Circulating TRB3 and GRP78 levels in type 2 diabetes patients: crosstalk between glucose homeostasis and endoplasmic reticulum stress

Establishment and Characterization of Hepatocyte Line from Turbot (Scophthalmus maximus L.) and Its Application in the Study of Glucose Metabolism

The present study was to establish a hepatocyte line and investigate its role in glucose metabolism. A continuous cell line, THL (turbot hepatocyte line), was established from the liver tissue of turbot (Scophthalmus maximus L.). It has been successfully passaged more than 60 generations. The THL cells showed an epithelial-like morphology and the normal chromosome number was 44. Different methods were used to identify the hepatocytes. Periodic acid-Schiff (PAS) staining for THL cells was positive, and two key functional proteins of hepatocytes, cytokeratin- 18 (CK- 18) and albumin (ALB), were detected in THL cells. The results of CCK- 8 indicated that a medium containing 15 mM glucose showed optimal cell viability of THL. Conversely, elevating glucose concentrations beyond 50 mM markedly impaired THL cell viability. Western blot and qRT-PCR were employed to assess the gene and protein expression in cells treated with varying concentrations of glucose. The results of cells incubated with 0 mM, 15 mM, and 50 mM glucose concentrations showed that compared with the 0 mM glucose group, 15 mM glucose could increase the gene expression of glucokinase (gk) and decrease the gene expression of cytosolic phosphoenolpyruvate carboxykinase (cpepck), mitochondrial phosphoenolpyruvate (mpepck), glucose- 6-phosphatase 1 (g6pase1), forkhead box o1 (foxo1), and glucose-regulated protein 78 (grp78). Compared to 15 mM glucose treatment, the expression of gk in the 50 mM group was significantly decreased, but the expression of cpepck, mpepck, g6pase1, foxo1, and grp78 was significantly increased. Moreover, the protein expression of FoxO1 and GRP78 in 50 mM treatment group was significantly increased compared to that in the15 mM group. In the present study, it was found that excessive glucose level can activate the pathways of FoxO1-mediated gluconeogenesis and GRP78-mediated endoplasmic reticulum stress and reduce the glycolytic pathway, thus disrupting the glucose homeostasis in hepatocytes.

Adipose tissue-derived microRNA-450a-5p induces type 2 diabetes mellitus by downregulating DUSP10

Type 2 diabetes mellitus (T2DM) has rapidly increased worldwide, emerging as the fifth leading cause of death. The treatment of T2DM is challenging due to the side effects of oral hypoglycemic drugs and the limited efficacy of long-term insulin therapy, which can lead to insulin resistance (IR). Consequently, there is significant in discovering new drugs that have minimal side effects and a pronounced hypoglycemic effect. In obesity, microRNA levels have been implicated in glucose metabolism disorders and T2DM, although many aspects remain unresolved. Here, we confirmed that visceral adipose tissue and serum microRNA-450a-5p content increased under obesity and T2DM, and it was significantly positively associated with fasting blood glucose, triglycerides, cholesterol, low-density lipoproteins-cholesterol levels of the subjects. In high-fat diet (HFD)-induced obese mice, microRNA-450a-5p expression was increased in the serum, liver, and white adipose tissue. Moreover, the adipose Dicer-knockout mouse model was constructed to identify adipose tissue as the main source of microRNA-450a-5p. microRNA-450a-5p could inactivate the insulin signal pathway by targeting the inhibited Dual Specificity Phosphatase 10 (DUSP10) and inducing IR and glucose metabolism disorders in vitro cultured hepatocytes and adipocytes. Additionally, microRNA-450a-5p was found to regulate DUSP10 expression and insulin signaling activity, influencing glucose tolerance and insulin sensitivity across various models, including normal diet, HFD-induced obese, adipose tissue-specific microRNA-450a-5p-knockout, and db/db mice. Furthermore, gallic acid might play a potential role in inhibiting glucose levels by decreasing microRNA-450a-5p expression. Thus, microRNA-450a-5p emerges as an attractive therapeutic target for addressing obesity, IR, and T2DM.

