Glucose-regulated Protein Research Articles

The Functions of SARS-CoV-2 Receptors in Diabetes-Related Severe COVID-19.

Angiotensin-converting enzyme 2 (ACE2) is considered a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor of high importance, but due to its non-ubiquitous expression, studies of other proteins that may participate in virus internalisation have been undertaken. To date, many alternative receptors have been discovered. Their functioning may provide an explanation for some of the events observed in severe COVID-19 that cannot be directly explained by the model in which ACE2 constitutes the central point of infection. Diabetes mellitus type 2 (T2D) can induce severe COVID-19 development. Although many mechanisms associated with ACE2 can lead to increased SARS-CoV-2 virulence in diabetes, proteins such as basigin (CD147), glucose-regulated protein 78 kDa (GRP78), cluster of differentiation 4 (CD4), transferrin receptor (TfR), integrins α5β1/αvβ3, or ACE2 co-receptors neuropilin 2 (NRP2), vimentin, and even syalilated gangliosides may also be responsible for worsening the COVID-19 course. On the other hand, some others may play protective roles. Understanding how diabetes-associated mechanisms can induce severe COVID-19 via modification of virus receptor functioning needs further extensive studies.

Polydatin ameliorates early brain injury after subarachnoid hemorrhage through up-regulating SIRT1 to suppress endoplasmic reticulum stress.

This study aims to investigate the inhibitory effect of Polydatin (PD) on endoplasmic reticulum (ER) stress following subarachnoid hemorrhage (SAH) and to elucidate the underlying mechanisms. A standard intravascular puncture model was established to mimic SAH in mice. Neurological functions were assessed using neurological scoring, Grip test, and Morris water maze. Brain edema and Evans blue extravasation were measured to evaluate blood-brain barrier permeability. Western blot and quantitative real-time polymerase chain reaction (PCR) analyses were performed to examine protein and mRNA expressions related to ER stress. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining was used to detect cell apoptosis, and transmission electron microscopy was used to observe the ultrastructure of the endoplasmic reticulum. The results indicated that PD significantly reduced brain edema and Evans blue extravasation after SAH, improving neurological function. Compared to the SAH group, the expression levels of ER stress-related proteins including glucose-regulated protein 78 (GRP78), phosphorylated protein kinase R-like endoplasmic reticulum kinase (p-PERK), phosphorylated eukaryotic initiation factor 2α (p-eIF2α), activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP), were significantly lower in the PD-treated group. Moreover, PD significantly enhances the protein expression of Sirtuin 1 (SIRT1). Validation with sh-SIRT1 confirmed the critical role of SIRT1 in ER stress, with PD's inhibitory effect on ER stress being dependent on SIRT1 expression. Additionally, PD attenuated ER stress-mediated neuronal apoptosis and SAH-induced ferroptosis through upregulation of SIRT1. PD alleviates ER stress following SAH by upregulating SIRT1 expression, thereby mitigating early brain injury. The protective effects of PD are mediated through SIRT1, which inhibits ER stress and reduces neuronal apoptosis and ferroptosis.

QRICH1 suppresses pediatric T-cell acute lymphoblastic leukemia by inhibiting GRP78

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy that commonly affects children and adolescents with a poor prognosis. The terminal unfolded protein response (UPR) is an emerging anti-cancer approach, although its role in pediatric T-ALL remains unclear. In our pediatric T-ALL cohort from different centers, a lower QRICH1 expression was found associated with a worse prognosis of pediatric T-ALL. Overexpression of QRICH1 significantly inhibited cell proliferation and stimulated apoptosis of T-ALL both in vitro and in vivo. Upregulation of QRICH1 significantly downregulated 78 KDa glucose-regulated protein (GRP78) and upregulated CHOP, thus activating the terminal UPR. Co-overexpression of GRP78 in T-ALL cells overexpressing QRICH1 partially reverted the inhibited proliferation and stimulated apoptosis. QRICH1 bound to the residues Asp212 and Glu155 of the nucleotide-binding domain (NBD) of GRP78, thereby inhibiting its ATP hydrolysis activity. In addition, QRICH1 was associated with endoplasmic reticulum (ER) stress in T-ALL, and overexpression of QRICH1 reversed drug resistance. Overall, low QRICH1 expression is an independent risk factor for a poor prognosis of pediatric T-ALL. By inhibiting GRP78, QRICH1 suppresses pediatric T-ALL.

