Search Results (126)

Cold stress poses a significant challenge to aquatic organisms, affecting their survival, growth, and metabolic processes. This review explores the molecular mechanisms by which fish, crustaceans, and mollusks respond to cold stress, highlighting the shared and species-specific pathways that facilitate adaptation. Common responses to cold stress include modulation of energy metabolism, regulation of oxidative stress, immune responses, and maintenance of proteostasis. In particular, the activation of the adenosine 5′-monophosphate-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) pathways plays a critical role in regulating energy balance and autophagy in response to low temperatures. Furthermore, we examine the specific adaptive mechanisms employed by different groups of aquatic organisms. Fish utilize pathways such as peroxisome proliferator-activated receptor alpha/peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPAR/PGC-1α) and fatty acid oxidation to optimize energy utilization and improve cold tolerance. Crustaceans rely on crustacean hyperglycemic hormone (CHH) signaling and AMPK pathway activation, while mollusks employ metabolic suppression and glycogen storage to survive cold exposure. Moreover, the regulation of autophagy and apoptosis, mediated by p53 and cyclin-dependent kinase 1 (Cdk1), ensures the survival of healthy cells under prolonged cold stress, with autophagy maintaining energy homeostasis and apoptosis eliminating damaged cells. This review also discusses the role of molecular chaperones like heat shock protein 70 (HSP70) and the ubiquitin-proteasome system (UPS) in protein homeostasis, highlighting their importance to protect cells under cold stress. The combined action of these molecular pathways allows aquatic organisms to cope with and adapt to cold environments, ensuring cellular integrity and enhancing survival. Future research should focus on integrating molecular, physiological, and ecological approaches to better understand cold tolerance mechanisms and improve aquaculture practices under climate change scenarios. Full article

Background: Chronic kidney disease (CKD) associated vascular calcification (VC) is a leading cause of cardiovascular mortality, partially driven by osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs). Chaperone-mediated autophagy (CMA) is a selective lysosomal degradation cellular process. However, the precise role and mechanism of CMA in CKD-associated vascular calcification remain unknown. Methods: We studied calcified arteries from CKD patients and rats fed on a high-phosphate diet using histological and ultrastructural methods. VSMCs’ calcification was induced by a calcification medium containing high phosphate and calcium. CMA activity was measured by a KFERQ reporter and lysosomal staining. The expression of LAMP2a and HSP90AA1 was knocked down by siRNA, overexpressed by plasmid, and activated by QX77.1. Bioinformatic analysis, protein interaction studies, immunofluorescence and co-immunoprecipitation were performed to investigate the potential mechanism of CMA in VC. Results: The expression of LAMP2a was increased in human calcified radial artery tissues (n = 3, p < 0.05) and rats’ calcified aortic tissues (n = 3, p < 0.01), accompanied by lysosomal abnormalities. The activity of CMA was increased during the osteogenic transdifferentiation of VSMCs, as indicated by increased expression of RUNX2 and reduced expression of SM22α (p < 0.05). LAMP2a knockdown attenuated VSMCs’ calcification (p < 0.05), whereas pharmacological activation of CMA aggravated calcification in VSMCs (p < 0.01). Bioinformatic screening identified HSP90AA1 as a candidate involved in CMA in vascular calcification. Elevated HSP90AA1 expression was observed in human calcified radial artery tissues (n = 3, p < 0.01) and rat calcified aortic tissues (n = 3, p < 0.01), which promoted osteogenic transdifferentiation of VSMCs (p < 0.05). HSP90AA1 interacted with LAMP2a and positively regulated its expression (p < 0.01). Conclusions: These findings support an association between CMA activation and CKD vascular calcification. It suggests that HSP90AA1 facilitates vascular calcification in chronic kidney disease involving chaperone-mediated autophagy. Full article

