, or respiratory system irritation. To the best of our knowledge, the toxicological properties have not been thoroughly investigated.”
GHK-Copper 2+ increased superoxide dismutase (SOD) activity in mice as detailed below in Section 4 [42].

3.2.2. Albumin, GHK and Copper Transport

Both albumin and GHK transport copper 2+ to cells and tissues. However, in human blood, there are 700 albumin molecules for each GHK molecule, so albumin is the major source of copper for tissue use. GHK and albumin have high and very similar binding constants for copper 2+ (Albumin = pK binding log 10 |16.2|; GHK = pK binding log 10 |16.4|). Human plasma contains about 15 micromolar copper and 12% (1.8 micromolar) of this is bound to albumin. But GHK-Cu is maximally active on most cells around one nanomolar or less. Aqueous dialysis studies established that GHK can obtain copper 2+ from albumin. We assume that this also occurs in cell culture and within mammals and that GHK has adequate copper for biological actions.
Our studies over the past 39 years have indicated that virtually all biological GHK effects require the presence of copper 2+ chelated to the tripeptide. Strong copper chelators such as bathocuproine abolish GHK actions. GHK alone is often effective in murine wound healing or hair growth models, but GHK-Cu always produced much stronger responses. GHK attached to radioactive copper-64 increases copper uptake into cultured hepatoma cells [7].
The intravenous injection of tritiated copper-free GHK into mice was found, after 4 h, to concentrate most densely within the animals’ kidneys and brain. See Figure 2 [43].
The best evidence that GHK can obtain copper 2+ from body fluids was from a study that used biotinylated GHK bound to collagen films placed over wounds in rats. The GHK pads raised the copper concentration by ninefold at the wound site when compared to non-GHK collagen films. Such biotinylated GHK collagen films also increased wound healing, cell proliferation, and increased the expression of antioxidant enzymes in the treated group [9].
Most importantly, GHK activates numerous regenerative and protective genes. Albumin will not mimic the GHK activated systems. So GHK must act through a separate pathway, not the albumin pathway. Albumin’s copper feeds cells; GHK’s copper activates regenerative and protective genes.
GHK-Cu’s regenerative and protective actions on tissue are very similar to those found by John R Sorenson throughout his 33 years of work on various copper salicylates. See Table 1. It appears that GHK-Copper and Sorenson’s DIPS-Cu (diisopropylsalicylate-copper 2+) both activate the same pathway, a pathway strongly associated with tissue health and repair. GHK-copper 2+ (molecular weight 404) and Sorenson’s DIPS-Cu (molecular weight 506) are both very small molecules while albumin is much larger (molecular weight 64,000). Hence, they are likely to use different cell receptor systems [44,45,46,47,48,49]. See Figure 3.

3.3. Anti-Anxiety (Anxiolytic) and Anti-Pain

Anxiety and pain are serious issues in patients with dementia and other disabling mental conditions. Opiate peptides often possess both anti-pain and wound healing properties [50]. When healthy human males were fed a low copper diet (1 mg/day of copper) for 11 weeks, their plasma opiate levels dropped by 80%. As soon as copper was restored (with a diet containing 3 mg/day of copper), the levels returned to normal [51].
GHK has been found to possess analgesic and anxiolytic effects (anti-anxiety) in animal experiments. GHK reduced pain after thermal injury to rats at a dose of 0.5 milligrams/kg. Within 12 min after intraperitoneal injection, it also increased the amount of time the rats spent exploring more open areas of the maze and decreased time spent immobile (the freeze reaction), which indicated reduction of fear and anxiety. These effects were observed at 0.5 micrograms/kg [52,53].
These effects also prove that GHK rapidly affects the brain perception and function. This is an area where GHK could be used on patients today.
A manual search of genes affected by GHK found that seven anti-pain genes increased and two genes decreased. See Table 2 and Table 3.

3.4. Antioxidant Activity of the GHK Peptide

High metabolic activity found in the brains of both humans and animals results in elevated oxygen consumption and constant production of reactive oxygen species (ROS) in mitochondria. At the same time, the brain tissue is rich in unsaturated fatty acids and transition metal ions, yet has relatively fewer antioxidants compared to other organs, creating favorable conditions for oxidative damage. Since the blood-brain barrier prevents many dietary antioxidants from entering the brain, it largely relays on endogenous antioxidants such as Cu and Zn dependent superoxide dismutase (Cu, Zn SOD1). This enzyme requires the metal ions copper and zinc in order to be active. Hence, copper deficiency can lead to reduced SOD activity and increased oxidative brain damage. When pregnant rats were fed a copper deficient diet, the embryos displayed low SOD activity, increased super oxide anion radical level, and higher incidence of DNA damage and malformations [54].
GHK has broad and powerful anti-oxidation properties in both mammals and cell culture, and it is known to increase anti-oxidant gene expression. Tissue oxidation has been postulated as a causative factor in Parkinson’s disease and other various nerve diseases of aging [55,56,57,58,59].
Diminished copper has been found in cells expressing SOD1 mutations postulated to cause ALS in mice and increase memory loss [60,61].
A peptidomimetic inhibitor (P6), based on GHK, interacts with amyloid beta (Aβ) peptide and its aggregates. P6 prevents the formation of toxic Aβ oligomeric species, fibrillar aggregates and DNA damage. It is a potential therapeutic candidate to ameliorate the multifaceted Aβ toxicity in Alzheimer’s [62].

3.4.1. GHK’s Anti-Oxidant Effects in Mammals and Cell Culture

The use of GHK-Cu in mice protected their lung tissue from lipopolysaccharide-induced acute lung injury (ALI). When GHK-Cu was used by mice with LPS-induced ALI, it attenuated related histological alterations in the lungs and suppressed the infiltration of inflammatory cells into the lung parenchyma. The GHK-Cu also increased superoxide dismutase (SOD) activity while decreasing TNF-α and IL-6 production through the suppression of the phosphorylation of NF-κB p65 and p38 MAPK in the nucleus of lung cells [42].
P38 mitogen-activated protein kinases are responsive to stress stimuli, such as cytokines, ultraviolet irradiation, heat shock, and osmotic shock, and are involved in cell differentiation, apoptosis, and autophagy. NF-κB/RELA p65 activation has been found to be correlated with cancer development, suggesting the potential of RELA as a cancer biomarker. Specific modification patterns of RELA have also been observed in many cancer types.
Multiple antioxidant actions of GHK have been demonstrated in vitro and in animal wound healing studies. They include inhibiting the formation of reactive carbonyl species (RCS), detoxifying toxic products of lipid peroxidation such as acrolein, protecting keratinocytes from lethal UVB radiation, and preventing hepatic damage by dichloromethane radicals.
The ability of GHK to prevent oxidative stress was tested in vitro using Cu(2+)-dependent oxidation of low-density lipoproteins (LDL). LDL were treated with 5 μM Cu(2+) for 18 h in either phosphate buffered saline (PBS) or Ham’s F-10 medium. There was increased production of thiobarbituric acid reactive substances (TBARSs), which indicated increased oxidation. GHK and histidine “entirely blocked” (quoted from the article) the in vitro Cu(2+)-dependent oxidation of low-density lipoproteins (LDL). In comparison, superoxide dismutase (SOD1) provided only 20% reduction of oxidation [63].
Acrolein, a well-known carbonyl toxin, is produced by lipid peroxidation of polyunsaturated fatty acids. GHK effectively reduces the formation of both acrolein and another product of oxidation, 4-hydroxynonenal. GHK also blocks lethal ultraviolet radiation damage to cultured skin keratinocytes by binding and inactivating reactive carbonyl species such as 4-hydroxynoneal, acrolein, malondialdehyde, and glyoxal [64,65,66].
The intraperitoneal injection of 1.5 mg/kg of GHK into rats for five days before dichloromethane poisoning and five days thereafter provided protection of the functional activity of hepatocytes and immunological responsiveness. Dichloromethane is toxic to hepatic tissue via the formation of a dichloromethane free radical that induces acute toxic damage [67].
In rats with experimental bone fractures peptides, GHK (0.5 μg/kg), dalargin (1.2 μg/kg), and thymogen (0.5 μg/kg) were injected intraperitoneally. Within 10 days, there was a decrease of malonic dialdehyde and an increase of catalase activity in blood. There was also a marked increase of reparative activity. Each combination of peptides was more potent than any of the studied peptides injected separately. The synergetic action of peptides Gly-His-Lys, thymogen, and dalargin was proposed for stimulation of reparative osteogenesis [68].
GHK-Cu reduced iron release from ferritin by 87%. Iron has also been shown to have a direct role in the initiation of lipid peroxidation. An Fe(2+)/Fe(3+) complex can serve as an initiator of lipid oxidation. In addition, many iron complexes can catalyze the decomposition of lipid hydroperoxides to the corresponding lipid alkoxy radicals. The major storage site for iron in serum and tissue is ferritin. Ferritin in blood plasma can store up to 4500 atoms of iron per protein molecule, and superoxide anions can promote the mobilization of iron from ferritin. This free iron may then catalyze lipid peroxidation and the conversion of a superoxide anion to the more damaging hydroxyl radical [69].