P112 SUPPRESSION OF PROTEIN KINASE RNA-LIKE ENDOPLASMIC RETICULUM KINASE BY PROBIOTICS CIRCUMVENTS CARDIOVASCULAR RISK PROFILE IN EXPERIMENTALLY-INDUCED PCOS MODEL

Background and Objective: The global cause of death attributable to cardiovascular diseases (CVD). including in women of reproductive age is alarming. Individuals with PCOS usually present CVD as a long-term life-threatening effect of PCOS. Protein kinase RNA-like endoplasmic reticulum kinase (PERK) has been implicated in cardiomyopathy. However, its role in PCOS-induced CVD risk has not been established. Studies have shown that probiotics improves metabolic-related disorders. The present study was designed to investigate the role of PERK in CVD risk associated with PCOS in experimental rat model, and the therapeutic benefits of probiotics. Methods: Eight-week-old female Wistar rats were assigned into four groups (n=6). Polycystic ovarian syndrome was induced by uninterrupted administration of letrozole (1 mg/kg) for 21 days, thereafter, probiotics (2 x 107 CFU) was administered for 6 weeks. Gene expression, biochemical parameters and histological evaluations were performed with Western blot, ELISA, and H&E staining techniques Results: The present findings revealed that animals with PCOS were characterized with phenotypic features such as hyperandrogenemia and multiple cysts in the ovaries. In addition, PCOS rats manifested insulin resistance and increase in glucose regulatory protein (GRP78), together with increased levels of circulating corticosterone, cardiac triglyceride, inflammatory mediators (NF- kappaB/TNF-alpha), TGF-beta1, Caspase-6, and HDAC2, while a decrease in HIF-1alpha and NrF2 was observed when compared with control animals. These were accompanied by elevated expression of PERK. However, treatment with probiotics reversed these systemic, endocrine, metabolic and cardiac anomalies. Conclusion: The present study suggests that probiotics attenuates CVD risk profile in experimental PCOS rat model by suppression of PERK/HDAC2-dependent pathway.

Quercetin alleviates depressive-like behavior by modulating acetyl-H3K9 mediated ferroptosis pathway in hypothalamus of perimenopausal depression rat model

Perimenopausal depression is a subtype of depression and is prevalent among perimenopausal women, which has brought a heavy burden to family and society. The pathogenesis of perimenopausal depression is still unclear, which affects the prevention and treatment of perimenopausal depression to a certain extent. Quercetin is a flavonoid compound, and has estrogenic activity and pharmacological effects such as antioxidant, anti-inflammatory, and neuroprotective effects. This study investigated whether quercetin improved perimenopausal depression-like behaviors and potential mechanism. The results demonstrated that quercetin could alleviate the depression-like behaviors in perimenopausal depression rat model, inhibit astrocyte activation, improve ferroptosis-associated mitochondrial damage (such as mitochondrial pyknosis and mitochondrial cristae reduction) in hypothalamus, increase the expressions of histone 3 lysine 9 acetylation (acetyl-H3K9), ferroptosis-associated protein including glutathione peroxidase 4 (GPX4) and Xc- antiporter (SLC7A11), and reduce the expressions of endoplasmic reticulum stress-related proteins including inositol-requiring enzyme 1 (IRE1α), phosphorylated IRE1α (p-IRE1α), X-box binding protein 1 (XBP1) and glucose-regulated protein 78 (GRP78) in hypothalamus of perimenopausal depression rat model. Furtherly, in vitro study indicated that quercetin could restore histone acetylase (HAT)/histone deacetylase (HDAC) homeostasis through binding to estrogen receptors and increase the expression of acetyl-H3K9, inhibiting ferroptosis through IRE1α/XBP1 pathway in astrocytes of hypothalamus. Our findings demonstrated that acetyl-H3K9 is a crucial target in development of perimenopausal depression, and quercetin exhibited antidepressant effects through modulating acetyl-H3K9 mediated ferroptosis in perimenopausal depression. Quercetin might be the prevention and adjuvant treatment strategy of perimenopausal depression.

Synthetic and non-synthetic inhibition of ADAM10 and ADAM17 reduces inflammation and oxidative stress in LPS-induced acute kidney injury in male and female mice

Acute kidney injury (AKI) is a severe medical condition that can lead to illness and death. A disintegrin and metalloprotease (ADAM) protein family is a potential treatment target for AKI due to its involvement in inflammation, growth, and differentiation. While ADAM10 and ADAM17 have been identified as significant contributors to inflammation, it is unclear whether they play a critical role in AKI. In this study, we induced AKI in male and female mice using lipopolysaccharide, a bacterial endotoxin that causes inflammation and oxidative stress. The role of kaempferol, which is found in many natural products and known to have antioxidant and anti-inflammatory activity in many pre-clinical studies, was investigated through ADAM10/17 enzymes in AKI. We also investigated the efficacy of a selective synthetic inhibitor named GW280264X for ADAM10/17 inhibition in AKI. Blood urea nitrogen and creatinine levels were measured in serum, while tumor necrosis factor-α, vascular adhesion molecule, interleukin (IL)-1β, glucose regulatory protein-78, IL-10, nuclear factor κ-B, thiobarbituric acid reactive substances, total thiol, ADAM10, and ADAM17 levels were measured in kidney tissue. We also evaluated kidney tissue histologically using hematoxylin and eosin, periodic acid-schiff, and caspase-3 staining. This research demonstrates that GW280264X and kaempferol reduces inflammation and oxidative stress, as evidenced by biochemical and histopathological results in AKI through ADAM10/17 inhibition. These findings suggest that inhibiting ADAM10/17 may be a promising therapeutic approach for treating acute kidney injury.

