Endoplasmic Reticulum Stress and Autophagy

Chinese Tuina ameliorates muscle damage by regulating endoplasmic reticulum stress and autophagy in a rat model of skeletal muscle contusion

Chinese Tuina has been used to treat skeletal muscle contusion (SMC) for a long time in China, yet its efficacy and mechanisms remain unclear. Previous studies have shown the vital roles of endoplasmic reticulum (ER) stress and autophagy during injured skeletal muscle recovery, we postulated that Chinese Tuina could expedite the healing of SMC by fine-tuning these processes. In this study, we established a rat model of SMC through weight-dropping and divided the rats into three groups: SMC, SMC+Tuina, and SMC+Tuina+ 3-methyladenine (3-MA) groups, while using untreated normal SD rats as a control. We assessed gait and edema via CatWalk gait analysis and swelling measurements, respectively. Tumor necrosis factor-α (TNF-α) expression was determined by immunohistochemistry (IHC). Morphological and ultrastructural alterations in the damaged muscle tissue were examined using hematoxylin and eosin (HE) staining and transmission electron microscopy (TEM), respectively. Expression of GRP78, LC3B and FAM134b was determined by western blot, and Colocalization of LC3B and FAM134b was examined by immunofluorescence. SMC+Tuina exhibited significantly improved gait and reduced edema. SMC+Tuina showed improvements in morphology and ultrastructure of damaged muscles, as well as decreased expression of TNF-α. Additionally, in SMC+Tuina, expression of GRP78 was downregulated, while expressions of FAM134 and LC3B were upregulated, and colocalization of FAM134 and LC3B was also enhanced. However, autophagy inhibitor 3-MA weakened the aforementioned effects of Chinese Tuina. The obtained results indicated that Chinese Tuina has a positive therapeutic effect in rats with SMC, potentially by promoting autophagy to reduce inflammation and ER stress.

PTPN2 inhibits TG-induced ERS-initiated TNBC apoptosis through the mitochondrial pathway

Triple negative breast cancer (TNBC) is the most malignant subtype of breast cancer that portends a poor prognosis and limited treatment. PTPN2 is a member of the non-receptor protein tyrosine phosphatase family that regulates biological processes by dephosphorylating various signaling molecules. Endoplasmic reticulum stress (ERS) plays a dual regulatory role by promoting both survival and apoptosis. This study aims to elucidate the role of PTPN2 in mediating the pro-apoptotic effects of ERS induced by Thapsigargin (TG), and its influence on the fate of TNBC cells, utilizing both loss-of-function and gain-of-function methodologies. Our findings indicate that PTPN2 modulates TG-induced ERS via the IRE1-XBP1 and PERK/EIF2α/ATF-4 signaling pathways. Furthermore, PTPN2 mitigates the TG-induced reduction in cell proliferation and the concomitant increase in apoptosis. Specifically, PTPN2 appears to inhibit several facets of TG-induced apoptosis, including: (1) Ca2+ elevation in mitochondria, (2) the production of reactive oxygen species (ROS), and (3) Bax/Bcl-2 augmentation which dictates mitochondria-mediated apoptosis. Additionally, we observed that the knockdown of PTPN2 enhances TG-induced autophagy; however, our results suggest that autophagy may serve a protective role against TG-induced apoptosis. Consequently, targeting PTPN2 in conjunction with ERS-inducing agents may represent a promising therapeutic strategy for the treatment of TNBC.

Using endoplasmic reticulum engineering to improve recombinant protein production in CHO cells

Chinese hamster ovary (CHO) cells are commonly used to produce recombinant therapeutic proteins (RTPs). While recent strategies have significantly improved the expression levels of RTPs in CHO cells, insufficient secretion and endoplasmic reticulum (ER) stress remain major bottlenecks. Therefore, further understanding of the mechanism of the ER stress response, optimization of ER-related folding and degradation pathways, and development of more efficient ER engineering tools are expected to overcome this issue and maximize RTP production. In this review, we summarize the role of ER in recombinant proteins production and explore ER engineering strategies to improve the yield of recombinant proteins in CHO cells. We further discuss ER-related strategies that can improve recombinant protein production, future research directions, and prospective applications.

Autophagy in cardiac pathophysiology: Navigating the complex roles and therapeutic potential in cardiac fibrosis

Cardiac fibrosis is a critical factor in cardiac structural remodeling and dysfunction, closely associated with the progression of various cardiovascular diseases (CVDs), including heart failure and myocardial infarction (MI). It is characterized by excessive extracellular matrix (ECM) deposition, which disrupts normal cardiac architecture and impairs cardiac function. Autophagy, a cellular degradation and recycling mechanism, is essential for maintaining cardiac homeostasis, mitigating stress responses, and preventing cellular damage. Recent studies have revealed a significant link between autophagy and cardiac fibrosis, suggesting that autophagic dysregulation can exacerbate fibrosis by promoting fibroblast activation and ECM accumulation. Conversely, proper autophagic activity may attenuate cardiac fibrosis by removing damaged cellular components and regulating fibrotic signaling pathways. This review examines the role of autophagy in cardiac fibrosis. It also emphasizes potential pharmacological strategies that can be used to modulate autophagic processes. These strategies may serve as therapeutic approaches for treating cardiac fibrosis, with the ultimate goal of preventing excessive fibrosis and enhancing cardiac function.

Effects of ER-phagy regulatory genes on the microenvironment of hepatocellular carcinoma: a comprehensive analysis

The relationships between gene regulatory functions and hepatocellular carcinoma (HCC) occurrence and progression are constantly being clarified. However, tumour microenvironment complexity has hindered the classification of the role of genes. A comprehensive analysis to further clarify gene functions could provide additional benefits to HCC patients. In the present study, we combined single-cell sequencing data, Mendelian randomization, and bioinformatics analysis for comprehensive analysis. After the study was completed we found that T cell, dendritic cell (DC), macrophage and monocyte contents and the interaction between immune cells in the HCC microenvironment differed between the microvascular invasion-positive (MVI +) and microvascular invasion-negative (MVI-) groups. Mendelian randomization analysis indicated that causal relationships between several endoplasmic reticulum autophagy (ER-phagy) genes and T cell, DC, macrophage and monocyte contents. Single-cell sequencing data were used to validate the association of these genes with immune cells in the microenvironment. Based on the above results, we preliminarily elucidated the potential role of ER autophagy in the HCC microenvironment. Furthermore, a prognostic model was constructed using these causal association genes, which could accurately predict the prognosis and survival of HCC patients.

GRP78: A new promising candidate in colorectal cancer pathogenesis and therapy

Colorectal cancer (CRC) is a significant global health challenge, marked by varying incidence and mortality rates across different regions. The pathogenesis of CRC involves multiple stages, including initiation, promotion, progression, and metastasis, influenced by genetic and epigenetic factors. The chaperone protein glucose-regulated protein 78 (GRP78), crucial in regulating the unfolded protein response (UPR) during endoplasmic reticulum (ER) stress, plays a pivotal role in CRC pathogenesis. This review discusses the expression profile of GRP78 in CRC, highlighting its potential as a prognostic biomarker and its role in modulating the cellular mechanisms of CRC, including ER response regulation, cell proliferation, migration and invasion. The complex molecular interactions of GRP78 with key signaling pathways such as protein kinase B (Akt), Wnt, protein kinase R-like ER kinase (PERK), vascular endothelial growth factor (VEGF), and Kirsten rat sarcoma virus (Kras) are explored, elucidating its contributions to tumor survival, proliferation, invasion, and chemoresistance. GRP78's involvement in autophagy, glycolysis, and immune regulation further underscores its importance in CRC progression. The review also covers the therapeutic potential of targeting GRP78 in CRC, examining various natural products like curcumin, epigallocatechin gallate (EGCG), and aloe-emodin, which modulate GRP78 expression and activity. Additionally, GRP78's role in mediating resistance to chemotherapeutic agents like 5-fluorouracil (5-FU) and oxaliplatin is discussed, emphasizing its significance in the development of resistance mechanisms in CRC. In conclusion, GRP78 emerges as a central player in CRC pathogenesis and a promising target for therapeutic interventions aimed at improving treatment outcomes and overcoming chemoresistance in colorectal cancer.

Gut microbiota modulate intestinal inflammation by endoplasmic reticulum stress-autophagy-cell death signaling axis

The intestinal tract, a complex organ responsible for nutrient absorption and digestion, relies heavily on a balanced gut microbiome to maintain its integrity. Disruptions to this delicate microbial ecosystem can lead to intestinal inflammation, a hallmark of inflammatory bowel disease (IBD). While the role of the gut microbiome in IBD is increasingly recognized, the underlying mechanisms, particularly those involving endoplasmic reticulum (ER) stress, autophagy, and cell death, remain incompletely understood. ER stress, a cellular response to various stressors, can trigger inflammation and cell death. Autophagy, a cellular degradation process, can either alleviate or exacerbate ER stress-induced inflammation, depending on the specific context. The gut microbiome can influence both ER stress and autophagy pathways, further complicating the interplay between these processes. This review delves into the intricate relationship between ER stress, autophagy, and the gut microbiome in the context of intestinal inflammation. By exploring the molecular mechanisms underlying these interactions, we aim to provide a comprehensive theoretical framework for developing novel therapeutic strategies for IBD. A deeper understanding of the ER stress-autophagy axis, the gut microbial-ER stress axis, and the gut microbial-autophagy axis may pave the way for targeted interventions to restore intestinal health and mitigate the impact of IBD.