Relevant Serum Endoplasmic Reticulum Stress Biomarkers in Type 2 Diabetes and Its Complications: A Systematic Review and Meta-Analysis

Endoplasmic reticulum stress (ERS) is activated in all cells by stressors such as hyperglycemia. However, it remains unclear which specific serum biomarkers of ERS are consistently altered in type 2 diabetes (T2D). We aimed to identify serum ERS biomarkers that are consistently altered in T2D and its complications, and their correlation with metabolic and anthropometric variables. We performed a systematic review and meta-analysis following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-Analyses and Systematic Reviews of Observational Studies (MOOSE). The risk of bias was assessed using the Newcastle-Ottawa scale. Random-effects models weighted by the inverse variance were employed to estimate the standardized mean difference and correlations as effect size measures. Indicators of heterogeneity and meta-regressions were evaluated. Of the 1206 identified studies, 22 were finally included, representing 11,953 subjects (2224 with T2D and 9992 non-diabetic controls). Most studies were of high quality. Compared with controls, subjects with T2D had higher circulating levels of heat shock protein 70 (HSP70; SMD: 2.30, 95% CI 1.13-3.46; p < 0.001) and secretagogin (SMD: 0.60, 95%CI 0.19-1.01; p < 0.001). They also had higher serum levels of peroxiredoxin-1, -2, -4, and -6. Secretagogin inversely correlated with HOMA-IR, yet positively correlated with HOMA-B, HbA1c, and FPG. PRX4 negatively correlated with HbA1c and FPG, while HSP70 positively correlated with HbA1c. In conclusion, six ERS biomarkers are consistently elevated in human T2D and correlate with glycemic control, insulin resistance, and β-cell function. Emerging evidence links serum ERS biomarkers to diabetes complications, but further research should evaluate their prognostic implications.

Associations of Placental Inflammation and Oxidative Stress Biomarkers with Glucolipid Metabolism in Children: A Birth Cohort Study in China

BACKGROUND

The maternal intrauterine immune environment may affect offspring long-term health. We aimed to investigate the association between the intrauterine placental immunological milieu and glycolipid metabolic health in children.

METHODS AND RESULTS

This study enrolled 1803 mother-child pairs from the Ma'anshan birth cohort (2013-2014). Placental mRNA expression of inflammatory cytokines (interleukin-1β [IL-1β], IL-10, monocyte chemoattractant protein-1, tumor necrosis factor-α, IL-4, IL-6, IL-8, C-reactive protein, and interferon-γ) and oxidative stress biomarkers (heme oxygenase-1, hypoxia-inducible factor-1alpha, and glucose-related protein 78) was quantified using real-time quantitative polymerase chain reaction. Fasting blood glucose, insulin, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total cholesterol were assessed at 5 to 6 years old. Statistical analyses included multiple linear regression, binary logistic regression, restricted cubic spline model, and the Bayesian kernel machine regression model. Placental inflammatory cytokines (IL-1β, monocyte chemoattractant protein-1, C-reactive protein, IL-6, IL-8, IL-10) and oxidative stress biomarkers (heme oxygenase-1, hypoxia-inducible factor-1alpha, glucose-related protein 78) showed positive associations with children's fasting blood glucose levels. Heme oxygenase-1 and glucose-related protein 78 exhibited negative correlations with children's fasting insulin levels. Elevated IL-6, heme oxygenase-1, hypoxia-inducible factor-1alpha, and glucose-related protein 78 were associated with increased risk of prediabetes in children. Overall upregulation of placental proinflammatory cytokines and oxidative stress factors mRNA expression correlated with higher prediabetes risk in children. Bayesian kernel machine regression analysis indicated a joint positive effect of the 12 placental inflammation and oxidative stress mixtures on children's risk of high fasting blood glucose.

