Endoplasmic reticulum stress and eIF2α phosphorylation: The Achilles heel of pancreatic β cells

Effects of electroacupuncture on neural function and the expression of inflammation-related proteins NLRP3/caspase-1 in rats with ischemic stroke

This study aimed to investigate the neuroprotective effects of electroacupuncture (EA) at the Baihui and Dazhui acupoints in a rat model of ischemia-reperfusion injury. Ninety-six male Sprague-Dawley rats were randomly assigned to four groups ( n  = 24 per group): Sham, middle cerebral artery occlusion (MCAO), MCAO+EA, and MCAO+MCC950. The MCAO model was induced using filament embolization. Neurological function was assessed using Zea Longa scores on days 1 and 7 posttreatment, while cerebral infarction volume was measured using 2,3,5-triphenyltetrazolium chloride staining. Gene expression levels of NLRP3 and GSDMD were quantified by RT-qPCR, and protein expressions of NLRP3, GSDMD, caspase-1, IL-1β, and IL-18 were evaluated via Western blotting, immunohistochemistry, immunofluorescence staining, and ELISA. On day 1, compared with the MCAO group, the MCAO+EA and MCAO+MCC950 groups exhibited significantly reduced mRNA and protein expressions of NLRP3 and GSDMD ( P  < 0.05), as well as decreased levels of caspase-1, IL-1β, and IL-18 ( P  < 0.05). However, no significant differences were observed in neurological deficit scores or cerebral infarction volume. By day 7, both the MCAO+EA and MCAO+MCC950 groups showed significant improvements in neurological function ( P  < 0.05), reductions in cerebral infarction volume ( P  < 0.05), and further decreases in the expression of NLRP3, GSDMD, caspase-1, IL-1β, and IL-18 ( P  < 0.05). EA at the Baihui and Dazhui acupoints alleviates neurological deficits in ischemic stroke rats by inhibiting the NLRP3/caspase-1 inflammatory pathway and reducing the expression of apoptosis-related proteins such as NLRP3, GSDMD, caspase-1, IL-1β, and IL-18.

A Compound Screen Based on Isogenic hESC-Derived β Cell Reveals an Inhibitor Targeting ZnT8-Mediated Zinc Transportation to Protect Pancreatic β Cell from Stress-Induced Cell Death

Pancreatic β cell loss by cellular stress contributes to diabetes pathogenesis. Nevertheless, the fundamental mechanism of cellular stress regulation remains elusive. Here, it is found that elevated zinc transportation causes excessive cellular stress in pancreatic β cells in diabetes. With gene-edited human embryonic stem cell-derived β cells (SC-β cells) and human primary islets, the results reveal that elevated zinc transportation initiates the integrated stress response (ISR), and ultimately leads to β cell death. By contrary, genetic abolishment of zinc transportation shields β cells from exacerbated endoplasmic reticulum stress (ER stress) and concurrent ISR. To target excessive zinc transportation with a chemical inhibitor, an isogenic SC-β cells based drug-screening platform is established. Surprisingly, independent of its traditional role as protein synthesis inhibitor at a high-dose (10 µm), low-dose (25 nm) anisomycin significantly inhibits zinc transportation and effectively prevents β cell loss. Remarkably, in vivo administration of anisomycin in mice demonstrates protective effects on β cells and prevents type 2 diabetes induced by high-fat diet. Overall, elevated zinc transportation is identified as a crucial driver of β cell loss and low-dose anisomycin as a potential therapeutic molecule for diabetes.

The Role of Estrogen and ER Stress in Glycemic Regulation in the Sexually Dimorphic TALLYHO/JngJ Mouse Model of Diabetes

The global incidence of diabetes mellitus is increasing, causing a heavy burden on health care management and costs. Sex differences in the incidence and prevalence of diabetes mellitus do exist, with premenopausal women being protected from developing this disease, compared to men or postmenopausal women. The mechanisms underlying these differences are not yet known and experimental animal models can significantly advance our understanding of these processes. In this study we characterized a mouse model of polygenic type 2 diabetes, the TALLYHO/JngJ mouse, which shows sexual dimorphism in blood glucose regulation. Male TALLYHO/JngJ mice develop chronic hyperglycemia by 5 weeks of age, while females remain normoglycemic. We analyzed the role of endoplasmic reticulum (ER) stress and the activation of the unfolded protein response (UPR) in the development of hyperglycemia in this mouse model. Additionally, we evaluated the effect of estrogen depletion in female TALLYHO/JngJ mice through ovariectomies. Ovariectomized female mice and males become chronically hyperglycemic (fasting blood glucose threshold >15 mM) and show significantly increased expression of GRP78/GRP94, markers of the adaptive unfolded protein response (UPR). GADD153/CHOP, a marker of the apoptotic UPR, is significantly increased in ovariectomized female mice. Treatment with a chemical chaperone 4-PBA, an ER stress alleviator, improves but does not normalize blood glucose levels in male and ovariectomized female TALLYHO/JngJ mice. Together, these findings support a protective role for estrogen and identify the UPR as a pathway through which estrogen may maintain pancreatic beta cell health.

Eukaryotic translation initiation factor 2A protects pancreatic beta cells during endoplasmic reticulum stress while rescuing global translation inhibition

AIMS/HYPOTHESIS

The endoplasmic reticulum (ER) stress-induced unfolded protein response helps determine beta cell survival rate in diabetes. The alternative eukaryotic translation initiation factor 2A (EIF2A) has been proposed to mediate translation initiation independent of the α subunit of EIF2 (EIF2S1) during cellular stress, but its role in beta cells has not been comprehensively examined.

METHODS

For in vitro experiments, we used MIN6 cells, primary mouse pancreatic islets, and human islets obtained under informed consent. Thapsigargin (1 µmol/l) or palmitate complexed with BSA (0.5 mmol/l) was used to induce ER stress. Transient transfection and lentiviral infection were used for transgene delivery. For in vivo experiments, adeno-associated viral particles expressing EIF2A or GFP under the control of a rat insulin promoter were delivered via intraductal injection to 6-week-old female Akita mice randomised into three groups (two cohorts, n=10-11). Tail blood was collected for blood glucose measurements for single time points as well as during glucose and insulin tolerance tests.

RESULTS

EIF2A protein abundance and specificity was high in human and mouse islets relative to other tissues. We used STRING and AlphaFold pulldown to predict interacting proteins and binding partners, verifying EIF1AX with co-immunoprecipitation. Both thapsigargin and palmitate significantly increased EIF2A mRNA and EIF2A protein levels in MIN6 cells, mouse islets and human islets. Knockdowns of EIF2A, the related factor EIF2D or both EIF2A and EIF2D were not sufficient to cause apoptosis. On the other hand, transient or stable EIF2A overexpression protected MIN6 cells, primary mouse islets and human islets from ER stress-induced, caspase-3-dependent apoptosis. Mechanistically, EIF2A overexpression decreased endoplasmic reticulum to nucleus signalling 1 (ERN1, also known as inositol-requiring enzyme 1 α or IRE1α) expression in thapsigargin-treated MIN6 cells or human islets. In vivo, beta cell-specific EIF2A viral overexpression reduced ER stress and improved insulin secretion and glucose tolerance in Ins2Akita/WT mice. EIF2A overexpression significantly increased expression of genes involved in mRNA translation and reduced expression of pro-apoptotic genes (e.g. Aldh1a3). Proteomic analysis of EIF2A-overexpressing human islets revealed significant changes in pathways associated with ribosomes and protein processing in ER. Remarkably, the decrease in global protein synthesis during unfolded protein response was prevented by EIF2A, despite ER stress-induced EIF2S1 phosphorylation. The protective effects of EIF2A were additive to those of ISRIB, a drug that counteracts the effects of EIF2S1 phosphorylation. Cells overexpressing EIF2A showed higher expression of translation factor EIF2B5, which may contribute to the lack of translational inhibition in these cells.

CONCLUSIONS/INTERPRETATION

We conclude that EIF2A is a novel target for beta cell protection and the circumvention of EIF2S1-mediated translational repression.

Endoplasmic reticulum stress in non-small cell lung cancer

The Endoplasmic reticulum (ER), an organelle present in various eukaryotic cells, is responsible for protein synthesis, modification, folding, and transport, as well as for the regulation of lipid metabolism and Ca2+ homeostasis. ER stress plays a pivotal role in the pathogenesis and therapeutic response of non-small cell lung cancer (NSCLC), significantly influencing cellular fate decisions through its unique sensing and regulatory mechanisms. This review aims to elucidate the key role of ER stress sensors and to explore how they mediate cell autophagy, apoptosis, and non-apoptotic modes of cell death in the context of drug-treated NSCLC. This investigation lays a solid foundation for optimizing future treatment strategies for NSCLC.