Molecular mechanisms of endoplasmic reticulum stress-mediated acute kidney injury in juvenile rats and the protective role of mesencephalic astrocyte-derived neurotrophic factor

OBJECTIVES

This study examined the role of endoplasmic reticulum stress in pediatric acute kidney injury and the therapeutic effect of midbrain astrocyte-derived neurotrophic factor.

METHODS

Two-week-old Sprague-Dawley rats were divided into: Sham, ischemia-reperfusion injury-induced acute kidney injury (AKI), mesencephalic astrocyte-derived neurotrophic factor (MANF)-treated, tauroursodeoxycholic acid (TUDCA)-treated. Analyses were conducted 24 h post-treatment. Serum creatinine, cystatin C, Albumin, MANF levels were measured, cytokine concentrations in serum and renal tissues were determined using a Luminex assay. Histopathology was assessed via light and electron microscopy. Western blotting and RT-qPCR analyzed markers for oxidative stress, apoptosis, endoplasmic reticulum (ER) stress, and autophagy. HK-2 cells underwent hypoxia/reoxygenation (H/R) to simulate AKI and were treated with MANF or TUDCA.

RESULTS

AKI rats had increased serum creatinine, cystatin C, and inflammatory cytokines, along with significant renal damage, and showed loose and swollen ER structures, reduced cell proliferation, and elevated levels of IRE1, PERK, ATF6, CHOP, LC3-II/I, KIM-1, TLR4, JNK, and NF-κB. MANF treatment reduced these biomarkers and protein levels, improved ER structure and cell proliferation, alleviated oxidative stress, apoptosis, ER stress, and inhibited JNK/TLR4/NF-κB signaling. In HK-2 cells, MANF reduced ER stress and inflammation post-H/R exposure.

CONCLUSIONS

MANF treatment alleviates ER stress, oxidative stress, apoptosis, and inflammation in pediatric AKI, improving renal function and morphology.

SIRT5 modulates mitochondria function via mitophagy and antioxidant mechanisms to facilitate oocyte maturation in mice

Mitochondrial homeostasis, closely associated with mitophagy and antioxidant mechanisms, is essential for proper meiotic spindle assembly and chromosome segregation during oocyte maturation. SIRT5, known to modulate mitochondrial function under various conditions, has been shown to impact oocyte quality when inhibited, however, the precise mechanisms linking SIRT5 to mitochondrial homeostasis during meiotic progression remain unclear. In this study, we demonstrate that SIRT5 localizes predominantly at the periphery of the meiotic spindle and is enriched on chromosomes during oocyte maturation. Inhibition of SIRT5 led to significant meiotic defects, including disrupted spindle organization and chromosome misalignment. These defects were associated with increased histone acetylation, which impaired kinetochore-microtubule attachments. Moreover, SIRT5 inhibition resulted in mitochondrial dysfunction, subsequently elevating ROS levels and triggering oxidative stress, which further exacerbated meiotic abnormalities. Mechanistically, SIRT5 inhibition disrupted the balance of Parkin-dependent mitophagy by inducing ULK phosphorylation. Additionally, it activated the PI3K/Akt signaling pathway, which increased NADPH consumption and reduced GSH levels. Collectively, these findings reveal that SIRT5 plays dual roles in maintaining mitochondrial homeostasis during oocyte maturation: (1) by regulating Parkin-dependent mitophagy to prevent excessive mitochondrial clearance, and (2) by preserving the NADPH/GSH antioxidant system to ensure redox balance. These insights provide potential targets for improving oocyte quality and addressing mitochondrial dysfunction-related reproductive disorders in females.

Protective effect of curcumin against endoplasmic reticulum stress and lipid metabolism disorders in AFB1-intoxicated duck liver

Aflatoxin B1 (AFB1) is a stable and highly toxic toxin that causes multi-organ toxicity with sustained ingestion, most typically in the duck liver. Previous research has shown that AFB1 can bring about endoplasmic reticulum stress (ERS) in animals, and ERS is strongly associated with lipid metabolism. However, the relationship between AFB1-induced duck liver toxicity and ERS and lipid metabolism is currently unclear. Great attention has been paid to the prevention and treatment of AFB1 because of its great harm. Curcumin, a natural polyphenol, is notable for its powerful anti-inflammatory and antioxidant properties. Studies have shown curcumin to be protective against afb1-induced avian multi-organ toxicity. However, the effects of curcumin on the liver of ducks exposed to AFB1 are largely unknown. In the present study, we aimed to investigate whether AFB1 exposure induces ERS and lipid metabolism disorders in duck liver, while exploring the positive role of curcumin in it. One-day-old ducks (n = 80) were randomly divided in four groups: control group, AFB1 group (0.1 mg / kg.bw AFB1), Cur group (400 mg/kg curcumin), and AFB1 + Cur group (0.1 mg/kg.bw AFB1 + 400 mg/kg curcumin), and blood and liver were collected for the study after 21 days of continuous administration. Our research has found that AFB1 exposure significantly increases the levels of liver function indicators ALP, AST, and ALT in ducks' serum (P < 0.05). Duck liver undergoes fatty degeneration under the influence of AFB1. Under the effect of curcumin, AFB1-induced structural damage in duck liver was somewhat controlled. Further experimental results showed that AFB1 treatment significantly increased the expression of glucose-regulated protein 78 (P < 0.001), and activated the endoplasmic reticulum stress pathway. Meanwhile, AFB1 inhibited the LKB1-AMPK signaling pathway and disrupted lipid metabolic homeostasis. And curcumin treatment effectively reversed these changes. Overall, our results suggest that curcumin attenuates AFB1-induced hepatotoxicity in ducks by inhibiting ERS and lipid metabolism disorders.

Catechin promotes endoplasmic reticulum stress-mediated gastric cancer cell apoptosis via NOX4-induced reactive oxygen species

Catechin, a polyphenolic compound in various foods and beverages, shows strong anti-cancer effects against gastric cancer (GC) cells. This study explored the effect of catechin on GC cell apoptosis and endoplasmic reticulum (ER) stress. GC cells were treated with different catechin concentrations to assess effects on cell viability, LDH release, invasion, migration, apoptosis, intracellular calcium (Ca2⁺), ER stress markers, and reactive oxygen species (ROS). siRNA knockdown targeted GRP78, PERK, CHOP, and NOX4 to examine their roles in catechin-induced ER stress and apoptosis. Catechin treatment significantly reduced GC cell viability, increased LDH release, and induced apoptosis dose-dependently. Catechins elevated intracellular Ca2⁺ and ER stress markers. Co-treatment with thapsigargin (TG) intensified these effects, implicating ER stress in apoptosis. Knocking down GRP78, PERK, and CHOP mitigated catechin-induced apoptosis and restored viability. Additionally, catechins raised ROS levels, while co-treatment with Diphenyleneiodonium (DPI) or N-acetylcysteine (NAC) lowered ROS, cell damage, and ER stress markers. NOX4 knockdown countered catechin-induced viability loss and upregulated CHOP and cleaved caspase-3. Catechin induces apoptosis in GC cells through ER stress and ROS generation. Key mediators include GRP78, PERK, CHOP, and NOX4, suggesting potential therapeutic targets for enhancing catechin efficacy in GC treatment.

Licochalcone A Ameliorates Cognitive Dysfunction in an Alzheimer's Disease Model by Inhibiting Endoplasmic Reticulum Stress-Mediated Apoptosis

BackgroundEndoplasmic reticulum (ER) stress-induced neurodegeneration has been considered an underlying cause of Alzheimer disease (AD). Here, we investigated the beneficial effects of licochalcone A (Lico A), a valuable flavonoid of the root of the Glycyrrhiza species, against cognitive impairment in AD by regulating ER stress.MethodsThe triple transgenic mouse AD models were used and were administrated 5 or 15 mg/kg Lico A. Cognitive deficits, Aβ deposition, ER stress, and neuronal apoptosis were determined using Morris Water Maze test, probe trial, immunofluorescence staining, western blotting, and TUNEL staining. To investigate the mechanisms of how Lico A exerts anti-AD effects, primary hippocampal neurons were isolated from the AD model mice and treated with Lico A, salubrinal, an eIF2α phosphatase inhibitor, ML385, a Nrf2 inhibitor, or LY294002, an inhibitor of PI3K. Pharmacokinetics and toxicity of Lico A (15 mg/kg) in AD mice were evaluated.ResultsWe found that Lico A improved cognitive impairment, decreased Aβ plaques, inhibited ER stress, and reduced neuronal apoptosis in the hippocampus and cortex of AD mice. Treatment with Lico A in primary hippocampal neurons exerted the same effects as it did in vivo. Additionally, cotreatment with ML385 or LY294002 significantly impeded the effects of Lico A against ER stress. Moreover, 15 mg/kg Lico A had a good bioavailability and low toxicity in AD mice.ConclusionOur results demonstrated that Lico A ameliorates ER stress-induced neuronal apoptosis by inhibiting PERK/eIF2α/ATF4/CHOP signaling, suggesting the therapeutic potential of Lico A in AD treatment.

