Search Results (550)

Alzheimer’s disease (AD) is increasingly recognized as a multifactorial disorder driven by a combination of disruptions in proteostasis and organelle communication. The 2020 Lancet commission reported that approximately 10 million people worldwide were affected by AD in the mid-20th century. AD is the most prevalent cause of dementia. By early 2030, the global cost of dementia is projected to rise by USD 2 trillion per year, with up to 85% of that cost attributed to daily patient care. Several factors have been implicated in the progression of neurodegeneration, including increased oxidative stress, the accumulation of misfolded proteins, the formation of amyloid plaques and aggregates, the unfolded protein response (UPR), and mitochondrial–endoplasmic reticulum (ER) calcium homeostasis. However, the exact triggers that initiate these pathological processes remain unclear, in part because clinical symptoms often emerge gradually and subtly, complicating early diagnosis. Among the early hallmarks of neurodegeneration, elevated levels of reactive oxygen species (ROS) and the buildup of misfolded proteins are believed to play pivotal roles in disrupting proteostasis, leading to cognitive deficits and neuronal cell death. The accumulation of amyloid-β (Aβ) plaques and tau neurofibrillary tangles is a characteristic feature of AD. These features contribute to chronic neuroinflammation, which is marked by the release of pro-inflammatory cytokines and chemokines that exacerbate oxidative stress. Given these interconnected mechanisms, targeting stress-related signaling pathways, such as oxidative stress (ROS) generated in the mitochondria and ER, ER stress, UPR, and cytosolic chaperones, represents a promising strategy for therapeutic intervention. This review focuses on the relationship between stress chaperone responses and organelle function, particularly the interaction between mitochondria and the ER, in the development of new therapies for AD and related neurodegenerative disorders. Full article

Chinese hamster ovary (CHO) cells are the most common protein production platform for glycosylated biopharmaceuticals due to their relatively efficient secretion systems, post-translational modification (PTM) machinery, and quality control mechanisms. However, high productivity and titer demands can overburden these processes. In particular, the endoplasmic reticulum (ER) can become overwhelmed with misfolded proteins, triggering the unfolded protein response (UPR) as evidence of ER stress. The UPR increases the expression of multiple genes/proteins, which are beneficial to protein folding and secretion. However, if the stressed ER cannot return to a state of homeostasis, a prolonged UPR results in apoptosis. Because ER stress poses a substantial bottleneck for secreting protein therapeutics, CHO cells are both selected for and engineered to improve high-quality protein production through optimized UPR and ER stress management. This is vital for optimizing industrial CHO cell fermentation. This review begins with an overview of common ER-stress related markers. Next, the optimal UPR profile of high-producing CHO cells is discussed followed by the context-dependency of a UPR profile for any given recombinant CHO cell line. Recent efforts to control and engineer ER stress-related responses in CHO cell lines through the use of various bioprocess operations and activation/inhibition strategies are elucidated. Finally, this review concludes with a discussion on future directions for engineering the CHO cell UPR. Full article

Vesicle-associated membrane protein (VAMP)-associated protein B (VAPB) serves as a tethering factor that interacts with various proteins and recruits these proteins to the ER surface, exerting multiple functions, such as organelle membrane tethering, lipid transfer between organelles, regulation of calcium homeostasis, autophagy, and the unfolded protein response (UPR). Its interaction is often mediated by its MSP (major sperm) domain, which binds with FFAT (two phenylalanines in an acidic tract)-motif-containing proteins. However, pathogenic variations, such as P56S, P56H, and T46I, in the VAPB MSP domain lead to the familial form of amyotrophic lateral sclerosis (ALS8). Still, the underlying pathophysiology of ALS8 due to pathogenic variations in the VAPB MSP domain remains elusive. In this study, we conducted molecular dynamics (MD) simulations to understand the pathogenic-variant-derived changes in the structural dynamics of the VAPB MSP domain. We found that pathogenic variants altered the fluctuations and conformational dynamics of the VAPB protein. Analyzing the organizations of the secondary structure revealed that pathogenic variants changed the composition of secondary structure elements, especially increasing the proportion of α-helix while reducing β-sheet formation, which might affect the organelle tethering and other functions of VAPB, as well as VAPB homodimer and heterodimer formation. Taken together, these findings can be further investigated through in vivo and/or in vitro studies to not only clarify the pathophysiology of ALS8 resulting from VAPB MSP domain pathogenic variants but also develop novel therapeutics for the disease that restore the native structural organizations as well as fluctuations and motions. Full article