In-silico Identification of citrus phytochemicals for chemical interaction of CotH of Mucor and human GRP78 receptor and its experimental verification through FTIR spectroscopy

After suffering from serious critical disease such as recent COVID-19 pandemic, secondary fungal infection (Specially Mucormycosis) has become a serious concern throughout the world. Glucose regulated protein 78 (GRP78) is a multifunctional protein which acts as a receptor in human body for spore Coat homolog (CotH) cell surface protein of Mucorales. The development of immunity with easily available plant products is vital and essential due to having less effect on other biological activities. Here, In-silico method has been employed to screen antifungal citrus phyto-chemicals through molecular docking with CotH and its ADMET study due its rapid and cost effective quality compared to the trial and error methods using experimental studies. Limonin and naringin have been selected as potential ligands due to having its low binding affinity and no risk factor as per Lipinski's rule of five and medicinal chemistry. Molecular interaction of naringin and limonin with CotH obtained by molecular docking shows better binding affinity of −8.7 and – 8.9 kcal/mol respectively. The binding of CotH-GRP78 complex (developed through protein-protein molecular docking) with limonin resists more in the spreading of Mucormycosis in comparison to naringin. The FTIR spectra of limonin-CotH and Naringin-CotH sample exhibits the evidences of hydrogen bond for the formation of both strong limonin-CotH and naringin-CotH complex assuring the development of immunity with citrus fruit containing limonin and naringin.

Evaluation of Endoplasmic Reticulum Stress in an Experimental Intestinal Ischemia-Reperfusion Model in Rats: The Role of Ozone Therapy and Trimetazidine.

The objective of the study was to assess the impact of ozone (O3) and trimetazidine on the intestines following ischemia-reperfusion (I/R) injury through the investigation of endoplasmic reticulum stress. Forty Sprague Dawley rats were separated into five groups. The groups were named as follows: control, O3, I/R, I/R + trimetazidine (TMZ), and I/R + O3. The control group had laparotomy and exploration of the superior mesenteric artery (SMA) only. Furthermore, alongside laparotomy and SMA exploration, an intraperitoneal (i.p.) administration of a 0.7 mg/kg ozone-oxygen (O3-O2) combination was given to the O3 group. In the experimental groups, the SMA was blocked with the silk suture ligation technique for a duration of 1 h and then restored to normal blood flow for another hour. In the I/R + O3 group, ozone was delivered i.p. at a dosage of 0.7 mg/kg, 30 min after ischemia. In the I/R + TMZ group, a dose of 20 mg/kg/day of trimetazidine was administered orally via gavage for a duration of 7 days, beginning 1 week prior to the induction of ischemia. Intestinal tissues were taken to assess indicators of intestinal mucosal injury and oxidative stress. The level of the lipid peroxidation marker malondialdehyde (MDA) was significantly reduced in the experimental groups as compared to the I/R group (p < 0.05). The experimental groups had considerably greater levels of glutathione (GSH), which reflects antioxidant capacity, compared to the I/R group (p < 0.05). Nevertheless, the concentration of GSH was observed to be increased in the I/R + O3 group in comparison to the I/R + TMZ group (p < 0.05). The histopathological damage score showed a substantial decrease in the experimental groups as compared to the I/R group (p < 0.05). The I/R + O3 group had the lowest injury score. The experimental groups exhibited significantly reduced positivity of the endoplasmic reticulum (ER) stress markers C/EBP homologous protein (CHOP) and glucose-regulated protein (GRP)-78 compared to the I/R group (p < 0.05). The findings provide evidence for the potential advantages of utilizing ozone therapy in the treatment of intestinal ischemia-reperfusion injury. Additionally, they propose that ozone should be assessed in more extensive clinical trials in the future as a therapeutic agent that can disrupt endoplasmic reticulum stress.

The renoprotective effects of cannabidiol on lipopolysaccharide-induced systemic inflammation model of rats.