CONCLUSIONS

This exploratory study underscores significant correlations between maternal intrauterine placental inflammation, oxidative stress markers, and offspring fasting blood glucose and insulin levels. These findings highlight the potential role of intrauterine holistic immunity in shaping offspring glucose metabolism health.

Potential Effects of Hyperglycemia on SARS-CoV-2 Entry Mechanisms in Pancreatic Beta Cells

The COVID-19 pandemic has revealed a bidirectional relationship between SARS-CoV-2 infection and diabetes mellitus. Existing evidence strongly suggests hyperglycemia as an independent risk factor for severe COVID-19, resulting in increased morbidity and mortality. Conversely, recent studies have reported new-onset diabetes following SARS-CoV-2 infection, hinting at a potential direct viral attack on pancreatic beta cells. In this review, we explore how hyperglycemia, a hallmark of diabetes, might influence SARS-CoV-2 entry and accessory proteins in pancreatic β-cells. We examine how the virus may enter and manipulate such cells, focusing on the role of the spike protein and its interaction with host receptors. Additionally, we analyze potential effects on endosomal processing and accessory proteins involved in viral infection. Our analysis suggests a complex interplay between hyperglycemia and SARS-CoV-2 in pancreatic β-cells. Understanding these mechanisms may help unlock urgent therapeutic strategies to mitigate the detrimental effects of COVID-19 in diabetic patients and unveil if the virus itself can trigger diabetes onset.

The role of endoplasmic reticulum-mitochondria-associated membranes in diabetic kidney disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease worldwide. The pathomechanisms of DKD are multifactorial, yet haemodynamic and metabolic changes in the early stages of the disease appear to predispose towards irreversible functional loss and histopathological changes. Recent studies highlight the importance of endoplasmic reticulum-mitochondria-associated membranes (ER-MAMs), structures conveying important cellular homeostatic and metabolic effects, in the pathology of DKD. Disruption of ER-MAM integrity in diabetic kidneys is associated with DKD progression, but the regulation of ER-MAMs and their pathogenic contribution remain largely unknown. Exploring the cell-specific components and dynamic changes of ER-MAMs in diabetic kidneys may lead to the identification of new approaches to detect and stratify diabetic patients with DKD. In addition, these insights may lead to novel therapeutic approaches to target and/or reverse disease progression. In this review, we discuss the association of ER-MAMs with key pathomechanisms driving DKD such as insulin resistance, dyslipidaemia, ER stress, and inflammasome activation and the importance of further exploration of ER-MAMs as diagnostic and therapeutic targets in DKD.

Integration of dietary nutrition and TRIB3 action into diabetes mellitus

Despite intensive studies for decades, the common mechanistic correlations among the underlying pathology of diabetes mellitus (DM), its complications, and effective clinical treatments remain poorly characterized. High-quality diets and nutrition therapy have played an indispensable role in the management of DM. More importantly, tribbles homolog 3 (TRIB3), a nutrient-sensing and glucose-responsive regulator, might be an important stress-regulatory switch, linking glucose homeostasis and insulin resistance. Therefore, this review aimed to introduce the latest research progress on the crosstalk between dietary nutrition intervention and TRIB3 in the development and treatment of DM. This study also summarized the possible mechanisms involved in the signaling pathways of TRIB3 action in DM, in order to gain an in-depth understanding of dietary nutrition intervention and TRIB3 in the pathogenesis of DM at the organism level.