The unfolded protein response is a potential therapeutic target in pathogenic fungi

Pathogenic fungal infections cause significant morbidity and mortality, particularly in immunocompromised patients. The frequent emergence of multidrug-resistant strains challenges existing antifungal therapies, driving the need to investigate novel antifungal agents that target new molecular moieties. Pathogenic fungi are subjected to various environmental stressors, including pH, temperature, and pharmacological agents, both in natural habitats and the host body. These stressors elevate the risk of misfolded or unfolded protein production within the endoplasmic reticulum (ER) which, if not promptly mitigated, can lead to the accumulation of these proteins in the ER lumen. This accumulation triggers an ER stress response, potentially jeopardizing fungal survival. The unfolded protein response (UPR) is a critical cellular defense mechanism activated by ER stress to restore the homeostasis of protein folding. In recent years, the regulatory role of the UPR in pathogenic fungi has garnered significant attention, particularly for its involvement in fungal adaptation, regulation of virulence, and drug resistance. In this review, we comparatively analyze the UPRs of fungi and mammals and examine the potential utility of the UPR as a molecular antifungal target in pathogenic fungi. By clarifying the specificity and regulatory functions of the UPR in pathogenic fungi, we highlight new avenues for identifying potential therapeutic targets for antifungal treatments.

IER3IP1 Mutations Cause Neonatal Diabetes Due to Impaired Proinsulin Trafficking

ARTICLE HIGHLIGHTS

IER3IP1 mutations are linked to the development of microcephaly, epilepsy, and early-onset diabetes syndrome 1. However, the underlying molecular mechanisms of cell dysfunction are unknown. Using targeted genome editing, we generated specific IER3IP1 mutations in human embryonic stem cell lines that were differentiated into pancreatic islet lineages. Loss of IER3IP1 resulted in a threefold reduction in endoplasmic reticulum-to-Golgi trafficking of proinsulin in stem cell-derived β-cells, leading to β-cell dysfunction both in vitro and in vivo. Loss of IER3IP1 also triggered increased markers of endoplasmic reticulum stress, indicating the pivotal role of the endoplasmic reticulum-to-Golgi trafficking pathway for β-cell homeostasis and function.

Mettl3 deficiency leads to impaired insulin secretion via regulating Ire1a of mature β-cells in mice

The modification of N6-methyladenosine (m6A) influences the translation and stability of transcripts, allowing for the coordination of gene regulation during cell state maintenance and transition. Deregulation of components in the m6A regulatory network is associated with glucose homeostasis and development of diabetes. In this study, we investigated the functional role of Mettl3, which is the key component of the m6A methyltransferase complex, in regulating β-cell identity and function in two pancreatic β-cell-specific Mettl3 knockout mouse models. The glucose metabolic phenotype, β-cell proliferation, islet architecture and insulin secretion were analyzed in vivo. We next analyzed the expression levels of genes associated with endoplasmic reticulum (ER) stress in the Mettl3 ablated islets. MeRIP-qPCR was applied to detect the m6A modification enrichment of Ire1α mRNA. Adenovirus-mediated Mettl3 infection was performed on islets to explore the effect of Mettl3 overexpression on ER stress and insulin secretion. Our results showed that Mettl3 deficiency led to loss of β-cell identity and impaired insulin secretion in mice. Depletion of Mettl3 verified the m6A modification in Ire1α and consequently induced ER stress in islet cells. Mettl3 overexpression in islets could alleviate ER stress and improve the insulin secretion capacity. Our findings demonstrated that Mettl3 was an important regulator of ER stress and insulin secretion in mouse pancreatic β-cells.

The role of endoplasmic reticulum stress in type 2 diabetes mellitus mechanisms and impact on islet function

Type 2 diabetes mellitus (T2DM) is a globally prevalent metabolic disorder characterized by insulin resistance and dysfunction of islet cells. Endoplasmic reticulum (ER) stress plays a crucial role in the pathogenesis and progression of T2DM, especially in the function and survival of β-cells. β-cells are particularly sensitive to ER stress because they require substantial insulin synthesis and secretion energy. In the early stages of T2DM, the increased demand for insulin exacerbates β-cell ER stress. Although the unfolded protein response (UPR) can temporarily alleviate this stress, prolonged or excessive stress leads to pancreatic cell dysfunction and apoptosis, resulting in insufficient insulin secretion. This review explores the mechanisms of ER stress in T2DM, particularly its impact on islet cells. We discuss how ER stress activates UPR signaling pathways to regulate protein folding and degradation, but when stress becomes excessive, these pathways may contribute to β-cell death. A deeper understanding of how ER stress impacts islet cells could lead to the development of novel T2DM treatment strategies aimed at improving islet function and slowing disease progression.

Processing of genomic RNAs by Dicer in bat cells limits SARS-CoV-2 replication

Bats are reservoirs for numerous viruses that cause serious diseases in other animals and humans. Several mechanisms are proposed to contribute to the tolerance of bats to these pathogens. This study investigates the response of bat cells to double-stranded RNA generated by SARS-CoV-2 replication. Here, we found the involvement of Dicer in the processing of viral genomic RNAs during SARS-CoV-2 infection. Examining RNA sequencing of infected cells, small-interfering RNA (siRNA)-like fragments were found derived from viral RNAs. Depletion of Dicer showed a reduction in these RNAs and an increase in viral loads suggesting unlike other mammals, bats may use Dicer to limit viral replication. This prompted the exploration of key dsRNA sensors in bat cells. Our analysis showed significant upregulation of OAS1 and MX1 in response to dsRNA, while PKR levels remained low, suggesting alternative dsRNA-response mechanisms are present that eschew the common PKR-based system. These results further show how bats employ distinct strategies for antiviral defense that may contribute to tolerating viral infections. They suggest the involvement of Dicer in antiviral mechanisms in bats, a function not observed in other mammals. This highlights a mechanism for bat originating viruses to evolve features that in other animals could cause extreme antiviral responses such as is seen with SARS-CoV-2.

Exploring proinsulin proteostasis: insights into beta cell health and diabetes

Proinsulin misfolding is central to diabetes. This review examines the cellular mechanisms regulating proinsulin proteostasis in pancreatic β-cells, encompassing genetic factors such as insulin gene mutations, and exploring the roles of endoplasmic reticulum (ER) stress and the unfolded protein response (UPR), ER redox balance, mitochondrial function, and the influence of extrinsic factors. Mutations in the INS gene, particularly those affecting cysteine residues, impair folding and disulfide bond formation, often exhibiting dominant-negative effects on the wild-type proinsulin. The importance of ER quality control mechanisms, including chaperones and oxidoreductases, in facilitating proper folding and degradation of misfolded proinsulin is emphasized. Disruptions in these systems, due to genetic mutations, ER stress, or impaired ER-to-Golgi trafficking, lead to proinsulin accumulation and β-cell dysfunction. The unfolded protein response (UPR), especially the PERK and IRE1α-XBP1 pathways, emerges as a central regulator of protein synthesis and ER stress management. The review also discusses the role of mitochondrial health, ER redox state, and extrinsic factors such as diet and medications in influencing proinsulin proteostasis. Finally, the structural insights from NMR and molecular dynamics simulations are discussedhighlighting the dynamics of misfolding and underscoring the importance of disulfide bonds. These mechanistic insights suggest innovative strategies targeting thiol/disulfide redox systems in cells to mitigate protein misfolding diseases including diabetes.

Decoding the Contribution of IAPP Amyloid Aggregation to Beta Cell Dysfunction: A Systematic Review and Epistemic Meta-Analysis of Type 1 Diabetes

Diabetes Mellitus Type 1 (DM1) is an autoimmune disease characterized by the destruction of beta cells in the pancreas. Although amyloid formation has been well-studied in Diabetes Mellitus Type 2 (DM2), its role in DM1 remains unclear. Understanding how islet amyloid polypeptide (IAPP) contributes to beta cell dysfunction and death in DM1 could provide critical insights into disease mechanisms and pave the way for novel diagnostic and therapeutic strategies. A systematic review and epistemic meta-analysis was conducted using a modified PICO framework, focusing on studies related to DM1 and the IAPP aggregation process. Searches in PubMed, BIREME, and Web of Science yielded 37 relevant articles, which were analyzed and individually evaluated based on specific quality criteria. Studies that experimentally identified the formation of IAPP oligomers in DM1 were selected, along with relevant review articles. Experimental studies from human and animal models detected the presence of IAPP oligomers in DM1 patients, as well as in nonobese diabetic (NOD) and homozygous mice. Techniques like Western Blot (WB), Transmission Electron Microscopy (TEM) and Congo red staining detected various oligomers sizes, with smaller ones showing higher cytotoxicity. IAPP oligomers have been detected in the pancreatic islets of DM1 patients, contributing to beta cell damage and disease progression.