Baicalin plays a protective role by regulating ferroptosis in multiple diseases

Ferroptosis is a new kind of cell death discovered in recent years, usually accompanied by a large number of lipid peroxidation and iron accumulation in the process of cell death. Ferroptosis has been proven to play an important role in various diseases, including ischemic reperfusion injury, cancer, and neurodegeneration. Therefore, the regulation of ferroptosis will have a vital impact on the occurrence and development of diseases. Baicalin is a flavonoid compound extracted and isolated from the dried roots of Scutellaria baicalensis Georgi, a plant in the family Lamiaceae. It has various biological activities such as antioxidant, anti-proliferative, anti-inflammatory, anti-thrombotic, and regulates apoptosis and ferroptosis. Recently, increasing evidence indicates that baicalin regulation of ferroptosis is involved in multiple diseases. However, the relevant mechanisms are not yet fully understood. Here, we summarized the role of baicalin regulation of ferroptosis in different kinds of diseases, and conducted an in-depth analysis of the relevant mechanisms, hoping to provide the theoretical references for future related researches.

Dissection of the potential mechanism of polystyrene microplastic exposure on cardiomyocytes

Microplastics (MPs) are ubiquitous in the global biosphere, have widespread contact with humans, and increase exposure risks. Increasing evidence indicates that MPs exposure increases the risks of cardiovascular disease, however, a comprehensive exploration of the fundamental cellular mechanisms has yet to be undertaken. In this study, we used AC16 cells as a model and exposed them to 10 to 50 μg/mL of polystyrene MPs (PS-MPs), chosen based on the average daily intake and absorption of MPs by humans, to investigate their roles and mechanisms in cell injury. Proteomic analysis reveals that PS-MP-induced differentially expressed genes were enriched on endoplasmic reticulum (ER) stress and autophagy-related entries. The findings from immunofluorescence and western blotting provided further verification of the activation of ER stress by PS-MPs. Although the expression of LC3-II, a canonical autophagy marker was increased, PS-MPs inhibited autophagic flux instead of inducing autophagy. Importantly, ER stress not only contributes to PS-MPs-induced cell injury but also involved in PS-MPs-induced autophagic flux inhibition. Furthermore, the inhibition of autophagy, and the partial restoration of cell injury induced by PS-MPs was achieved through the activation of autophagy. Overall, the results reveal that activation of ER stress and inhibition of autophagic flux plays a significant role in the cell injury caused by PS-MPs in human cardiomyocytes, offering a novel perspective on the mechanism behind MPs-induced cardiomyocyte toxicity.

CHOP aggravates hepatocyte apoptosis upon endoplasmic reticulum stress by downregulating autophagy

Endoplasmic reticulum (ER) stress-induced apoptosis plays a crucial role in various liver diseases. Hepatocytes respond to ER stress by activating the unfolded protein response and autophagy, which is essential for maintaining ER homeostasis. However, failure to restore ER balance via autophagy contributes to apoptosis. In this study, we aimed to explore the role of C/EBP homologous protein (CHOP) in regulating ER stress-induced apoptosis in rat hepatocytes. We found that CHOP downregulates autophagy, aggravating apoptosis. Our results revealed that inhibition of CHOP expression enhanced autophagy and reduced DTT-induced apoptosis in BRL-3A cells, whereas CHOP overexpression worsened apoptosis. Chromatin immunoprecipitation assays revealed that CHOP negatively regulates autophagy-related genes, such as ATG12, ATG5, and LC3. These findings suggest that CHOP modulation plays a crucial role in ER stress-induced hepatocyte apoptosis by regulating autophagy.

Key Genes and Biological Pathways in Pulmonary Arterial Hypertension Related to Endoplasmic Reticulum Stress Identified by Bioinformatics

ABSTRACT

Pulmonary arterial hypertension (PAH) is a cardiopulmonary vascular condition with an unclear pathogenesis. Targeting endoplasmic reticulum (ER) stress has been suggested as a novel treatment approach for PAH, but the mechanisms involving ER stress-related genes in PAH are not well understood. Microarray data for PAH and ER stress-related genes were analyzed. Differential and Venn analyses identified 17 differentially expressed ER stress-related genes in PAH. Candidate drugs targeting these genes were predicted using the CMap database. A protein-protein interaction (PPI) network was constructed, and hub genes (LCN2, IGF1, VCAM1, EDN1, HMOX1, TLR4) with complex interplays were identified using the STRING database and Cytoscape plugins. The clinical diagnostic performance of the hub genes was evaluated using ROC curves. The GeneMANIA Web site was utilized to predict enriched pathways associated with the hub genes and their functionally similar genes. MiRNAs and transcription factors targeting the hub genes were predicted using the Networkanalyst Web site. The immune levels in control samples and PAH samples were assessed using various algorithms. Nine drug candidates were found to potentially target the identified ER stress-related genes. The hub genes and their correlated genes were significantly enriched in immune-related pathways. The PAH group showed increased immune cell infiltration, indicating a heightened immune response. This study sheds light on the role of ER stress-associated hub genes in PAH and proposes potential drugs targeting these genes. These findings provide valuable insights into PAH mechanisms and support the exploration of ER stress as a therapeutic target.

A review on endoplasmic reticulum-dependent anti-breast cancer activity of herbal drugs: possible challenges and opportunities

Breast cancer (BC) is a major cause of cancer-related mortality across the globe and is especially highly prevalent in females. Based on the poor outcomes and several limitations of present management approaches in BC, there is an urgent need to focus and explore an alternate target and possible drug candidates against the target in the management of BC. The accumulation of misfolded proteins and subsequent activation of unfolded protein response (UPR) alters the homeostasis of endoplasmic reticulum (ER) lumen that ultimately causes oxidative stress in ER. The UPR activates stress-detecting proteins such as IRE1α, PERK, and ATF6, these proteins sometimes may lead to the activation of pro-apoptotic signaling pathways in cancerous cells. The ER stress-dependent antitumor activity could be achieved either through suppressing the adaptive UPR to make cells susceptible to ER stress or by causing chronic ER stress that may lead to triggering of pro-apoptotic signaling pathways. Several herbal drugs trigger ER-dependent apoptosis in BC cells. Therefore, this review discussed the role of fifty-two herbal drugs and their active constituents, focusing on disrupting the balance of the ER within cancer cells. Further, several challenges and opportunities have also been discussed in ER-dependent management in BC.Breast cancer (BC) is a major cause of cancer-related mortality across the globe and is especially highly prevalent in females. Based on the poor outcomes and several limitations of present management approaches in BC, there is an urgent need to focus and explore an alternate target and possible drug candidates against the target in the management of BC. The accumulation of misfolded proteins and subsequent activation of unfolded protein response (UPR) alters the homeostasis of endoplasmic reticulum (ER) lumen that ultimately causes oxidative stress in ER. The UPR activates stress-detecting proteins such as IRE1α, PERK, and ATF6, these proteins sometimes may lead to the activation of pro-apoptotic signaling pathways in cancerous cells. The ER stress-dependent antitumor activity could be achieved either through suppressing the adaptive UPR to make cells susceptible to ER stress or by causing chronic ER stress that may lead to triggering of pro-apoptotic signaling pathways. Several herbal drugs trigger ER-dependent apoptosis in BC cells. Therefore, this review discussed the role of fifty-two herbal drugs and their active constituents, focusing on disrupting the balance of the ER within cancer cells. Further, several challenges and opportunities have also been discussed in ER-dependent management in BC.

Endoplasmic reticulum's role in multiple sclerosis, exploring potential biomarkers, and pioneering therapeutic strategies: a comprehensive review of literature

BACKGROUND

Multiple Sclerosis (MS) is a complex and chronic autoimmune disease that affects the central nervous system. Inflammation and demyelination characterize it, which results in a range of neurological impairments. The increasing worldwide occurrence of MS, affecting an estimated 2.8 million individuals in 2020, highlights the urgent requirement for further research to tackle the significant impact it has on individuals and healthcare systems globally.

OBJECTIVE

In this study, we wanted to explore the complex function of the endoplasmic reticulum (ER) in the origin, development, and resolution of MS, emphasizing its importance in neuroinflammatory illnesses. The ER has become a central focus in comprehending the pathogenesis of MS. Upon reviewing the literature, we observed a lack of thorough analysis that explores the involvement of endoplasmic reticulum stress in multiple sclerosis. Thus, we aimed through this research to examine the correlations between ER stress and its influence on immunological dysregulation, demyelination, and neurodegeneration in MS.

FINDINGS

Based on the latest clinical trials, we suggested theories that explore possible biomarkers linked to ER stress and the unfolded protein response. Identifying molecules that are suggestive of early stages of illness and can serve as prognostic tools for improving our understanding of the heterogeneity of MS and offering novel approaches for managing the disease. Finally, through our comprehensive search, we wanted to offer a plan for future research, suggesting new and creative methods for managing MS and encouraging the creation of specific treatments that aim to reduce the impact of MS on individuals worldwide.

Qing Hua Chang Yin ameliorates chronic colitis in mice by inhibiting PERK-ATF4-CHOP pathway of ER stress and the NF-κB signalling pathway

CONTEXT

Ulcerative colitis has been clinically treated with Qing Hua Chang Yin (QHCY), a traditional Chinese medicine formula. However, its precise mechanisms in mitigating chronic colitis are largely uncharted.

OBJECTIVE

To elucidate the therapeutic efficiency of QHCY on chronic colitis and explore its underlying molecular mechanisms.