Cell surface GRP78: A potential therapeutic target for high glucose-induced endothelial injury

Endothelial cell inflammation and oxidative stress are critical to developing diabetic vascular complications. GRP78 translocation to the cell surface has been observed in different types of endothelial cells, but the potential role of cell surface GRP78 in modulating endothelial inflammation and oxidative stress remains uncertain. In this study, we investigated whether inhibiting cell surface GRP78 function using a novel anti-GRP78 monoclonal antibody (MAb159) could suppress high glucose (HG)-induced endothelial inflammation and oxidative stress. Our findings demonstrated that the expression of cell surface GRP78 was increased in HG-treated HUVECs. Inhibition of cell surface GRP78 using MAb159 attenuated HG-induced endothelial injury, inflammation and oxidative stress, while activation of GRP78 by recombinant GRP78 further amplified HG-induced endothelial damage, inflammation and oxidative stress. Additionally, we discovered that cell surface GRP78 promoted HG-induced inflammation and oxidative stress by activating the TLR4/NF-κB signalling pathway. Moreover, HG-induced GRP78 translocation to the cell surface is dependent on ER stress. Our data demonstrate that targeting cell surface GRP78 could be a promising therapeutic strategy for mitigating endothelial injury, inflammation and oxidative stress.

COVID-19, Obesity, and GRP78: Unraveling the Pathological Link

The coronavirus disease 2019 (COVID-19) pandemic, driven by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to an unprecedented global surge in infections and fatalities. Notably, obesity has emerged as an important susceptibility factor for COVID-19; however, the pathological mechanisms for this remain poorly understood. Recent studies proposed a role for glucose-regulated protein 78 (GRP78), a protein implicated in both obesity and metabolic syndrome, which may function as a binding partner and/or co-receptor for SARS-CoV-2. Given its crucial involvement in diverse biological processes, GRP78 likely plays a major role in multiple facets of the viral life cycle and the pathology of COVID-19. This perspective review discusses the potential contributions of GRP78 to the dynamics of SARS-CoV-2 infection and pathology, particularly in the context of obesity. The primary objective is to facilitate a deeper understanding of the pathogenesis of COVID-19. Through this exploration, we aim to illuminate the complex interactions underpinning the nexus of COVID-19, obesity, and GRP78, ultimately paving the way for informed therapeutic strategies and preventive measures.

Unveiling the dark side of glucose-regulated protein 78 (GRP78) in cancers and other human pathology: a systematic review

Glucose-Regulated Protein 78 (GRP78) is a chaperone protein that is predominantly expressed in the lumen of the endoplasmic reticulum. GRP78 plays a crucial role in protein folding by assisting in the assembly of misfolded proteins. Under cellular stress conditions, GRP78 can translocate to the cell surface (csGRP78) were it interacts with different ligands to initiate various intracellular pathways. The expression of csGRP78 has been associated with tumor initiation and progression of multiple cancer types. This review provides a comprehensive analysis of the existing evidence on the roles of GRP78 in various types of cancer and other human pathology. Additionally, the review discusses the current understanding of the mechanisms underlying GRP78's involvement in tumorigenesis and cancer advancement. Furthermore, we highlight recent innovative approaches employed in downregulating GRP78 expression in cancers as a potential therapeutic target.

Differentially Expressed Genes Regulating Glutathione Metabolism, Protein-Folding, and Unfolded Protein Response in Pancreatic β-Cells in Type 2 Diabetes Mellitus

Impaired redox homeostasis in the endoplasmic reticulum (ER) may contribute to proinsulin misfolding and thus to activate the unfolded protein response (UPR) and apoptotic pathways, culminating in pancreatic β-cell loss and type 2 diabetes (T2D). The present study was designed to identify differentially expressed genes (DEGs) encoding enzymes for glutathione metabolism and their impact on the expression levels of genes regulating protein folding and UPR in β-cells of T2D patients. The GEO transcriptome datasets of β-cells of diabetics and non-diabetics, GSE20966 and GSE81608, were analyzed for 142 genes of interest using limma and GREIN software, respectively. Diabetic β-cells showed dataset-specific patterns of DEGs (FDR ≤ 0.05) implicated in the regulation of glutathione metabolism (ANPEP, PGD, IDH2, and CTH), protein-folding (HSP90AB1, HSP90AA1, HSPA1B, HSPA8, BAG3, NDC1, NUP160, RLN1, and RPS19BP1), and unfolded protein response (CREB3L4, ERP27, and BID). The GCLC gene, encoding the catalytic subunit of glutamate-cysteine ligase, the first rate-limiting enzyme of glutathione biosynthesis, was moderately down-regulated in diabetic β-cells from both datasets (p ≤ 0.05). Regression analysis established that genes involved in the de novo synthesis of glutathione, GCLC, GCLM, and GSS affect the expression levels of genes encoding molecular chaperones and those involved in the UPR pathway. This study showed for the first time that diabetic β-cells exhibit alterations in the expression of genes regulating glutathione metabolism, protein-folding, and UPR and provided evidence for the molecular crosstalk between impaired redox homeostasis and abnormal protein folding, underlying ER stress in type 2 diabetes.