The growth of tumor cells is accompanied by an increased rate of endoplasmic reticulum stress (ERS), the accumulation of misfolded proteins, and the activation of a network of adaptive signaling pathways known as the unfolded protein response (UPR). Although the UPR is an adaptive reaction aiming to restore ER proteostasis, prolonged and severe ERS leads to cell death. Taking into account that the components of the ERS/UPR machinery in cancers of different types can be overexpressed or downregulated, both the induction of excessive ERS and suppression of UPR have been proposed as therapeutic strategies to sensitize cells to conventional chemotherapy. This narrative review presents a several examples of using natural and synthetic compounds that can either induce persistent ERS by selectively blocking ER Ca²⁺ pumps (SERCA) to disrupt ER Ca²⁺ homeostasis, or altering the activity of UPR chaperones and sensors (GRP78, PERK, IRE1α, and ATF6) to impair protein degradation signaling. The molecular alterations induced by miscellaneous inhibitors of ERS/UPR effectors are described as well. These agents showed promising therapeutic effects as a part of combination therapy in preclinical experimental settings; however, the number of clinical trials is still limited, while their results are inconsistent. Multiple side effects, high toxicity to normal cells, or poor bioavailability also hampers their clinical application. Since the pharmacological modulation of ERS/UPR is a valuable approach to sensitize cancer cells to standard chemotherapy, the search for more selective agents with better stability and low toxicity, as well as the development of more efficient delivery systems that can increase their therapeutic specificity, are highly required goals for future studies. Full article

Trachinotus ovatus is a euryhaline, warm-water pelagic fish species with strong adaptability, rapid growth, and a high survival rate, making it one of the most important marine aquaculture species in China. In recent years, extensive experience has been accumulated in the cage farming of T. ovatus, but whether it can adapt to deep-sea environments and grow normally remains a current research focus. This study used RNA-Seq sequencing technology to analyze the gene expression changes in the liver of T. ovatus under three conditions: rest (0 cm/s), medium flow velocity (54 cm/s), and high flow velocity (90 cm/s). Through differential expression analysis, Short Time-series Expression Miner (STEM) analysis and protein–protein interaction (PPI) network analysis, a total of 5107 differentially expressed genes (DEGs), three significantly expressed gene profiles (profile6, profile1, and profile5), and 15 hub genes were identified. The results showed that changes in flow speed significantly impacted key biological processes such as energy metabolism, protein homeostasis, and endoplasmic reticulum (ER) stress response. Under moderate and high flow conditions, glycolysis-related genes were upregulated to meet the energy demands of swimming, while the downregulation of the PPARγ-RXRG complex and its downstream genes in the lipid metabolism pathway suggested a limitation in its fatty acid β-oxidation capacity. At the same time, protein synthesis was enhanced, and the unfolded protein response (UPR) was activated to help cope with ER stress. Furthermore, when the flow speed reached 90 cm/s, the expression of UPR- related genes and the anti-apoptotic factor JNK significantly decreased, suggesting that the stress response was nearing its limit and could potentially trigger cell apoptosis. These findings provide new insights into the molecular adaptation mechanisms of T. ovatus to flow speed stress and offer theoretical support for its rational farming in deep-sea cages, suggesting that the water flow speed in farming should not exceed 90 cm/s. Full article

