Search Results (33)

Protozoa use iron to grow, feed, and cause harm through elaborate mechanisms to obtain it from the host. In addition, expression of virulence genes is affected by iron. In Entamoeba histolytica, the parasite that causes amoebic dysentery and complications in human organs, our group have previously reported the presence of an IRE/IRP-like (Iron Responsive Element/Iron Regulatory Protein) mechanism. Giardia duodenalis is another parasite of medical interest that causes giardiasis, including nutrient malabsorption syndrome and dysbiosis, among other complications, such as anemia in children with giardiasis. Moreover, expression of many putative giardial virulence factors by free-iron levels has been reported. Recently, we have reported stem-loop structures in some mRNAs coding virulence proteins from both parasites. However, much remains to be studied about the role of iron in pathogenesis. In this review, we summarize several aspects of gene expression regulation by iron in these protozoa as well as an iron regulatory mechanism in E. histolytica and discuss the possibility of an iron regulatory IRE/IRP-like mechanism in G. duodenalis. Full article

Alpha-synuclein (α-Syn) protein plays a crucial role in the pathophysiology of Parkinson’s disease (PD). In the 5′-untranslated regions (5′-UTRs) of α-Syn, mRNA has a structured iron-responsive element (IRE) with a stem loop that regulates translation. Iron (labile as Fe²⁺) enhances protein synthesis rates through an IRE mRNA. This investigation aimed to describe the way in which α-Syn IRE interacts with eIF4F and establish a relationship between binding affinity and translation efficiency. The strong binding affinity of α-Syn IRE with eIF4F was demonstrated by a fluorescence-based experiment, with K_a = 8.4 × 10⁶ M⁻¹ at 25 °C. Fe²⁺ further increased (~three-fold) the affinity of α-Syn IRE with eIF4F, outcompeting binding with IRP1. With an increase in temperature (10–30 °C), K_d values increased from 35.8 ± 1.6 nM to 158 ± 8.7 nM for the interaction of α-Syn IRE with eIF4F; however, adding Fe²⁺ demonstrated significantly increased affinity throughout the same temperature range. Thermodynamic analyses demonstrated that α-Syn IRE/eIF4F binding occurred spontaneously, with the presence of van der Waals and hydrogen bonding. Fe²⁺ enhanced the α-Syn IRE/eIF4F complex’s change in enthalpic and binding free energy contributions, which led to a more stable complex formation through the involvement of more hydrogen bonding. Exogenous addition of eIF4F in depleted WG or RR lysates restored α-Syn protein synthesis. Fe²⁺ further boosted α-Syn mRNA translation. IRP1 repressed α-Syn translation, although the addition of Fe²⁺ reversed this effect by boosting activator eIF4F binding and decreasing repressor IRP1 binding. These findings reveal the significance of iron in the α-synuclein mRNA regulatory process and validate its contribution as a strong enhancer of α-Syn mRNA translation. Full article

To investigate the immunomodulatory activity of polysaccharides derived from the rhizome of Imperata cylindrica, polysaccharides (IRPs-H) were extracted using hot water extraction and further purified via DEAE-52 ion-exchange chromatography, yielding three fractions: IRPs-H1, IRPs-H2, and IRPs-H3. The structural features of these fractions were characterized by Fourier-transform infrared spectroscopy (FT-IR), high-performance gel permeation chromatography (HPGPC), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). Their immunological activities were evaluated in vitro. All three fractions were identified as neutral pyranose-type polysaccharides, primarily composed of glucose and xylose, exhibiting good thermal stability and lacking long-chain structures. In vitro assays using RAW264.7 macrophages demonstrated that these polysaccharides promoted cell proliferation (50–800 μg/mL), enhanced phagocytic activity, and induced morphological changes characteristic of macrophage activation, including irregular shapes and pseudopod formation. ELISA and flow cytometry analyses revealed dose-dependent increases in nitric oxide (NO), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and reactive oxygen species (ROS) levels. Notably, the IRPs-H3 fraction stimulated TNF-α and IL-6 production to levels of 438.02 ± 14.14 pg/mL and 30.13 ± 1.27 pg/mL, respectively, which were comparable to those induced by lipopolysaccharide (LPS), the positive control (460.83 ± 16.10 pg/mL and 31.87 ± 1.72 pg/mL, respectively). These results suggest that polysaccharides extracted from the rhizome of Imperata cylindrica possess significant immunostimulatory properties and hold potential for development as functional food ingredients or immune-enhancing agents. Full article