Sepsis-induced renal damage poses a significant threat, necessitating effective therapeutic strategies. Cannabidiol (CBD) has beneficial effects on tissues and their functions by exhibiting antioxidant and anti-inflammatory effects. This study investigates the potential protective effects of CBD in mitigating lipopolysaccharide (LPS)-induced renal injury in Wistar Albino rats. Thirty-two Wistar Albino rats were categorized into control, LPS (5mg/kg i.p.), LPS + CBD, and CBD (5mg/kg i.p.) groups. After the experiment, samples were collected for biochemical, genetic, histopathological, and immunohistochemical analyses. Oxidative stress markers as total oxidant status (TOS) and total antioxidant status (TAS), oxidative stress index (OSI), superoxide dismutase (SOD), glutathione peroxidase (GPx), malondialdehyde (MDA), immune staining as tumor necrosis factor alpha (TNF-α), interleukin-10 (IL-10), caspase-3, gene expressions as nuclear factor erythroid 2-related factor 2 (NRF2), C/EBP homologous protein (CHOP), caspase-9, glucose-regulating protein 78 (GRP78), B-cell leukemia/lymphoma 2 (Bcl2), and tissue histology have been examined. The LPS-exposed group exhibited significant renal abnormalities, mitigated by CBD intervention in the LPS + CBD group. CBD reduced immunoexpression scores for TNF-α, caspase-3, and IL-10. Biochemically, CBD induced a positive shift in the oxidative balance, increasing TAS, SOD, and GPx, while decreasing TOS, OSI, and MDA levels. Genetic analyses highlighted CBD's regulatory impact on NRF2, CHOP, caspase-9, GRP78, and Bcl2, providing molecular insights into its protective role against LPS-induced renal damage. This study underscores CBD as a promising protective agent against sepsis-induced renal damage. Our findings could provide valuable insights into potential therapeutic avenues for addressing renal complications in sepsis.

BRD4 absence inactivates endoplasmic reticulum stress to retard dehydroepiandrosterone-triggered ovarian granular cell apoptosis in polycystic ovary syndrome via GRP78

Polycystic ovary syndrome (PCOS) is a hormonal disorder and significantly affects reproductive and metabolic function. Bromodomain-containing protein 4 (BRD4) is reported to promote ovarian fibrosis in PCOS. The present work was conducted to investigate the detailed role of BRD4 and the corresponding functional mechanism in PCOS. Functional experiments including CCK-8 method, EDU staining and TUNEL staining were used to detect the key cellular processes. Western blot examined the expression of BRD4, apoptosis- and endoplasmic reticulum stress (ERS)-associated proteins. HDOCK server predicted the binding of BRD4 with Glucose-Regulated Protein 78 (GRP78), which was validated by Co-IP assay. BRD4 expression was increased and ERS was activated in dehydroepiandrosterone (DHEA)-induced KGN cells. Inhibition of BRD4 improved the viability whereas it inhibited the apoptosis and ERS of KGN cells induced by DHEA. In addition, BRD4 bound to GRP78. GRP78 elevation or ERS activator tunicamycin (TM) partly abolished the impacts of BRD4 silencing on the ERS, proliferation and apoptosis in DHEA-treated KGN cells. Anyway, knockdown of BRD4 may reduce DHEA-induced ovarian granular cell damage in PCOS via inactivating GRP78-mediated ERS.

Dietary xylo-oligosaccharides alleviates LPS-induced intestinal injury via endoplasmic reticulum-mitochondrial system pathway in piglets.

The beneficial effects of xylo-oligosaccharides (XOS) on the intestine have been widely reported, including anti-inflammation, antioxidant, maintenance of intestinal epithelial barrier, and treatment of intestinal injury. However, the specific mechanism of XOS in mitigating intestinal injury in weaned piglets remains unclear. Therefore, this study aimed to explore the specific mechanism of XOS in mitigating intestinal injury. The study is a complete randomized design with 24 weaned piglets in a 2 × 2 factorial arrangement that includes diet treatments (basal diet vs 0.02% XOS) and immunological challenge [saline vs lipopolysaccharide (LPS)]. All piglets were fed a basal diet or a XOS diet for 21 days. On day 22, all piglets received an injection of LPS or saline. In this study, dietary XOS increased jejunal villus height, reduced crypt depth and oxidative stress, and enhanced the gene and protein expression of Claudin-1, Occludin, and zonula occludens 1 (P < 0.05). The piglets fed the XOS diet had lower serum Diamine oxidase activity and D-lactic acid content (P < 0.05). In addition, dietary XOS regulates endoplasmic reticulum (ER)-mitochondria system function and the expression of key molecules, including mitochondrial dynamics dysfunction [mitofusin (Mfn)-1, optic atrophy 1, fission 1, and dynamin-related protein 1], ER stress [activating transcription factor 4 (ATF4), ATF6, C/EBP homologous protein, eukaryotic initiation factor 2α, glucose-regulated protein (GRP) 78, GRP94 and protein kinase R-like ER kinase] and the mitochondria-associated ER membranes (MAM) disorders (Mfn2, GRP75 and voltage-dlependent anion channel 1) (P < 0.05). Therefore, the findings to indicate that dietary XOS is effective against LPS-induced jejunal injury may be attributed to its ability to alleviate mitochondrial dynamics dysfunction, ER stress, and MAM disorders.