Disturbance of neuron-microglia crosstalk mediated by GRP78 in Neuropsychiatric systemic lupus erythematosus mice

OBJECTIVES

Neuropsychiatric systemic lupus erythematosus (NPSLE) is a serious phenotype of systemic lupus erythematosus (SLE). The disturbance of neuron-microglia crosstalk is recently revealed in many neuropsychiatric diseases but was not well studied in NPSLE. We found glucose regulatory protein 78 (GRP78), a marker of endoplasmic reticulum stress, was significantly increased in the cerebrospinal fluid (CSF) of our NPSLE cohort. We, therefore, investigated whether GRP78 can act as a mediator between the neuron-microglia crosstalk and is involved in the pathogenic process of NPSLE.

METHODS

Serum and CSF parameters were analyzed in 22 NPSLE patients and controls. Anti-DWEYS IgG was injected intravenously into mice to establish a model of NPSLE. Behavioral assessment, histopathological staining, RNA-seq analyses, and biochemical assays were performed to examine the neuro-immunological alterations in the mice. Rapamycin was intraperitoneally administered to define the therapeutic effect.

RESULTS

The level of GRP78 was elevated significantly in the CSF of the patients with NPSLE. An increase in GRP78 expression, accompanied by neuroinflammation and cognitive impairment, was also found in the brain tissues of the NPSLE model mice induced by anti-DWEYS IgG deposition on hippocampal neurons. In vitro experiments demonstrated that anti-DWEYS IgG could stimulate neurons to release GRP78, which activated microglia via TLR4/MyD88/NFκB pathway to produce more pro-inflammatory cytokines and promote migration and phagocytosis. Rapamycin ameliorated GRP78-inducing neuroinflammation and cognitive impairment in anti-DWEYS IgG-transferred mice.

CONCLUSION

GRP78 acts as a pathogenic factor in neuropsychiatric disorders via interfering neuron-microglia crosstalk. Rapamycin may be a promising therapeutic candidate for NPSLE.

The beneficial effects of astragaloside IV on ameliorating diabetic kidney disease

Diabetic kidney disease (DKD) has become the major cause of chronic kidney disease or end-stage renal disease. There is still a need for innovative treatment strategies for preventing, arresting, treating, and reversing DKD, and a plethora of scientific evidence has revealed that Chinese herbal monomers can attenuate DKD in multiple ways. Astragaloside IV (AS-IV) is one of the active ingredients of Astragalus membranaceus and was selected as a chemical marker in the Chinese Pharmacopeia for quality control purposes. An increasing amount of studies indicate that AS-IV is a promising novel drug for the treatment of DKD. AS-IV has been shown to improve DKD by combating oxidative stress, attenuating endoplasmic reticulum stress, regulating calcium homeostasis, alleviating inflammation, improving vascular function, improving epithelial to mesenchymal transition and so on. This review briefly summarizes the pathogenesis of DKD, systematically reviews the mechanisms by which AS-IV improves DKD, and aims to facilitate related pharmacological research and development to promote the utilization of Chinese herbal monomers in DKD.