3.4.2. Synthesis of GHK-Cu Analogs with Higher Anti-ROS Activity

GHK-Cu has, on a molar basis, about 1% to 3% of the activity of the Cu, Zn superoxide dismutase protein. By simple modifications to the peptide, it is possible to raise the SOD-mimetic activity up 223-fold. Given the broad range of the antioxidant actions of GHK, it is likely that modifications will increase its countering reactive species such as RCS and dichloromethane radicals. See Table 4 [70].

3.4.3. Antioxidant Gene Expression Analysis

A manual search of antioxidant associated genes effected by GHK yielded 18 genes with significant antioxidant activity. See Table 5 and Table 6.

3.5. DNA Repair, Cell Culture, and Gene Expression

A lack of adequate DNA repair may be related to neurological degeneration in the aging population [90,91,92,93].
DNA damage is a major problem in the life cycle of biological cells. Normal cellular metabolism releases compounds that damage DNA such as reactive oxygen species, reactive nitrogen species, reactive carbonyl species, lipid peroxidation products and alkylating agents, among others, while hydrolysis cleaves chemical bonds in DNA. It is estimated that each normally functioning cell in the human body suffers at least 10,000 DNA damaging incidents daily [94].
Radiation therapy is believed to stop cell replication by damaging cellular DNA. A study of cultured primary human dermal fibroblast cell lines from patients who had undergone radiation therapy for head and neck cancer found that the procedure slowed the population doubling times for the cells. But treatment with one nanomolar GHK-Cu restored population doubling times to normal. Irradiated cells treated with GHK-Cu also produced significantly more basic fibroblast growth factor and vascular endothelial growth factor than untreated irradiated cells [5].
GHK is primarily stimulatory for gene expression of DNA Repair genes (47 UP, 5 DOWN), suggesting an increased DNA repair activity. Here we searched the Gene Ontology descriptions for “DNA Repair”. See Table 7 and Table 8.

3.6. Restoring Regeneration After Cortisone Treatment

Steroid dementia syndrome describes the signs and symptoms of hippocampal and prefrontal cortical dysfunction, such as deficits in memory, attention, and executive function, induced by glucocorticoids. Dementia-like symptoms have been found in some individuals who have been exposed to glucocorticoid medication, often dispensed in the form of asthma, arthritis, and anti-inflammatory steroid medications. The condition reverses, but not always completely, within months after steroid treatment is stopped [95].
In the human body, cortisone and cortisol are easily interconvertible and have similar anti-inflammatory actions. They also profoundly inhibit tissue regeneration, such as wound repair. DHEA (dehydroepiandrosterone) is an androgenic hormone. It is a precursor for testosterone and the estrogens. DHEA antagonizes the effects of cortisol but decreases about 80% from age 20 to age 80 while cortisone/cortisol levels remain high. It has been proposed that many of the deleterious effects of aging are due to excessive cortisol that is not balanced by DHEA.
GHK-Cu, when administered systemically to mice, rats, and pigs, counters the wound healing inhibition of cortisone throughout the animal [96].

3.7. Gene Expression—Clearing Damaged Protein—Ubiquitin Proteasome System

The ubiquitin proteasome system (UPS) clears damaged proteins. Insufficient activity of this system is postulated to produce an accumulation of toxic protein oligomers which start the neurodegenerative process. During aging, there is decreased activity of the ubiquitin proteasome system. To date, no effective therapies have been developed that can specifically increase the UPS activity [97,98,99,100].
GHK strongly stimulates the gene expression of the UPS system with 41 genes increased and 1 gene suppressed. Here we searched gene title for “ubiquitin” or “proteasome”. See Table 9 and Table 10.

3.8. Gene Expression—Neurons

Neurons are cells that carry messages between the brain and other parts of the body; they are the basic units of the nervous system.
GHK is primarily stimulatory for gene expression of neuron related genes. Here we searched the Gene Ontology descriptions for “Neuron”. See Table 11 and Table 12.

3.9. Motor Neurons

Motor neurons are nerve cells forming part of a pathway along which impulses pass from the brain or spinal cord to a muscle or gland.
Here we searched Gene Ontology descriptions for “motor neuron”. See Table 13 and Table 14.

3.10. Gene Expression—Glial Cells

Glial cells are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the central and peripheral nervous systems.
Here we searched Gene Ontology descriptions for “glial”. See Table 15 and Table 16.

3.11. Astrocyte

Astrocytes are characteristic star-shaped glial cells in the brain and spinal cord. The astrocyte proportion varies by region and ranges from 20% to 40% of all glial cells. They perform many functions, including biochemical support of endothelial cells that form the blood–brain barrier, provision of nutrients to the nervous tissue, maintenance of extracellular ion balance, and a role in the repair and scarring process of the brain and spinal cord following traumatic injuries.
Here we searched Gene Ontology descriptions for “astrocyte”. See Table 17 and Table 18.

3.12. Schwann Cells

Schwann cells are cells of the peripheral nervous system that wrap around a nerve fiber, jelly-roll fashion, forming the myelin sheath.
Here we searched Gene Ontology descriptions for “Schwann”. See Table 19 and Table 20.

3.13. Myelin

Myelin is a mixture of proteins and phospholipids that form a whitish insulating sheath around many nerve fibers, increasing the speed at which impulses are conducted.
Here we searched Gene Ontology descriptions for “myelin”. See Table 21 and Table 22.

3.14. Gene Expression—Dendrites

Dendrites are short branched extensions of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body.
Here we searched Gene Ontology descriptions for “dendrite”. See Table 23 and Table 24.

3.15. Gene Expression—Oligodendrocytes

Oligodendrocytes are glial cells similar to astrocytes, but with fewer protuberances, which are concerned with the production of myelin in the central nervous system.
Here we searched Gene Ontology descriptions for “oligodendrocyte”. See Table 25 and Table 26.

3.16. Gene Expression—Sensory Nerve cells

Sensory neurons are nerves that transmit sensory information (sight, sound, feeling, etc.). They are activated by sensory input and send projections to other elements of the nervous system, ultimately conveying sensory information to the brain or spinal cord.
Here we searched Gene Ontology descriptions for “sensory”. See Table 27 and Table 28.

3.17. Spinal Nerve Cells

Spinal nerve cells transfer information, which travels down the spinal cord, as a conduit for sensory information in the reverse direction, and finally as a center for coordinating certain reflexes.
Here we searched Gene Ontology descriptions for “spinal”. See Table 29 and Table 30.

4. Possible Methods of Therapeutic Use of GHK for Nerve Diseases

4.1. Mode of Administering GHK-Cu to Patients

4.1.1. Skin Cream or Patch

GHK-Cu has an unexpectedly rapid passage through skin’s stratum corneum. When tested by Howard Maibach’s group (Univerisity of California at San Francisco), 0.68% GHK-Cu was applied to dermatomed skin. Over 48 h, 136 micrograms of GHK-Cu passed through the skin per centimeter squared. This is a significant amount of GHK-Cu, and a transdermal patch of a several centimeters squared may pass therapeutically effective amounts throughout the human body [101].
Russian studies reported that 0.5 micrograms/kg reduced anxiety in rats. Scaled up for a human weight of 70 kg, this would be 35 micrograms in a human [52]. Our studies on activation of systemic healing in mice, rats, and pigs suggest that about 50 milligrams of GHK-Cu would be effective throughout the human body, although dose-ranging to determine the minimum active dosage was never performed.

4.1.2. Liposomal Encapsulated Oral Tablet

Alternately, the use of encapsulated liposomal GHK-Cu would allow its oral administration at relatively high dosages. Some sellers of an encapsulated liposomal tripeptide glutathione claim that 60% of the orally administrated peptide enters the human blood stream [102]. Direct administration in a regular pill form is unlikely to work because of GHK’s extreme sensitivity to breakdown by intestinal carboxypeptidase [103].
GHK-Cu costs about $8/gram in kilogram amounts. For a 50 mg dosage, the GHK-Cu would cost about $0.40. It is possible that GHK alone would be effective in humans and be able to obtain sufficient amounts of copper 2+ from albumin. If so, this would simplify its therapeutic use. The minimum effective dosage of GHK-Cu for various uses is unknown since such studies were never performed.
GHK-Cu does lower blood pressure, but the LD50 (Lethal Dose for 50% of mice) for such effects would be about a single dosage of 23,000 mgs of GHK-Cu in a 70 kg human. In GHK-Cu’s long history of use in cosmetics, no health issues have ever arisen. We were never able to find an LD 50 for GHK without copper.
In our studies, equimolar mixtures of GHK-Cu and GHK (no copper) are often used to avoid any release of loosely bound copper. Also, copper chelators such as penicillamine have been reported to cause psychosis in humans [104].