Lysosomal dysfunction and endoplasmic reticulum (ER) stress play essential roles in cancer cell survival, growth, and stress adaptation. Among the various stressors in the tumor microenvironment, oxidative stress (OS) is a central driver that exacerbates both lysosomal and ER dysfunction. In healthy cells, the ER manages protein folding and redox balance, while lysosomes regulate autophagy and degradation. Cancer cells, however, are frequently exposed to elevated levels of reactive oxygen species (ROS), which disrupt protein folding in the ER and damage lysosomal membranes and enzymes, promoting dysfunction. Persistent OS activates the unfolded protein response (UPR) and contributes to lysosomal membrane permeabilization (LMP), leading to pro-survival autophagy or cell death depending on the context and on the modulation of pathways like PERK, IRE1, and ATF6. Cancer cells exploit these pathways by enhancing their tolerance to OS and shifting UPR signaling toward survival. Moreover, lysosomal impairment due to ROS accumulation compromises autophagy, resulting in the buildup of damaged organelles and further amplifying oxidative damage. This vicious cycle of ROS-induced ER stress and lysosomal dysfunction contributes to tumor progression, therapy resistance, and metabolic adaptation. Thus, targeting lysosomal and ER stress responses offers potential as cancer therapy, particularly in increasing oxidative stress and promoting apoptosis. This review explores the interconnected roles of lysosomal dysfunction, ER stress, and OS in cancer, focusing on the mechanisms driving their crosstalk and its implications for tumor progression and therapeutic resistance. Full article

Ethylmalonic encephalopathy (EE) is a serious metabolic disorder that usually appears in early childhood development and the effects are seen primarily in the brain, gastrointestinal tract, and peripheral vessels. EE is caused by pathogenic variants in the gene that encodes the ETHE1 protein, and its main features are high levels of acidic compounds in body fluids and decreased activity of the mitochondrial complex IV, which limits energy production in tissues that require a large supply of energy. ETHE1 is a mitochondrial sulfur dioxygenase that plays the role of hydrogen sulfide (H₂S) detoxification, and, when altered, it leads to the accumulation of this gaseous molecule due to its deficient elimination. In this article, we characterised the pathophysiology of ETHE1 deficiency in cellular models, fibroblasts, and induced neurons, derived from a patient with a homozygous pathogenic variant in ETHE1. Furthermore, we evaluated the effect of the activation of the mitochondrial unfolded protein response (mtUPR) on the mutant phenotype. Our results suggest that mutant fibroblasts have alterations in ETHE1 protein expression levels, associated with elevated levels of H₂S and protein persulfidation, mitochondrial dysfunction, iron/lipofuscin accumulation, and oxidative stress. We also identified a cocktail of compounds consisting of pterostilbene, nicotinamide, riboflavin, thiamine, biotin, lipoic acid, and L-carnitine that improved the cellular and metabolic alterations. The positive effect of the cocktail was dependent on sirtuin 3 activation (SIRT3) and was also confirmed in induced neurons obtained by direct reprogramming. In conclusion, personalised precision medicine in EE using patient-derived cellular models can be an interesting approach for the screening and evaluation of potential therapies. In addition, the activation of the SIRT3 axe of mtUPR is a promising therapeutic strategy for rescuing ETHE1 pathogenic variants. Full article