Bilirubin improves renal function by reversing the endoplasmic reticulum stress and inflammation in the kidneys of type 2 diabetic rats fed high-fat diet

Diabetic kidney disease (DKD), as a chronic diabetes-induced complication, is considered the most frequent leading cause of end-stage renal disease (ESRD). Regarding the observed protective effects of bilirubin, as a potential endogenous antioxidant/anti-inflammatory compound, against DKD progression, we planned to evaluate the effects of bilirubin administration on endoplasmic reticulum (ER) stress and inflammation in type 2 diabetic (T2D) rats fed high-fat diet (HFD). In this regard, thirty 8-week adult male Sprague Dawley rats were divided into five groups (n = 6). T2D and obesity were induced by streptozotocin (STZ) (35 mg/kg) and HFD (700 kcal/day), respectively. Bilirubin treatment was carried out for 6- and 14-week intervals (10 mg/kg/day), intraperitoneally. Then, the expression levels of ER stress-related genes (i.e. binding immunoglobulin protein (Bip), C/EBP homologous protein (Chop), and spliced x-box-binding protein 1 (sXbp1), as well as nuclear factor-κB (NF-κB) were analyzed using quantitative Real-time PCR experiments. Moreover, histopathological and stereological changes of kidney and its related structures were investigated for the studied rats. Bip, Chop, and NF-κB expression levels were significantly decreased under bilirubin treatment, while sXbp1 was up-regulated following the bilirubin administration. More interestingly, glomerular constructive damages seen in HFD-T2D rats, were considerably improved in the animals received bilirubin. Stereological assessments also revealed that bilirubin could desirably reverse the mitigation of kidney's total volume and its related structures, such as cortex, glomeruli, and convoluted tubules. Taken together, bilirubin has potential protective/ameliorative effects on DKD progression, especially through alleviating the renal ER stress and inflammatory responses in T2D rats with injured kidneys. In this era, clinical benefits of mild hyperbilirubinemia can be considered in human DKD.

Long non-coding RNAs TUG1 and MEG3 in patients with type 2 diabetes and their association with endoplasmic reticulum stress markers

BACKGROUND

Long non-coding RNAs (lncRNAs), including taurine upregulated gene 1 (TUG1), metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), and maternally expressed 3 (MEG3) play a regulatory role in endoplasmic reticulum (ER) stress. The present study aimed to investigate the expression of these lncRNAs in patients with type 2 diabetes and their association with biochemical and ER stress parameters.

MATERIALS AND METHODS

Participants included 57 patients with diabetes and 32 healthy individuals. Real-time PCR was performed to assess MALAT1, TUG1, MEG3, ATF4, and CHOP gene expression in peripheral blood mononuclear cells. Plasma GRP78, advanced glycation end products (AGEs), and insulin were measured using enzyme-linked immunosorbent assay (ELISA), and insulin resistance (IR) was calculated by the homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

The expression of TUG1, MEG3, ATF4, and CHOP genes was significantly increased in the patients with diabetes compared to healthy individuals. MALAT1 gene expression was also higher in patients group; although it did not reach significant levels. TUG1 and MEG3 expression revealed significant positive correlations with the indices of glycemic control, including FBS, HbA1c, HOMA-IR, and AGEs, as well as markers of ER stress. MALAT1 expression was also positively correlated with ATF4 and AGEs.

CONCLUSION

The expression levels of TUG1 and MEG3 lncRNAs were increased in patients with diabetes and were associated with glycemic control and components of ER stress. Thus, these lncRNAs might be considered appropriate markers to identify ER stress due to hyperglycemia.