Background: Multiple myeloma (MM) is characterised by clonal expansion of plasma cells (PCs) in the bone marrow (BM). Disease assessment and monitoring typically rely on invasive, single-site procedures, such as BM biopsies (BMBs), which may inadequately capture intra- and extra-medullary spatial heterogeneity. Circulating plasma cells (CPCs), enriched from peripheral blood (PB), may represent a minimally invasive alternative or adjunct for molecular profiling. Objectives: This study aimed to evaluate the feasibility of using CPCs, enriched from PB, for mRNA analysis in plasma cell dyscrasia, including MM. A secondary objective was to assess whether mRNA expression levels of the endoplasmic reticulum (ER) stress sensors X-box-binding protein 1 (uXBP1) and activating transcription factor 6 (ATF6), and the chaperone-mediated autophagy marker Lysosomal-Associated Membrane Protein 2 (LAMP2A) by droplet digital PCR (ddPCR), were associated with resistance to the second-generation proteasome inhibitor (PI) carfilzomib (Cfz). Methods: Multiple myeloma (MM) cell lines (H929 and U266) and their carfilzomib-adapted derivatives were used to establish and validate droplet digital PCR (ddPCR) assays targeting ER stress (uXBP1, ATF6) and autophagy-related (LAMP2A) transcripts. Solid tumour cell lines, including serum-starved HeLa cells, served as biological controls to support assay specificity and sensitivity. Total RNA was extracted and reverse-transcribed to complementary DNA prior to analysis. Transcript levels were normalised to those of β-actin or GAPDH, as appropriate. ddPCR was performed using the BioRad QX200 system, with results reported as the normalised transcript copy number per microlitre of reaction. Matched bone marrow aspirate (BMA) and peripheral blood (PB) samples were collected at a single clinical time point from adults undergoing investigation for plasma cell dyscrasia between January 2021 and December 2023. Samples were obtained as part of standard clinical care and/or during treatment with Bortezomib (Btz) or Cfz. Mononuclear cells were isolated by density gradient centrifugation, and CD138⁺ plasma cells were enriched by fluorescence-activated cell sorting. Enrichment purity was assessed qualitatively by immunofluorescence microscopy using CD138 and CD117 markers. Samples yielding fewer than 1000 CD138⁺ plasma cells were excluded, resulting in 10 evaluable matched patient pairs. Results: Carfilzomib-adapted MM cell lines demonstrated reduced levels of uXBP1, ATF6, and LAMP2A mRNA compared to treatment-naïve cells. In matched BM and PB samples, uXBP1 mRNA levels were consistently lower in circulating PCs than in BM-derived PCs, whereas ATF6 mRNA levels were concordant between compartments. LAMP2A mRNA levels exhibited marked inter-patient heterogeneity. Conclusions: This study demonstrates the feasibility of using CPCs as a minimally invasive source for mRNA-based biomarker assessment and highlights ddPCR as a sensitive platform for quantifying ER stress and chaperone-mediated autophagy related transcripts in CPCs. Cfz adaptation was associated with reduced levels of uXBP1 and LAMP2A mRNA in MM cell lines. Future prospective studies evaluating the clinical utility of ER stress and chaperone-mediated autophagy associated transcripts in CPCs as predictors of resistance to PI are warranted. Full article

Autophagy is increasingly recognized as a context-dependent regulatory process that links cellular quality control with systemic metabolic and neurological homeostasis. However, how distinct autophagy pathways contribute to disease progression, and how they are dynamically modulated by host–microbiota interactions, remain incompletely understood. In this review, we synthesize recent advances in the molecular regulation of macroautophagy, microautophagy, and chaperone-mediated autophagy (CMA), with a particular emphasis on selective autophagy and its disease-specific functions. We examine emerging evidence implicating autophagy as a bidirectional modulator in neurodegenerative and metabolic disorders, highlighting conditions under which autophagy exerts protective versus maladaptive effects. Importantly, we integrate recent findings on the microbiota–gut–brain axis to illustrate how microbial signals reshape autophagic responses and influence disease susceptibility and progression. Finally, we summarize current progress and limitations in autophagy-targeted therapeutic strategies, including nanomedicine-based delivery systems, and propose conceptual frameworks to guide the development of precise, context-aware autophagy interventions. This review provides an updated and integrative perspective that bridges molecular mechanisms, host–microbiota crosstalk, and translational opportunities in autophagy-related diseases. Full article