Iron accumulation in the brain is widespread in Alzheimer’s disease (AD), the most common cause of dementia. According to numerous studies, too much iron triggers the development of neurofibrillary tangles (NFTs) and amyloid-β (Aβ) plaques, both of which accelerate the onset of AD. Iron sequestration and storage were disrupted by high iron, and the pattern of interaction between iron regulatory proteins (IRPs) and iron-responsive elements (IREs) was altered. The 5′-untranslated regions (5′-UTRs) of their APP mRNA transcripts have an IRE stem-loop, which is where iron influx enhances the translation of the amyloid precursor protein (APP). Iron regulated APP expression via the release of the repressor interaction of APP mRNA with IRP1 by a pathway similar to the iron control translation of the ferritin mRNA by the IREs in their 5′-UTRs. This leads to an uncontrolled buildup of redox active Fe²⁺, which exacerbates neurotoxic oxidative stress and neuronal death. Fe²⁺ overload upregulates the APP expression and increases the cleavage of APP and the accumulation of Aβ in the brain. The level of APP and Aβ, and protein aggregates, can be downregulated by IRPs, but are upregulated in the presence of iron overload. Therefore, the inhibition of the IRE-modulated expression of APP or Fe²⁺ chelation offers therapeutic significance to AD. In this article, I discuss the structural and functional features of IRE in the 5′-UTR of APP mRNA in relation to the cellular Fe²⁺ level, and the link between iron and AD through the amyloid translational mechanism. Although there are currently no treatments for AD, a progressive neurodegenerative disease, there are a number of promising RNA inhibitor and Fe²⁺ chelating agent therapeutic candidates that have been discovered and are being validated in April 2025 clinical trials. Future studies are expected to further show the therapeutic efficacy of iron-chelating medications, which target the APP 5′-UTR and have the ability to lower APP translation and, consequently, Aβ levels. As a result, these molecules have a great deal of promise for the development of small-molecule RNA inhibitors for the treatment of AD. Full article

The myogenic differentiation of muscle satellite cells (MuSCs) is an important biological process that plays a key role in the regeneration and repair of skeletal muscles. However, the mechanisms regulating myoblast myogenesis require further investigation. In this study, we found that STEAP3 is involved in myogenic differentiation based on the Yunan black pig MuSCs model in vitro using cell transfection and other methods. Furthermore, the expression of myogenic differentiation marker genes MyoG and MyoD and the number of myotubes formed by the differentiation of cells from the si-STEAP3 treated group were significantly decreased but increased in the STEAP3 overexpression group compared to that in the control group. STEAP3 played a role in iron ion metabolism, affecting myogenic differentiation via the uptake of iron ions and enhancing IRP-IRE homeostasis. STEAP3 also activated the PI3K/AKT pathway, thus promoting myoblast differentiation of Yunan black pig MuSCs. The results of this study showed that STEAP3 overexpression increased intracellular iron ion content and activated the homeostatic IRP-IRE system to regulate intracellular iron ion metabolism. Full article