5. Conclusions

Given all the failed attempts to develop effective treatment methods for nerve degeneration, it is suggested that researchers must take a very broad view of the possible factors causing neurodegenerative diseases and not focus on limited possible causes. It is sensible to concentrate research efforts on the reversion of affected tissues to a healthier condition more characteristic of younger humans. GHK gene studies have increasingly led to the conclusion that the conditions and diseases of aging cannot be scientifically treated without understanding the extensive changes in overall gene activity during aging.
There are three sources of evidence on GHK actions:
  • The best data is in vivo mammalian data, including human clinical studies. As reviewed in this paper, these studies give overwhelming evidence of GHK’s effects on cells and tissue growth, as well as anti-cancer, anti-oxidant, wound-healing, anti-inflammation, anti-pain, anti-anxiety and skin regeneration actions.
  • A second form of data is in vitro cell culture and organ culture results. Culture results give evidence about the effect of GHK on cellular production of collagen and other structural proteins, the effect on stem cell function, the recovery of cellular function after anticancer radiation or ultraviolet radiation, and sensitivity of cells to oxidative molecules.
  • A third source of data is in Human Gene expression. Data analysis found that GHK induces a 50% or greater (plus or minus) change of expression in 31.2% of human genes, affecting genes linked to multiple biochemical pathways in many organs and tissue, including the nervous system.
Many studies highlight gene expression effects of various molecules. Given today’s advances in computer modeling, it is not that difficult to find substances which affect gene expression in one way or another. However, in most cases, computer-based predictions do not have the same supporting evidence of in vivo and in vitro laboratory data as GHK has. Also, in many cases, the safety and cost of the proposed treatments are a big concern. GHK is safe, inexpensive, and can be used in humans today.
The future research should be focused on further making sense of the very extensive gene data, which has to be paralleled with laboratory and clinical studies. GHK has a wealth of biological data in the areas of wound healing, hair and skin regeneration, intestinal tract and bone repair. However, there is a surprising lack of GHK research in the area of neurodegeneration and cognitive health. We hope that our gene data will encourage researchers to take a better look at biological actions and significance of GHK in connection with cognitive health and nervous system function.
The best administration method, in our opinion, would be GHK-Cu incorporated into liposomes, then administered as an enteric capsule for oral use. A dosage of 10 mgs per dose would be a good starting point, at least for safety studies, but inducing positive actions will most likely require a higher dosage.

Acknowledgments

We would like to thank Germaine Emilie Pugh and Cassia McClain for their invaluable work in the manuscript preparation.