Autophagy is a critical cellular mechanism that regulates the degradation of misfolded and aggregated proteins and non-functional intracellular organelles. Based on the fundamental qualities of the substrates targeted for degradation and the distinct molecular mechanisms involved, autophagy can be classified into three major types: macroautophagy, microautophagy, and chaperone-mediated autophagy (CMA). Sequestosome 1 (SQSTM1)/p62, which functions as a signaling hub integrating nuclear factor kappa B (NF-κB), the mechanistic target of rapamycin complex 1 (mTORC1), and Kelch-like ECH-associated protein 1 (Keap1)–nuclear factor erythroid 2–related factor 2 (NRF2) pathways, serves as a selective macroautophagy/autophagy receptor that binds ubiquitinated cargo proteins and recruits them to the autophagosome for subsequent degradation in the autolysosome. Furthermore, the phase separation of p62 is an important regulatory process in the autophagy mechanism, but recent studies have demonstrated that impaired or excessive autophagy mediated by p62 is associated with cancer development. This review summarizes the role of autophagy—including its types, mechanisms, and the pathway related to the ubiquitin-dependent selective autophagy receptor p62—in cancer progression. Full article

Sympathetic nervous system (SNS) imbalance is a common pathological basis for cardiovascular diseases, non-alcoholic fatty liver disease, and diabetes. This review focuses on these diseases, analyzing two core mechanisms: excessive sympathetic excitation induced by endoplasmic reticulum stress (ERS) or autophagy dysfunction in key central nuclei (e.g., hypothalamus, rostral ventrolateral medulla); and ERS/autophagy abnormalities in peripheral target organs caused by chronic SNS overactivation. Existing studies confirm that chronic SNS overactivation promotes peripheral metabolic overload via sustained catecholamine release, inducing persistent ERS and disrupting the protective unfolded protein response (UPR)–autophagy network, ultimately leading to cell apoptosis, inflammation, and fibrosis. Notably, central ERS or autophagy dysfunction further perturbs autonomic homeostasis, exacerbating sympathetic overexcitation. This review systematically elaborates on SNS overactivation as a critical bridge mediating UPR–autophagy network dysregulation in central and peripheral tissues, and explores therapeutic prospects of targeting key nodes (e.g., chemical chaperones, specific UPR modulators, nanomedicine), providing a theoretical basis for basic research and clinical translation. Full article

Background: Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver disorder associated with impaired lipid metabolism and oxidative stress. As a natural antioxidant and dithiol compound, α-lipoic acid (ALA) may play a beneficial role in modulating hepatic metabolism. This study investigates the potential mechanisms through which ALA may alleviate NAFLD. Methods: To construct an NAFLD model, NCTC 1469 cells were exposed to oleic acid and palmitic acid (OA/PA) and glucose for 24 h. RT-qPCR, Western blotting, and siRNA analyses were used to examine the effects and mechanisms of ALA. In vivo, C57BL/6J mice were fed a high-fat diet for 11 weeks and treated with ALA (200 mg/kg/day, intragastrical) for 4 weeks to evaluate its impact on NAFLD. Results: In NCTC 1469 cells exposed to OA/PA and glucose, ALA markedly reduced lipid accumulation by activating TFEB, which in turn promoted fatty acid β-oxidation and chaperone-mediated autophagy (CMA). Furthermore, ALA activated NRF2-dependent CMA and mitigated oxidative stress. Inhibition of AMPK or silencing of TFEB/NRF2 abolished these effects, indicating the key role of the AMPK–TFEB/NRF2 axis. In HFD-fed mice, ALA alleviated hepatic steatosis, serum lipid abnormalities, and liver injury, consistent with its activation of CMA and β-oxidation and reduction in oxidative stress via this pathway. Conclusions: ALA synchronously activates CMA, β-oxidation, and antioxidant responses via a unified AMPK pathway to reduce lipid accumulation and oxidative stress, providing a mechanistically integrated therapeutic strategy for NAFLD. Full article