MATERIALS AND METHODS

A total ion chromatogram fingerprint of QHCY was analysed. Chronic colitis was induced in male C57BL/6 mice using 2% dextran sodium sulphate (DSS) over 49 days. Mice were divided into control, DSS, DSS + QHCY (0.8, 1.6 and 3.2 g/kg/d dose, respectively) and DSS + mesalazine (0.2 g/kg/d) groups (n = 6). Mice were intragastrically administered QHCY or mesalazine for 49 days. The changes of disease activity index (DAI), colon length, colon histomorphology and serum pro-inflammatory factors in mice were observed. RNA sequencing was utilized to identify the differentially expressed transcripts (DETs) in colonic tissues and the associated signalling pathways. The expression of endoplasmic reticulum (ER) stress-related protein and NF-κB signalling pathway-related proteins in colonic tissues was detected by immunohistochemistry staining.

RESULTS

Forty-seven compounds were identified in QHCY. Compared with the DSS group, QHCY significantly improved symptoms of chronic colitis like DAI increase, weight loss, colon shortening and histological damage. It notably reduced serum levels of IL-6, IL-1β and TNF-α. QHCY suppressed the activation of PERK-ATF4-CHOP pathway of ER stress and NF-κB signalling pathways in colonic tissues.

DISCUSSION AND CONCLUSIONS

The findings in this study provide novel insights into the potential of QHCY in treating chronic colitis patients.

Endoplasmic reticulum stress-mediated apoptosis and autophagy in osteoarthritis: From molecular mechanisms to therapeutic applications

Osteoarthritis (OA) is characterized primarily by the degeneration of articular cartilage, with a high prevalence and disability rate. The functional phenotype of chondrocytes, as the sole cell type within cartilage, is vital for OA progression. Due to the avascular nature of cartilage and its limited regenerative capacity, repair following injury poses significant challenges. Various cellular stressors, including hypoxia, nutrient deprivation, oxidative stress, and collagen mutations, can lead to the accumulation of misfolded proteins in the endoplasmic reticulum (ER), resulting in ER stress (ERS). In response to restore ER homeostasis as well as cellular vitality and function, a series of adaptive mechanisms are triggered, including the unfolded protein response, ER-associated degradation, and ER-phagy. Prolonged or severe ERS may exceed the adaptive capacity of cells, leading to dysregulation in apoptosis and autophagy-key pathogenic factors contributing to chondrocyte damage and OA progression. This review examines the relationship between ERS in OA chondrocytes and both apoptosis and autophagy in order to identify potential therapeutic targets and strategies for prevention and treatment of OA.

A Marine-Derived Small Molecule Inhibits Prostate Cancer Growth by Promoting Endoplasmic Reticulum Stress Induced Apoptosis and Autophagy

MHO7 (6-epi-ophiobolin G), a novel component extracted from a mangrove fungus, exhibits significant anticancer effects against breast cancer. However, the precise mechanism underlying the anticancer effects of MHO7 in prostate cancer (PCa) is yet to be fully elucidated. Therefore, this study was undertaken to assess the effect of MHO7 on PCa cells and elucidate its underlying mechanism. A series of in vitro experiments were conducted, including Cell Counting Kit-8, and plate clone formation assays, flow cytometry analysis, electron microscopy, immunofluorescence staining, western blotting, and molecular dynamics simulation. Additionally, in vivo tumor xenograft models were employed. Our findings revealed that MHO7 could induce cellular autophagy at low concentration (2 μM) and apoptosis at relatively high concentration (4 and 8 μM), leading to significant PCa cell growth inhibition. Furthermore, MHO7 triggered endoplasmic reticulum (ER) stress, which subsequently stimulated autophagy and apoptosis via IRE1α/XBP-1s signaling pathway activation. Notably, IRE1α knockdown markedly reduced MHO7-induced autophagy and apoptosis. Moreover, MHO7 targeted the IRE1α protein, thereby enhancing its stability. MHO7 also exhibited substantial anticancer activity in tumor xenograft models. Our study revealed that MHO7 holds considerable potential as an anticancer agent against PCa, attributable to its activation of ER stress-induced autophagy and apoptosis at different concentrations, facilitated by the upregulation of IRE1α expression.

Biomimetic mesenchymal stem cell membrane-coated nanoparticle delivery of MKP5 inhibits hepatic fibrosis through the IRE/XBP1 pathway

Hepatic fibrosis is a common disease with high morbidity and mortality rates. The complex and poorly understood mechanisms underlying hepatic fibrosis represent a significant challenge for the development of more effective therapeutic strategies. MKP5 is a potential regulator of multiple fibrotic diseases. However, its precise role and mechanism of action in hepatic fibrosis remains unclear. This study identified a reduction in MKP5 expression in fibrotic liver tissues of mice treated with CCl4 and observed that MKP5 knockout mice exhibited a more pronounced development of hepatic fibrosis. In addition, RNA-seq data indicated activation of protein processing in the endoplasmic reticulum signalling pathway in fibrotic liver tissues of mice lacking MKP5. Mechanistically, MKP5 inhibits the activation of hepatic stellate cells (HSCs) and hepatocyte apoptosis through the regulation of the IRE/XBP1 pathway. Based on these findings, we developed PLGA-MKP5 nanoparticles coated with a mesenchymal stem cell membrane (MSCM). Our results demonstrated that MSCM-PLGA-MKP5 was most effective in attenuating hepatic inflammation and fibrosis in murine models by modulating the IRE/XBP1 axis. This study contributes to the current understanding of the pathogenesis of hepatic fibrosis, suggesting that the targeted delivery of MKP5 via a nano-delivery system may represent a promising therapeutic approach to treat hepatic fibrosis.

Tempol mitigates inflammation, oxidative stress, and histopathological alterations of cadmium-induced parotid gland injury in rats

Cadmium (Cd) is a potent environmental pollutant that causes functional and structural damage to the salivary glands. Tempol (TEM) has powerful antioxidant activity that can potentially preserve organ function.

AIMS

This study was designed to investigate the protective effects of TEM on Cd-induced toxicity in rat parotid salivary glands.

MATERIALS AND METHODS

Twenty-four adult Wistar male rats were randomly assigned to four equal groups: control, TEM (27.5 g/100 ml), Cd (0.6 g/100 ml), and TEM plus Cd (at the same doses). All treatments were dissolved in distilled water and administered subcutaneously four times a week for four weeks. Parotid gland tissues were isolated and subjected to molecular and histo-biochemical assessments.

KEY FINDINGS

TEM exerted a prophylactic effect against Cd-induced toxicity in the parotid glands by controlling inflammation through the downregulation of toll-like receptor 4/myeloid differentiation primary response 88/nuclear factor kappa B/ interleukin-1 beta mRNA expression, upregulation of aquaporin-5 mRNA expression, improvement of the oxidant/antioxidant status in the parotid gland, mitigation of endoplasmic reticulum stress, and repair of the associated histological and ultrastructural abnormalities.

SIGNIFICANCE

TEM protects against Cd-induced toxicity in the parotid glands of rats, attributable at least in part to its anti-inflammatory and antioxidant properties, as well as its ability to inhibit ER stress and facilitate glandular repair. However, the protective effects of TEM did not reach the levels observed in the control group. TEM could be a promising clinical candidate for protecting the salivary glands, particularly in high-risk groups such as workers exposed to Cd and cigarette smokers.

Role of Irisin in exercise training-regulated endoplasmic reticulum stress, autophagy and myogenesis in the skeletal muscle after myocardial infarction

Patients with heart failure (HF) are often accompanied by skeletal muscle abnormalities, which can lead to exercise intolerance and compromise daily activities. Irisin, an exercise training (ET) -induced myokine, regulates energy metabolism and skeletal muscle homeostasis. However, the precise role of Irisin in the benefits of ET on inhibiting skeletal muscle atrophy, particularly on endoplasmic reticulum (ER) stress, autophagy, and myogenesis following myocardial infarction (MI) remains unclear. In this study, we investigated the expression of Irisin protein in wild-type mice with MI, and assessed its role in the beneficial effects of ET using an Fndc5 knockout mice. Our findings revealed that MI reduced muscle fiber cross-sectional area (CSA), while downregulating the expression of Irisin, PGC-1α and SOD1. Concurrently, MI elevated the levels of ER stress and apoptosis, and inhibited autophagy in skeletal muscle. Conversely, ET mitigated ER stress and apoptosis in the skeletal muscle of infarcted mice. Notably, Fndc5 knockout worsened MI-induced ER stress and apoptosis, suppressed autophagy and myogenesis, and abrogated the beneficial effects of ET. In conclusion, our findings highlight the role of Irisin in the ET-mediated alleviation of skeletal muscle abnormalities. This study provides valuable insights into MI-induced muscle abnormalities and enhances our understanding of exercise rehabilitation mechanisms in clinical MI patients.

RHBDF1 promotes PERK expression through the JNK/FoxO3 pathway in breast cancer cells

Human rhomboid family-1 ( RHBDF1) gene is recognized as an oncogene involved in breast cancer development. Previous studies have indicated that RHBDF1 contributes significantly to endoplasmic reticulum (ER) protein homeostasis by stabilizing the binding immunoglobulin protein (BiP) and promoting the unfolded protein response (UPR). Here, we report a relationship between RHBDF1 and the ER stress sensors PERK, IRE1, and ATF6. We show that RHBDF1 deficiency in breast cancer cells results in decreased levels of PERK, pPERK, and peIF2α. These protein levels can be restored in RHBDF1-deficient breast cancer cells by artificial overexpression of RHBDF1 but not IRE1 or ATF6. Additionally, we show that the transcription factor FoxO3 is essential for the RHBDF1-mediated production of PERK. Subsequent analysis reveals that RHBDF1 activates JNK, which causes FoxO3 to translocate into the cell nucleus. These findings demonstrate that RHBDF1 supports the UPR by upregulating the PERK/peIF2α pathway via the JNK/FoxO3 axis and that the functions of RHBDF1 are essential for preserving the homeostasis of ER proteins.