Author Contributions

The authors have equally contributed to the writing and revision of this article.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 1. (Top)—Control; (Bottom)—Addition of 200 ng/mL of GHK to culture media (Phase contrast ×250, photo micrographs used with permission of John Wiley and Sons).
Figure 1. (Top)—Control; (Bottom)—Addition of 200 ng/mL of GHK to culture media (Phase contrast ×250, photo micrographs used with permission of John Wiley and Sons).
Brainsci 07 00020 g001
Figure 2. Uptake of glycyl-l-histidyl-l-lysine (GHK) into various mouse tissues. (Reprinted from Pickart, L. [43]).
Figure 2. Uptake of glycyl-l-histidyl-l-lysine (GHK) into various mouse tissues. (Reprinted from Pickart, L. [43]).
Brainsci 07 00020 g002
Figure 3. Proposed cell receptor for GHK-Cu.
Figure 3. Proposed cell receptor for GHK-Cu.
Brainsci 07 00020 g003
Table 1. Similarity of Actions of GHK-Copper and Diisopropylsalicylate-Copper.
Table 1. Similarity of Actions of GHK-Copper and Diisopropylsalicylate-Copper.
ActionGHK-Copper 2+Diisopropylsalicylate-Copper 2+
Wound HealingYesYes
Inhibit Cancer GrowthYesYes
Anti-UlcerYesYes
Anti-PainYesYes
Improve Recovery After RadiationYesYes
Increase Stem Cell ActivityYesYes
Table 2. Distribution of Genes Affected by GHK and Associated with Pain.
Table 2. Distribution of Genes Affected by GHK and Associated with Pain.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%00
100%–199%52
200%–299%10
300%–399%00
400%–499%00
500%+10
Total72
Table 3. GHK and Genes Associated with Pain.
Table 3. GHK and Genes Associated with Pain.
UPGenePercent Change in Gene ExpressionComments
1OPRMI1294Opioid mu 1-High Affinity for enkephalins and beta-endorphins
2OPRL1246Receptor for neuropeptide nociceptin
3CCKAR190Cholecystokinin A receptor, cholecystokinin affects satiety, release of beta-endorphin and dopamine
4CNR1172Cannabinoid receptor, pain-reducing
5SIGMAR1155Non-opioid receptor
6PNOC150Prepronociceptin, complex interactions with pain and anxiety induction
7OXT136Ocytocin, bonding protein—gene also increases human chorionic gonadotropin
DOWNGenePercent Change in Gene ExpressionComments
1AMPA 3/GRIA3−126.00%Glutamate receptor, retrograde endocannaboid signaling, nervous system
2OPRK1−119.00%Reduced cocaine effects
Table 4. Superoxide Dismutase Mimetic Activity of GHK and Analogs.
Table 4. Superoxide Dismutase Mimetic Activity of GHK and Analogs.
MoleculeSuperoxide Dismutase Mimetic Activity
Gly-His-Lys:Cu(2+)100
Lys-His-Gly-Amide:Cu(2+)21
Gly-His-Lys-Ala-Phe-Ala:Cu(2+)561
Ala-His-Lys:Cu(2+)563
Gly-His-Lys-Octyl Ester:Cu(2+)810
Gly-His-Caprolactam:Cu(2+)4500
His-Gly-Lys:Cu(2+)22,300
Table 5. Distribution of Genes Affected by GHK with Antioxidant Activity.
Table 5. Distribution of Genes Affected by GHK with Antioxidant Activity.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%20
100%–199%71
200%–299%20
300%–399%10
400%–499%10
500%+31
Total162
Table 6. GHK and Genes Associate with Antioxidant Activity.
Table 6. GHK and Genes Associate with Antioxidant Activity.
UPGenesPercent Change in Gene ExpressionComments
1TLE1762Inhibits the oxidative/inflammatory gene NF-κB [71].
2SPRR2C721This proline-rich, antioxidant protein protects outer skin cells from oxidative damage from reactive oxygen species (ROS). When the ROS level is low, the protein remains in the outer cell membrane, but when the ROS level is high, the protein clusters around the cell’s DNA to protect it [72,73].
3ITGB4609Up-regulation of ITGB4 promotes wound repair ability and antioxidative ability [74].
4APOM403Binds oxidized phospholipids and increases the antioxidant effect of high-density lipoproteins (HDL) [75].
5PON3319Absence of PON3 (paraoxonase 3) in mice resulted in increased rates of early fetal and neonatal death. Knockdown of PON3 in human cells reduced cell proliferation and total antioxidant capacity [76].
6IL18BP295The protein encoded by this gene is an inhibitor of the pro-inflammatory cytokine IL18. IL18BP abolished IL18 induction of interferon-gamma (IFN gamma), IL8, and activation of NF-κB in vitro. Blocks neutrophil oxidase activity [77].
7HEPH217Inhibits the conversion of Fe(2+) to Fe(3+). HEPH increases iron efflux, lowers cellular iron levels, suppresses reactive oxygen species production, and restores mitochondrial transmembrane potential [78].
8GPSM3193Acts as a direct negative regulator of NLRP3. NLRP3 triggers the maturation of the pro-inflammatory cytokines IL-1β and IL-18 [79].
9FABP1186Reduces intracellular ROS level. Plays a significant role in reduction of oxidative stress [80,81].
10AGTR2171AGTR2 exerts an anti-inflammatory response in macrophages via enhanced IL-10 production and ERK1/2 phosphorylation, which may have protective roles in hypertension and associated tissue injury [82].
11PON1149PON1 (paraoxonase 1) is a potent antioxidant and a major anti-atherosclerotic component of HDL [83].
12MT3142Metallothioneins (MTs) display in vitro free radical scavenging capacity, suggesting that they may specifically neutralize hydroxyl radicals. Metallothioneins and metallothionein-like proteins isolated from mouse brain act as neuroprotective agents by scavenging superoxide radicals [84,85].
13PTGS2120Produces cyclooxygenase-II (COX-II), which has antioxidant activities [86].
14SLC2A9117The p53-SLC2A9 pathway is a novel antioxidant mechanism. During oxidative stress, SLC2A9 undergoes p53-dependent induction, and functions as an antioxidant by suppressing ROS, DNA damage, and cell death [87].
DOWNGenesPercent Change in Gene ExpressionComments
1IL17A−1018This cytokine can stimulate the expression of IL6 and cyclooxygenase-2 (PTGS2/COX-2), as well as enhance the production of nitric oxide (NO). High levels of this cytokine are associated with several chronic inflammatory diseases including rheumatoid arthritis, psoriasis, and multiple sclerosis ([88]).
2TNF−115GHK suppresses this pro-oxidant TNF gene [89].
Table 7. Distribution of Genes Affected by GHK and Associated with DNA Repair.
Table 7. Distribution of Genes Affected by GHK and Associated with DNA Repair.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–100%414
100%–150%21
150%–200%10
200%–250%20
250%–300%10
Total475
Table 8. GHK and Genes Associate with DNA Repair.
Table 8. GHK and Genes Associate with DNA Repair.
UPGene TitlePercent Change in Gene Expression
1poly (ADP-ribose) polymerase family, member 3, PARP3253
2polymerase (DNA directed), mu, POLM225
3MRE11 meiotic recombination 11 homolog A MRE11A212
4RAD50 homolog (S. cerevisiae), RAD50175
5eyes absent homolog 3 (Drosophila), EYA3128
6retinoic acid receptor, alpha, RARA123
DOWNGene TitlePercent Change in Gene Expression
1cholinergic receptor, nicotinic, alpha 4, CHRNA4−105
Table 9. Distribution of Genes Affected by GHK and Associated with the Ubiquitin Proteasome System.
Table 9. Distribution of Genes Affected by GHK and Associated with the Ubiquitin Proteasome System.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%311
100%–199%70
200%–299%00
300%–399%10
400%–499%10
500%+10
Total411
Table 10. GHK and Genes Associated with the Ubiquitin Proteasome System.
Table 10. GHK and Genes Associated with the Ubiquitin Proteasome System.
UPGene TitlePercent Change
1ubiquitin specific peptidase 29, USP291056
2ubiquitin protein ligase E3 component n-recognin 2, UBR2455
3gamma-aminobutyric acid (GABA) B receptor, 1 /// ubiquitin D, GABBR1 /// UBD310
4ubiquitin specific peptidase 34, USP34195
5parkinson protein 2, E3 ubiquitin protein ligase (parkin), PARK2169
6ubiquitin-conjugating enzyme E2I (UBC9 homolog, yeast), UBE2I150
7ubiquitin protein ligase E3 component n-recognin 4, UBR4146
8ubiquitin protein ligase E3B, UBE3B116
9ubiquitin specific peptidase 2, USP2104
10ubiquitin-like modifier activating enzyme 6, UBA6104
Table 11. Distribution of Genes Affected by GHK and Associated with Neurons.
Table 11. Distribution of Genes Affected by GHK and Associated with Neurons.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%23080
100%–199%9980
200%–299%4535
300%–399%1914
400%–499%910
500%+611
Total408230
Table 12. GHK and Genes Associated with Neurons.
Table 12. GHK and Genes Associated with Neurons.
UPGene TitlePercent Change
1opioid receptor, mu 1, OPRM11294
2tumor protein p73, TP73938
3potassium voltage-gated channel, Shal-related subfamily, member 1, KCND1845
4solute carrier family 8 (sodium/calcium exchanger), member 2, SLC8A2737
5contactin associated protein-like 2, CNTNAP2581
6stathmin-like 3, STMN3500
7latrophilin 3, LPHN3494
8angiopoietin 1, ANGPT1487
9synapsin III, SYN3478
10dipeptidyl-peptidase 6, DPP6448
11somatostatin receptor 2, SSTR2442
12G protein-coupled receptor, family C, group 5, member B, GPRC5B431
13sodium channel, voltage-gated, type III, alpha subunit, SCN3A423
14smoothened homolog (Drosophila), SMO415
15tryptophan hydroxylase 1, TPH1409
16caspase 8, apoptosis-related cysteine peptidase, CASP8399