Safflower Yellow Injection Alleviates Myocardial Ischemia/Reperfusion Injury by Reducing Oxidative and Endoplasmic Reticulum Stress.

Safflower yellow is an extract of the famous Chinese medicine Carthamus tinctorious L, and safflower yellow injection (SYI) is widely used clinically to treat angina pectoris. However, there are few studies on the anti-myocardial ischemia/reperfusion (I/R) injury effect of SYI, and its mechanisms are unclear. In the present study, we aimed to investigate the protective effect of SYI on myocardial I/R injury and explore its underlying mechanisms. Male Sprague Dawley rats were randomly divided into a control group, sham group, model group, and SYI group (20 mg/kg, femoral vein injection 1 h before modeling). The left anterior descending coronary artery was ligated to establish a myocardial I/R model. H9c2 cells were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) after incubation with 80 μg/mL SYI for 24 h. In vivo, TsTC, HE, and TUNEL staining were performed to evaluate myocardial injury and apoptosis. A kit was used to detect superoxide dismutase (SOD) and malondialdehyde (MDA) to assess oxidative stress. In vitro, flow cytometry was used to detect the reactive oxygen species (ROS) content and apoptosis rate. Protein levels were determined via Western blotting. Pretreatment with SYI significantly reduced infarct size and pathological damage in rat hearts and suppressed cardiomyocyte apoptosis in vivo and in vitro. In addition, SYI inhibited oxidative stress by increasing SOD activity and decreasing MDA content and ROS production. Myocardial I/R and OGD/R activate endoplasmic reticulum (ER) stress, as evidenced by increased expression of activating transcription factor 6 (ATF6), glucose-regulated protein 78 (GRP78), cysteinyl aspartate-specific proteinase caspase-12, and C/EBP-homologous protein (CHOP), which were all inhibited by SYI. SYI ameliorated myocardial I/R injury by attenuating apoptosis, oxidative damage, and ER stress, which revealed new mechanistic insights into its application.

Regulation of lipid metabolism in grass carpprimaryhepatocytes by exosomes derived from fatty hepatocytes though GRP78.

Exosomes regulate lipid metabolism by carrying miRNAs, nucleic acids, and proteins, thereby influencing the function of receptor cells. Glucose-regulated protein 78 (GRP78) is also involved in the regulation of lipid metabolism. However, it remains unclear whether exosomes derived from fatty hepatocytes (OA-Exo) regulate lipid metabolism through the enrichment of GRP78. In this study, we observed the expression of GRP78 was significantly increased in fatty hepatocytes (incubating hepatocytes with oleic acid (OA) for 24h) and OA-Exo (P < 0.05). In addition, OA-Exo (50μg/mL) and GRP78 protein (1μg/mL) significant increasedthe content of triacylglycerol (TG) and total cholesterol (TC), as well as up-regulatedthe expression of GRP78 and inositol-requiring enzyme-1alpha (IRE1α) protein (P < 0.05). We further used YUM70 (an inhibitor of GRP78) to inhibit endogenous GRP78, and compared with the YUM70 group, OA-Exo reversed the effect of YUM70 and increased the content of TG, TC, and the expression of GRP78 protein in hepatocytes (P < 0.05). Furthermore, the inhibition of the IRE1α pathway with 4μ8C resulted in a significant decrease in TG content compared to the control group (P < 0.05). However, when compared with the 4μ8C group, OA-Exo and GRP78 reversed the effect of 4μ8C and significantly increased TG content (P < 0.05). Taken together, these results indicated that OA-Exo activated IRE1α to promote lipid accumulation in hepatocytes through the enrichment of GRP78. This study provided a new perspective for further exploration of exosomal lipid metabolism in fish.