α-Synuclein (α-Syn) is implicated in the pathophysiology of Parkinson’s disease (PD) and plays a significant role in neuronal degeneration. Iron response proteins (IRPs) bind to iron response elements (IREs) found in the 5′-untranslated regions (5′-UTRs) of the messenger RNA that encode the α-Syn gene. This study used multi-spectroscopic approach techniques to investigate the impact of iron on α-Syn IRE RNA binding to IRP1. The formation of a stable complex between α-Syn RNA and IRP1 was suggested by fluorescence quenching results. Fluorescence measurements showed that α-Syn RNA and IRP1 had a strong interaction, with a binding constant (K_a) of 21.0 × 10⁶ M⁻¹ and 1:1 binding stoichiometry. About one binding site per IRP1 molecule was suggested by the α-Syn RNA binding. The K_a for α-Syn RNA•IRP1 with added Fe²⁺ (50 μM) was 6.4 μM⁻¹. When Fe²⁺ was added, the K_a of α-Syn RNA•IRP1 was reduced by 3.3 times. These acquired K_a values were used to further understand the thermodynamic characteristics of α-Syn RNA•IRP1 interactions. The thermodynamic properties clearly suggested that α-Syn RNA binding to IRP1 was an entropy-favored and enthalpy-driven event, with significant negative ΔH and small positive ΔS. For α-Syn RNA•IRP1, the Gibbs free energy (ΔG) was −43.7 ± 2.7 kJ/mol, but in the presence of Fe²⁺, it was −36.3 ± 2.1 kJ/mol. These thermodynamic calculations indicated that hydrogen bonding as well as van der Waals interactions might help to stabilize the complex formation. Additionally, far-UV CD spectra verified α-Syn RNA•IRP1 complex formation, and α-Syn RNA and Fe²⁺ induce secondary structural alteration of IRP1. According to our findings, iron alters the hydrogen bonding in α-Syn RNA•IRP1 complexes and induces a structural change in IRP1. This suggests that iron selectively affects the thermodynamics of these RNA–protein interactions. Full article

The hallmark of Alzheimer’s disease (AD) is the buildup of amyloid-β (Aβ), which is produced when the amyloid precursor protein (APP) misfolds and deposits as neurotoxic plaques in the brain. A functional iron responsive element (IRE) RNA stem loop is encoded by the APP 5′-UTR and may be a target for regulating the production of Alzheimer’s amyloid precursor protein. Since modifying Aβ protein expression can give anti-amyloid efficacy and protective brain iron balance, targeted regulation of amyloid protein synthesis through modulation of 5′-UTR sequence function is a novel method for the prospective therapy of Alzheimer’s disease. Numerous mRNA interference strategies target the 2D RNA structure, even though messenger RNAs like tRNAs and rRNAs can fold into complex, three-dimensional structures, adding even another level of complexity. The IRE family is among the few known 3D mRNA regulatory elements. This review seeks to describe the structural and functional aspects of IREs in transcripts, including that of the amyloid precursor protein, that are relevant to neurodegenerative diseases, including AD. The mRNAs encoding the proteins involved in iron metabolism are controlled by this family of similar base sequences. Like ferritin IRE RNA in their 5′-UTR, iron controls the production of APP in their 5′-UTR. Iron misregulation by iron regulatory proteins (IRPs) can also be investigated and contrasted using measurements of the expression levels of tau production, Aβ, and APP. The development of AD is aided by iron binding to Aβ, which promotes Aβ aggregation. The development of small chemical therapeutics to control IRE-modulated expression of APP is increasingly thought to target messenger RNAs. Thus, IRE-modulated APP expression in AD has important therapeutic implications by targeting mRNA structures. Full article