17gamma-aminobutyric acid (GABA) A receptor, alpha 5 /// gamma-aminobutyric acid receptor subunit alpha-5-like, GABRA5 /// LOC100509612392
18transcription factor 7 (T-cell specific, HMG-box), TCF7372
19solute carrier family 17 (sodium-dependent inorganic phosphate cotransporter), member 6, SLC17A6369
20doublecortin-like kinase 1, DCLK1365
21p21 protein (Cdc42/Rac)-activated kinase 1, PAK1363
22neurogenic differentiation 4, NEUROD4362
23zinc finger protein 335, ZNF335358
24wingless-type MMTV integration site family, member 3, WNT3352
25ADAM metallopeptidase domain 8, ADAM8352
26neuropeptide Y, NPY346
27potassium voltage-gated channel, Shaw-related subfamily, member 3, KCNC3332
28EPH receptor B1, EPHB1330
29LIM domain kinase 1, LIMK1322
30myeloid/lymphoid or mixed-lineage leukemia (trithorax homolog, Drosophila), MLL318
31growth associated protein 43, GAP43305
32FBJ murine osteosarcoma viral oncogene homolog, FOS305
33sal-like 1 (Drosophila), SALL1302
34synovial sarcoma, X breakpoint 2 /// synovial sarcoma, X breakpoint 2B, SSX2 /// SSX2B301
35inositol 1,4,5-triphosphate receptor, type 3, ITPR3298
36bone morphogenetic protein receptor, type IB, BMPR1B298
37synuclein, gamma (breast cancer-specific protein 1), SNCG292
38calcium channel, voltage-dependent, P/Q type, alpha 1A subunit, CACNA1A286
39capping protein (actin filament) muscle Z-line, beta, CAPZB285
40plexin C1, PLXNC1282
41nuclear factor I/B, NFIB279
42islet amyloid polypeptide, IAPP276
43nephroblastoma overexpressed gene, NOV275
44hyperpolarization activated cyclic nucleotide-gated potassium channel 4, HCN4269
45calsyntenin 2, CLSTN2268
46potassium intermediate/small conductance calcium-activated channel, subfamily N, member 1, KCNN1266
47sodium channel, voltage-gated, type II, alpha subunit, SCN2A264
48neuroligin 1, NLGN1261
49ELKS/RAB6-interacting/CAST family member 2, ERC2261
50scratch homolog 1, zinc finger protein (Drosophila), SCRT1252
51low density lipoprotein receptor-related protein 1, LRP1249
52hypothetical protein LOC728392 /// NLR family, pyrin domain containing 1, LOC728392 /// NLRP1249
53opiate receptor-like 1, OPRL1246
54myosin, heavy chain 14, non-muscle, MYH14243
55nitric oxide synthase 1 (neuronal), NOS1240
56wingless-type MMTV integration site family, member 2B, WNT2B238
57glutamate receptor, metabotropic 1, GRM1231
58glutamate receptor interacting protein 1, GRIP1230
59myelin associated glycoprotein, MAG229
60chemokine (C-C motif) ligand 3 /// chemokine (C-C motif) ligand 3-like 1 /// chemokine (C-C motif) ligand 3-like 3, CCL3 /// CCL3L1 /// CCL3L3228
61family with sequence similarity 162, member A, FAM162A228
62sphingosine-1-phosphate receptor 5, S1PR5227
63protein tyrosine phosphatase, receptor type, R, PTPRR225
64IKAROS family zinc finger 1 (Ikaros), IKZF1225
65potassium intermediate/small conductance calcium-activated channel, subfamily N, member 3, KCNN3221
66solute carrier family 18 (vesicular monoamine), member 2, SLC18A2219
67glutamate receptor, ionotropic, N-methyl d-aspartate 1, GRIN1216
68v-src sarcoma (Schmidt-Ruppin A-2) viral oncogene homolog (avian), SRC216
69jagged 1, JAG1215
70adenylate cyclase activating polypeptide 1 (pituitary), ADCYAP1215
71ATPase, Ca++ transporting, plasma membrane 2, ATP2B2214
72tripartite motif-containing 2, TRIM2213
73netrin 1, NTN1212
74paired related homeobox 1, PRRX1209
75purinergic receptor P2X, ligand-gated ion channel, 3, P2RX3207
76inhibitor of DNA binding 4, dominant negative helix-loop-helix protein, ID4203
77solute carrier family 5 (choline transporter), member 7, SLC5A7202
78empty spiracles homeobox 1, EMX1202
79muscle, skeletal, receptor tyrosine kinase, MUSK200
80GATA binding protein 2, GATA2193
81cadherin 13, H-cadherin (heart), CDH13192
82Rho/Rac guanine nucleotide exchange factor (GEF) 2, ARHGEF2191
83anaplastic lymphoma receptor tyrosine kinase, ALK191
84cholecystokinin A receptor, CCKAR190
85GLI family zinc finger 2, GLI2183
86cholinergic receptor, nicotinic, beta 1 (muscle), CHRNB1182
87NK2 homeobox 2, NKX2-2181
88purinergic receptor P2X, ligand-gated ion channel, 4, P2RX4180
89gamma-aminobutyric acid (GABA) receptor, rho 2, GABRR2179
90PDZ and LIM domain 5, PDLIM5177
91plasminogen activator, urokinase, PLAU172
92cannabinoid receptor 1 (brain), CNR1172
93chondrolectin, CHODL172
94neurexin 2, NRXN2171
95parkinson protein 2, E3 ubiquitin protein ligase (parkin), PARK2169
96calcium channel, voltage-dependent, L type, alpha 1F subunit, CACNA1F168
97neuregulin 1, NRG1164
98zinc finger protein 536, ZNF536162
99endothelin 3, EDN3161
100paired box 7, PAX7161
101calcium/calmodulin-dependent protein kinase II beta, CAMK2B161
102solute carrier family 30 (zinc transporter), member 3, SLC30A3160
103ciliary neurotrophic factor /// zinc finger protein 91 homolog (mouse) /// ZFP91-CNTF readthrough transcript, CNTF /// ZFP91 /// ZFP91-CNTF159
104calcium channel, voltage-dependent, T type, alpha 1I subunit, CACNA1I156
105membrane associated guanylate kinase, WW and PDZ domain containing 2, MAGI2155
106sigma non-opioid intracellular receptor 1, SIGMAR1155
107leptin, LEP152
108microtubule-associated protein tau, MAPT150
109erythropoietin receptor, EPOR147
110frizzled homolog 8 (Drosophila), FZD8147
111nuclear mitotic apparatus protein 1, NUMA1147
112ninjurin 2, NINJ2144
113probable transcription factor PML-like /// promyelocytic leukemia, LOC652346 /// PML144
114fasciculation and elongation protein zeta 1 (zygin I), FEZ1143
115ribonucleotide reductase M1, RRM1142
116retinoic acid receptor, beta, RARB142
117metallothionein 3, MT3142
118vascular endothelial growth factor A, VEGFA141
119glycoprotein M6A, GPM6A140
120runt-related transcription factor 1, RUNX1136
121cholinergic receptor, nicotinic, delta, CHRND135
122testis specific, 10, TSGA10135
123growth hormone secretagogue receptor, GHSR135
124guanine nucleotide binding protein (G protein), beta polypeptide 3, GNB3134
125glycine receptor, beta, GLRB132
126runt-related transcription factor 1; translocated to, 1 (cyclin D-related), RUNX1T1131
127synaptotagmin V, SYT5131
128bridging integrator 1, BIN1130
129general transcription factor IIi, GTF2I128
130mitogen-activated protein kinase kinase 7, MAP2K7127
131peroxisome proliferator-activated receptor gamma, coactivator 1 alpha, PPARGC1A126
132v-erb-a erythroblastic leukemia viral oncogene homolog 4 (avian), ERBB4125
133retinoic acid receptor, alpha, RARA123
134baculoviral IAP repeat-containing protein 1-like /// NLR family, apoptosis inhibitory protein, LOC100510692 /// NAIP123
135myosin VA (heavy chain 12, myoxin), MYO5A122
136heat shock protein 90kDa alpha (cytosolic), class B member 1, HSP90AB1121
137voltage-dependent anion channel 1, VDAC1120
138prostaglandin-endoperoxide synthase 2 (prostaglandin G/H synthase and cyclooxygenase), PTGS2120
139spectrin, beta, non-erythrocytic 1, SPTBN1120
140tubulin, beta 2A /// tubulin, beta 2B, TUBB2A /// TUBB2B119
141misshapen-like kinase 1, MINK1119
142neural cell adhesion molecule 1, NCAM1119
143kelch-like 1 (Drosophila), KLHL1119
144sperm associated antigen 9, SPAG9118
145gonadotropin-releasing hormone 1 (luteinizing-releasing hormone), GNRH1116
146cholinergic receptor, nicotinic, beta 3, CHRNB3115
147neuralized homolog (Drosophila), NEURL115
148SRY (sex determining region Y)-box 14, SOX14115
149purinergic receptor P2X, ligand-gated ion channel, 1, P2RX1112
150transcription factor 4, TCF4112
151lysozyme, LYZ111
152MYC associated factor X, MAX111
153synaptojanin 1, SYNJ1108
154ret proto-oncogene, RET108
155cadherin 2, type 1, N-cadherin (neuronal), CDH2108
156AXL receptor tyrosine kinase, AXL108
157ataxia telangiectasia mutated, ATM107
158parvalbumin, PVALB107
159glyceraldehyde-3-phosphate dehydrogenase, GAPDH107
160Rap guanine nucleotide exchange factor (GEF) 1, RAPGEF1106
161protein kinase C, gamma, PRKCG106
162neurofibromin 2 (merlin), NF2105
163serrate RNA effector molecule homolog (Arabidopsis), SRRT105
164syntaxin 3, STX3105
165X-box binding protein 1, XBP1104
166potassium large conductance calcium-activated channel, subfamily M, beta member 2, KCNMB2104
167chemokine (C-X3-C motif) receptor 1, CX3CR1104
168aldehyde dehydrogenase 1 family, member A2, ALDH1A2103
169drebrin 1, DBN1103
170UDP glycosyltransferase 8, UGT8103
171achaete-scute complex homolog 1 (Drosophila), ASCL1103
172POU class 4 homeobox 3, POU4F3102
173neurofibromin 1, NF1102
174steroidogenic acute regulatory protein, STAR101
175histamine receptor H3, HRH3101
176nuclear receptor subfamily 2, group F, member 6, NR2F6100
177transforming growth factor, beta 1, TGFB1100
178homeobox D3, HOXD3100
DOWNGene TitlePercent Change
815-hydroxytryptamine (serotonin) receptor 3A, HTR3A−100
82neuroligin 3, NLGN3−101
83aquaporin 1 (Colton blood group), AQP1−101
84SH3 and multiple ankyrin repeat domains 2, SHANK2−102
85neurochondrin, NCDN−102
86astrotactin 1, ASTN1−102
87mitogen-activated protein kinase 8 interacting protein 2, MAPK8IP2−103