Glucose-Regulated Protein 78, via Releasing β-Catenin from Adherens Junctions, Facilitates Its Interaction with STAT3 in Mediating Retinal Neovascularization

Retinopathy due to neovascularization is one of the major causes of vision loss. To understand the mechanisms underlying retinal neovascularization, using the oxygen-induced retinopathy (OIR) model, we performed two-dimensional gel matrix-assisted laser desorption/ionization time-of-flight/time-of-flight analysis of normoxic and 24-hour post-OIR mice pups' retinas. Two-dimensional gel analysis revealed that glucose-regulated protein 78 (GRP78) is one of the several molecules induced by OIR in the retinal endothelial cells (ECs). Vascular endothelial growth factor A (VEGFA) also induced GRP78 expression independent of endoplasmic reticulum stress response in human retinal microvascular endothelial cells, and depletion of its levels reduced VEGFA-induced EC angiogenic responses. Consistent with these observations, EC-specific deletion of GRP78 inhibited OIR-induced retinal neovascularization. In exploring the mechanisms, we found that GRP78 binds with vascular endothelial-cadherin and releases adherens junction- but not Wnt-mediated β-catenin and that β-catenin, in turn, via interacting with STAT3, triggers cyclin D1 expression. Furthermore, depletion of β-catenin or cyclin D1 levels negated VEGFA-induced EC angiogenic responses and OIR-induced retinal neovascularization. EC-specific deletion of GRP78 also suppressed OIR-induced vascular leakage. In elucidating the upstream signaling, we found that activating transcription factor 6 mediates GRP78 induction in the modulation of VEGFA-induced EC angiogenic responses and OIR-induced retinal neovascularization. Together, these observations reveal that GRP78, independent of its response to endoplasmic reticulum stress, is involved in mediating EC angiogenic responses by VEGFA and retinal neovascularization by OIR. In view of these findings, it appears that GRP78 could be a desirable target for drug development against diabetic retinopathy.

Small molecules targeting GRP78 mitigate anti-GRP78 autoantibody–mediated tissue factor procoagulant activity in cultured endothelial cells

BackgroundThe 78-kDa glucose-regulated protein (GRP78) expressed on the cell surface (csGRP78) has been reported to regulate tissue factor (TF) procoagulant activity (PCA) in lesion-resident endothelial cells (ECs), which is further enhanced by circulating anti-GRP78 autoantibodies that bind to the Leu98-Leu115 epitope in GRP78. ObjectivesDetermine the effects of the engagement of the anti-GRP78 autoantibody to csGRP78 on ECs and the underlying mechanisms that impact TF PCA. MethodsImmunofluorescent staining was used to determine the presence of csGRP78 in tumor necrosis factor α–treated ECs. An established TF PCA assay was used to evaluate human ECs following treatment with anti-GRP78 autoantibodies. The Fura 2-AM assay (Abcam) was used to quantify changes in intracellular Ca2+ levels. Small molecules predicted to bind GRP78 were identified using artificial intelligence. Enzyme-linked immunosorbent assays were used to assess the ability of these GRP78 binders to mitigate TF activity and interfere with the autoantibody/csGRP78 complex. ResultsIn tumor necrosis factor α–treated ECs, anti-GRP78 autoantibodies increased TF PCA. This observation was further enhanced by endoplasmic reticulum stress-induced elevation of csGRP78 levels. Anti-GRP78 autoantibody treatment increased intracellular Ca2+ levels. Sequestering the anti-GRP78 autoantibody with a conformational peptide or blocking with heparin attenuated anti-GRP78 autoantibody–induced TF PCA. We identified B07∗, as a GRP78 binder that diminished anti-GRP78 autoantibody–induced TF PCA on ECs. ConclusionThese findings show how anti-GRP78 autoantibodies enhance TF PCA that contributes to thrombosis and identify novel GRP78 binders that represent a potential novel therapeutic strategy for treating and managing atherothrombotic disease.

PDZD8 Augments Endoplasmic Reticulum-Mitochondria Contact and Regulates Ca2+ Dynamics and Cypd Expression to Induce Pancreatic β-Cell Death during Diabetes.

Diabetes mellitus (DM) is a chronic metabolic disease that poses serious threats to human physical and mental health worldwide. The PDZ domain-containing 8 (PDZD8) protein mediates mitochondria-associated endoplasmic reticulum (ER) membrane (MAM) formation in mammals. We explored the role of PDZD8 in DM and investigated its potential mechanism of action. High-fat diet (HFD)- and streptozotocin-induced mouse DM and palmitic acid (PA)-induced insulin 1 (INS-1) cell models were constructed. PDZD8 expression was detected using immunohistochemistry, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blotting. MAM formation, interactions between voltage-dependent anion-selective channel 1 (VDAC1) and inositol 1,4,5-triphosphate receptor type 1 (IP3R1), pancreatic β-cell apoptosis and proliferation were detected using transmission electron microscopy (TEM), proximity ligation assay (PLA), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, immunofluorescence staining, and Western blotting. The mitochondrial membrane potential, cell apoptosis, cytotoxicity, and subcellular Ca2+ localization in INS-1 cells were detected using a JC-1 probe, flow cytometry, and an lactate dehydrogenase kit. PDZD8 expression was up-regulated in the islets of HFD mice and PA-treated pancreatic β-cells. PDZD8 knockdown markedly shortened MAM perimeter, suppressed the expression of MAM-related proteins IP3R1, glucose-regulated protein 75 (GRP75), and VDAC1, inhibited the interaction between VDAC1 and IP3R1, alleviated mitochondrial dysfunction and ER stress, reduced the expression of ER stress-related proteins, and decreased apoptosis while increased proliferation of pancreatic β-cells. Additionally, PDZD8 knockdown alleviated Ca2+ flow into the mitochondria and decreased cyclophilin D (Cypd) expression. Cypd overexpression alleviated the promoting effect of PDZD8 knockdown on the apoptosis of β-cells. PDZD8 knockdown inhibited pancreatic β-cell death in DM by alleviated ER-mitochondria contact and the flow of Ca2+ into the mitochondria.