Zoledronic Acid Accelerates ER Stress-Mediated Inflammation by Increasing PDE4B Expression in Bisphosphonate-Related Osteonecrosis of the Jaw

Long-term administration of bisphosphonates can lead to a significant side effect known as bisphosphonate-related osteonecrosis of the jaw (BRONJ). Although macrophage-mediated inflammation has been established as an important factor in BRONJ, the underlying mechanism remains elusive. In the current study, the roles of endoplasmic reticulum (ER) stress in zoledronic acid (ZOL)-induced inflammation were analyzed in macrophages, and the regulatory mechanism of ER stress activation was next investigated. An in vitro model of BRONJ was established by treating RAW264.7 cells with ZOL. The activation of ER stress was analyzed by western blotting and transmission electron microscopy, and inflammation was assessed by quantitative real-time PCR and enzyme-linked immunosorbent assay. ER stress was significantly activated in ZOL-treated macrophages, and inhibition of ER stress by TUDCA, an ER stress inhibitor, suppressed ZOL-induced inflammation in macrophages. Mechanistically, phosphodiesterase 4B (PDE4B) was significantly increased in ZOL-treated macrophages. Forced expression of PDE4B promoted ER stress and inflammation, whereas PDE4B knockdown decreased ZOL-induced ER stress and inflammation in macrophages. More importantly, PDE4B inhibitor could improve ZOL-induced BRONJ in vivo. These data suggest that ZOL accelerates ER stress-mediated inflammation in BRONJ by increasing PDE4B expression. PDE4B inhibition may represent a potential therapeutic strategy for BRONJ. Subsequent research should concentrate on formulating medications that selectively target PDE4B, thereby mitigating the risk of BRONJ in patients undergoing bisphosphonate treatment.

Calreticulin from Apostichopus japonicus relieves endoplasmic reticulum stress induced by Vibrio splendidus through autophagy

When organisms are exposed to external stimuli, misfolded proteins accumulate continuously, resulting in endoplasmic reticulum (ER) stress. Autophagy is of great significance for eliminating aggregated proteins and maintaining cellular homeostasis. However, the molecular mechanism of activating autophagy in response to ER stress in sea cucumber is remain unclear. In the current study, we demonstrated that the pathogen Vibrio splendidus can cause ER stress in Apostichopus japonicus coelomocytes and identified a Ca2+ binding partner calreticulin (designated as AjCRT), which increased with the occurrence of ER stress. The nucleotide sequence analysis showed that the open reading frame of AjCRT was 1242 bp and encoded a 413-amino-acid residue polyprotein with calreticulin domains. The spatial expression analysis revealed that AjCRT was ubiquitously expressed in all examined tissues with large magnitude in the coelomocytes and was minimally expressed in muscle. Furthermore, silencing AjCRT in vivo could significantly exacerbate ER stress induced by V. splendidus and resulted in the significant reduction of coelomocyte autophagy. These findings indicate a calreticulin-based mechanism that positively regulates autophagy in response to ER stress induced by pathogen infection. The results will provide a basis for understanding the way of host alleviating ER stress through autophagy, and pharmacological approaches may have potential for managing ER stress induced by pathogen and related cellular disorders.

The effect of selenium on the intestinal health of juvenile grass carp based on the ERS-autophagy pathway

Selenium (Se), a trace element, is vital for the maintenance of cellular redox balance, thyroid hormone metabolism, inflammation, and immunity. Aeromonas hydrophila (A. hydrophila) is a common Gram-negative conditional pathogenic bacterium in fish culture, posing a serious threat to intensive aquaculture. Our study investigated the influence of dietary Se on the intestinal immune function of grass carp (Ctenopharyngodon idella) and the related regulatory mechanisms. The 2160 healthy juvenile grass carp (9.76 ± 0.005 g) were randomly assigned to 6 test groups of 6 replicates each, and fed graded selenomethionine (0.05, 0.20, 0.40, 0.61, 0.77, 0.98 mg Se/kg diet) for 70 days and then injected with A. hydrophila for a 6-day attack test. The results indicated that appropriate Se levels (0.40 mg/kg diet) alleviated intestinal damage caused by A. hydrophila and increased intestinal immune substances C3 and C4 levels as well as the activity of acid phosphatase (ACP) and lysozyme (LZ) (P > 0.05). Appropriate levels of Se (0.40 mg/kg-0.61 mg/kg diet) decreased intestinal pro-inflammatory cytokines (IFN-γ2, IL-6, IL-12p35, IL-17 A F and IL-17D) mRNA levels (P > 0.05) and increased intestinal anti-inflammatory factors (TGF-β1, IL-4/13A, IL-4/13B, IL-10 and IL-22) mRNA levels (P > 0.05) in juvenile grass carp. Further studies revealed that Se (0.40 mg/kg-0.61 mg/kg diet) inhibited intestinal endoplasmic reticulum stress (ERS)-related signaling pathway. Furthermore, we found that appropriate levels of Se (0.40 mg/kg-0.61 mg/kg diet) inhibited intestinal autophagy in juvenile grass carp, which may be related to ULK1, Beclin 1, ATG5, ATG12, LC3, and P62. In conclusion, appropriate levels of Se can alleviate intestinal inflammation and inhibit ERS and autophagy in juvenile grass carp. A quadratic regression analysis of intestinal ACP and LZ also indicated that the Se requirements of juvenile grass carp were 0.59 and 0.51 mg/kg, respectively.

DMDD, isolated from Averrhoa carambola L., ameliorates diabetic nephropathy by regulating endoplasmic reticulum stress-autophagy crosstalk

BACKGROUND

Studies have shown that Averrhoa carambola L. possesses therapeutic potential for diabetes and related complications. However, the specific beneficial effects and molecular mechanisms of 2-dodecyl-6-meth-oxycyclohexa-2,5-diene-1,4-dione (DMDD) isolated from Averrhoa carambola L. on diabetic nephropathy (DN) require further investigation.

METHODS

80 C57BL/6 J male mice were subjected to a 1-week adaptive feeding, followed by a high-fat diet and intraperitoneal injection of 100 mg/kg streptozotocin (STZ) to construct an in vivo DN model. Additionally, human renal proximal tubular epithelial cells (HK-2) induced by high glucose (HG) were used as an in vitro DN model. The expression levels of epithelial-mesenchymal transition (EMT), endoplasmic reticulum stress (ERS), and autophagy-related proteins in renal tubular cells were detected by Western Blot, flow cytometry, immunofluorescence, and enzyme-linked immunosorbent assay (ELISA) staining. Transcriptome analysis revealed was conducted to elucidate the specific mechanism of by which DMDD mitigates DN by inhibiting ERS and autophagy. HK-2 cells were transfected with IRE1α overexpression lentivirus to reveal the role of IRE1α overexpression in HG-induced HK-2.

RESULTS

The experimental data showed that DMDD significantly reduced blood glucose levels and improved renal pathological alterations in DN mice. Additionally, DMDD inhibited the calcium (Ca2+) pathway, manifested by decreased autophagosome formation and downregulation of LC3II/I, Beclin-1, and ATG5 expression. Moreover, in HG-induced HK-2 cells, DMDD suppressed the overexpression of GRP78, CHOP, LC3II/I, Beclin1, and ATG5. Notably, IRE1α overexpression significantly increased autophagy incidence; however, DMDD treatment subsequently reduced the expression of LC3II/I, Beclin1, and ATG5.

CONCLUSION

DMDD effectively inhibits excessive ERS and autophagy, thereby reducing renal cell apoptosis through the IRE1α pathway and Ca 2+ pathway.

Medium-Chain Chlorinated Paraffins Trigger Thyroid Hormone Synthesis and Interfere with Mitochondrial Function in the Thyroid Gland

Medium-chain chlorinated paraffins (MCCPs, C14-C17) are frequently detected in diverse environmental media. It has been proposed to be listed in Annex A of the Convention on Persistent Organic Pollutants in 2023. Although MCCPs are a crucial health concern, their toxicity remains unclear. This study investigated the toxic effects of MCCPs (0.1-50 mg/kg body weight/day) on the thyroid gland of female Sprague-Dawley rats and characterized the potential toxic pathways via transcriptomics and metabolomics approaches. MCCPs exposure caused histopathological changes to the endoplasmic reticula and mitochondria in thyroid follicular cells at a dose of 50 mg/kg bw/d and increased serum thyrotropin-releasing hormone, thyroid-stimulating hormones, and thyroxine when exposed to a higher dose of MCCPs. Transcriptomic analysis indicated the excessive expression of key genes related to thyroid hormone synthesis induced by MCCPs. Integrating the dual-omics analysis revealed mitochondrial dysfunction of the thyroid by mediating fatty acid oxidation, Kreb's cycle, and oxidative phosphorylation. Significant metabolic toxicity on the thyroid might be linked to the characteristics of the chlorine content of MCCPs. This study revealed the toxicity of MCCPs to the thyroid gland via triggering thyroid hormone synthesis and interfering with mitochondrial function, which can provide new insights into the modes of action and mechanism-based risk assessment of MCCPs.