88limbic system-associated membrane protein, LSAMP−103
89calcium binding protein 1, CABP1−106
90integrin, beta 1 (fibronectin receptor, beta polypeptide, antigen CD29 includes MDF2, MSK12), ITGB1−107
91discs, large (Drosophila) homolog-associated protein 2, DLGAP2−108
92doublecortin, DCX−108
93colony stimulating factor 3 (granulocyte), CSF3−108
94advanced glycosylation end product-specific receptor, AGER−108
95corticotropin releasing hormone receptor 1, CRHR1−109
96neuropeptides B/W receptor 2, NPBWR2−109
97even-skipped homeobox 1, EVX1−110
98retinoid X receptor, gamma, RXRG−110
99cytoplasmic polyadenylation element binding protein 3, CPEB3−112
100alpha tubulin acetyltransferase 1, ATAT1−113
101paralemmin, PALM−115
102tumor necrosis factor, TNF−115
103fatty acid binding protein 7, brain, FABP7−118
104olfactory marker protein, OMP−118
105Amphiregulin, AREG−118
106opioid receptor, kappa 1, OPRK1−119
107calbindin 2, CALB2−119
108phosphodiesterase 10A, PDE10A−121
109early growth response 1, EGR1−121
110cell cycle exit and neuronal differentiation 1, CEND1−123
1115-hydroxytryptamine (serotonin) receptor 3B, HTR3B−123
112synaptosomal-associated protein, 23kDa, SNAP23−123
113sodium channel, voltage-gated, type XI, alpha subunit, SCN11A−124
114growth arrest-specific 7, GAS7−124
115contactin 1, CNTN1−125
116neuroligin 4, X-linked, NLGN4X−128
117gamma-aminobutyric acid (GABA) A receptor, alpha 1, GABRA1−130
118leucine zipper, putative tumor suppressor 1, LZTS1−130
119mesenchyme homeobox 2, MEOX2−131
120TYRO3 protein tyrosine kinase, TYRO3−131
121synaptophysin, SYP−132
122coiled-coil domain containing 64, CCDC64−132
123leucine-rich, glioma inactivated 1, LGI1−132
124nerve growth factor receptor, NGFR−132
125cholinergic receptor, nicotinic, beta 4, CHRNB4−135
1265-hydroxytryptamine (serotonin) receptor 2A, HTR2A−135
127myocyte enhancer factor 2C, MEF2C−138
128cholinergic receptor, nicotinic, alpha 4, CHRNA4−139
129prodynorphin, PDYN−142
130discs, large homolog 2 (Drosophila), DLG2−142
131neurexin 1, NRXN1−144
132secretin, SCT−148
133serpin peptidase inhibitor, clade F (alpha-2 antiplasmin, pigment epithelium derived factor), member 1, SERPINF1−148
134tachykinin receptor 3, TACR3−150
135Ras homolog enriched in brain, RHEB−150
136PARK2 co-regulated, PACRG−153
137glutamate receptor, ionotropic, kainate 5, GRIK5−159
138bone morphogenetic protein 2, BMP2−159
139choline O-acetyltransferase, CHAT−160
140sodium channel, voltage-gated, type I, alpha subunit, SCN1A−162
141TOX high mobility group box family member 3, TOX3−163
142gastric inhibitory polypeptide, GIP−164
143corticotropin releasing hormone receptor 2, CRHR2−165
144kinesin family member 1A, KIF1A−165
145RAB35, member RAS oncogene family, RAB35−166
146protein kinase C, theta, PRKCQ−167
147cell adhesion molecule with homology to L1CAM (close homolog of L1), CHL1−171
148unc-51-like kinase 4 (C. elegans), ULK4−172
149wingless-type MMTV integration site family, member 4, WNT4−175
150thyroid stimulating hormone receptor, TSHR−175
151potassium voltage-gated channel, Shal-related subfamily, member 3, KCND3−175
152contactin 2 (axonal), CNTN2−180
153glutamate receptor, ionotropic, N-methyl D-aspartate 2A, GRIN2A−180
154fibronectin leucine rich transmembrane protein 1, FLRT1−183
155gamma-aminobutyric acid (GABA) A receptor, gamma 3, GABRG3−186
156calcium/calmodulin-dependent protein kinase IG, CAMK1G−187
157interleukin 6 receptor, IL6R−190
158calsyntenin 3, CLSTN3−191
159vesicle-associated membrane protein 1 (synaptobrevin 1), VAMP1−193
160promyelocytic leukemia, PML−196
161ATPase, H+ transporting, lysosomal accessory protein 2, ATP6AP2−209
162mitogen-activated protein kinase 8 interacting protein 3, MAPK8IP3−209
163estrogen receptor 2 (ER beta), ESR2−216
164cytochrome b-245, beta polypeptide, CYBB−217
165purinergic receptor P2Y, G-protein coupled, 11 /// PPAN-P2RY11 readthrough, P2RY11 /// PPAN-P2RY11−219
166sonic hedgehog, SHH−220
167growth differentiation factor 11, GDF11−221
168protein tyrosine phosphatase, receptor type, D, PTPRD−221
169ELK1, member of ETS oncogene family, ELK1−224
170regulating synaptic membrane exocytosis 1, RIMS1−225
171hairy/enhancer-of-split related with YRPW motif-like, HEYL−228
172neurotrophic tyrosine kinase, receptor, type 3, NTRK3−230
173potassium voltage-gated channel, Shab-related subfamily, member 2, KCNB2−233
174regulator of G-protein signaling 6, RGS6−235
175glycine receptor, alpha 3, GLRA3−235
176potassium voltage-gated channel, shaker-related subfamily, beta member 1, KCNAB1−235
177guanine nucleotide binding protein (G protein), alpha transducing activity polypeptide 1, GNAT1−242
178proprotein convertase subtilisin/kexin type 2, PCSK2−242
179nerve growth factor (beta polypeptide), NGF−243
180corticotropin releasing hormone, CRH−243
181laminin, alpha 1, LAMA1−245
182cyclic nucleotide gated channel alpha 3, CNGA3−249
183glutamate receptor, ionotropic, kainate 1, GRIK1−254
184lin-28 homolog A (C. elegans), LIN28A−259
185empty spiracles homeobox 2, EMX2−260
186cyclin-dependent kinase 5, regulatory subunit 1 (p35), CDK5R1−260
187agrin, AGRN−264
188T-box, brain, 1, TBR1−272
189stathmin-like 2, STMN2−274
190microcephalin 1, MCPH1−275
191ELAV (embryonic lethal, abnormal vision, Drosophila)-like 4 (Hu antigen D), ELAVL4−282
192mitogen-activated protein kinase 8 interacting protein 1, MAPK8IP1−289
193calcium channel, voltage-dependent, N type, alpha 1B subunit, CACNA1B−290
194FEZ family zinc finger 2, FEZF2−295
195dopamine receptor D4, DRD4−296
196zinc finger E-box binding homeobox 1, ZEB1−300
197T-cell leukemia homeobox 1, TLX1−311
198sterile alpha motif domain containing 4A, SAMD4A−315
199opioid binding protein/cell adhesion molecule-like, OPCML−333
200fibroblast growth factor receptor 2, FGFR2−337
201SRY (sex determining region Y)-box 1, SOX1−337
202neurogenin 1, NEUROG1−345
203PTK2B protein tyrosine kinase 2 beta, PTK2B−348
204somatostatin receptor 5, SSTR5−353
205myelin basic protein, MBP−361
206EPH receptor A7, EPHA7−365
207G protein-coupled receptor 173, GPR173−373
208S100 calcium binding protein A5, S100A5−374
209acyl-CoA synthetase long-chain family member 6, ACSL6−384
210family with sequence similarity 107, member A, FAM107A−407
211Kv channel interacting protein 1, KCNIP1−413
212Fas apoptotic inhibitory molecule 2, FAIM2−416
213bradykinin receptor B1, BDKRB1−426
214discs, large homolog 4 (Drosophila), DLG4−452
215adenylate cyclase 10 (soluble), ADCY10−460
216cyclin-dependent kinase 5, regulatory subunit 2 (p39), CDK5R2−481
217EPH receptor A3, EPHA3−485
218phosphodiesterase 1A, calmodulin-dependent, PDE1A−485
219chemokine (C-X-C motif) receptor 4, CXCR4−496
220membrane metallo-endopeptidase, MME−540
221paired-like homeodomain 3, PITX3−541
222notch 3, NOTCH3−547
223discs, large (Drosophila) homolog-associated protein 1, DLGAP1−547
224slit homolog 1 (Drosophila), SLIT1−553
225bassoon (presynaptic cytomatrix protein), BSN−563
226cadherin, EGF LAG seven-pass G-type receptor 1 (flamingo homolog, Drosophila), CELSR1−647
227calcium channel, voltage-dependent, beta 4 subunit, CACNB4−672
228necdin homolog (mouse), NDN−729
229endothelin receptor type B, EDNRB−768
230cholinergic receptor, muscarinic 2, CHRM2−1049
Table 13. Distribution of Genes Affected by GHK and Associated with Motor Neurons.
Table 13. Distribution of Genes Affected by GHK and Associated with Motor Neurons.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%95
100%–199%20
200%–299%21
300%–399%00
400%–499%02
500%+01
Total139
Table 14. GHK and Genes Associate with Motor Neurons.
Table 14. GHK and Genes Associate with Motor Neurons.
UPGene TitlePercent Change
1calcium channel, voltage-dependent, P/Q type, alpha 1A subunit, CACNA1A286
2plexin C1, PLXNC1282
3GLI family zinc finger 2, GLI2183
4NK2 homeobox 2, NKX2-2181
DOWNGene TitlePercent Change
1slit homolog 1 (Drosophila), SLIT1−553
2chemokine (C-X-C motif) receptor 4, CXCR4−496
3EPH receptor A3, EPHA3−485
4sonic hedgehog, SHH−220
Table 15. Distribution of Genes Affected by GHK and Associated with Glial Cells.
Table 15. Distribution of Genes Affected by GHK and Associated with Glial Cells.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%114
100%–199%73
200%–299%44
300%–399%21
400%–499%01
500%+02
Total2415
Table 16. GHK and Genes Associated with Glial Cells.
Table 16. GHK and Genes Associated with Glial Cells.
UPGene TitlePercent Change
1neurogenic differentiation 4, NEUROD4362
2growth associated protein 43, GAP43305
3nuclear factor I/B, NFIB279
4caspase 1, apoptosis-related cysteine peptidase (interleukin 1, beta, convertase), CASP1257
5Kruppel-like factor 15, KLF15238
6adenylate cyclase activating polypeptide 1 (pituitary), ADCYAP1215
7neuregulin 1, NRG1164
8versican, VCAN134
9protein kinase C, eta, PRKCH124
10SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 4, SMARCA4107
11chemokine (C-X3-C motif) receptor 1, CX3CR1104