Mechanism of acupuncture and moxibustion in ameliorating liver injury induced by cisplatin by regulating IRE-1 signaling pathway.

To investigate the mechanism of the effect of acupuncture and moxibustion on improving liver injury in cisplatin (DDP) induced liver injury model mice by observing the changes of inositol-requiring enzyme (IRE) -1 signaling pathway. Forty KM mice were randomly divided into control, model, acupuncture and moxibustion groups, with 10 mice in each group. The liver injury model was replicated by intraperitoneal injection of DDP (10 mg/kg). In the acupuncture group and the moxibustion group, acupuncture and moxibustion were performed at "Dazhui"(GV14), and bilateral "Ganshu"(BL18), "Shenshu" (BL23), and "Zusanli"(ST36), respectively for 6 min, once per day for 7 d. The apoptosis of hepatocytes was detected by TUNEL staining. The expression of phosphorylation(p)-IRE-1α, glucose-regulated protein (Grp) 78 and cysteine aspartic protease (Caspase) -12 in liver tissue were detected by immunohistochemistry and Western blot, respectively. The expression levels of Grp78 and Caspase-12 mRNA in liver tissue were detected by quantitative real-time PCR. Compared with the control group, the apoptosis rate of hepatocytes was increased (P<0.05), the positive expression and protein expression of p-IRE-1α, Grp78, and Caspase-12 were increased (P<0.05), the expression levels of Grp78 and Caspase-12 mRNA were increased (P<0.05) in the model group. Compared with the model group, all these indicators showed opposite trends (P<0.05) in the acupuncture and moxibustion groups. Acupuncture and moxibustion can reduce liver injury due to DDP chemotherapy by modulating IRE-1 signaling pathway, inhibiting the excessive activation of endoplasmic reticulum stress, and reducing liver cell apoptosis.

Astragaloside IV Alleviates Podocyte Injury in Diabetic Nephropathy through Regulating IRE-1α/NF-κ B/NLRP3 Pathway.

To investigate the effects of astragaloside IV (AS-IV) on podocyte injury of diabetic nephropathy (DN) and reveal its potential mechanism. In in vitro experiment, podocytes were divided into 4 groups, normal, high glucose (HG), inositol-requiring enzyme 1 (IRE-1) α activator (HG+thapsigargin 1 µmol/L), and IRE-1α inhibitor (HG+STF-083010, 20 µmol/L) groups. Additionally, podocytes were divided into 4 groups, including normal, HG, AS-IV (HG+AS-IV 20 µmol/L), and IRE-1α inhibitor (HG+STF-083010, 20 µmol/L) groups, respectively. After 24 h treatment, the morphology of podocytes and endoplasmic reticulum (ER) was observed by electron microscopy. The expressions of glucose-regulated protein 78 (GRP78) and IRE-1α were detected by cellular immunofluorescence. In in vivo experiment, DN rat model was established via a consecutive 3-day intraperitoneal streptozotocin (STZ) injections. A total of 40 rats were assigned into the normal, DN, AS-IV [AS-IV 40 mg/(kg·d)], and IRE-1α inhibitor [STF-083010, 10 mg/(kg·d)] groups (n=10), respectively. The general condition, 24-h urine volume, random blood glucose, urinary protein excretion rate (UAER), urea nitrogen (BUN), and serum creatinine (SCr) levels of rats were measured after 8 weeks of intervention. Pathological changes in the renal tissue were observed by hematoxylin and eosin (HE) staining. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were used to detect the expressions of GRP78, IRE-1α, nuclear factor kappa Bp65 (NF-κBp65), interleukin (IL)-1β, NLR family pyrin domain containing 3 (NLRP3), caspase-1, gasdermin D-N (GSDMD-N), and nephrin at the mRNA and protein levels in vivo and in vitro, respectively. Cytoplasmic vacuolation and ER swelling were observed in the HG and IRE-1α activator groups. Podocyte morphology and ER expansion were improved in AS-IV and IRE-1α inhibitor groups compared with HG group. Cellular immunofluorescence showed that compared with the normal group, the fluorescence intensity of GRP78 and IRE-1α in the HG and IRE-1α activator groups were significantly increased whereas decreased in AS-IV and IRE-1α inhibitor groups (P<0.05). Compared with the normal group, the mRNA and protein expressions of GRP78, IRE-1α, NF-κ Bp65, IL-1β, NLRP3, caspase-1 and GSDMD-N in the HG group was increased (P<0.05). Compared with HG group, the expression of above indices was decreased in the AS-IV and IRE-1α inhibitor groups, and the expression in the IRE-1α activator group was increased (P<0.05). The expression of nephrin was decreased in the HG group, and increased in AS-IV and IRE-1α inhibitor groups (P<0.05). The in vivo experiment results revealed that compared to the normal group, the levels of blood glucose, triglyceride, total cholesterol, BUN, blood creatinine and urinary protein in the DN group were higher (P<0.05). Compared with DN group, the above indices in AS-IV and IRE-1α inhibitor groups were decreased (P<0.05). HE staining revealed glomerular hypertrophy, mesangial widening and mesangial cell proliferation in the renal tissue of the DN group. Compared with the DN group, the above pathological changes in renal tissue of AS-IV and IRE-1α inhibitor groups were alleviated. Quantitative RT-PCR and Western blot results of GRP78, IRE-1α, NF-κ Bp65, IL-1β, NLRP3, caspase-1 and GSDMD-N were consistent with immunofluorescence analysis. AS-IV could reduce ERS and inflammation, improve podocyte pyroptosis, thus exerting a podocyte-protective effect in DN, through regulating IRE-1α/NF-κ B/NLRP3 signaling pathway.