Malignant cells exhibit elevated rates of protein synthesis and secretion to facilitate tumor growth, proliferation, and tumorigenesis. Upon malignant transformation, the endoplasmic reticulum (ER) experiences stress due to the accumulation of unfolded or misfolded proteins in the ER lumen, lack of nutrient availability and overall hostile tumor microenvironment conditions. The demand for regulated protein turnover and proteostasis reinstatement results in the activation of the unfolded protein response (UPR) pathway for cellular adaptation and survival. The UPR machinery utilizes the BiP chaperone and three ER-bound sensors, PERK, IRE1, and ATF6, to substantiate signal transduction and orchestrate gene expression associated with protein folding, degradation and recycling, inflammation, autophagy, and programmed cell death. The pleiotropic function of UPR emerges as a central mediator for tumor progression, especially in multiple myeloma and glioblastoma pathologies. Numerous studies have recently pointed out that communication of the extracellular matrix (ECM) with surrounding tumor cells dictates in part UPR activity and vice versa. In the context of this dynamic interplay, ER stress and UPR mechanisms have been proposed as potential targets to elicit novel and effective therapeutic approaches in clinical trials. Full article

Genistein, a natural isoflavone, exerts anticancer effects on human breast cancer cells by modulating the unfolded protein response (UPR). However, the effect of genistein on UPR in canine mammary gland tumor (CMT) cells remains unknown. The aim of the present study was to investigate the anticancer effects of genistein on CMT-U27 cells, focusing on the regulation of UPR-related pathways and the associated cell death mechanisms. CMT-U27 cells were treated with genistein. Cell viability, apoptosis, and UPR-related protein expression were analyzed using MTS assay, Annexin V-Propidium Iodide (PI) staining, Western blotting, and immunocytochemistry. Genistein treatment significantly reduced cell viability and induced apoptosis, accompanied by an increased Bcl-2-associated X (Bax) ratio of B-cell lymphoma-2 (Bcl-2) and cleaved caspase-8 and caspase-3. On regulation of the UPR system, genistein treatment showed a dual-function by enhancing the protein kinase R-like endoplasmic reticulum kinase (PERK) signaling while suppressing the inositol-requiring enzyme 1 alpha (IRE1α)–X-box-binding protein 1 (XBP1) axis. Furthermore, genistein downregulated estrogen receptor alpha (ERα), which may contribute to the inhibition of IRE1α signaling through a disrupted positive feedback loop. These findings suggested that genistein modulates the UPR to induce apoptosis in CMT-U27 cells, highlighting its potential as a therapeutic or adjuvant agent for CMTs. Full article

In a susceptible individual, persistent, low-level injury to the airway epithelium initiates an exaggerated wound repair response, ultimately leading to idiopathic pulmonary fibrosis (IPF). The mechanisms driving this fibroproliferative response are not fully understood. Here, we review recent spatially resolved transcriptomics and proteomics studies that provide insight into two distinct matricellular microenvironments important in this pathological fibroproliferation. First, in response to alveolar epithelial injury, alveolar differentiation intermediate (ADI) basal cells arising from Secretoglobin (Scgb1a1) progenitors re-populate the injured alveolus remodeling the extracellular matrix (ECM). ADI cells exhibit an interconnected cellular stress response involving the unfolded protein response (UPR), epithelial–mesenchymal transition (EMT) and senescence pathways. These pathways reprogram cellular metabolism to support fibrillogenic ECM remodeling. In turn, the remodeled ECM tonically stimulates EMT in the ADI population, perpetuating the transitional cell state. Second, fibroblastic foci (FF) are a distinct microenvironment composed of activated aberrant “basaloid” cells supporting transition of adjacent mesenchyme into hyaluronan synthase (HAS^hi)-expressing fibroblasts and myofibroblasts. Once formed, FF are the major matrix-producing factories that invade and disrupt the alveolar airspace, forming a mature scar. In both microenvironments, the composition and characteristics of the ECM drive persistence of atypical epithelium sustaining matrix production. New approaches to monitor cellular trans-differentiation and matrix characteristics using positron emission tomography (PET)–magnetic resonance imaging (MRI) and optical imaging are described, which hold the potential to monitor the effects of therapeutic interventions to modify the ECM. Greater understanding of the bidirectional interrelationships between matrix and cellular phenotypes will identify new therapeutics and diagnostics to affect the outcomes of this lethal disease. Full article