12achaete-scute complex homolog 1 (Drosophila), ASCL1103
13neurofibromin 1, NF1102
DOWNGene TitlePercent Change
1necdin homolog (mouse), NDN−729
2insulin-like growth factor 1 (somatomedin C), IGF1−522
3forkhead box D4 /// forkhead box D4-like 1, FOXD4 /// FOXD4L1−498
4PTK2B protein tyrosine kinase 2 beta, PTK2B−348
5pleiomorphic adenoma gene 1, PLAG1−276
6lin-28 homolog A (C. elegans), LIN28A−259
7sonic hedgehog, SHH−220
8forkhead box E1 (thyroid transcription factor 2), FOXE1−204
9allograft inflammatory factor 1, AIF1−144
10GDNF family receptor alpha 2, GFRA2−141
11chondroitin sulfate proteoglycan 4, CSPG4−113
Table 17. Distribution of Gene Affected by GHK and Associated with Astrocytes.
Table 17. Distribution of Gene Affected by GHK and Associated with Astrocytes.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%83
100%–199%52
200%–299%21
300%–399%00
400%–499%00
500%+00
Total156
Table 18. GHK and Genes Associated with Astrocytes.
Table 18. GHK and Genes Associated with Astrocytes.
UPGene TitlePercent Change
1chemokine (C-C motif) ligand 3 /// chemokine (C-C motif) ligand 3-like 1 /// chemokine (C-C motif) ligand 3-like 3, CCL3 /// CCL3L1 /// CCL3L3228
2inhibitor of DNA binding 4, dominant negative helix-loop-helix protein, ID4203
3NK2 homeobox 2, NKX2-2181
4metallothionein 3, MT3142
5bridging integrator 1, BIN1130
6matrix metallopeptidase 14 (membrane-inserted), MMP14114
7neurofibromin 1, NF1102
DOWNGene TitlePercent Change
1neurotrophic tyrosine kinase, receptor, type 3, NTRK3−230
2contactin 2 (axonal), CNTN2−180
3bone morphogenetic protein 2, BMP2−159
Table 19. Distribution of Genes Affected by GHK and Associated with Schwann Cells.
Table 19. Distribution of Genes Affected by GHK and Associated with Schwann Cells.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%51
100%–199%20
200%–299%00
300%–399%11
400%–499%00
500%+00
Total82
Table 20. GHK and Genes Associated with Schwann Cells.
Table 20. GHK and Genes Associated with Schwann Cells.
UPGene TitlePercent Change
1Mediator complex subunit 12, MED12393
2neurofibromin 2 (merlin), NF2105
3neurofibromin 1, NF1102
DOWNGene TitlePercent Change
1cytochrome P450, family 11, subfamily A, polypeptide 1, CYP11A1−393
Table 21. Distribution of Genes Affected by GHK and Associated with Myelin.
Table 21. Distribution of Genes Affected by GHK and Associated with Myelin.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%245
100%–199%88
200%–299%40
300%–399%03
400%–499%02
500%+00
Total3618
Table 22. GHK and Genes Associated with Myelin.
Table 22. GHK and Genes Associated with Myelin.
UPGene TitlePercent Change
1inositol 1,4,5-triphosphate receptor, type 3, ITPR3298
2sodium channel, voltage-gated, type II, alpha subunit, SCN2A264
3myelin associated glycoprotein, MAG229
4inhibitor of DNA binding 4, dominant negative helix-loop-helix protein, ID4203
5aspartoacylase, ASPA195
6probable transcription factor PML-like /// promyelocytic leukemia, LOC652346 /// PML144
7retinoic acid receptor, beta, RARB142
8retinoic acid receptor, alpha, RARA123
9myosin VA (heavy chain 12, myoxin), MYO5A122
10neurofibromin 1, NF1102
11histamine receptor H3, HRH3101
12transforming growth factor, beta 1, TGFB1100
DOWNGene TitlePercent Change
1chemokine (C-X-C motif) receptor 4, CXCR4−496
2gap junction protein, gamma 2, 47kDa, GJC2−428
3lethal giant larvae homolog 1 (Drosophila), LLGL1−393
4myelin basic protein, MBP−361
5chromosome 11 open reading frame 9, C11orf9−342
6promyelocytic leukemia, PML−196
7myelin protein zero, MPZ−180
8contactin 2 (axonal), CNTN2−180
9toll-like receptor 2, TLR2−169
10laminin, alpha 2, LAMA2−150
11retinoid X receptor, gamma, RXRG−110
12integrin, beta 1 (fibronectin receptor, beta polypeptide, antigen CD29 includes MDF2, MSK12), ITGB1−107
13thyroglobulin, TG−100
Table 23. Distribution of Genes Affected by GHK and Associated with Dendrites.
Table 23. Distribution of Genes Affected by GHK and Associated with Dendrites.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%4714
100%–199%1931
200%–299%1115
300%–399%83
400%–499%03
500%+22
Total8768
Table 24. GHK and Genes Associated with Dendrites.
Table 24. GHK and Genes Associated with Dendrites.
UPGene TitlePercent Change
1potassium voltage-gated channel, Shal-related subfamily, member 1, KCND1845
2contactin associated protein-like 2, CNTNAP2581
3leukocyte specific transcript 1, LST1395
4gamma-aminobutyric acid (GABA) A receptor, alpha 5 /// gamma-aminobutyric acid receptor subunit alpha-5-like, GABRA5 /// LOC100509612392
5chemokine (C-C motif) ligand 19, CCL19378
6doublecortin-like kinase 1, DCLK1365
7p21 protein (Cdc42/Rac)-activated kinase 1, PAK1363
8potassium voltage-gated channel, Shaw-related subfamily, member 3, KCNC3332
9EPH receptor B1, EPHB1330
10gamma-aminobutyric acid (GABA) B receptor, 1 /// ubiquitin D, GABBR1 /// UBD310
11calcium channel, voltage-dependent, P/Q type, alpha 1A subunit, CACNA1A286
12nephroblastoma overexpressed gene, NOV275
13obscurin-like 1, OBSL1263
14neuroligin 1, NLGN1261
15low density lipoprotein receptor-related protein 1, LRP1249
16glutamate receptor, ionotropic, kainate 3, GRIK3246
17RNA binding protein, fox-1 homolog (C. elegans) 2, RBFOX2245
18glutamate receptor, metabotropic 1, GRM1231
19glutamate receptor interacting protein 1, GRIP1230
20glutamate receptor, ionotropic, N-methyl d-aspartate 1, GRIN1216
21MCF.2 cell line derived transforming sequence, MCF2202
22purinergic receptor P2X, ligand-gated ion channel, 4, P2RX4180
23synapsin I, SYN1170
24Abl-interactor 2, ABI2168
25calcium channel, voltage-dependent, L type, alpha 1F subunit, CACNA1F168
26membrane associated guanylate kinase, WW and PDZ domain containing 2, MAGI2155
27ubiquitin-conjugating enzyme E2I (UBC9 homolog, yeast), UBE2I150
28nuclear mitotic apparatus protein 1, NUMA1147
29glutamate receptor, ionotropic, N-methyl d-aspartate 2C, GRIN2C146
30probable transcription factor PML-like /// promyelocytic leukemia, LOC652346 /// PML144
31fasciculation and elongation protein zeta 1 (zygin I), FEZ1143
32glutamate receptor, metabotropic 7, GRM7140
33acetylcholinesterase, ACHE131
34retinoic acid receptor, alpha, RARA123
35misshapen-like kinase 1, MINK1119
36kelch-like 1 (Drosophila), KLHL1119
37neuralized homolog (Drosophila), NEURL115
38protein kinase C, gamma, PRKCG106
39drebrin 1, DBN1103
40neurofibromin 1, NF1102
DOWNGene TitlePercent Change
1bassoon (presynaptic cytomatrix protein), BSN−563
2membrane metallo-endopeptidase, MME−540
3adenylate cyclase 10 (soluble), ADCY10−460
4discs, large homolog 4 (Drosophila), DLG4−452
5Kv channel interacting protein 1, KCNIP1−413
6EPH receptor A7, EPHA7−365
7PTK2B protein tyrosine kinase 2 beta, PTK2B−348
8sterile alpha motif domain containing 4A, SAMD4A−315
9dopamine receptor D4, DRD4−296
10FEZ family zinc finger 2, FEZF2−295
11calcium channel, voltage-dependent, N type, alpha 1B subunit, CACNA1B−290
12mitogen-activated protein kinase 8 interacting protein 1, MAPK8IP1−289
13regulator of G-protein signaling 11, RGS11−266
14cyclin-dependent kinase 5, regulatory subunit 1 (p35), CDK5R1−260
15glutamate receptor, ionotropic, kainate 1, GRIK1−254
16thyroid hormone receptor, alpha (erythroblastic leukemia viral (v-erb-a) oncogene homolog, avian), THRA−253
17cyclic nucleotide gated channel alpha 3, CNGA3−249
18adenylate cyclase 2 (brain), ADCY2−247
19proprotein convertase subtilisin/kexin type 2, PCSK2−242
20Rho guanine nucleotide exchange factor (GEF) 15, ARHGEF15−230
21potassium voltage-gated channel, Shal-related subfamily, member 3, KCND3−224
22protein tyrosine phosphatase, receptor type, D, PTPRD−221
23cytochrome b-245, beta polypeptide, CYBB−217
24GABA(A) receptors associated protein like 3, pseudogene, GABARAPL3−197
25neutrophil cytosolic factor 1C pseudogene, NCF1C−196
26promyelocytic leukemia, PML−196
27C-reactive protein, pentraxin-related, CRP−182
28glutamate receptor, ionotropic, N-methyl d-aspartate 2A, GRIN2A−180
29tubby like protein 1, TULP1−176
30Mitogen-activated protein kinase 8 interacting protein 3, MAPK8IP3−174
31cell adhesion molecule with homology to L1CAM (close homolog of L1), CHL1−171
32choline O-acetyltransferase, CHAT−160
33glutamate receptor, ionotropic, kainate 5, GRIK5−159
34glutamate receptor, ionotropic, kainate 4, GRIK4−155
355-hydroxytryptamine (serotonin) receptor 6, HTR6−150
36tachykinin receptor 3, TACR3−150
375-hydroxytryptamine (serotonin) receptor 5A, HTR5A−149
38protease, serine, 12 (neurotrypsin, motopsin), PRSS12−141
39cholinergic receptor, nicotinic, alpha 4, CHRNA4−139
405-hydroxytryptamine (serotonin) receptor 2A, HTR2A−135
41leucine zipper, putative tumor suppressor 1, LZTS1−130
42neuroligin 4, X-linked, NLGN4X−128
43glutamate receptor, ionotrophic, AMPA 3, GRIA3−126
44glutamate receptor, metabotropic 6, GRM6−120
45paralemmin, PALM−115
46copine VI (neuronal), CPNE6−114
47cytoplasmic polyadenylation element binding protein 3, CPEB3−112