Semaglutide alleviates the pancreatic β cell function via the METTL14 signaling and modulating gut microbiota in type 2 diabetes mellitus mice

AIMS

Semaglutide, a novel long-acting GLP-1RA, stimulates insulin and suppresses islet-secreted glucagon to reduce glucose levels. It has been unveiled that m6A mRNA modification plays a pivotal role in regulating β cell function. However, it remains unclear whether semaglutide can elicit protective effects through manipulating m6A modification and the underlying mechanism. We aimed to elucidate the role played by semaglutide in m6A modification, and to explore its specific regulatory targets. Furthermore, we also delve into its effects on gut microbiota.

MAIN METHODS

Five-week-old male C57BL/6 mice were assigned to two dietary groups and fed a control or high-fat diet for 4 weeks. Then T2DM was induced in high-fat diet-fed mice via streptozotocin (STZ), the main groups were resampled to include treatment with semaglutide (SEM, 40 μg/kg) for another 4 weeks, totaling three groups: Control, Model (T2DM), T2DM + SEM. Additionally, we elucidated specific regulatory targets and signaling pathways in palmitic acid (PA)-stimulated beta-TC-6 cells. Immunofluorescence, Western blot, and RT-qPCR were used in the study.

KEY FINDINGS

Semaglutide mitigated pancreatic damage, enhanced islet cell proliferation, and restored islet size and alpha- and beta-cell masses. It also improved the expression of METTL14, pancreatic duodenal homeobox 1 (PDX-1), and protecting mitochondria, and modulated the PDX1 expression in an m6A-dependent manner. Concurrently, semaglutide significantly decreases the abundance of Firmicutes, Actinobacteriota, and Lactobacillus, while increasing the Bacteroides and norank_f_Muribaculaceae content, and the production of short-chain fatty acids (SCFA).

SIGNIFICANCE

Semaglutide positively influences by regulating m6A modifications to alleviate pancreatic beta cell dysfunction and modulate the gut microbiome.

Obesity in Prediabetic Patients: Management of Metabolic Complications and Strategies for Prevention of Overt Diabetes

Obesity and prediabetes affect a substantial part of the general population, but are largely underdiagnosed, underestimated, and undertreated. Prediabetes differs from diabetes only in the degree of hyperglycaemia consequent to the progressive decline in residual beta-cell function. Both prediabetes and diabetes occur as a consequence of insulin resistance that starts several years before the clinical onset of overt diabetes. Macrovascular complications in patients with diabetes are mainly caused by insulin resistance. This is why in prediabetes, the overall cardiovascular risk is, by all means, similar to that in patients with diabetes. It is important, therefore, to identify prediabetes and treat patients not only to prevent or delay the onset of diabetes, but to reduce the cardiovascular risk associated with prediabetes. This review provides an overview of the pathophysiology of prediabetes in patients with obesity and the progression toward overt diabetes. We have reviewed nutritional and pharmacological approaches to the management of obesity and reduced glucose tolerance, and the treatment of the major comorbidities in these patients, including hypertension, dyslipidaemia, and Metabolic dysfunction-associated Steatotic Liver Disease (MASLD), has also been reviewed. In patients with obesity and prediabetes, the nutritional approach is similar to that adopted for patients with obesity and diabetes; treatments of dyslipidaemia and hypertension also have the same targets compared to patients with diabetes. MASLD is a critical issue in these patients; in the prediabetic state, MASLD rarely progresses into fibrosis. This highlights the importance of the early recognition of this pathological condition before patients become diabetic when the risk of fibrosis is much higher. It is necessary to raise awareness of the clinical relevance of this pathological condition in order to prompt early intervention before complications occur. The single most important therapeutic goal is weight loss, which must be early and persistent.

Astaxanthin-S-Allyl Cysteine Ester Protects Pancreatic β-Cell From Glucolipotoxicity by Suppressing Oxidative Stress, Endoplasmic Reticulum Stress and mTOR Pathway Dysregulation

Glucolipotoxicity (GLT) has emerged as established mechanism in the progression of diabetes. Identifying compounds that mitigate GLT-induced deleterious effect on β-cells are considered important strategy to overcome diabetes. Hence, in the present study, astaxanthin-s-allyl cysteine (AST-SAC) diester was studied against GLT in β-cells. Mus musculus pancreatic β-cell line (βTC-tet) was treated with high glucose (25 mM; HG) and 95 μM palmitate (PA) for 24 h to induce GLT. AST-SAC at various concentrations (5, 10, and 15 μg/ml) were treated to understand the protective effect against HG + PA exposure in β-cells. Under HG + PA exposure conditions oxidative stress, deregulation of mTOR pathway and endoplasmic reticulum (ER) stress are witnessed. AST-SAC treatment eased oxidative stress, mitochondrial depolarization, DNA damage, calcium overload and accumulation of autophagosome against HG + PA exposure conditions thereby protected the cell viability of β-cells. AST-SAC maintained the level of proteins involved in mTOR pathway under HG + PA exposure conditions. Also, AST-SAC treatment has mitigated the increased expression of genes and proteins such as IRE1 and PERK involved in ER stress-mediated unfolded protein response (UPR) signaling pathways. In correspondence to it, the expression of genes involved in insulin secretion was preserved by AST-SAC. Due to these protective effects of AST-SAC the insulin secretion was well-maintained in β-cells under HG + PA exposure conditions. AST-SAC through normalizing antioxidant status and mTOR axis as well as preventing the harmful effect of ER-stress mediated UPR pathway has promoted the β-cell survival and insulin secretion against GLT. Simultaneously targeting oxidative stress/mTOR axis/ER stress is required to efficiently overcome GLT in β-cells.

Illness stress-induced transient hyperglycemia in a patient with a novel YIPF5 homozygous missense variant: expanding the phenotype

A recently described type of neonatal diabetes mellitus is caused by mutations in the YIPF5 gene and is combined with manifestations from the central nervous system, including developmental delay, epilepsy, and microcephaly. The molecular pathophysiology behind this phenotype involves the breakdown of the endoplasmic reticulum stress response due to the loss of protein folding capacity. This results in overt diabetes present from very early in life. Herein, we describe a patient with a newly reported variant in the YIPF5 gene, who presented with short events of severe hyperglycemia, induced by the stress of common illnesses, which completely resolved after recovery. We discuss the nature of transient hyperglycemia in the context of the YIPF5 gene variant and compare this phenotype with the previously described cases.

Beyond glucose: The crucial role of redox signaling in β-cell metabolic adaptation

OBJECTIVE

Redox signaling mediated by reversible oxidative cysteine thiol modifications is crucial for driving cellular adaptation to dynamic environmental changes, maintaining homeostasis, and ensuring proper function. This is particularly critical in pancreatic β-cells, which are highly metabolically active and play a specialized role in whole organism glucose homeostasis. Glucose stimulation in β-cells triggers signals leading to insulin secretion, including changes in ATP/ADP ratio and intracellular calcium levels. Additionally, lipid metabolism and reactive oxygen species (ROS) signaling are essential for β-cell function and health.

METHODS

We employed IodoTMT isobaric labeling combined with tandem mass spectrometry to elucidate redox signaling pathways in pancreatic β-cells.

RESULTS

Glucose stimulation significantly increases ROS levels in β-cells, leading to targeted reversible oxidation of proteins involved in key metabolic pathways such as glycolysis, the tricarboxylic acid (TCA) cycle, pyruvate metabolism, oxidative phosphorylation, protein processing in the endoplasmic reticulum (ER), and insulin secretion. Furthermore, the glucose-induced increase in reversible cysteine oxidation correlates with the presence of other post-translational modifications, including acetylation and phosphorylation.

CONCLUSIONS

Proper functioning of pancreatic β-cell metabolism relies on fine-tuned regulation, achieved through a sophisticated system of diverse post-translational modifications that modulate protein functions. Our findings demonstrate that glucose induces the production of ROS in pancreatic β-cells, leading to targeted reversible oxidative modifications of proteins. Furthermore, protein activity is modulated by acetylation and phosphorylation, highlighting the complexity of the regulatory mechanisms in β-cell function.