Despite affecting millions worldwide, major depressive disorder (MDD) remains a therapeutic challenge, with approximately one-third of patients failing to respond to standard treatments. The need for innovative, molecularly driven therapies has turned attention to ketamine and its enantiomers. While S-ketamine is clinically approved for treatment-resistant depression (TRD), it has various psychoactive side effects and potential for abuse. Hence, it is necessary to identify alternative compounds, such as R-ketamine, and their metabolites (e.g., 2S,6S-hydroxynorketamine and 2R,6R-hydroxynorketamine, collectively referred to as HNKs). Emerging evidence suggests that the pathophysiology of MDD involves two processes regulated by the unfolded protein response (UPR): endoplasmic reticulum (ER) stress and neuroinflammation. As such, they represent promising therapeutic targets. The study provides the first direct comparison of ketamine enantiomers and their metabolites in modulating ER stress and inflammatory signaling in human microglial cells (HMC3), which play key roles in neuroimmune communication. Both S-ketamine and R-ketamine, along with their metabolites, significantly reduced both the expression and protein levels of CHOP and GRP78—two critical UPR components—under tunicamycin-induced ER stress conditions. Additionally, the compounds significantly decreased IL-6 levels and, to a lesser extent, IL-8 levels in lipopolysaccharide (LPS)-stimulated microglia, indicating anti-inflammatory potential. Taken together, these findings highlight a novel glia-targeted mechanism by which ketamine and its metabolites modulate ER stress and neuroinflammation. CHOP and GRP78 appear to be stress-responsive molecular markers within the UPR pathway. These results justify further in vivo validation and support the development of antidepressants with fewer psychoactive effects. Full article

Background: Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder caused by mutations in the SERPINA1 gene, leading to reduced levels or impaired alpha-1 antitrypsin (AAT) function. This condition predominantly affects the lungs and liver. The Z allele, a specific mutation in the SERPINA1 gene, is the most severe form and results in the production of misfolded AAT proteins. The misfolded proteins accumulate in the endoplasmic reticulum (ER) of liver cells, triggering ER stress and activating the unfolded protein response (UPR), a cellular mechanism designed to restore ER homeostasis. Currently, there is limited knowledge regarding specific nutritional recommendations for patients with AATD. The liver is essential for the regulation of zinc homeostasis, with zinc widely recognized for its hepatoprotective properties. However, the effects of AATD on zinc metabolism remain poorly understood. Similarly, the potential benefits of zinc supplementation for individuals with AATD have not been thoroughly investigated. Objective: This study explored the relationship between AATD and zinc metabolism through a combination of in vitro experiments and computational analysis. Results: The expression of the mutant Z variant of ATT (ATZ) in cultured mouse hepatocytes was associated with decreased labile zinc levels in cells and dysregulation of zinc homeostasis genes. Analysis of two data series from the Gene Expression Omnibus (GEO) revealed that mice expressing ATZ (PiZ mice), a murine model of AATD, exhibited significant differences in mRNA levels related to zinc homeostasis and UPR when compared to wildtype mice. Bayesian network analysis of GEO data uncovered novel gene-to-gene interactions among zinc transporters, as well as between zinc homeostasis, UPR, and other associated genes. Conclusions: The findings provide valuable insights into the role of zinc homeostasis genes in UPR processes linked to AATD. Full article