The roles and mechanisms of endoplasmic reticulum stress-mediated autophagy in animal viral infections

The endoplasmic reticulum (ER) is a unique organelle responsible for protein synthesis and processing, lipid synthesis in eukaryotic cells, and the replication of many animal viruses is closely related to ER. A considerable number of viral proteins are synthesised during viral infection, resulting in the accumulation of unfolded and misfolded proteins in ER, which in turn induces endoplasmic reticulum stress (ERS). ERS further drives three signalling pathways (PERK, IRE1, and ATF6) of the cellular unfolded protein response (UPR) to respond to the ERS. In numerous studies, ERS has been shown to mediate autophagy, a highly conserved cellular degradation mechanism to maintain cellular homeostasis in eukaryotic cells, through the UPR to restore ER homeostasis. ERS-mediated autophagy is closely linked to the occurrence and development of numerous viral diseases in animals. Host cells can inhibit viral replication by regulating ERS-mediated autophagy, restoring the ER's normal physiological process. Conversely, many viruses have evolved strategies to exploit ERS-mediated autophagy to achieve immune escape. These strategies include the regulation of PERK-eIF2α-Beclin1, PERK-eIF2α-ATF4-ATG12, IRE1α-JNK-Beclin1, and other signalling pathways, which provide favourable conditions for the replication of animal viruses in host cells. The ERS-mediated autophagy pathway has become a hot topic in animal virological research. This article reviews the most recent research regarding the regulatory functions of ERS-mediated autophagy pathways in animal viral infections, emphasising the underlying mechanisms in the context of different viral infections. Furthermore, it considers the future direction and challenges in the development of ERS-mediated autophagy targeting strategies for combating animal viral diseases, which will contribute to unveiling their pathogenic mechanism from a new perspective and provide a scientific reference for the discovery and development of new antiviral drugs and preventive strategies.

PKD regulates mitophagy to prevent oxidative stress and mitochondrial dysfunction during mouse oocyte maturation

Mitochondria play dominant roles in various cellular processes such as energy production, apoptosis, calcium homeostasis, and oxidation-reduction balance. Maintaining mitochondrial quality through mitophagy is essential, especially as its impairment leads to the accumulation of dysfunctional mitochondria in aging oocytes. Our previous research revealed that PKD expression decreases in aging oocytes, and its inhibition negatively impacts oocyte quality. Given PKD's role in autophagy mechanisms, this study investigates whether PKD regulates mitophagy to maintain mitochondrial function and support oocyte maturation. When fully grown oocytes were treated with CID755673, a potent PKD inhibitor, we observed meiosis arrest at the metaphase I stage, along with decreased spindle stability. Our results demonstrate an association with mitochondrial dysfunction, including reduced ATP production and fluctuations in Ca2+ homeostasis, which ultimately lead to increased ROS accumulation, stimulating oxidative stress-induced apoptosis and DNA damage. Further research has revealed that these phenomena result from PKD inhibition, which affects the phosphorylation of ULK, thereby reducing autophagy levels. Additionally, PKD inhibition leads to decreased Parkin expression, which directly and negatively affects mitophagy. These defects result in the accumulation of damaged mitochondria in oocytes, which is the primary cause of mitochondrial dysfunction. Taken together, these findings suggest that PKD regulates mitophagy to support mitochondrial function and mouse oocyte maturation, offering insights into potential targets for improving oocyte quality and addressing mitochondrial-related diseases in aging females.

The role of taurine through endoplasmic reticulum in physiology and pathology

Taurine is a sulfur-containing amino acid found in many cell organelles that plays a wide range of biological roles, including bile salt production, osmoregulation, oxidative stress reduction, and neuromodulation. Taurine treatments have also been shown to ameliorate the onset and development of many diseases, including hypertension, fatty liver, neurodegenerative diseases and ischemia-reperfusion injury, by exerting antioxidant, anti-inflammatory, and antiapoptotic effects. The endoplasmic reticulum (ER) is a dynamic organelle involved in a wide range of cellular functions, including lipid metabolism, calcium storage and protein stabilization. Under stress, the disruption of the ER environment leads to the accumulation of misfolded proteins and a characteristic stress response called the unfolded protein response (UPR). The UPR protects cells from stress and helps to restore cellular homeostasis, but its activation promotes cell death under prolonged ER stress. Recent studies have shown that ER stress is closely related to the onset and development of many diseases. This article reviews the beneficial effects and related mechanisms of taurine by regulating the ER in different physiological and pathological states, with the aim of providing a reference for further research and clinical applications.

Implications of endoplasmic reticulum stress and autophagy in aging and cardiovascular diseases

The average lifespan of humans has been increasing, resulting in a rapidly rising percentage of older individuals and high morbidity of aging-associated diseases, especially cardiovascular diseases (CVDs). Diverse intracellular and extracellular factors that interrupt homeostatic functions in the endoplasmic reticulum (ER) induce ER stress. Cells employ a dynamic signaling pathway of unfolded protein response (UPR) to buffer ER stress. Recent studies have demonstrated that ER stress triggers various cellular processes associated with aging and many aging-associated diseases, including CVDs. Autophagy is a conserved process involving lysosomal degradation and recycling of cytoplasmic components, proteins, organelles, and pathogens that invade the cytoplasm. Autophagy is vital for combating the adverse influence of aging on the heart. The present report summarizes recent studies on the mechanism of ER stress and autophagy and their overlap in aging and on CVD pathogenesis in the context of aging. It also discusses possible therapeutic interventions targeting ER stress and autophagy that might delay aging and prevent or treat CVDs.

Cellular response during cellular starvation: A battle for cellular survivability

Cellular starvation occurs when a cell is deprived of nutrition and oxygen availability. The genesis of this state of deprivation is exclusively contingent upon the inadequacy in the supply of essential components, namely amino acids, glucose, and oxygen. Consequently, the impact of this altered condition manifests in the regulation of cellular respiratory, metabolic, and stress responses. Subsequently, as a reactive outcome, cell death may transpire through mechanisms such as autophagy or apoptosis, particularly under prolonged circumstances. However, the cell combats such situations by evolving altered activity in their metabolic and protein level. Modulated signaling cascades help them to conquer starvation. But as in a prolonged condition, the battle that a cell has to evolve will come into and result in the form of cellular death. Therefore, in cancer therapy, cellular starvation may also act as a possible way out so that the cancer cell can undergo its death pathway in an induced starved condition. This review has collectively depicted the mechanism of cellular starvation. Besides this, the cellular response in this starved condition has also been summarized. Gaining such knowledge of the causation of cell starvation and cellular response during starvation not only generates new insight into the mechanism of cell survivability but also may act as a beneficial role in combating cellular diseases like cancer.

Eukaryotic Initiation Translation Factor 2A activation by cannabidiolic acid alters the protein homeostasis balance in glioblastoma cells

Eukaryotic Initiation Translation Factor 2A (EIF2A) is considered to be primarily responsible for the initiation of translation when a cell is subjected to stressful conditions. However, information regarding this protein is still incomplete. Using a combination of proteomic approaches, we demonstrated that EIF2A is the molecular target of the naturally occurring bioactive compound cannabidiolic acid (CBDA) within human glioblastoma cells. This finding allowed us to undertake a study aimed at obtaining further information on the functions that EIF2A plays in tumor cells. Indeed, our data showed that CBDA is able to activate EIF2A when the cells are in no-stress conditions. It induces conformational changes in the protein structure, thus increasing EIF2A affinity towards the proteins participating in the Eukaryotic Translation Machinery. Consequently, following glioblastoma cells incubation with CBDA we observed an enhanced neosynthesis of proteins involved in the stress response, nucleic acid translation and organization, and protein catabolism. These changes in gene expression resulted in increased levels of ubiquitinated proteins and accumulation of the autophagosome. Our results, in addition to shedding light on the molecular mechanism underlying the biological effect of a phytocannabinoid in cancer cells, demonstrated that EIF2A plays a critical role in regulation of protein homeostasis.

New insights into the interplay between autophagy, gut microbiota and insulin resistance in metabolic syndrome

Metabolic syndrome (MetS) is a widespread and multifactorial disorder, and the study of its pathogenesis and treatment remains challenging. Autophagy, an intracellular degradation system that maintains cellular renewal and homeostasis, is essential for maintaining antimicrobial defense, preserving epithelial barrier integrity, promoting mucosal immune response, maintaining intestinal homeostasis, and regulating gut microbiota and microbial metabolites. Dysfunctional autophagy is implicated in the pathological mechanisms of MetS, involving insulin resistance (IR), chronic inflammation, oxidative stress, and endoplasmic reticulum (ER) stress, with IR being a predominant feature. The study of autophagy represents a valuable field of research with significant clinical implications for identifying autophagy-related signals, pathways, mechanisms, and treatment options for MetS. Given the multifactorial etiology and various potential risk factors, it is imperative to explore the interplay between autophagy and gut microbiota in MetS more thoroughly. This will facilitate the elucidation of new mechanisms underlying the crosstalk among autophagy, gut microbiota, and MetS, thereby providing new insights into the diagnosis and treatment of MetS.

Autophagy: A Silent Protagonist in Kidney Transplantation

Autophagy is a lysosome-dependent regulated mechanism that recycles unnecessary cytoplasmic components. It is now known that autophagy dysfunction may have a pathogenic role in several human diseases and conditions, including kidney transplantation. Both defective and excessive autophagy may induce or aggravate several complications of kidney transplantation, such as ischemia-reperfusion injury, alloimmune response, and immunosuppressive treatment and side effects. Although it is still complicated to measure autophagy levels in clinical practice, more attention should be paid to the factors that may influence autophagy. In kidney transplantation, the association of low doses of a mammalian target of rapamycin inhibitor with low doses of a calcineurin inhibitor may be of benefit for autophagy modulation. However, further studies are needed to explore the role of other autophagy regulators.

