Endoplasmic Reticulum Stress-related Markers Research Articles

Role and Mechanism of Endoplasmic Reticulum Stress in Mice Pancreatic Islet Dysfunction After Severe Burns.

This study attempted to investigate the role and mechanism of endoplasmic reticulum (ER) stress in the islet dysfunction in mice after severe burns. C57BL/6 mice were randomly divided into the sham group, burn group, and burn+4-phenylbutyric acid (4-PBA) group. Mice were burned with full thickness of 30% total surface area (TBSA), and 4-PBA solution was intraperitoneally injected into mice in burn+4-PBA group. Glucose-stimulated insulin secretion (GSIS), Fasting blood glucose (FBG) and glucose tolerance were detected 24 hours post severe burns. The ER stress-related pathway markers immunoglobulin binding protein (BIP), X-box binding protein 1 (XBP1), phosphorylation-PKR-like ER kinase (p-PERK), phosphorylation-eukaryotic translation initiation factor 2α (p-eIF2α), CHOP, activating transcription factor 6 (ATF6), apoptosis-related protein Cleaved-Caspase 3, and islet cell apoptosis were measured. Mice were characterized with elevated FBG, decreased glucose tolerance and GSIS levels post severe burns. The expression of BIP, XBP1, p-PERK, p-eIF2α, CHOP, ATF6, Cleaved-Caspase 3, and islet cell apoptosis were increased significantly after severe burns. 4-PBA treatment contributed to decreased FBG, improved glucose tolerance, increased GSIS, inhibited islet ER stress, and reduced pancreatic islet cell apoptosis in mice post severe burns. ER stress occurs in islets of severely burned mice, which leads to increased apoptosis of islet cells, thus resulting in islet dysfunction.

Sulforaphane ameliorates bisphenol A-induced hepatic lipid accumulation by inhibiting endoplasmic reticulum stress

The aim of the present study was to investigate the role of endoplasmic reticulum (ER) stress in bisphenol A (BPA) – induced hepatic lipid accumulation as well as the protective effects of Sulforaphane (SFN) in this process. Human hepatocyte cell line (LO2) and C57/BL6J mice were used to examine BPA-triggered hepatic lipid accumulation and the underlying mechanism. Hepatic lipid accumulation, triglycerides (TGs) levels, the expression levels of lipogenesis-related genes and proteins in the ER stress pathway were measured. It was revealed that BPA treatment increased the number of lipid droplets, the levels of TG and mRNAs expression of lipogenesis-related genes, and activated the ER stress pathway. These changes were inhibited by an ER stress inhibitor 4-phenylbutyric acid. SFN treatment abrogated BPA-altered hepatic lipid metabolism and ameliorated BPA-induced ER stress-related markers. Together, these findings suggested that BPA activated ER stress to promote hepatic lipid accumulation, and that SFN reversed those BPA effects by alleviating ER stress.

Angiotensin(1–7) attenuates visceral adipose tissue expansion and lipogenesis by suppression of endoplasmic reticulum stress via Mas receptor

BackgroundWhite adipose tissue can be classified based on its location as subcutaneous and visceral fat, and the latter accumulation is reported to be more detrimental to metabolism. Endoplasmic reticulum (ER) stress has been demonstrated to regulate lipogenesis. The peptide angiotensin(1–7) [Ang(1–7)], which can be produced from angiotensin II (AngII) by angiotensin-converting enzyme 2 (ACE2), plays its role through Mas receptor, also participates in the regulation of lipid metabolism in adipose tissue, however, whether ER stress is involved in the mechanism remains unclear. Therefore, we aimed to explore the role of Ang(1–7) pathway in regulating visceral adipose tissue expansion and ER stress.MethodsACE2 knockout (KO), Mas KO and C57BL/6 J mice were fed with high fat diet. Db/db mice were treated with either normal saline, Ang(1–7) or Ang(1–7) combined with Mas receptor inhibitor A779 using mini osmotic pumps. Fat mass was weighted, fat distribution was evaluated by MRI, and lipid profile and adipokines in epididymal adipose tissue were measured by ELISA kits, and histology of epididymal adipose tissue was also analyzed in multiple animal models. Additionally, differentiated 3T3-L1 cells were pre-loaded with palmitic acid to induce ER stress, then treated with drugs as those administrated to db/db mice. ER stress and lipogenesis related proteins in mice adipose and differentiated 3T3L-1 cells were analyzed by Western blot.ResultsACE2 or Mas KO mice exhibited increased visceral adipose tissue, adipocyte size and protein expression of lipogenesis and ER stress related markers in epididymal adipose tissue compared to wild-type mice. Db/db mice treated with Ang(1–7) displayed decreased visceral fat mass, adipocyte size and protein expression of lipogenesis and ER stress markers in epididymal adipose tissue compared to those treated with normal saline, while A779 partly attenuated these effects. Additionally, Ang(1–7) improved ER stress and lipogenesis markers in differentiated 3T3-L1 cells pre-loaded with palmitic acid.ConclusionsOur findings indicated that Ang(1–7) attenuated visceral adipose tissue expansion and lipogenesis by suppression of ER stress via Mas receptor. The present study provides a potential perspective for Ang(1–7) for the therapeutics of obesity and related disorders.

Expression of ER stress markers (GRP78 and PERK) in experimental nephrotoxicity induced by cisplatin and gentamicin: roles of inflammatory response and oxidative stress.