SRSF2 is essential for maintaining pancreatic beta-cell identity and regulating glucose homeostasis in mice

Diabetes is characterized by decreased beta-cell mass and islet dysfunction. The splicing factor SRSF2 plays a crucial role in cell survival, yet its impact on pancreatic beta cell survival and glucose homeostasis remains unclear. We observed that the deletion of Srsf2 specifically in beta cells led to time-dependent deterioration in glucose tolerance, impaired insulin secretion, decreased islet mass, an increased number of alpha cells, and the onset of diabetes by the age of 10 months in mice. Single-cell RNA sequencing (scRNA-seq) analyses revealed that, despite an increase in populations of unfolded protein response (UPR)-activated and undifferentiated beta cells within the SRSF2_KO group, there was a notable decrease in the expression of UPR-related and endoplasmic reticulum (ER)-related genes, accompanied by a loss of beta-cell identity. This suggests that beta cells have transitioned from an adaptive phase to a maladaptive phase in islets of 10-month-old SRSF2_KO mice. Further results demonstrated that deletion of SRSF2 caused decreased proliferation in beta cells within 3-month-old islets and Min6 cells. These findings underscore the essential role of SRSF2 in controlling beta-cell proliferation and preserving beta-cell function in mice.

Effects of novel flame retardants tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and triphenyl phosphate (TPhP) on function and homeostasis in human and rat pancreatic beta-cell lines

Despite the fact that environmental pollution has been implicated in the global rise of diabetes, the research on the impact of emerging pollutants such as novel flame retardants remains limited. In line with the shift towards the use of non-animal approaches in toxicological testing, this study aimed to investigate the effects of two novel flame retardants tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and triphenyl phosphate (TPhP) in rat (INS1E) and human (NES2Y) pancreatic beta-cell lines. One-week exposure to 1 μM and 10 μM TDCIPP and TPhP altered intracellular insulin and proinsulin levels, but not the levels of secreted insulin (despite the presence of a statistically insignificant trend). The exposures also altered the protein expression of several factors involved in beta-cell metabolic pathways and signaling, including ATP citrate lyase, isocitrate dehydrogenase 1, perilipins, glucose transporters, ER stress-related factors, and antioxidant enzymes. This study has brought new and valuable insights into the toxicity of TDCIPP and TPhP on beta-cell function and revealed alterations that might impact insulin secretion after more extended exposure. It also adds to the scarce studies using in vitro pancreatic beta-cells models in toxicological testing, thereby promoting the development of non-animal testing strategy for identifying pro-diabetic effects of chemical pollutants.

Bioinformatical analysis and experimental validation of endoplasmic reticulum stress-related biomarker genes in type 2 diabetes mellitus

Introduction

Endoplasmic reticulum stress (ERS) is a prominent etiological factor in the pathogenesis of diabetes. Nevertheless, the mechanisms through which ERS contributes to the development of diabetes remain elusive.

Methods

Transcriptional expression profiles from the Gene Expression Omnibus (GEO) datasets were analyzed and compared to obtain the differentially expressed genes (DEGs) in T2DM. Following the intersection with ERS associated genes, the ERS related T2DM DEGs were identified. Receiver operating characteristic (ROC) and Least Absolute Shrinkage and Selection Operator (LASSO) analysis were performed to screen out the ERS related biomarker genes and validate their diagnostic values. Gene expression level was detected by qPCR and Elisa assays in diabetic mice and patient serum samples.

Results

By analyzing the transcriptional expression profiles of the GEO datasets, 49 T2DM-related DEGs were screened out in diabetic islets. RTN1, CLGN, PCSK1, IAPP, ILF2, IMPA1, CCDC47, and PTGES3 were identified as ERS-related DEGs in T2DM, which were revealed to be involved in protein folding, membrane composition, and metabolism regulation. ROC and LASSO analysis further screened out CLGN, ILF2, and IMPA1 as biomarker genes with high value and reliability for diagnostic purposes. These three genes were then demonstrated to be targeted by the transcription factors and miRNAs, including CEBPA, CEBPB, miR-197-5p, miR-6133, and others. Among these miRNAs, the expression of miR-197-5p, miR-320c, miR-1296-3P and miR-6133 was down-regulated, while that of miR-4462, miR-4476-5P and miR-7851-3P was up-regulated in diabetic samples. Small molecular drugs, including D002994, D001564, and others, were predicted to target these genes potentially. qPCR and Elisa analysis both validated the same expression alteration trend of the ERS-related biomarker genes in diabetic mice and T2DM patients.

Discussion

These findings will offer innovative perspectives for clinical diagnosis and treatment strategies for T2DM.

Islet Transplantation: Current Limitations and Challenges for Successful Outcomes

Islet transplantation is a promising approach for treating patients with unstable T1DM. However, it is confronted with numerous obstacles throughout the various stages of the transplantation procedure. Significant progress has been made over the last 25 years in understanding the mechanisms behind the loss of functional islet mass and in developing protective strategies. Nevertheless, at present, two to three pancreases are still needed to treat a single patient, which limits the maximal number of patients who can benefit from islet transplantation. Thus, this publication provides an overview of recent scientific findings on the various issues affecting islet transplantation. Specifically, we will focus on the understanding of the mechanisms involved and the strategies developed to alleviate these problems from the isolation stage to the post-transplantation phase. Finally, we hope that this review will highlight new avenues of action, enabling us to propose pancreatic islet transplantation to a maximum number of patients with T1DM.

Implications of endoplasmic reticulum stress and beta-cell loss in immunodeficient diabetic NRG-Akita mice for understanding monogenic diabetes

BACKGROUND

Immunodeficient mice models have become increasingly important as in vivo models engrafted with human cells or tissues for research. The NOD-Rag1 null Ins2 Akita Il2r null (NRG-Akita) mice is a model combined with immunodeficient NRG and monogenic diabetes Akita mice that develop spontaneous hyperglycemia with progressive loss of pancreatic insulin-producing beta-cells with age. This model is one of the monogenic diabetic models, which has been providing a powerful platform for transplantation experiments of stem cells-generated human β-cells. This research aimed to provide insights into the mechanisms underlying this monogenic diabetes, which remains incompletely understood.

METHODS

Histological and immunofluorescence analyses were conducted on endocrine pancreatic islets to compare NRG wild-type (Wt) controls with NRG-Akita mice. Our investigation focused on assessing the expression of endocrine hormones, transcription factors, proliferation, ER stress, and apoptosis.

RESULTS

Histological analyses on NRG-Akita mice revealed smaller islets at 6-weeks-old, due to fewer β-cells in the islets, compared to NRG-Wt controls, which further progressed with age. The proliferation rate decreased, and apoptosis was abundant in β-cells in NRG-Akita mice. Interestingly, our mechanistic analyses revealed that β-cells in NRG-Akita mice progressively accumulated the endoplasmic reticulum (ER) stresses, leading to a decreased expression of pivotal β-cell transcriptional factor PDX1.

CONCLUSIONS

Altogether, our mechanistic insight into β-cell loss in this model could shed light on essential links between ER stress, proliferation, and cell identity, which might open the door to new therapeutic strategies for various diseases since ER stress is one of the most common features not only in diabetes but also in other degenerative diseases.

Beyond insulin: Unraveling the complex interplay of ER stress, oxidative damage, and CFTR modulation in CFRD

CF-related diabetes (CFRD) is a prevalent comorbidity in people with Cystic Fibrosis (CF), significantly impacting morbidity and mortality rates. This review article critically evaluates the current understanding of CFRD molecular mechanisms, including the role of CFTR protein, oxidative stress, unfolded protein response (UPR) and intracellular communication. CFRD manifests from a complex interplay between exocrine pancreatic damage and intrinsic endocrine dysfunction, further complicated by the deleterious effects of misfolded CFTR protein on insulin secretion and action. Studies indicate that ER stress and subsequent UPR activation play critical roles in both exocrine and endocrine pancreatic cell dysfunction, contributing to β-cell loss and insulin insufficiency. Additionally, oxidative stress and altered calcium flux, exacerbated by CFTR dysfunction, impair β-cell survival and function, highlighting the significance of antioxidant pathways in CFRD pathogenesis. Emerging evidence underscores the importance of exosomal microRNAs (miRNAs) in mediating inflammatory and stress responses, offering novel insights into CFRD's molecular landscape. Despite insulin therapy remaining the cornerstone of CFRD management, the variability in response to CFTR modulators underscores the need for personalized treatment approaches. The review advocates for further research into non-CFTR therapeutic targets, emphasizing the need to address the multifaceted pathophysiology of CFRD. Understanding the intricate mechanisms underlying CFRD will pave the way for innovative treatments, moving beyond insulin therapy to target the disease's root causes and improve the quality of life for individuals with CF.

Developmental endothelial locus 1: the present and future of an endogenous factor in vessels

Developmental Endothelial Locus-1 (DEL-1), also known as EGF-like repeat and discoidin I-like domain-3 (EDIL3), is increasingly recognized for its multifaceted roles in immunoregulation and vascular biology. DEL-1 is a protein that is mainly produced by endothelial cells. It interacts with various integrins to regulate the behavior of immune cells, such as preventing unnecessary recruitment and inflammation. DEL-1 also helps in resolving inflammation by promoting efferocytosis, which is the process of clearing apoptotic cells. Its potential as a therapeutic target in immune-mediated blood disorders, cardiovascular diseases, and cancer metastasis has been spotlighted due to its wide-ranging implications in vascular integrity and pathology. However, there are still unanswered questions about DEL-1's precise functions and mechanisms. This review provides a comprehensive examination of DEL-1's activity across different vascular contexts and explores its potential clinical applications. It underscores the need for further research to resolve existing controversies and establish the therapeutic viability of DEL-1 modulation.