Chaperone-mediated autophagy (CMA) is a selective lysosomal degradation pathway that relies on the molecular chaperone heat shock cognate 70 kDa protein (HSC70) and the lysosomal receptor LAMP-2A. By recognizing substrate proteins containing KFERQ-like pentapeptide motif, CMA plays a central role in multiple infectious contexts. In host defense and cellular homeostasis, CMA contributes to organelle quality control by selectively degrading damaged or misfolded proteins, including stress- or organelle-associated substrates, thereby limiting pathogen replication while mitigating infection-induced stress and preserving cellular function. Although its detailed mechanisms remain incompletely defined, CMA is thought to involve coordinated steps in which molecular chaperones recognize specific target sequences, recruit autophagy-related components, and deliver substrates for lysosomal translocation and degradation. Recent studies have revealed substantial progress in understanding CMA during viral, bacterial, and fungal infections, identifying key regulatory nodes and signaling pathways. These advances underscore the therapeutic potential of CMA-targeted strategies, such as stabilizing LAMP-2A or enhancing HSC70-mediated substrate recognition. However, the spatiotemporal specificity of CMA’s pro- or antiviral effects remains a major challenge for clinical translation. This review summarizes current progress in this emerging field and highlights unresolved questions, particularly whether tissue- or cell-type-specific regulation of CMA occurs during infection and how precise modulation of CMA activity might achieve optimal anti-infective outcomes. Full article

Crohn’s disease (CD) and colorectal cancer (CRC) are clinically distinct but pathogenetically related conditions in which significant abnormalities in autophagy are observed. The aim of the study was to evaluate the expression of three key autophagy-related genes, i.e., BECN1 (macroautophagy), PINK1 (mitophagy), and LAMP2 (chaperone-mediated autophagy) in tissue samples from patients with CD and CRC. The study material included samples from 48 patients with CD (n = 96 biopsy samples) and 87 patients with CRC (n = 87 tumors; n = 87 normal paired controls). Transcriptomic analyses were performed using Affymetrix HG-U133A microarrays. They were confirmed by RT-qPCR. The Kruskal–Wallis test with Dunn’s post hoc analysis (α = 0.05) and Spearman’s correlation coefficients were used for statistical evaluation. Expression of BECN1 and LAMP2 was significantly decreased in both CD and CRC compared to the controls (p = 0.009; p = 0.023, respectively). However, PINK1 showed significantly higher expression levels in CD compared to CRC and the controls (p < 0.001). The clinical stages of CRC (I–IV) did not significantly affect the expression of the analyzed genes. The study findings confirm the presence of common abnormalities in autophagy in CD and CRC, with decreased macroautophagy and chaperone-mediated autophagy, with the compensatory activation of mitophagy. BECN1, PINK1, and LAMP2 expressions may have a diagnostic and therapeutic value in the context of chronic inflammation and colorectal carcinogenesis. Full article