Investigation of the site 2 pocket of Grp94 with KUNG65 benzamide derivatives

Glucose-regulated protein 94 (Grp94) is an isoform of the heat shock protein 90 kDa (Hsp90) family of molecular chaperones. Inhibiting Grp94 has been implicated for many diseases. Co-crystal structures of two generations of Grp94 inhibitors revealed the importance of investigating the ester group, which is projected into the site 2 pocket unique to Grp94. Therefore, a series of KUNG65 benzamide analogs was designed and synthesized to evaluate their impact on the affinity and selectivity for Grp94. The data demonstrated that substituents with small and saturated ring systems that contain hydrogen bond acceptors exhibited increased affinity for Grp94, whereas larger saturated ring system manifested increased selectivity for Grp94 over Hsp90α.

SIRT1 inhibits apoptosis of human lens epithelial cells through suppressing endoplasmic reticulum stress in vitro and in vivo.

To explore the effect of silent information regulator factor 2-related enzyme 1 (SIRT1) on modulating apoptosis of human lens epithelial cells (HLECs) and alleviating lens opacification of rats through suppressing endoplasmic reticulum (ER) stress. HLECs (SRA01/04) were treated with varying concentrations of tunicamycin (TM) for 24h, and the expression of SIRT1 and C/EBP homologous protein (CHOP) was assessed using real-time quantitative polymerase chain reaction (RT-PCR), Western blotting, and immunofluorescence. Cell morphology and proliferation was evaluated using an inverted microscope and cell counting kit-8 (CCK-8) assay, respectively. In the SRA01/04 cell apoptosis model, which underwent siRNA transfection for SIRT1 knockdown and SRT1720 treatment for its activation, the expression levels of SIRT1, CHOP, glucose regulated protein 78 (GRP78), and activating transcription factor 4 (ATF4) were examined. The potential reversal of SIRT1 knockdown effects by 4-phenyl butyric acid (4-PBA; an ER stress inhibitor) was investigated. In vivo, age-related cataract (ARC) rat models were induced by sodium selenite injection, and the protective role of SIRT1, activated by SRT1720 intraperitoneal injections, was evaluated through morphology observation, hematoxylin and eosin (H&E) staining, Western blotting, and RT-PCR. SIRT1 expression was downregulated in TM-induced SRA01/04 cells. Besides, in SRA01/04 cells, both cell apoptosis and CHOP expression increased with the rising doses of TM. ER stress was stimulated by TM, as evidenced by the increased GRP78 and ATF4 in the SRA01/04 cell apoptosis model. Inhibition of SIRT1 by siRNA knockdown increased ER stress activation, whereas SRT1720 treatment had opposite results. 4-PBA partly reverse the adverse effect of SIRT1 knockdown on apoptosis. In vivo, SRT1720 attenuated the lens opacification and weakened the ER stress activation in ARC rat models. SIRT1 plays a protective role against TM-induced apoptosis in HLECs and slows the progression of cataract in rats by inhibiting ER stress. These findings suggest a novel strategy for cataract treatment focused on targeting ER stress, highlighting the therapeutic potential of SIRT1 modulation in ARC development.