Knockdown of circ_0044226 promotes endoplasmic reticulum stress-mediated autophagy and apoptosis in hepatic stellate cells via miR-4677-3p/SEC61G axis

Downregulation of circ_0044226 has been demonstrated to reduce pulmonary fibrosis, but the role of circ_0044226 in liver fibrosis remains to be explored. In this work, we found that circ_0044226 expression was upregulated during liver fibrosis. Knockdown of circ_0044226 inhibited proliferation, promoted autophagy and apoptosis of hepatic stellate cell LX-2. Bioinformatic analysis and dual luciferase reporter assays confirmed the interaction between circ_0044226, miR-4677-3p and SEC61G. Mechanistically, knockdown of circ_0044226 suppressed SEC61G expression by releasing miR-4677-3p, thereby enhancing endoplasmic reticulum stress. Overexpression of SEC61G or endoplasmic reticulum stress inhibitor 4-phenylbutiric acid partially reversed the effect of knockdown circ_0044226 on LX-2 cell function. In vivo experiments showed that inhibition of circ_0044226 attenuated CCL4-induced liver fibrosis in mice. These imply that circ_0044226 may be a potential target for the treatment of liver fibrosis.

Arrestin beta-2 deficiency exacerbates periodontal inflammation by mediating activating transcription factor 6 activation and abnormal remodelling of the extracellular matrix

AIM

To investigate the specific role of arrestin beta-2 (ARRB2) in the progression of periodontitis and the underlying mechanisms.

MATERIALS AND METHODS

Single-cell RNA sequencing data were used to analyse gene expression in periodontal tissues from healthy controls and patients with periodontitis. Real-time quantitative polymerase chain reaction, Western blotting and immunohistochemical staining were performed to detect the expression of ARRB2. Furthermore, a ligature-induced periodontitis model was created. Using radiographic and histological methods, RNA sequencing and luciferase assay, the role of ARRB2 in periodontitis and the underlying mechanisms were explored. Finally, the therapeutic effect of melatonin, an inhibitor of activating transcription factor 6 (ATF6), on periodontitis in mice was assessed in both in vivo and in vitro experiments.

RESULTS

ARRB2 expression was up-regulated in inflammatory periodontal tissue. In the ligature-induced mouse model, Arrb2 knockout exacerbated alveolar bone loss (ABL) and extracellular matrix (ECM) degradation. ARRB2 exerted a negative regulatory effect on ATF6, an essential targeted gene. Melatonin ameliorated ABL and an imbalance in ECM remodelling in Arrb2-deficient periodontitis mice.

CONCLUSIONS

ARRB2 mediates ECM remodelling via inhibition of the ATF6 signalling pathway, which ultimately exerts a protective effect on periodontal tissues.

Cadmium toxicity and autophagy: a review

Cadmium (Cd) is an important environmental pollutant that poses a threat to human health and represents a critical component of air pollutants, food sources, and cigarette smoke. Cd is a known carcinogen and has toxic effects on the environment and various organs in humans. Heavy metals within an organism are difficult to biodegrade, and those that enter the respiratory tract are difficult to remove. Autophagy is a key mechanism for counteracting extracellular (microorganisms and foreign bodies) or intracellular (damaged organelles and proteins that cannot be degraded by the proteasome) stress and represents a self-protective mechanism for eukaryotes against heavy metal toxicity. Autophagy maintains cellular homeostasis by isolating and gathering information about foreign chemicals associated with other molecular events. However, autophagy may trigger cell death under certain pathological conditions, including cancer. Autophagy dysfunction is one of the main mechanisms underlying Cd-induced cytotoxicity. In this review, the toxic effects of Cd-induced autophagy on different human organ systems were evaluated, with a focus on hepatotoxicity, nephrotoxicity, respiratory toxicity, and neurotoxicity. This review also highlighted the classical molecular pathways of Cd-induced autophagy, including the ROS-dependent signaling pathways, endoplasmic reticulum (ER) stress pathway, Mammalian target of rapamycin (mTOR) pathway, Beclin-1 and Bcl-2 family, and recently identified molecules associated with Cd. Moreover, research directions for Cd toxicity regarding autophagic function were proposed. This review presents the latest theories to comprehensively reveal autophagy behavior in response to Cd toxicity and proposes novel potential autophagy-targeted prevention and treatment strategies for Cd toxicity and Cd-associated diseases in humans.

FerrylHb induces inflammation and cell death in grass carp (Ctenopharyngodon idella) hepatocytes

Grass carp hemorrhagic disease is a significant problem in grass carp aquaculture. It releases highly oxidizing hemoglobin (Hb) into tissues, induces rapid autooxidation, and subsequently discharges cytotoxic reactive oxygen species (ROS). However, the mechanism underlying Hb damage to the teleost remains unclear. Here, we employed ferrylHb and heme to incubate L8824 (grass carp liver) cells and quantitatively analyzed the corresponding molecular regulation using the RNA-seq method. Based on the RNA-seq analysis data, after 12 h of incubation of the L8824 cells with ferrylHb, a total of 3738 differentially expressed genes (DEGs) were identified, 1824 of which were upregulated, and 1914 were downregulated. A total of 4434 DEGs were obtained in the heme treated group, with 2227 DEGs upregulated and 2207 DEGs downregulated. KEGG enrichment analysis data revealed that the incubation of ferrylHb and heme significantly activated the pathways related to Oxidative Phosphorylation, Autophagy, Mitophagy and Protein Processing in Endoplasmic Reticulum. The genes associated with NF-κB, autophagy and apoptosis pathways were selected for further validation by quantitative real-time RT-PCR (qRT-PCR). The results were consistent with the RNA-seq data. Taken together, the incubation of Hb and heme induced the molecular regulation of L8824, which consequently led to programmed cell death through multiple pathways.

New insights into the roles of Irisin in diabetic cardiomyopathy and vascular diseases

Diabetes mellitus (DM) is a prevalent chronic disease in the 21st century due to increased lifespan and unhealthy lifestyle choices. Extensive research indicates that exercise can play a significant role in regulating systemic metabolism by improving energy metabolism and mitigating various metabolic disorders, including DM. Irisin, a well-known exerkine, was initially reported to enhance energy expenditure by indicating the browning of white adipose tissue (WAT) through peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) signaling. In this review, we summarize the potential mechanisms underlying the beneficial effects of Irisin on glucose dysmetabolism, including reducing gluconeogenesis, enhancing insulin energy expenditure, and promoting glycogenesis. Additionally, we highlight Irisin's potential to improve diabetic vascular diseases by stimulating nitric oxide (NO) production, reducing oxidative and nitrosative stress, curbing inflammation, and attenuating endothelial cell aging. Furthermore, we discuss the potential of Irisin to improve diabetic cardiomyopathy by preventing cardiomyocyte loss and reducing myocardial hypertrophy and fibrosis. Given Irisin's promising functions in managing diabetic cardiomyopathy and vascular diseases, targeting Irisin for therapeutic purposes could be a fruitful avenue for future research and clinical interventions.

Construction of a prognostic risk model for Stomach adenocarcinoma based on endoplasmic reticulum stress genes

OBJECTIVE

Stomach adenocarcinoma (STAD) is caused by malignant transformation of gastric glandular cells and is characterized by a high incidence rate and a poor prognosis. This study was designed to establish a prognostic risk model for STAD according to endoplasmic reticulum (ER) stress feature genes as cancer cells are susceptible to ER stress.

METHODS

The TCGA-STAD dataset was downloaded to screen differentially expressed genes (DEGs). By intersecting DEGs with ER stress genes retrieved from GeneCards, ER stress-related DEGs in STAD were obtained. Kmeans cluster analysis of STAD subtypes and Single sample gene set enrichment analysis (ssGSEA) analysis of immune infiltration were performed. Cox regression analysis was utilized to construct a risk prognostic model. Samples were split into high-risk and low-risk groups according to the median risk score. Survival analysis and Receiver Operating Characteristic (ROC) curves were conducted to assess the validity of the model. Gene set enrichment analysis (GSEA) was performed to investigate differential pathways in the two risk groups. Cox analysis was performed to verify the independence of the risk model, and a nomogram was generated.

RESULTS

A total of 162 ER stress-related DEGs in STAD were identified by bioinformatics analysis. Kmeans cluster analysis showed that STAD was divided into 3 subgroups. The ssGSEA showed that the levels of immune infiltration in subgroups 2 and 3 were significantly higher than subgroup 1. With 12 prognostic genes (MATN3, ATP2A1, NOX4, AQP11, HP, CAV1, STARD3, FKBP10, EGF, F2, SERPINE1, CNGA3) selected from ER stress-related DEGs using Cox regression analysis, we then constructed a prognostic model. Kaplan-Meier (K‑M) survival curves and ROC curves showed good prediction performance of the model. Significant enrichment of genes in the high-risk group was found in extracellular matrix (ECM) receptor interaction. Cox regression analysis combined with clinical factors showed that the risk model could be used as an independent prognostic factor. The prediction correction curve showed that the good prediction ability of the nomogram.

CONCLUSION

The STAD could be divided into three subgroups, and the 12-gene model constructed by ER stress signatures had a good prognostic performance for STAD patients.