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.

Endoplasmic reticulum stress in pancreatic β-cell dysfunctionality and diabetes mellitus: a promising target for generation of functional hPSC-derived β-cells in vitro

Diabetes mellitus (DM), is a chronic disorder characterized by impaired glucose homeostasis that results from the loss or dysfunction of pancreatic β-cells leading to type 1 diabetes (T1DM) and type 2 diabetes (T2DM), respectively. Pancreatic β-cells rely to a great degree on their endoplasmic reticulum (ER) to overcome the increased secretary need for insulin biosynthesis and secretion in response to nutrient demand to maintain glucose homeostasis in the body. As a result, β-cells are potentially under ER stress following nutrient levels rise in the circulation for a proper pro-insulin folding mediated by the unfolded protein response (UPR), underscoring the importance of this process to maintain ER homeostasis for normal β-cell function. However, excessive or prolonged increased influx of nascent proinsulin into the ER lumen can exceed the ER capacity leading to pancreatic β-cells ER stress and subsequently to β-cell dysfunction. In mammalian cells, such as β-cells, the ER stress response is primarily regulated by three canonical ER-resident transmembrane proteins: ATF6, IRE1, and PERK/PEK. Each of these proteins generates a transcription factor (ATF4, XBP1s, and ATF6, respectively), which in turn activates the transcription of ER stress-inducible genes. An increasing number of evidence suggests that unresolved or dysregulated ER stress signaling pathways play a pivotal role in β-cell failure leading to insulin secretion defect and diabetes. In this article we first highlight and summarize recent insights on the role of ER stress and its associated signaling mechanisms on β-cell function and diabetes and second how the ER stress pathways could be targeted in vitro during direct differentiation protocols for generation of hPSC-derived pancreatic β-cells to faithfully phenocopy all features of bona fide human β-cells for diabetes therapy or drug screening.

Targeting Protein Kinases to Protect Beta-Cell Function and Survival in Diabetes

The prevalence of diabetes is increasing worldwide. Massive death of pancreatic beta-cells causes type 1 diabetes. Progressive loss of beta-cell function and mass characterizes type 2 diabetes. To date, none of the available antidiabetic drugs promotes the maintenance of a functional mass of endogenous beta-cells, revealing an unmet medical need. Dysfunction and apoptotic death of beta-cells occur, in particular, through the activation of intracellular protein kinases. In recent years, protein kinases have become highly studied targets of the pharmaceutical industry for drug development. A number of drugs that inhibit protein kinases have been approved for the treatment of cancers. The question of whether safe drugs that inhibit protein kinase activity can be developed and used to protect the function and survival of beta-cells in diabetes is still unresolved. This review presents arguments suggesting that several protein kinases in beta-cells may represent targets of interest for the development of drugs to treat diabetes.

UNVEILING THE PROTECTIVE MECHANISMS OF PUERARIN AGAINST ACUTE LUNG INJURY: A COMPREHENSIVE EXPLORATION OF THE ROLES AND MECHANISMS OF MST1/ERS SIGNALING

ABSTRACT

Objectives: Puerarin, the principal active constituent extracted from Pueraria, is believed to confer protection against sepsis-induced lung injury. The study aimed to elucidate the role and mechanism of Mst1/ERS in puerarin-mediated protection against acute lung injury (ALI). Methods: Monolayer vascular endothelial cell permeability was assessed by gauging the paracellular flow of FITC-dextran 40,000 (FD40). ELISA was employed for the quantification of inflammatory cytokines. Identification of target proteins was conducted through western blotting. Histological alterations and apoptosis were scrutinized using hematoxylin-eosin staining and TUNEL staining, respectively. The ultrastructure of the endoplasmic reticulum was observed via transmission electron microscopy. Results: Puerarin significantly protected mice from LPS-induced ALI, reducing lung interstitial width, neutrophil and lymphocyte infiltration, pulmonary interstitial and alveolar edema, and lung apoptosis. Puerarin treatment also markedly attenuated levels of TNF-α and IL-1β in both alveolar lavage fluid and serum. Furthermore, puerarin significantly attenuated LPS-induced increases in Mst1, GRP78, CHOP, and Caspase12 protein expression and blunted LPS-induced decrease in ZO-1 protein expression in lung tissues. Puerarin obviously reduced endoplasmic reticulum expansion and vesiculation. Similarly, puerarin significantly mitigated the LPS-induced reduction in HUVEC cell viability and ZO-1 expression. Puerarin also attenuated LPS-induced increase in apoptosis, TNF-α and IL-1β, FD40 flux, and Mst1, GRP78, CHOP, and Caspase12 expression in HUVEC cells. Nevertheless, the inhibitory impact of puerarin on vascular endothelial cell injury, lung injury, and endoplasmic reticulum stress (ERS) was diminished by Mst1 overexpression. Conclusion: These findings demonstrated that the Mst1/ERS signaling pathway played a pivotal role in the development of LPS-induced vascular endothelial cell dysfunction and ALI. Puerarin exhibited the ability to attenuate LPS-induced vascular endothelial cell dysfunction and ALI by inhibiting the Mst1/ERS signaling pathway.

Mammalian integrated stress responses in stressed organelles and their functions

The integrated stress response (ISR) triggered in response to various cellular stress enables mammalian cells to effectively cope with diverse stressful conditions while maintaining their normal functions. Four kinases (PERK, PKR, GCN2, and HRI) of ISR regulate ISR signaling and intracellular protein translation via mediating the phosphorylation of eukaryotic translation initiation factor 2 α (eIF2α) at Ser51. Early ISR creates an opportunity for cells to repair themselves and restore homeostasis. This effect, however, is reversed in the late stages of ISR. Currently, some studies have shown the non-negligible impact of ISR on diseases such as ischemic diseases, cognitive impairment, metabolic syndrome, cancer, vanishing white matter, etc. Hence, artificial regulation of ISR and its signaling with ISR modulators becomes a promising therapeutic strategy for relieving disease symptoms and improving clinical outcomes. Here, we provide an overview of the essential mechanisms of ISR and describe the ISR-related pathways in organelles including mitochondria, endoplasmic reticulum, Golgi apparatus, and lysosomes. Meanwhile, the regulatory effects of ISR modulators and their potential application in various diseases are also enumerated.

Adipocyte-released adipomes in Chagas cardiomyopathy: Impact on cardiac metabolic and immune regulation

Chronic Trypanosoma cruzi infection leads to Chagas cardiomyopathy (CCM), with varying manifestations such as inflammatory hypertrophic cardiomyopathy, arrhythmias, and dilated cardiomyopathy. The factors responsible for the increasing risk of progression to CCM are not fully understood. Previous studies link adipocyte loss to CCM progression, but the mechanism triggering CCM pathogenesis remains unexplored. Our study uncovers that T. cruzi infection triggers adipocyte apoptosis, leading to the release of extracellular vesicles named "adipomes". We developed an innovative method to isolate intact adipomes from infected mice's adipose tissue and plasma, showing they carry unique lipid cargoes. Large and Small adipomes, particularly plasma-derived infection-associated L-adipomes (P-ILA), regulate immunometabolic signaling and induce cardiomyopathy. P-ILA treatment induces hypertrophic cardiomyopathy in wild-type mice and worsens cardiomyopathy severity in post-acute-infected mice by regulating adipogenic/lipogenic and mitochondrial functions. These findings highlight adipomes' pivotal role in promoting inflammation and impairing myocardial function during cardiac remodeling in CD.

Identification of common genes and pathways between type 2 diabetes and COVID-19

BACKGROUND

Numerous studies have reported a high incidence and risk of severe illness due to coronavirus disease 2019 (COVID-19) in patients with type 2 diabetes (T2DM). COVID-19 patients may experience elevated or decreased blood sugar levels and may even develop diabetes. However, the molecular mechanisms linking these two diseases remain unclear. This study aimed to identify the common genes and pathways between T2DM and COVID-19.

METHODS

Two public datasets from the Gene Expression Omnibus (GEO) database (GSE95849 and GSE164805) were analyzed to identify differentially expressed genes (DEGs) in blood between people with and without T2DM and COVID-19. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed on the common DEGs. A protein-protein interaction (PPI) network was constructed to identify common genes, and their diagnostic performance was evaluated by receiver operating characteristic (ROC) curve analysis. Validation was performed on the GSE213313 and GSE15932 datasets. A gene co-expression network was constructed using the GeneMANIA database to explore interactions among core DEGs and their co-expressed genes. Finally, a microRNA (miRNA)-transcription factor (TF)-messenger RNA (mRNA) regulatory network was constructed based on the common feature genes.