48corticotropin releasing hormone receptor 1, CRHR1−109
49doublecortin, DCX−108
50regulator of G-protein signaling 14, RGS14−108
51apolipoprotein E, APOE−107
52calcium binding protein 1, CABP1−106
53mitogen-activated protein kinase 8 interacting protein 2, MAPK8IP2−103
54neurochondrin, NCDN−102
Table 25. Distribution of Genes Affected by GHK and Associated with Oligodendrocytes.
Table 25. Distribution of Genes Affected by GHK and Associated with Oligodendrocytes.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%64
100%–199%63
200%–299%31
300%–399%01
400%–499%01
500%+10
Total1610
Table 26. GHK and Genes Associated with Oligodendrocytes.
Table 26. GHK and Genes Associated with Oligodendrocytes.
UPGene TitlePercent Change
1tumor protein p73, TP73938
2adenylate cyclase activating polypeptide 1 (pituitary), ADCYAP1215
3gelsolin, GSN214
4inhibitor of DNA binding 4, dominant negative helix-loop-helix protein, ID4203
5aspartoacylase, ASPA195
6NK2 homeobox 2, NKX2-2181
7dopamine receptor D3, DRD3164
8histone deacetylase 11, HDAC11105
9achaete-scute complex homolog 1 (Drosophila), ASCL1103
10neurofibromin 1, NF1102
DOWNGene TitlePercent Change
1chemokine (C-X-C motif) receptor 4, CXCR4−496
2chromosome 11 open reading frame 9, C11orf9−342
3sonic hedgehog, SHH−220
4zinc finger protein 287, ZNF287−143
5early growth response 1, EGR1−121
6apolipoprotein E, APOE−107
Table 27. Distribution of Genes Affected by GHK and Associated with Sensory Nerve Cells.
Table 27. Distribution of Genes Affected by GHK and Associated with Sensory Nerve Cells.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%4525
100%–199%2436
200%–299%186
300%–399%71
400%–499%13
500%+24
Total9775
Table 28. GHK and Gene Associate with Sensory Nerve Cells.
Table 28. GHK and Gene Associate with Sensory Nerve Cells.
UPGene TitlePercent Change
1opioid receptor, mu 1, OPRM11294
2T-box 1, TBX1553
3adrenergic, beta-1-, receptor, ADRB1477
4gamma-aminobutyric acid (GABA) A receptor, alpha 5 /// gamma-aminobutyric acid receptor subunit alpha-5-like, GABRA5 /// LOC100509612392
5calcium channel, voltage-dependent, L type, alpha 1D subunit, CACNA1D372
6olfactory receptor, family 2, subfamily W, member 1, OR2W1370
7guanine nucleotide binding protein (G protein), alpha activating activity polypeptide, olfactory type, GNAL366
8olfactory receptor, family 2, subfamily B, member 6, OR2B6345
9cyclic nucleotide gated channel beta 1, CNGB1330
10EPH receptor B1, EPHB1330
11inositol 1,4,5-triphosphate receptor, type 3, ITPR3298
12olfactory receptor, family 7, subfamily A, member 17, OR7A17285
13nuclear factor I/B, NFIB279
14islet amyloid polypeptide, IAPP276
15opiate receptor-like 1, OPRL1246
16potassium voltage-gated channel, KQT-like subfamily, member 4, KCNQ4245
17myosin, heavy chain 14, non-muscle, MYH14243
18taste receptor, type 2, member 13, TAS2R13237
19olfactory receptor, family 2, subfamily F, member 2, OR2F2232
20glutamate receptor, metabotropic 1, GRM1231
21chemokine (C-C motif) ligand 3 /// chemokine (C-C motif) ligand 3-like 1 /// chemokine (C-C motif) ligand 3-like 3, CCL3 /// CCL3L1 /// CCL3L3228
22polycystic kidney disease 2-like 1, PKD2L1225
23glutamate receptor, ionotropic, N-methyl d-aspartate 1, GRIN1216
24adenylate cyclase activating polypeptide 1 (pituitary), ADCYAP1215
25ATPase, Ca++ transporting, plasma membrane 2, ATP2B2214
26olfactory receptor, family 7, subfamily C, member 1, OR7C1207
27purinergic receptor P2X, ligand-gated ion channel, 3, P2RX3207
28neuropeptide Y receptor Y1, NPY1R201
29family with sequence similarity 38, member B, FAM38B193
30olfactory receptor, family 1, subfamily A, member 1, OR1A1189
31taste receptor, type 2, member 14, TAS2R14181
32purinergic receptor P2X, ligand-gated ion channel, 4, P2RX4180
33receptor accessory protein 2, REEP2174
34endothelin receptor type A, EDNRA173
35cannabinoid receptor 1 (brain), CNR1172
36melanocortin 1 receptor (alpha melanocyte stimulating hormone receptor), MC1R164
37olfactory receptor, family 12, subfamily D, member 3 /// olfactory receptor, family 5, subfamily V, member 1, OR12D3 /// OR5V1163
38odorant binding protein 2A /// odorant binding protein 2B, OBP2A /// OBP2B162
39prepronociceptin, PNOC150
40phospholipase C, beta 2, PLCB2148
41glutamate receptor, metabotropic 7, GRM7140
42oxytocin, prepropeptide, OXT136
43WD repeat domain 1, WDR1127
44olfactory receptor, family 1, subfamily D, member 4 (gene/pseudogene) /// olfactory receptor, family 1, subfamily D, member 5, OR1D4 /// OR1D5125
45UDP glucuronosyltransferase 2 family, polypeptide A1 /// UDP glucuronosyltransferase 2 family, polypeptide A2, UGT2A1 /// UGT2A2121
46prostaglandin-endoperoxide synthase 2 (prostaglandin G/H synthase and cyclooxygenase), PTGS2120
47taste receptor, type 2, member 4, TAS2R4118
48lysozyme, LYZ111
49protein kinase C, gamma, PRKCG106
50collagen, type XI, alpha 1, COL11A1103
51POU class 4 homeobox 3, POU4F3102
52nuclear receptor subfamily 2, group F, member 6, NR2F6100
DOWNGene TitlePercent Change
1taste receptor, type 2, member 9, TAS2R9−1494
2endothelin receptor type B, EDNRB−768
3necdin homolog (mouse), NDN−729
4membrane metallo-endopeptidase, MME−540
5EPH receptor A3, EPHA3−485
6arachidonate lipoxygenase 3, ALOXE3−461
7bradykinin receptor B1, BDKRB1−426
8gap junction protein, beta 4, 30.3kDa, GJB4−317
9nerve growth factor (beta polypeptide), NGF−243
10guanine nucleotide binding protein (G protein), alpha transducing activity polypeptide 1, GNAT1−242
11olfactory receptor, family 3, subfamily A, member 1, OR3A1−234
12apelin receptor, APLNR−230
13olfactory receptor, family 2, subfamily F, member 1 /// olfactory receptor, family 2, subfamily F, member 2, OR2F1 /// OR2F2−212
14olfactory receptor, family 12, subfamily D, member 3, OR12D3−201
15olfactory receptor, family 6, subfamily A, member 2, OR6A2−199
16cholecystokinin B receptor, CCKBR−198
17carbonic anhydrase VI, CA6−192
18olfactory receptor, family 5, subfamily I, member 1, OR5I1−191
19collagen, type XI, alpha 2, COL11A2−186
20olfactory receptor, family 10, subfamily H, member 3, OR10H3−182
21glutamate receptor, ionotropic, N-methyl D-aspartate 2A, GRIN2A−180
22protein phosphatase, EF-hand calcium binding domain 2, PPEF2−178
23sodium channel, nonvoltage-gated 1 alpha, SCNN1A−175
24trace amine associated receptor 5, TAAR5−168
25gastric inhibitory polypeptide, GIP−164
26olfactory receptor, family 2, subfamily H, member 1, OR2H1−156
27olfactory receptor, family 2, subfamily J, member 2, OR2J2−155
28otoferlin, OTOF−155
29discs, large homolog 2 (Drosophila), DLG2−142
30cholinergic receptor, nicotinic, alpha 4, CHRNA4−139
315-hydroxytryptamine (serotonin) receptor 2A, HTR2A−135
32tectorin alpha, TECTA−126
33sodium channel, voltage-gated, type XI, alpha subunit, SCN11A−124
34olfactory receptor, family 7, subfamily C, member 2, OR7C2−120
35taste receptor, type 2, member 16, TAS2R16−120
36glutamate receptor, metabotropic 6, GRM6−120
37opioid receptor, kappa 1, OPRK1−119
38ATPase, H+ transporting, lysosomal 56/58kDa, V1 subunit B1, ATP6V1B1−118
39olfactory marker protein, OMP−118
40contactin 5, CNTN5−116
41cysteinyl leukotriene receptor 2, CYSLTR2−113
42olfactory receptor, family 2, subfamily H, member 2, OR2H2−110
43rhodopsin, RHO−108
44interleukin 10, IL10−107
45olfactory receptor, family 11, subfamily A, member 1, OR11A1−107
46polymeric immunoglobulin receptor, PIGR−107
47guanine nucleotide binding protein (G protein), gamma 13, GNG13−106
48tubby homolog (mouse), TUB−101
49glutamate receptor, metabotropic 8, GRM8−101
50cystatin S, CST4−101
Table 29. Distribution of Genes Affected by GHK and Associated with Spinal Nerve Cells.
Table 29. Distribution of Genes Affected by GHK and Associated with Spinal Nerve Cells.
Percent Change in Gene ExpressionGenes UPGenes DOWN
50%–99%86
100%–199%93
200%–299%12
300%–399%01
400%–499%10
500%+11
Total2013
Table 30. GHK and Genes Associated with Spinal Nerve Cells.
Table 30. GHK and Genes Associated with Spinal Nerve Cells.
UPGene TitlePercent Change
1tumor protein p73, TP73938
2smoothened homolog (Drosophila), SMO415
3calcium channel, voltage-dependent, P/Q type, alpha 1A subunit, CACNA1A286
4GATA binding protein 2, GATA2193
5GLI family zinc finger 2, GLI2183
6NK2 homeobox 2, NKX2-2181
7dopamine receptor D3, DRD3164
8paired box 7, PAX7161
9slit homolog 3 (Drosophila), SLIT3154
10polycystic kidney disease 1 (autosomal dominant), PKD1137
11achaete-scute complex homolog 1 (Drosophila), ASCL1103
12neurofibromin 1, NF1102
DOWNGene TitlePercent Change
1slit homolog 1 (Drosophila), SLIT1−553
2SRY (sex determining region Y)-box 1, SOX1−337
3growth differentiation factor 11, GDF11−221
4sonic hedgehog, SHH−220
5glutamate receptor, ionotropic, N-methyl d-aspartate 2A, GRIN2A−180
6even-skipped homeobox 1, EVX1−110
7aquaporin 1 (Colton blood group), AQP1−101
Brain Sci. EISSN 2076-3425 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
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