Background: The effects of anesthetic drugs on myocardial cells have been a subject of research for the last 50 years. The clinical benefits of halogenated agents, particularly sevoflurane, have been demonstrated in cardiac surgery patients. These benefits are due to the action of different enzymes and a variety of molecular pathways mediated by the action of small noncoding RNAs (sRNA) such as microRNAs (miRNAs). However, the modulation potential induced by anesthetic drugs on the miRNA expression and their cardioprotective effects is unknown. Objective: To analyze the variation in the expression of a panel of miRNAs induced by halogenated agents to identify their cardioprotective effects. Aims: Variations in the expression of specific miRNAs induce the potential cardioprotective effects of halogenated agents. Methods: An ischemia/reperfusion (I/R) in vitro model of primary human cardiac myocytes (HCMs) was performed. Four study groups were performed: control group (standard culture conditions), I/R group (without hypnotic drugs exposition), I/R-propofol group (I/R-P), and I/R-sevoflurane group (I/R-S). The secretion of p53 and Akt1 cytokines was quantified in the different cell study groups using an Enzyme-Linked ImmunoSorbent Assay, and the differentially expressed miRNAs were identified carrying out a complete genomic sequencing using the Next Generation Sequencing (NGS). Results: HCMs subjected to the I/R procedure and exposed to sevoflurane showed lower secretion levels of p53 factor and higher levels of Akt-1 cytokine compared to HCMs exposed to propofol (p53: I/R-S: 10.43 ± 0.91 ng/mL; I/R-P: 137.92 ± 7.53 ng/mL; p > 0.05); (Akt1: I/R-S: 0.62 ± 0.12 ng/mL; I/R-P: 0.23 ± 0.05 ng/mL; p > 0.05). The miRNA gene expression analysis (NGS) showed significantly increased expression of the hsa-miR-140-5p and hsa-miR-455-5p, both miRNAs associated with cardiac function; the hsa-miR-98-5p and hsa-miR-193a-5p, both related to apoptosis inhibition; and the hsa-let-7d-5p associated with myocardial protection. This increase was observed in the HCMs group exposed to sevoflurane in comparison to the propofol group. Conclusions: Sevoflurane-induced miRNAs overexpression confers cardioprotection through various mechanisms at the DNA level and the different signaling pathways levels, such as Akt/ERK. Full article

(1) Background: Immune-related adverse events (irAEs) are a series of unique organ-specific inflammatory toxicities observed in patients with hepatocellular carcinoma (HCC) undergoing PD-1 inhibition combination therapy. The specific underlying mechanisms remain unclear. (2) Methods: We recruited 71 patients with HCC undergoing PD-1 inhibition combination therapy. These patients were then divided into two groups based on irAE occurrence: 34 had irAEs and 37 did not. Using Olink proteomics, we analyzed the aberrant inflammation-related proteins (IRPs) in these patient groups. For single-cell RNA sequencing (scRNA-seq) analysis, we collected peripheral blood mononuclear cells (PBMCs) from two representative patients at the pretreatment, irAE occurrence, and resolution stages. (3) Results: Our study revealed distinct plasma protein signatures in HCC patients experiencing irAEs after PD-1 inhibition combination therapy. We clarified the relationship between monocyte activation and irAEs, identified a strongly associated CD14-MC-CCL3 monocyte subset, and explored the role of the IFN-γ signaling pathway in monocyte activation during irAEs. (4) Conclusions: The activation of monocytes induced by the IFN-γ signaling pathway is an important mechanism underlying the occurrence of irAEs in HCC patients receiving PD-1 inhibition combination therapy. Full article

Background and Objectives: Lower limb skeletal muscle ischemia–reperfusion (IR) injury is associated with increased morbidity and mortality, and it is common in several clinical situations such as aortic aneurysms repairment, peripheral arterial surgery, vascular injury repairment, and shock. Although it is generally accepted that oxidative stress mediators have a significant role in IR injury, its precise mechanism is still unknown. Anecdotally, it is sustained not only by structural and functional changes in the organ it affects but also by damage to distant organs. The purpose of this report is to illustrate the effect of proanthocyanidin on IR injury. Materials and Methods: In our study, 18 male Wistar albino rats were used. The subjects were divided into three groups containing six mice each (control, C; ischemia–reperfusion, IR; ischemia–reperfusion and proanthocyanidin; IR-PRO). Intraperitoneal proanthocyanidin was given to the IR and proanthocyanidin groups 30 min before laparotomy, and 1 h ischemia led to these two groups. After one hour, reperfusion started. Muscle atrophy–hypertrophy, muscle degeneration–congestion, fragmentation–hyalinization, muscle oval-central nucleus ratio, leukocyte cell infiltration, catalase enzyme activity, and TBARS were all examined in lower-limb muscle samples after one hour of reperfusion. Results: When skeletal muscle samples were evaluated histopathologically, it was discovered that muscle atrophy–hypertrophy, muscle degeneration–congestion, fragmentation–hyalinization, and leukocyte cell infiltration with oval-central nucleus standardization were significantly higher in the IR group than in the C and IR-P groups. Oval-central nucleus standardization was significantly higher in the IR and IR-PRO groups than in the control group. TBARS levels were significantly higher in the IR group than in the control and IR-PRO groups, while catalase enzyme activity was found to be significantly lower in the IR group than in the control and IR-PRO groups. Conclusions: As a consequence of our research, we discovered that proanthocyanidins administered before IR have a protective impact on skeletal muscle in rats. Further research in this area is required. Full article