RESULTS

In the GSE95849 and GSE164805 datasets, 81 upregulated genes and 140 downregulated genes were identified. GO and KEGG enrichment analyses revealed that these DEGs were closely related to the negative regulation of phosphate metabolic processes, the positive regulation of mitotic nuclear division, T-cell co-stimulation, and lymphocyte co-stimulation. Four upregulated common genes (DHX15, USP14, COPS3, TYK2) and one downregulated common feature gene (RIOK2) were identified and showed good diagnostic accuracy for T2DM and COVID-19. The AUC values of DHX15, USP14, COPS3, TYK2, and RIOK2 in T2DM diagnosis were 0.931, 0.917, 0.986, 0.903, and 0.917, respectively. In COVID-19 diagnosis, the AUC values were 0.960, 0.860, 1.0, 0.9, and 0.90, respectively. Validation in the GSE213313 and GSE15932 datasets confirmed these results. The miRNA-TF-mRNA regulatory network showed that TYH2 was targeted by PITX1, PITX2, CRX, NFYA, SREBF1, RELB, NR1L2, and CEBP, whereas miR-124-3p regulates THK2, RIOK2, and USP14.

CONCLUSION

We identified five common feature genes (DHX15, USP14, COPS3, TYK2, and RIOK2) and their co-regulatory pathways between T2DM and COVID-19, which may provide new insights for further molecular mechanism studies.

Insights into the mechanism of transcription factors in Pb2+-induced apoptosis

The health risks associated with exposure to heavy metals, such as Pb2+, are increasingly concerning the public. Pb2+ can cause significant harm to the human body through oxidative stress, autophagy, inflammation, and DNA damage, disrupting cellular homeostasis and ultimately leading to cell death. Among these mechanisms, apoptosis is considered crucial. It has been confirmed that transcription factors play a central role as mediators during the apoptosis process. Interestingly, these transcription factors have different effects on apoptosis depending on the concentration and duration of Pb2+ exposure. In this article, we systematically summarize the significant roles of several transcription factors in Pb2+-induced apoptosis. This information provides insights into therapeutic strategies and prognostic biomarkers for diseases related to Pb2+ exposure.

Endoplasmic reticulum stress and its role in various neurodegenerative diseases

The Endoplasmic reticulum (ER), a critical cellular organelle, maintains cellular homeostasis by regulating calcium levels and orchestrating essential functions such as protein synthesis, folding, and lipid production. A pivotal aspect of ER function is its role in protein quality control. When misfolded proteins accumulate within the ER due to factors like protein folding chaperone dysfunction, toxicity, oxidative stress, or inflammation, it triggers the Unfolded protein response (UPR). The UPR involves the activation of chaperones like calnexin, calreticulin, glucose-regulating protein 78 (GRP78), and Glucose-regulating protein 94 (GRP94), along with oxidoreductases like protein disulphide isomerases (PDIs). Cells employ the Endoplasmic reticulum-associated degradation (ERAD) mechanism to counteract protein misfolding. ERAD disruption causes the detachment of GRP78 from transmembrane proteins, initiating a cascade involving Inositol-requiring kinase/endoribonuclease 1 (IRE1), Activating transcription factor 6 (ATF6), and Protein kinase RNA-like endoplasmic reticulum kinase (PERK) pathways. The accumulation and deposition of misfolded proteins within the cell are hallmarks of numerous neurodegenerative diseases. These aberrant proteins disrupt normal neuronal signalling and contribute to impaired cellular homeostasis, including oxidative stress and compromised protein degradation pathways. In essence, ER stress is defined as the cellular response to the accumulation of misfolded proteins in the endoplasmic reticulum, encompassing a series of signalling pathways and molecular events that aim to restore cellular homeostasis. This comprehensive review explores ER stress and its profound implications for the pathogenesis and progression of neurodegenerative diseases.

The advancement of polysaccharides in disease modulation: Multifaceted regulation of programmed cell death

Programmed cell death (PCD), also known as regulatory cell death (RCD), is a process that occurs in all organisms and is closely linked to both normal physiological processes and disease states. Various signaling pathways, such as TP53, KRAS, NOTCH, hypoxia, and metabolic reprogramming, have been found to regulate RCD. Polysaccharides, which are essential natural products, have been the subject of extensive research in the fields of food, nutrition, and medicine due to their wide range of pharmacological effects. Studies have shown that polysaccharides have biological activities and the potential to target signal transduction pathways for the treatment of diseases. This paper provides a review of the mechanisms through which polysaccharides exert their therapeutic effects at different levels and explores the relationship between different types of RCD and human diseases. The aim of this review is to provide a theoretical basis for the further clinical use and application of polysaccharide bioactivities.

Effect of CB1 Receptor Deficiency on Mitochondrial Quality Control Pathways in Gastrocnemius Muscle

This study aims to explore the complex role of cannabinoid type 1 receptor (CB1) signaling in the gastrocnemius muscle, assessing physiological processes in both CB1+/+ and CB1-/- mice. The primary focus is to enhance our understanding of how CB1 contributes to mitochondrial homeostasis. At the tissue level, CB1-/- mice exhibit a substantial miRNA-related alteration in muscle fiber composition, characterized by an enrichment of oxidative fibers. CB1 absence induces a significant increase in the oxidative capacity of muscle, supported by elevated in-gel activity of Complex I and Complex IV of the mitochondrial respiratory chain. The increased oxidative capacity is associated with elevated oxidative stress and impaired antioxidant defense systems. Analysis of mitochondrial biogenesis markers indicates an enhanced capacity for new mitochondria production in CB1-/- mice, possibly adapting to altered muscle fiber composition. Changes in mitochondrial dynamics, mitophagy response, and unfolded protein response (UPR) pathways reveal a dynamic interplay in response to CB1 absence. The interconnected mitochondrial network, influenced by increased fusion and mitochondrial UPR components, underlines the dual role of CB1 in regulating both protein quality control and the generation of new mitochondria. These findings deepen our comprehension of the CB1 impact on muscle physiology, oxidative stress, and MQC processes, highlighting cellular adaptability to CB1-/-. This study paves the way for further exploration of intricate signaling cascades and cross-talk between cellular compartments in the context of CB1 and mitochondrial homeostasis.

Investigating the Role of 17-Beta Estradiol in the Regulation of the Unfolded Protein Response (UPR) in Pancreatic Beta Cells

Diabetes mellitus is clinically defined by chronic hyperglycemia. Sex differences in the presentation and outcome of diabetes exist with premenopausal women having a reduced risk of developing diabetes, relative to men, or women after menopause. Accumulating evidence shows a protective role of estrogens, specifically 17-beta estradiol, in the maintenance of pancreatic beta cell health; however, the mechanisms underlying this protection are still unknown. To elucidate these potential mechanisms, we used a pancreatic beta cell line (BTC6) and a mouse model of hyperglycemia-induced atherosclerosis, the ApoE-/-:Ins2+/Akita mouse, exhibiting sexual dimorphism in glucose regulation. In this study we hypothesize that 17-beta estradiol protects pancreatic beta cells by modulating the unfolded protein response (UPR) in response to endoplasmic reticulum (ER) stress. We observed that ovariectomized female and male ApoE-/-:Ins2+/Akita mice show significantly increased expression of apoptotic UPR markers. Sham operated female and ovariectomized female ApoE-/-:Ins2+/Akita mice supplemented with exogenous 17-beta estradiol increased the expression of adaptive UPR markers compared to non-supplemented ovariectomized female ApoE-/-:Ins2+/Akita mice. These findings were consistent to what was observed in cultured BTC6 cells, suggesting that 17-beta estradiol may protect pancreatic beta cells by repressing the apoptotic UPR and enhancing the adaptive UPR activation in response to pancreatic ER stress.

Role of cytosolic and endoplasmic reticulum Ca2+ in pancreatic beta-cells: pros and cons

Pancreatic beta cells utilize Ca2+ to secrete insulin in response to glucose. The glucose-dependent increase in cytosolic Ca2+ concentration ([Ca2+]C) activates a series of insulin secretory machinery in pancreatic beta cells. Therefore, the amount of insulin secreted in response to glucose is determined in a [Ca2+]C-dependent manner, at least within a moderate range. However, the demand for insulin secretion may surpass the capability of beta cells. Abnormal elevation of [Ca2+]C levels beyond the beta-cell endurance capacity can damage them by inducing endoplasmic reticulum (ER) stress and cell death programs such as apoptosis. Therefore, while Ca2+ is essential for the insulin secretory functions of beta cells, it could affect their survival at pathologically higher levels. Because an increase in beta-cell [Ca2+]C is inevitable under certain hazardous conditions, understanding the regulatory mechanism for [Ca2+]C is important. Therefore, this review discusses beta-cell function, survival, ER stress, and apoptosis associated with intracellular and ER Ca2+ homeostasis.