Several studies showed that the incidence of Alzheimer’s disease (AD) is significantly lower in patients with non-muscle invasive bladder cancer (NMIBC) treated with intravesical bacillus Calmette–Guérin (BCG) instillations compared to treatment by alternative methods. Hypothetically, failure to clear misfolded and aggregated proteins (i.e., beta-amyloid) in AD brains and peripheral blood mononuclear cells (PBMCs) implicates BCG in upgrading the unfolded protein response (UPR). To test this hypothesis, pre- versus post-BCG PBMC proteins of the UPR pathway were compared in six NMIBC patients by capillary immunoelectrophoresis on an Abby instrument. PERK, the endoplasmic reticulum (ER) resident kinase, a stress-activated sensor, and its substrate alpha component of the eIF2 translation factor (eIF2a) complex inactivation were considered as potentially proapoptotic via a downstream proapoptotic transcription factor only if persistently high. GAPDH, a glycolytic marker of innate immunocyte training by BCG, and eight other UPR proteins were considered antiapoptotic. Summation of antiapoptotic %change scores per patient showed that the older the age, the lower the antiapoptotic %change. Higher antiapoptotic scores were observed upon a longer time from BCG treatment (with the exception of the patient in her ninth decade of life). Studies with more individuals could substantiate that BCG enhances the antiapoptotic aggregate-clearance effect of the UPR in PBMCs of NMIBC patients, which hypothetically protects brain cells against AD. Full article

Microglial cells, the resident immune cells of the central nervous system (CNS), are essential for maintaining CNS homeostasis. Dysregulation of microglial function is implicated in the pathogenesis of various neurodegenerative diseases. Vasoactive intestinal polypeptide receptors 1 and 2 (VPAC1 and VPAC2) are G-protein-coupled receptors (GPCRs) expressed by microglia, with their primary ligands being pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP). However, the specific roles of VPAC-type receptors in microglial regulation remain poorly understood. In this study, we generated VPAC1^+/− and VPAC2^+/− BV2 microglial cell lines using CRISPR-Cas9 gene editing and conducted a series of biological and molecular assays to elucidate the functions of these receptors. Our findings demonstrated that both mutant cell lines exhibited a polarized phenotype and increased migratory activity. VPAC1^+/− cells showed enhanced survivability and baseline activation of the unfolded protein response (UPR), a protective mechanism triggered by endoplasmic reticulum (ER) stress, whereas this response appeared impaired in VPAC2^+/− cells. In contrast, under lipopolysaccharide (LPS)-induced inflammatory conditions, UPR activation was impaired in VPAC1^+/− cells but restored in VPAC2^+/− cells, resulting in improved survival of VPAC2^+/− cells, whereas VPAC1^+/− cells exhibited reduced resilience. Overall, our findings suggest that VPAC1 and VPAC2 receptors play distinct yet complementary roles in BV2 microglia. VPAC2 is critical for regulating survival, ER stress responses, and polarization under basal conditions, while VPAC1 is essential for adaptive responses to inflammatory stimuli such as LPS. These insights advance our understanding of microglial receptor signaling and may inform therapeutic strategies targeting microglial dysfunction in neurodegenerative diseases. Full article

Darier′s disease (DD) is a rare, autosomal dominant genodermatosis caused by pathogenic variants in the ATP2A2 gene, which encodes the SERCA2 protein, an endoplasmic reticulum ATPase Ca²⁺ transporter. These mutations impair the intracellular calcium homeostasis leading to increased protein misfolding, endoplasmic reticulum (ER) stress response, and the activation of the unfolded protein response (UPR), culminating in keratinocyte apoptosis and anomalies in interfollicular epidermal stratification. Clinically, the disease is characterized by the presence of skin lesions with hyperkeratotic papules and an increased susceptibility to inflammatory reactions, bacterial and viral infections. The histological hallmarks include acantholysis, dyskeratosis, and increased apoptotic keratinocytes, referred to as “corp ronds”. The SERCA2b isoform is expressed not only in the epidermis but it is present ubiquitously in all tissues, suggesting that its alteration may have multi-organ effects. The review aims to provide a broad overview of the pathology, from intracellular dysfunction to the clinical manifestations, elucidating the molecular effects of SERCA2 variants found in DD patients and exploring the potential cell signaling pathways that may contribute to disease progression. Beginning with an examination of the cellular alterations, our work then shifts to exploring their impact in an organ-specific context, providing insights into new potential therapeutic strategies tailored to clinical manifestations. Full article