Pridopidine is a highly selective sigma-1 receptor (S1R) agonist in clinical development for Huntington’s disease (HD) and amyotrophic lateral sclerosis (ALS). The S1R is a ubiquitous chaperone protein enriched in the central nervous system and regulates multiple pathways critical for neuronal cell function and survival, including cellular stress responses, mitochondrial function, calcium signaling, protein folding, and autophagy. S1R has a crucial role in the ER mitochondria-associated membrane (MAM), whose dysfunction is implicated in several neurodegenerative diseases. By activating the S1R, pridopidine corrects multiple cellular pathways necessary to the cell’s ability to respond to stress, which are disrupted in neurodegenerative diseases. Pridopidine restores MAM integrity; rescues Ca²⁺ homeostasis and autophagy; mitigates ER stress, mitochondrial dysfunction, and oxidative damage; and enhances brain-derived neurotrophic factor (BDNF) axonal transport and secretion, synaptic plasticity, and dendritic spine density. Pridopidine demonstrates neuroprotective effects in in vivo models of neurodegenerative diseases (NDDs). Importantly, pridopidine demonstrates the biphasic dose response characteristic of S1R agonists. In clinical trials in HD and ALS, pridopidine has shown benefits across multiple endpoints. Pridopidine’s mechanism of action, modulating core cellular survival pathways, positions it as a promising candidate for disease modification for different nervous system disorders. Its broad therapeutic potential includes neurodevelopmental disorders, and rare diseases including Wolfram syndrome, Rett syndrome, and Vanishing White Matter Disease. Here, we review the experimental data demonstrating pridopidine’s S1R-mediated neuroprotective effects. These findings underscore the therapeutic relevance of S1R activation and support further investigation of pridopidine for the treatment of different neurodegenerative diseases including ALS and HD. Full article

Background/Objectives: Parkinson’s disease (PD) and Dementia with Lewy Bodies (DLB) are neurodegenerative disorders characterized by the accumulation of misfolded alpha-synuclein protein in the brain. Mutations in the glucocerebrosidase 1 (GBA1) gene have been identified as a significant genetic risk factor for both PD and DLB. GBA1 encodes for the lysosomal enzyme glucocerebrosidase, which is responsible for the breakdown of glucosylceramide (GC). Deficiencies in glucocerebrosidase activity lead to the accumulation of glucosylceramide within lysosomes, contributing to lysosomal dysfunction and impaired protein degradation. The aim of this narrative review is to update the underlying mechanisms by which GBA1 mutations contribute to the pathogenesis of PD and DLB. Methods: A comprehensive literature search was conducted across four major electronic databases (PubMed, Web of Science (Core Collection), Scopus, and Embase) from inception to 8 November 2025. The initial search identified approximately 1650 articles in total, with the number of hits from each database being as follows: PubMed (~450), Web of Science (~380), Scopus (~520), and Embase (~300). Results: The mechanism by which mutations in the GBA1 gene contribute to PD involves both loss-of- function and gain-of-function pathways, which are not mutually exclusive. Typically, GBA1 mutations lead to a loss of function by reducing the activity of the GCase enzyme, impairing the autophagy- lysosomal pathway and leading to α-synuclein accumulation. However, some mutant forms (GBA1L444P) of the GCase enzyme can also acquire a toxic gain of function, contributing to α-synuclein aggregation through mechanisms like endoplasmic reticulum stress and misfolding. While Venglustat effectively reduced GC levels, a key marker associated with GBA1-PD, the lack of clinical improvement led to the discontinuation of its development for this indication. Conclusions: GBA1-mediated lysosomal and lipid dysregulation represents a key pathogenic axis in PD and DLB. Understanding these mechanisms provides crucial insight into disease progression and highlights emerging therapeutic strategies—such as pharmacological chaperones, substrate reduction therapies, and gene-targeted approaches—aimed at restoring GCase function and lysosomal homeostasis to slow or prevent neurodegeneration. Full article

Parkinson’s disease (PD) is one of the most common neurodegenerative disorders among the elderly. The exact etiology of sporadic PD is still unknown; however, there is general consensus that the accumulation and aggregation of α-synuclein (α-syn) are among the prominent pathological features. The precise function of α-syn in the healthy human brain is not agreed upon, although it has been reported to play a role in vesicular trafficking and neurotransmitter release. Dutch Juvenile-1 (DJ-1) is a multifunctional protein involved in regulating an array of mechanisms, including oxidative stress, ferroptosis, mitochondrial and dopamine homeostasis. Loss-of-function of DJ-1 was reported to cause familial PD, and oxidative inactivation of DJ-1 has been observed in sporadic cases, suggesting that both genetic and post-translational events converge on common disease pathways. This review proposes that loss of DJ-1 function may elevate intracellular α-syn levels, leading to their aggregation and consequent neurotoxicity. Reports suggest that DJ-1 can inhibit α-syn aggregation, facilitate α-syn clearance via chaperone-mediated autophagy, and act as a deglycase or glyoxalase to neutralize glycated α-syn species. Clinical studies have also reported altered DJ-1 oxidation states in PD patient samples, supporting its potential as a biomarker. By bridging familial and sporadic PD mechanisms, DJ-1 emerges as a compelling therapeutic target with the potential to mitigate α-syn–mediated neurodegeneration across both forms. However, further research is required to fully establish its clinical relevance and translational potential. Full article