Independent activation of CREB3L2 by glucose fills a regulatory gap in mouse β-cells by co-ordinating insulin biosynthesis with secretory granule formation

OBJECTIVE

Although individual steps have been characterized, there is little understanding of the overall process whereby glucose co-ordinates the biosynthesis of insulin with its export out of the endoplasmic reticulum (ER) and incorporation into insulin secretory granules (ISGs). Here we investigate a role for the transcription factor CREB3L2 in this context.

METHODS

MIN6 cells and mouse islets were analysed by immunoblotting after treatment with glucose, fatty acids, thapsigargin and various inhibitors. Knockdown of CREB3L2 was achieved using si or sh constructs by transfection, or viral delivery. In vivo metabolic phenotyping was conducted after deletion of CREB3L2 in β-cells of adult mice using Ins1-CreER+. Islets were isolated for RNAseq and assays of glucose-stimulated insulin secretion (GSIS). Trafficking was monitored in islet monolayers using a GFP-tagged proinsulin construct that allows for synchronised release from the ER.

RESULTS

With a Km ≈3.5 mM, glucose rapidly (T1/2 0.9 h) increased full length (FL) CREB3L2 followed by a slower rise (T1/2 2.5 h) in its transcriptionally-active cleavage product, P60 CREB3L2. Glucose stimulation repressed the ER stress marker, CHOP, and this was partially reverted by knockdown of CREB3L2. Activation of CREB3L2 by glucose was not due to ER stress, however, but a combination of O-GlcNAcylation, which impaired proteasomal degradation of FL-CREB3L2, and mTORC1 stimulation, which enhanced its conversion to P60. cAMP generation also activated CREB3L2, but independently of glucose. Deletion of CREB3L2 inhibited GSIS ex vivo and, following a high-fat diet (HFD), impaired glucose tolerance and insulin secretion in vivo. RNAseq revealed that CREB3L2 regulated genes controlling trafficking to-and-from the Golgi, as well as a broader cohort associated with β-cell compensation during a HFD. Although post-Golgi trafficking appeared intact, knockdown of CREB3L2 impaired the generation of both nascent ISGs and proinsulin condensates in the Golgi, implying a defect in ER export of proinsulin and/or its processing in the Golgi.

CONCLUSION

The stimulation of CREB3L2 by glucose defines a novel, rapid and direct mechanism for co-ordinating the synthesis, packaging and storage of insulin, thereby minimizing ER overload and optimizing β-cell function under conditions of high secretory demand. Upregulation of CREB3L2 also potentially contributes to the benefits of GLP1 agonism and might in itself constitute a novel means of treating β-cell failure.

Endoplasmic reticulum stress exacerbates microplastics-induced toxicity in animal cells

Human and animal exposure to microplastics (MPs) contained in food is inevitable because of their widespread existence in the environment. Nevertheless, MPs toxicity studies in ruminants often lack attention. Here, we assessed the cytotoxicity of polystyrene microplastics (PS MPs) on goat mammary epithelial cells (GMECs). Compared to controls, PS MPs treatment significantly reduced cell viability, altered cell morphology and disrupted organelle integrity. Detection of membrane potential and reactive oxygen species (ROS) suggested that PS MPs induced mitochondrial dysfunction and oxidative stress. Further transcriptome analysis also confirmed alterations in these pathways. In addition, several genes related to endoplasmic reticulum (ER) homeostasis were significantly regulated in the transcriptional profile. Subsequent experiments confirmed that PS MPs induce ER stress via the PERK/eIF2α/CHOP pathway, accompanied by intracellular Ca2+ overload. Meanwhile, downstream activation of the Bax/Bcl-2 pathway and caspase cascade released apoptotic signals, which led to apoptosis in GMECs. Interestingly, the addition of PERK inhibitor (ISRIB) attenuated PS MPs-induced ER stress and apoptosis, which suggests that ER stress may exacerbate PS MPs-induced cytotoxicity. This work reveals the impact of MPs on mammalian cytotoxicity, enriches the mechanisms for the toxicity of MPs, and provides insight for further assessment of the risk of MPs in food.

The role of autophagy in insulin resistance and glucolipid metabolism and potential use of autophagy modulating natural products in the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a severe, long-term condition characterised by disruptions in glucolipid and energy metabolism. Autophagy, a fundamental cellular process, serves as a guardian of cellular health by recycling and renewing cellular components. To gain a comprehensive understanding of the vital role that autophagy plays in T2DM, we conducted an extensive search for high-quality publications across databases such as Web of Science, PubMed, Google Scholar, and SciFinder and used keywords like 'autophagy', 'insulin resistance', and 'type 2 diabetes mellitus', both individually and in combinations. A large body of evidence underscores the significance of activating autophagy in alleviating T2DM symptoms. An enhanced autophagic activity, either by activating the adenosine monophosphate-activated protein kinase and sirtuin-1 signalling pathways or inhibiting the mechanistic target of rapamycin complex 1 signalling pathway, can effectively improve insulin resistance and balance glucolipid metabolism in key tissues like the hypothalamus, skeletal muscle, liver, and adipose tissue. Furthermore, autophagy can increase β-cell mass and functionality in the pancreas. This review provides a narrative summary of autophagy regulation with an emphasis on the intricate connection between autophagy and T2DM symptoms. It also discusses the therapeutic potentials of natural products with autophagy activation properties for the treatment of T2DM conditions. Our findings suggest that autophagy activation represents an innovative approach of treating T2DM.

Endoplasmic Reticulum Stress and Its Impact on Adipogenesis: Molecular Mechanisms Implicated

Endoplasmic reticulum (ER) stress plays a pivotal role in adipogenesis, which encompasses the differentiation of adipocytes and lipid accumulation. Sustained ER stress has the potential to disrupt the signaling of the unfolded protein response (UPR), thereby influencing adipogenesis. This comprehensive review illuminates the molecular mechanisms that underpin the interplay between ER stress and adipogenesis. We delve into the dysregulation of UPR pathways, namely, IRE1-XBP1, PERK and ATF6 in relation to adipocyte differentiation, lipid metabolism, and tissue inflammation. Moreover, we scrutinize how ER stress impacts key adipogenic transcription factors such as proliferator-activated receptor γ (PPARγ) and CCAAT-enhancer-binding proteins (C/EBPs) along with their interaction with other signaling pathways. The cellular ramifications include alterations in lipid metabolism, dysregulation of adipokines, and aged adipose tissue inflammation. We also discuss the potential roles the molecular chaperones cyclophilin A and cyclophilin B play in adipogenesis. By shedding light on the intricate relationship between ER stress and adipogenesis, this review paves the way for devising innovative therapeutic interventions.

Neuroinflammation-Modulating Agent SB1617 Enhances LC3-Associated Phagocytosis to Mitigate Tau Pathology

Tau protein aggregation and propagation in neurons and surrounding microglia are well-known risk factors for neurodegenerative diseases. Therefore, emerging therapeutic strategies that target neuroinflammatory activity in microglia have the potential to prevent tauopathy. Here, we explored the microglia-mediated neuroprotective function of SB1617 against tau aggregation. Our study revealed that SB1617-inactivated pathogenic M1-like microglia, reduced the secretion of pro-inflammatory cytokines via translational regulation, and induced microglial polarization toward the M2 phenotype and phagocytic function. Furthermore, we observed that extracellular pathogenic tau aggregates were eliminated via LC3-associated phagocytosis. The in vivo efficacy of SB1617 was confirmed in mice with traumatic brain injury in which SB1617 exerted neuroprotective effects by reducing pathogenic tau levels through microglia-mediated anti-inflammatory activity. Our results indicated that SB1617-mediated microglial surveillance with LC3-associated phagocytosis is a critical molecular mechanism in the regulation of tau proteostasis. This study provides new insights into tauopathies and directions for developing novel therapies for neurodegenerative diseases.