Iron regulatory proteins (IRP1 and IRP2) are the master regulators of mammalian iron homeostasis. They bind to the iron-responsive elements (IREs) of the transcripts of iron-related genes to regulate their expression, thereby maintaining cellular iron availability. The primary method to measure the IRE-binding activity of IRPs is the electrophoresis mobility shift assay (EMSA). This method is particularly useful for evaluating IRP1 activity, since IRP1 is a bifunctional enzyme and its protein levels remain similar during conversion between the IRE-binding protein and cytosolic aconitase forms. Here, we exploited a method of using a biotinylated-IRE probe to separate IRE-binding IRPs followed by immunoblotting to analyze the IRE-binding activity. This method allows for the successful measurement of IRP activity in cultured cells and mouse tissues under various iron conditions. By separating IRE-binding IRPs from the rest of the lysates, this method increases the specificity of IRP antibodies and verifies whether a band represents an IRP, thereby revealing some previously unrecognized information about IRPs. With this method, we showed that the S711-phosphorylated IRP1 was found only in the IRE-binding form in PMA-treated Hep3B cells. Second, we found a truncated IRE-binding IRP2 isoform that is generated by proteolytic cleavage on sites in the 73aa insert region of the IRP2 protein. Third, we found that higher levels of SDS, compared to 1–2% SDS in regular loading buffer, could dramatically increase the band intensity of IRPs in immunoblots, especially in HL-60 cells. Fourth, we found that the addition of SDS or LDS to cell lysates activated protein degradation at 37 °C or room temperature, especially in HL-60 cell lysates. As this method is more practical, sensitive, and cost-effective, we believe that its application will enhance future research on iron regulation and metabolism. Full article

Iron is an essential nutrient and necessary for biological functions from DNA replication and repair to transcriptional regulation, mitochondrial respiration, electron transfer, oxygen transport, photosynthesis, enzymatic catalysis, and nitrogen fixation. However, due to iron’s propensity to generate toxic radicals which can cause damage to DNA, proteins, and lipids, multiple processes regulate the uptake and distribution of iron in living systems. Understanding how intracellular iron metabolism is optimized and how iron is utilized to regulate other intracellular processes is important to our overall understanding of a multitude of biological processes. One of the tools that the cell utilizes to regulate a multitude of functions is the ligation of the iron–sulfur (Fe-S) cluster cofactor. Fe-S clusters comprised of iron and inorganic sulfur are ancient components of living matter on earth that are integral for physiological function in all domains of life. FeS clusters that function as biological sensors have been implicated in a diverse group of life from mammals to bacteria, fungi, plants, and archaea. Here, we will explore the ways in which cells and organisms utilize Fe-S clusters to sense changes in their intracellular environment and restore equilibrium. Full article