RNA-seq analysis of the highly differentiated human retinal pigment epithelial (RPE) cell-line ARPE-19, cultured on transwells for ≥4 months, yielded 44,909 genes showing 83.35% alignment with the human reference genome. These included mRNA transcripts of RPE-specific genes and those involved in retinopathies. Monolayers were fed photoreceptor outer segments (POS), designed to be synchronously internalised, mimicking homeostatic RPE activity. Cells were subsequently fixed at 4, 6, 24 and 48 h when POS were previously shown to maximally co-localise with Rab5, Rab7, LAMP/lysosomes and LC3b/autophagic compartments. A comprehensive analysis of differentially expressed genes involved in proteolysis revealed a pattern of gene orchestration consistent with POS breakdown in the autophagy-lysosomal pathway. At 4 h, these included elevated upstream signalling events promoting early stages of cargo transport and endosome maturation compared to RPE without POS exposure. This transcriptional landscape altered from 6 h, transitioning to promoting cargo degradation in autolysosomes by 24–48 h. Longitudinal scrutiny of mRNA transcripts revealed nuanced differences even within linked gene networks. POS exposure also initiated transcriptional upregulation in ubiquitin proteasome and chaperone-mediated systems within 4–6 h, providing evidence of cross-talk with other proteolytic processes. These findings show detailed evidence of transcriptome-level responses to cargo trafficking and processing in RPE cells. Full article

Targeted degradation technologies, primarily referring to targeted protein degradation, have emerged as promising drug discovery strategies. In contrast to traditional “occupancy-driven” inhibition approaches, these technologies ingeniously leverage the cell’s endogenous degradation mechanisms to achieve specific elimination of disease-causing targets. Autophagy, a highly conserved cellular clearance pathway, possesses broad substrate recognition capabilities, enabling degradation of not only individual proteins but also protein aggregates, damaged organelles, and invading pathogens. Given these characteristics, researchers are actively exploring the application of autophagy mechanisms in targeted degradation technologies. Herein, we summarize recent advances in autophagy-dependent degradation approaches, including autophagosome tethering compounds (ATTEC), autophagy-targeting chimeras (AUTAC), autophagy-targeting Chimera (AUTOTAC), chaperone-mediated autophagy (CMA)-based methods, nanotechnology-based strategies, and the newly introduced autophagy-induced antibody (AUTAB) technique, highlighting their mechanisms, advantages, and potential applications in treating tumors, neurodegenerative diseases, and other challenging conditions. Full article

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder marked by neuronal loss, cognitive decline, and pathological hallmarks such as amyloid-beta (Aβ) plaques and tau neurofibrillary tangles. Recent evidence highlights autophagy as a pivotal mechanism in cellular homeostasis, mediating the clearance of misfolded proteins and damaged organelles. However, impaired autophagy contributes significantly to AD pathogenesis by disrupting proteostasis, exacerbating neuroinflammation, and promoting synaptic dysfunction. This review aims to scrutinize the intricate relationship between autophagy dysfunction and AD progression, explaining key pathways including macroautophagy, chaperone-mediated autophagy (CMA), and selective autophagy processes such as mitophagy and aggrephagy. This further extends the discussion beyond the central nervous system, evaluating the role of hepatic autophagy in Aβ clearance and systemic metabolic regulation. An understanding of autophagy’s involvement in AD pathology via various mechanisms could give rise to a novel therapeutic strategy targeting autophagic modulation to mitigate disease progression in the future. Full article