AMPK/autophagy-mediated alleviation of tendinopathy by IL-38: A novel strategy for the treatment of obesity-related tendinopathy

The effect of interleukin-38 (IL-38), a recently identified member of the IL-1 family with potential applications in various inflammation-related conditions, on ER stress has not been explored. Furthermore, its role in obesity-associated tendinopathy has not been investigated. In this study, human primary tenocytes were treated with palmitate (200 or 400 μM) and palmitate plus IL-38 (0-50 ng/mL) for 24 h. Western blotting was used to assess ER stress and tendinopathogenic markers in tenocytes. Monodansylcadaverine (MDC) staining was used to evaluate autophagosomes. Apoptosis was determined by cell viability assays, caspase 3 activity assays and TUNEL assays. Cell migration was evaluated by a cell scratch assay. Small interfering (si) RNA transfection was used for target gene silencing. Treatment of tenocytes with IL-38 attenuated apoptosis, restored the balance between MMPs and TIMP-1, and alleviated ER stress under palmitate conditions. IL-38 treatment enhanced AMPK phosphorylation and promoted the expression of autophagy markers related to LC3 conversion, p62 degradation, and autophagosome formation in cultured tenocytes. The effects of IL-38 on ER stress, apoptosis, and MMP-9, MMP-13, and TIMP-1 expression in palmitate-treated tenocytes were abrogated by AMPK siRNA or 3-methyladenine (3MA). These results suggest that IL-38 alleviates ER stress through the AMPK/autophagy pathway, thereby reducing apoptosis and preventing extracellular matrix (ECM) degradation in tenocytes under hyperlipidemic conditions. This study provides a promising therapeutic avenue for treating obesity-related tendinopathy using an endogenous compound such as IL-38.

Protein homeostasis maintained by HOOK1 levels promotes the tumorigenic and stemness properties of ovarian cancer cells through reticulum stress and autophagy

BACKGROUND

Ovarian cancer has a high mortality rate mainly due to its resistance to currently used therapies. This resistance has been associated with the presence of cancer stem cells (CSCs), interactions with the microenvironment, and intratumoral heterogeneity. Therefore, the search for new therapeutic targets, particularly those targeting CSCs, is important for improving patient prognosis. HOOK1 has been found to be transcriptionally altered in a substantial percentage of ovarian tumors, but its role in tumor initiation and development is still not fully understood.

METHODS

The downregulation of HOOK1 was performed in ovarian cancer cell lines using CRISPR/Cas9 technology, followed by growth in vitro and in vivo assays. Subsequently, migration (Boyden chamber), cell death (Western-Blot and flow cytometry) and stemness properties (clonal heterogeneity analysis, tumorspheres assay and flow cytometry) of the downregulated cell lines were analysed. To gain insights into the specific mechanisms of action of HOOK1 in ovarian cancer, a proteomic analysis was performed, followed by Western-blot and cytotoxicity assays to confirm the results found within the mass spectrometry. Immunofluorescence staining, Western-blotting and flow cytometry were also employed to finish uncovering the role of HOOK1 in ovarian cancer.

RESULTS

In this study, we observed that reducing the levels of HOOK1 in ovarian cancer cells reduced in vitro growth and migration and prevented tumor formation in vivo. Furthermore, HOOK1 reduction led to a decrease in stem-like capabilities in these cells, which, however, did not seem related to the expression of genes traditionally associated with this phenotype. A proteome study, along with other analysis, showed that the downregulation of HOOK1 also induced an increase in endoplasmic reticulum stress levels in these cells. Finally, the decrease in stem-like properties observed in cells with downregulated HOOK1 could be explained by an increase in cell death in the CSC population within the culture due to endoplasmic reticulum stress by the unfolded protein response.

CONCLUSION

HOOK1 contributes to maintaining the tumorigenic and stemness properties of ovarian cancer cells by preserving protein homeostasis and could be considered an alternative therapeutic target, especially in combination with inducers of endoplasmic reticulum or proteotoxic stress such as proteasome inhibitors.

Mogroside V reduced the excessive endoplasmic reticulum stress and mitigated the Ulcerative colitis induced by dextran sulfate sodium in mice

Ulcerative colitis (UC) is an idiopathic, chronic inflammatory condition of the colon, characterized by repeated attacks, a lack of effective treatment options, and significant physical and mental health complications for patients. The endoplasmic reticulum (ER) is a vital intracellular organelle in maintaining cellular homeostasis. Endoplasmic reticulum stress (ERS) is induced when the body is exposed to adverse external stimuli. Numerous studies have shown that ERS-induced apoptosis plays a vital role in the pathogenesis of UC. Mogroside V (MV), an active ingredient of Monk fruit, has demonstrated excellent anti-inflammatory and antioxidant effects. In this study, we investigated the therapeutic effects of MV on dextran sulfate sodium (DSS)-induced UC and its potential mechanisms based on ERS. The results showed that MV exerted a protective effect against DSS-induced UC in mice as reflected by reduced DAI scores, increased colon length, reduced histological scores of the colon, and levels of pro-inflammatory cytokines, as well as decreased intestinal permeability. In addition, the expression of ERS pathway including BIP, PERK, eIF2α, ATF4, CHOP, as well as the apoptosis-related protein including Caspase-12, Bcl-2 and Bax, was found to be elevated in UC. However, MV treatment significantly inhibited the UC and reversed the expression of inflammation signaling pathway including ERS and ERS-induced apoptosis. Additionally, the addition of tunicamycin (Tm), an ERS activator, significantly weakened the therapeutic effect of MV on UC in mice. These findings suggest that MV may be a therapeutic agent for the treatment of DSS-induced UC by inhibiting the activation of the ERS-apoptosis pathway, and may provide a novel avenue for the treatment of UC.

Effects of Natural Products through Inhibiting Endoplasmic Reticulum Stress on Attenuation of Idiopathic Pulmonary Fibrosis

With ever-increasing intensive studies of idiopathic pulmonary fibrosis (IPF), significant progresses have been made. Endoplasmic reticulum stress (ERS)/unfolded protein reaction (UPR) is associated with the development and progression of IPF, and targeting ERS/UPR may be beneficial in the treatment of IPF. Natural product is a tremendous source of new drug discovery, and accumulating studies have reported that many natural products show potential therapeutic effects for IPF via modulating one or more branches of the ERS signaling pathway. Therefore, this review focuses on critical roles of ERS in IPF development, and summarizes herbal preparations and bioactive compounds which protect against IPF through regulating ERS.

Multi-omics analysis revealed that the protein kinase MoKin1 affected the cellular response to endoplasmic reticulum stress in the rice blast fungus, Magnaporthe oryzae

BACKGROUND

Previous studies have shown that protein kinase MoKin1 played an important role in the growth, conidiation, germination and pathogenicity in rice blast fungus, Magnaporthe oryzae. ΔMokin1 mutant showed significant phenotypic defects and significantly reduced pathogenicity. However, the internal mechanism of how MoKin1 affected the development of physiology and biochemistry remained unclear in M. oryzae.

RESULT

This study adopted a multi-omics approach to comprehensively analyze MoKin1 function, and the results showed that MoKin1 affected the cellular response to endoplasmic reticulum stress (ER stress). Proteomic analysis revealed that the downregulated proteins in ΔMokin1 mutant were enriched mainly in the response to ER stress triggered by the unfolded protein. Loss of MoKin1 prevented the ER stress signal from reaching the nucleus. Therefore, the phosphorylation of various proteins regulating the transcription of ER stress-related genes and mRNA translation was significantly downregulated. The insensitivity to ER stress led to metabolic disorders, resulting in a significant shortage of carbohydrates and a low energy supply, which also resulted in severe phenotypic defects in ΔMokin1 mutant. Analysis of MoKin1-interacting proteins indicated that MoKin1 really took participate in the response to ER stress.

CONCLUSION

Our results showed the important role of protein kinase MoKin1 in regulating cellular response to ER stress, providing a new research direction to reveal the mechanism of MoKin1 affecting pathogenic formation, and to provide theoretical support for the new biological target sites searching and bio-pesticides developing.

Synthesis, Photophysical Properties, Theoretical Studies, and Living Cancer Cell Imaging Applications of New 7-(Diethylamino)quinolone Chalcones

In this article, three unsymmetrical 7-(diethylamino)quinolone chalcones with D-π-A-D and D-π-A-π-D type push-pull molecular arrangements were synthesized via a Claisen-Schmidt reaction. Using 7-(diethylamino)quinolone and vanillin as electron donor (D) moieties, these were linked together through the α,β-unsaturated carbonyl system acting as a linker and an electron acceptor (A). The photophysical properties were studied, revealing significant Stokes shifts and strong solvatofluorochromism caused by the ICT and TICT behavior produced by the push-pull effect. Moreover, quenching caused by the population of the TICT state in THF-H2O mixtures was observed, and the emission in the solid state evidenced a red shift compared to the emission in solution. These findings were corroborated by density functional theory (DFT) calculations employing the wb97xd/6-311G(d,p) method. The cytotoxic activity of the synthesized compounds was assessed on BHK-21, PC3, and LNCaP cell lines, revealing moderate activity across all compounds. Notably, compound 5b exhibited the highest activity against LNCaP cells, with an LC50 value of 10.89 μM. Furthermore, the compounds were evaluated for their potential as imaging agents in living prostate cells. The results demonstrated their favorable cell permeability and strong emission at 488 nm, positioning them as promising candidates for cancer cell imaging applications.