The present study aimed to investigate the impact of hydrogen (H₂) on chronic intermittent hypoxia (CIH)-induced cardiac hypertrophy in mice by modulating iron metabolism. C57BL/6N mice were randomly allocated into four groups: control (Con), CIH, CIH + H₂, and H₂. The mice were exposed to CIH (21–5% FiO₂, 3 min/cycle, 8 h/d), and received inhalation of a hydrogen–oxygen mixture (2 h/d) for 5 weeks. Cardiac and mitochondrial function, levels of reactive oxygen species (ROS), and iron levels were evaluated. The H9C2 cell line was subjected to intermittent hypoxia (IH) and treated with H₂. Firstly, we found H₂ had a notable impact on cardiac hypertrophy, ameliorated pathological alterations and mitochondrial morphology induced by CIH (p < 0.05). Secondly, H₂ exhibited a suppressive effect on oxidative injury by decreasing levels of inducible nitric oxide synthase (i-NOS) (p < 0.05) and 4-hydroxynonenal (4-HNE) (p < 0.01). Thirdly, H₂ demonstrated a significant reduction in iron levels within myocardial cells through the upregulation of ferroportin 1 (FPN1) proteins (p < 0.01) and the downregulation of transferrin receptor 1 (TfR1), divalent metal transporter 1 with iron-responsive element (DMT1(+ire)), and ferritin light chain (FTL) mRNA or proteins (p < 0.05). Simultaneously, H₂ exhibited the ability to decrease the levels of Fe²⁺ and ROS in H9C2 cells exposed to IH (p < 0.05). Moreover, H₂ mediated the expression of hepcidin, hypoxia-inducible factor-1α (HIF-1α) (p < 0.01), and iron regulatory proteins (IRPs), which might be involved in the regulation of iron-related transporter proteins. These results suggested that H₂ may be beneficial in preventing cardiac hypertrophy, a condition associated with reduced iron toxicity. Full article

Trichomonas vaginalis is one of the most common sexually transmitted parasites in humans. This protozoan has high iron requirements for growth, metabolism, and virulence. However, iron concentrations also differentially modulate T. vaginalis gene expression as in the genes encoding cysteine proteinases TvCP4 and TvCP12. Our goal was to identify the regulatory mechanism mediating the upregulation of tvcp12 under iron-restricted (IR) conditions. Here, we showed by RT-PCR, Western blot, and immunocytochemistry assays that IR conditions increase mRNA stability and amount of TvCP12. RNA electrophoretic mobility shift assay (REMSA), UV cross-linking, and competition assays demonstrated that a non-canonical iron-responsive element (IRE)-like structure at the 3′-untranslated region of the tvcp12 transcript (IRE-tvcp12) specifically binds to human iron regulatory proteins (IRPs) and to atypical RNA-binding cytoplasmic proteins from IR trichomonads, such as HSP70 and α-Actinin 3. These data were confirmed by REMSA supershift and Northwestern blot assays. Thus, our findings show that a positive gene expression regulation under IR conditions occurs at the posttranscriptional level possibly through RNA-protein interactions between atypical RNA-binding proteins and non-canonical IRE-like structures at the 3′-UTR of the transcript by a parallel mechanism to the mammalian IRE/IRP system that can be applied to other iron-regulated genes of T. vaginalis. Full article

Iron is essential for life. Many enzymes require iron for appropriate function. However, dysregulation of intracellular iron homeostasis produces excessive reactive oxygen species (ROS) via the Fenton reaction and causes devastating effects on cells, leading to ferroptosis, an iron-dependent cell death. In order to protect against harmful effects, the intracellular system regulates cellular iron levels through iron regulatory mechanisms, including hepcidin–ferroportin, divalent metal transporter 1 (DMT1)–transferrin, and ferritin–nuclear receptor coactivator 4 (NCOA4). During iron deficiency, DMT1–transferrin and ferritin–NCOA4 systems increase intracellular iron levels via endosomes and ferritinophagy, respectively. In contrast, repleting extracellular iron promotes cellular iron absorption through the hepcidin–ferroportin axis. These processes are regulated by the iron-regulatory protein (IRP)/iron-responsive element (IRE) system and nuclear factor erythroid 2-related factor 2 (Nrf2). Meanwhile, excessive ROS also promotes neuroinflammation by activating the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). NF-κB forms inflammasomes, inhibits silent information regulator 2-related enzyme 1 (SIRT1), and induces pro-inflammatory cytokines (IL-6, TNF-α, and IL-1β). Furthermore, 4-hydroxy-2,3-trans-nonenal (4-HNE), the end-product of ferroptosis, promotes the inflammatory response by producing amyloid-beta (Aβ) fibrils and neurofibrillary tangles in Alzheimer’s disease, and alpha-synuclein aggregation in Parkinson’s disease. This interplay shows that intracellular iron homeostasis is vital to maintain inflammatory homeostasis. Here, we review the role of iron homeostasis in inflammation based on recent findings. Full article