The Role of ER Stress in Diabetes: Exploring Pathological Mechanisms Using Wolfram Syndrome

The endoplasmic reticulum (ER) is a cytosolic organelle that plays an essential role in the folding and processing of new secretory proteins, including insulin. The pathogenesis of diabetes, a group of metabolic disorders caused by dysfunctional insulin secretion (Type 1 diabetes, T1DM) or insulin sensitivity (Type 2 diabetes, T2DM), is known to involve the excess accumulation of "poorly folded proteins", namely, the induction of pathogenic ER stress in pancreatic β-cells. ER stress is known to contribute to the dysfunction of the insulin-producing pancreatic β-cells. T1DM and T2DM are multifactorial diseases, especially T2DM; both environmental and genetic factors are involved in their pathogenesis, making it difficult to create experimental disease models. In recent years, however, the development of induced pluripotent stem cells (iPSCs) and other regenerative technologies has greatly expanded research capabilities, leading to the development of new candidate therapies. In this review, we will discuss the mechanism by which dysregulated ER stress responses contribute to T2DM pathogenesis. Moreover, we describe new treatment methods targeting protein folding and ER stress pathways with a particular focus on pivotal studies of Wolfram syndrome, a monogenic form of syndromic diabetes caused by pathogenic variants in the WFS1 gene, which also leads to ER dysfunction.

GRP78 Activity Moderation as a Therapeutic Treatment against Obesity

Glucose-regulated protein 78 (GRP78), a molecular chaperone, is overexpressed in patients suffering from obesity, fatty liver, hyperlipidemia and diabetes. GRP78, therefore, can be not only a biomarker to predict the progression and prognosis of obesity and metabolic diseases but also a potential therapeutic target for anti-obesity treatment. In this paper, GRP78 inhibitors targeting its ATPase domain have been reviewed. Small molecules and proteins that directly bind GRP78 have been described. Putative mechanisms of GRP78 in regulating lipid metabolism were also summarized so as to investigate the role of GRP78 in obesity and other related diseases and provide a theoretical basis for the development and design of anti-obesity drugs targeting GRP78.

GRP78, a Novel Host Factor for SARS-CoV-2: The Emerging Roles in COVID-19 Related to Metabolic Risk Factors

The outbreak of coronavirus disease 19 (COVID-19), caused by the infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in an unprecedented amount of infection cases and deaths, leading to the global health crisis. Despite many research efforts, our understanding of COVID-19 remains elusive. Recent studies have suggested that cell surface glucose-regulated protein 78 (GRP78) acts as a host co-receptor for SARS-CoV-2 infection and is related to COVID-19 risks, such as older age, obesity, and diabetes. Given its significance in a wide range of biological processes, such as protein homeostasis and cellular signaling, GRP78 might also play an important role in various stages of the viral life cycle and pathology of SARS-CoV-2. In this perspective, we explore the emerging and potential roles of GRP78 in SARS-CoV-2 infection. Additionally, we discuss the association with COVID-19 risks and symptoms. We hope this review article will be helpful to understand COVID-19 pathology and promote attention and study of GRP78 from many clinical and basic research fields.

AGEs-Induced and Endoplasmic Reticulum Stress/Inflammation-Mediated Regulation of GLUT4 Expression and Atherogenesis in Diabetes Mellitus

In recent decades, complex and exquisite pathways involved in the endoplasmic reticulum (ER) and inflammatory stress responses have been demonstrated to participate in the development and progression of numerous diseases, among them diabetes mellitus (DM). In those pathways, several players participate in both, reflecting a complicated interplay between ER and inflammatory stress. In DM, ER and inflammatory stress are involved in both the pathogenesis of the loss of glycemic control and the development of degenerative complications. Furthermore, hyperglycemia increases the generation of advanced glycation end products (AGEs), which in turn refeed ER and inflammatory stress, contributing to worsening glycemic homeostasis and to accelerating the development of DM complications. In this review, we present the current knowledge regarding AGEs-induced and ER/inflammation-mediated regulation of the expression of GLUT4 (solute carrier family 2, facilitated glucose transporter member 4), as a marker of glycemic homeostasis and of cardiovascular disease (CVD) development/progression, as a leading cause of morbidity and mortality in DM.