Sustained hyperglycemia specifically targets translation of mRNAs for insulin secretion

Pancreatic β cells are specialized for coupling glucose metabolism to insulin peptide production and secretion. Acute glucose exposure robustly and coordinately increases translation of proinsulin and proteins required for secretion of mature insulin peptide. By contrast, chronically elevated glucose levels that occur during diabetes impair β cell insulin secretion and have been shown experimentally to suppress insulin translation. Whether translation of other genes critical for insulin secretion is similarly downregulated by chronic high glucose is unknown. Here, we used high-throughput ribosome profiling and nascent proteomics in MIN6 insulinoma cells to elucidate the genome-wide impact of sustained high glucose on β cell mRNA translation. Before induction of ER stress or suppression of global translation, sustained high glucose suppressed glucose-stimulated insulin secretion and downregulated translation of not only insulin, but also mRNAs related to insulin secretory granule formation, exocytosis, and metabolism-coupled insulin secretion. Translation of these mRNAs was also downregulated in primary rat and human islets following ex vivo incubation with sustained high glucose and in an in vivo model of chronic mild hyperglycemia. Furthermore, translational downregulation decreased cellular abundance of these proteins. Our study uncovered a translational regulatory circuit during β cell glucose toxicity that impairs expression of proteins with critical roles in β cell function.

Characterizing the extracellular vesicle proteomic landscape of the human airway using in vitro organotypic multi-cellular models

Extracellular vesicle (EV)-mediated intercellular communication significantly influences pulmonary cell health and disease, yet in vitro methods to investigate these mechanisms are limited. We hypothesize that organotypic models of the airway can be leveraged to investigate EV-mediated intercellular signaling, focusing on EV proteomic content as a case study. Two in vitro airway culture models were evaluated by mass spectrometry-based proteomics analysis: a tri-culture model consisting of alveolar epithelial, fibroblast, and lung microvascular endothelial cells and a co-culture model of alveolar epithelial and fibroblasts. EVs isolated from the tri-culture model were enriched with EV proteins regulating RNA-to-protein translation. EVs isolated from the co-culture model were enriched with EV biogenesis and extracellular matrix signaling proteins. These model-specific differences suggest that different pulmonary cell types uniquely affect EV composition and the biological pathways influenced by the EV proteome in recipient cells. These findings can inform future studies surrounding EV-related pulmonary disease pathogenesis and therapeutics.

Nrf2: Therapeutic target of islet function protection in diabetes and islet transplantation

Nuclear factor-erythroid 2-related factor 2 (Nrf2) has been reported as a major intracellular regulator of antioxidant stress, notably in islet β cells with low antioxidant enzyme content. Nrf2 is capable of regulating antioxidant function, while it can also regulate insulin secretion, proliferation, and differentiation of β cells, ER stress, as well as mitochondrial function. Thus, Nrf2 pharmacological activators have been employed in the laboratory for the treatment of diabetic mice. Islet cells are exposed to oxidative environment when islet is being transplanted. Accordingly, less than 50% of islet cells are well transplanted, and their normal function is maintained. The pharmacological activation of Nrf2 has been confirmed to protect islet cells at different stages of transplantation stages during experiments for islet transplantation.

Sustained hyperglycemia specifically targets translation of mRNAs for insulin secretion

Pancreatic β-cells are specialized for coupling glucose metabolism to insulin peptide production and secretion. Acute glucose exposure robustly and coordinately increases translation of proinsulin and proteins required for secretion of mature insulin peptide. By contrast, chronically elevated glucose levels that occur during diabetes impair β-cell insulin secretion and have been shown experimentally to suppress insulin translation. Whether translation of other genes critical for insulin secretion are similarly downregulated by chronic high glucose is unknown. Here, we used high-throughput ribosome profiling and nascent proteomics in MIN6 insulinoma cells to elucidate the genome-wide impact of sustained high glucose on β-cell mRNA translation. Prior to induction of ER stress or suppression of global translation, sustained high glucose suppressed glucose-stimulated insulin secretion and downregulated translation of not only insulin, but also of mRNAs related to insulin secretory granule formation, exocytosis, and metabolism-coupled insulin secretion. Translation of these mRNAs was also downregulated in primary rat and human islets following ex-vivo incubation with sustained high glucose and in an in vivo model of chronic mild hyperglycemia. Furthermore, translational downregulation decreased cellular abundance of these proteins. Our findings uncover a translational regulatory circuit during β-cell glucose toxicity that impairs expression of proteins with critical roles in β-cell function.

DSCC1 interacts with HSP90AB1 and promotes the progression of lung adenocarcinoma via regulating ER stress

Lung cancer is a leading cause of cancer-related deaths, and the most common type is lung adenocarcinoma (LUAD). LUAD is frequently diagnosed in people who never smoked, patients are always diagnosed at advanced inoperable stages, and the prognosis is ultimately poor. Thus, there is an urgent need for the development of novel targeted therapeutics to suppress LUAD progression. In this study, we demonstrated that the expression of DNA replication and sister chromatid cohesion 1 (DSCC1) was higher in LUAD samples than normal tissues, and the overexpression of DSCC1 or its coexpressed genes were highly correlated with poor outcomes of LUAD patients, highlighting DSCC1 might be involved in LUAD progression. Furthermore, the expression of DSCC1 was positively correlated with multiple genetic mutations which drive cancer development, including TP53, TTN, CSMD, and etc. More importantly, DSCC1 could promote the cell proliferation, stemness, EMT, and metastatic potential of LUAD cells. In addition, DSCC1 interacted with HSP90AB1 and promoted the progression of LUAD via regulating ER stress. Meanwhile, DSCC1 expression negatively correlated with immune cell infiltration in lung cancer, and DSCC1 positively regulated the expression of PD-L1 in LUAD cells. Collectively, this study revealed that DSCC1 is a novel therapeutic target to treat LUAD and a biomarker for predicting the efficiency of PD-1/PD-L1 blockade treatment.

Inferring regulators of cell identity in the human adult pancreas

Cellular identity during development is under the control of transcription factors that form gene regulatory networks. However, the transcription factors and gene regulatory networks underlying cellular identity in the human adult pancreas remain largely unexplored. Here, we integrate multiple single-cell RNA-sequencing datasets of the human adult pancreas, totaling 7393 cells, and comprehensively reconstruct gene regulatory networks. We show that a network of 142 transcription factors forms distinct regulatory modules that characterize pancreatic cell types. We present evidence that our approach identifies regulators of cell identity and cell states in the human adult pancreas. We predict that HEYL, BHLHE41 and JUND are active in acinar, beta and alpha cells, respectively, and show that these proteins are present in the human adult pancreas as well as in human induced pluripotent stem cell (hiPSC)-derived islet cells. Using single-cell transcriptomics, we found that JUND represses beta cell genes in hiPSC-alpha cells. BHLHE41 depletion induced apoptosis in primary pancreatic islets. The comprehensive gene regulatory network atlas can be explored interactively online. We anticipate our analysis to be the starting point for a more sophisticated dissection of how transcription factors regulate cell identity and cell states in the human adult pancreas.

FoxM1 coordinates cell division, protein synthesis, and mitochondrial activity in a subset of β cells during acute metabolic stress

Pancreatic β cells display functional and transcriptional heterogeneity in health and disease. The sequence of events leading to β cell heterogeneity during metabolic stress is poorly understood. Here, we characterize β cell responses to early metabolic stress in vivo by employing RNA sequencing (RNA-seq), assay for transposase-accessible chromatin with sequencing (ATAC-seq), single-cell RNA-seq (scRNA-seq), chromatin immunoprecipitation sequencing (ChIP-seq), and real-time imaging to decipher temporal events of chromatin remodeling and gene expression regulating the unfolded protein response (UPR), protein synthesis, mitochondrial function, and cell-cycle progression. We demonstrate that a subpopulation of β cells with active UPR, decreased protein synthesis, and insulin secretary capacities is more susceptible to proliferation after insulin depletion. Alleviation of endoplasmic reticulum (ER) stress precedes the progression of the cell cycle and mitosis and ensures appropriate insulin synthesis. Furthermore, metabolic stress rapidly activates key transcription factors including FoxM1, which impacts on proliferative and quiescent β cells by regulating protein synthesis, ER stress, and mitochondrial activity via direct repression of mitochondrial-encoded genes.

Reversing pancreatic β-cell dedifferentiation in the treatment of type 2 diabetes

The maintenance of glucose homeostasis is fundamental for survival and health. Diabetes develops when glucose homeostasis fails. Type 2 diabetes (T2D) is characterized by insulin resistance and pancreatic β-cell failure. The failure of β-cells to compensate for insulin resistance results in hyperglycemia, which in turn drives altered lipid metabolism and β-cell failure. Thus, insulin secretion by pancreatic β-cells is a primary component of glucose homeostasis. Impaired β-cell function and reduced β-cell mass are found in diabetes. Both features stem from a failure to maintain β-cell identity, which causes β-cells to dedifferentiate into nonfunctional endocrine progenitor-like cells or to trans-differentiate into other endocrine cell types. In this regard, one of the key issues in achieving disease modification is how to reestablish β-cell identity. In this review, we focus on the causes and implications of β-cell failure, as well as its potential reversibility as a T2D treatment.