This study aimed to establish the relationship between two endoplasmic reticulum (ER) stress proteins, glucose-regulated protein 78 (GRP78/BiP) and PKR-like endoplasmic reticulum kinase (PERK), and oxidative stress markers in cisplatin (CIS)-induced and gentamicin (GEN)-induced nephrotoxicity.The study consisted of five groups: control (saline solution only), CIS D2 (2.5mg/kg for 2days), CIS D7 (2.5mg/kg for 7days), GEN D2 (160mg/kg for 2days), and GEN D7 (160mg/kg for 7days). All rats were sacrificed 24h after the last injection for standard clinical chemistry, and ultrastructural and histological evaluation of the kidney.CIS and GEN increased blood urea nitrogen (BUN) and serum creatinine (Cr) levels, as well as total oxidant status (TOS), while decreasing total antioxidant status (TAS) level in CIS D7 and GEN D7 groups. Histopathological and ultrastructural findings were also consistent with renal tubular damage. In addition, expression of markers of renal inflammation (tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β)) and ER stress markers (GRP78 and PERK) was significantly increased in the kidney tissue of rats treated with CIS and GEN for 7days.These findings suggest that CIS and GEN administration for 7days aggravates nephrotoxicity through the enhancement of oxidative stress, inflammation, and ER stress-related markers. As a result, the recommended course of action is to utilize CIS and GEN as an immediate but brief induction therapy, stopping after 3days and switching to other drugs instead.

Alliin, capsaicin, and gingerol attenuate endoplasmic reticulum stress-induced hepatic steatosis in HepG2 cells and C57BL/6N mice

Recently, food ingredients that suppress endoplasmic reticulum (ER) stress have been studied for their potential application in non-alcoholic fatty liver disease (NAFLD) treatment. Kimchi active components can suppress ER stress-related markers; therefore, we investigated the inhibitory effects of alliin, capsaicin, and gingerol on tunicamycin-induced hepatic steatosis in HepG2 cells and C57BL/6N mice by measuring ER stress-, lipogenesis-, and inflammation-related gene expression, and lipid accumulation. Alliin, capsaicin, and gingerol efficiently decreased triglyceride content and all gene expression in tunicamycin-induced cells without cytotoxicity. Alliin, capsaicin, and gingerol inhibited lipogenesis-related gene expression that increased following T0901317 treatment and decreased following AICAR treatment. Furthermore, alliin, capsaicin, and gingerol decreased serum lipid and hepatic lipid levels and all marker expression in tunicamycin-induced mice without hepatic toxicity. They also inhibited lipid accumulation in tunicamycin-induced mice. Collectively, kimchi active components prevented triglyceride accumulation and hepatic steatosis in ER stress-induced HepG2 cells and C57BL/6N mice.

Effects and molecular mechanism of exogenous L-carnitine on excessive endoplasmic reticulum stress-mediated hepatic pyroptosis in severely scald rats

Effects and molecular mechanism of exogenous L-carnitine on excessive endoplasmic reticulum stress-mediated hepatic pyroptosis in severely scald rats

Tendon microstructural disruption promotes tendon-derived stem cells to express chondrogenic genes by activating endoplasmic reticulum stress.

The erroneous differentiation of tendon-derived stem cells (TDSCs) into adipocytes, chondrocytes, and osteoblasts is believed to play an important role in the development of tendinopathy. However, the regulatory mechanisms of TDSC differentiation remain unclear. The aim of this study is to investigate the contribution and mechanism of the tendon microstructural disruption to the differentiation of TDSCs. Bovine Achilles tendons were sliced. The tendon slices were stretched with different tensile strains to mimic the tendon structure alteration at various scales. The TDSCs were cultured on the tendon slices. The differentiation of TDSCs and endoplasmic reticulum (ER) stress in the TDSCs were investigated with quantitative reverse transcription polymerase chain reaction, immunostaining and western blot. The effect of ER stress inhibition on chondrogenic differentiation of the TDSCs was further investigated. The structural alteration did not affect the viability of TDSCs. However, the structural alteration of tendon slices with 6.4% strain promoted TDSCs to express the chondrogenic genes. ER stress-related markers, ATF-4 and PERK, were also upregulated. With the inhibition of ER stress, the expression of ATF-4 and the chondrogenic gene SOX9 of TDSCs were inhibited. The study indicated that tendon microdamage could induce the chondrogenic differentiation of TDSCs through triggering ER stress to activate ATF-4 and SOX9 subsequently.

Induction of Endoplasmic Reticulum Stress-Mediated Apoptosis by Aminosteroid RM-581 Efficiently Blocks the Growth of PC-3 Cancer Cells and Tumors Resistant or Not to Docetaxel.

Aminosteroid derivative RM-581 was previously identified as an endoplasmic-reticulum (ER) stress inducer with potent in vitro and in vivo anticancer activities. We report its evaluation in androgen-independent prostate cancer (PC-3) cells. RM-581 efficiently blocks PC-3 cell proliferation with stronger activity than that of a selection of known antineoplastic agents. This later also showed a synergistic effect with docetaxel, able to block the proliferation of docetaxel-resistant PC-3 cells and, contrary to docetaxel, did not induce cell resistance. RM-581 induced an increase in the expression level of ER stress-related markers of apoptosis, potentially triggered by the presence of RM-581 in the ER of PC-3 cells. These in vitro results were then successfully translated in vivo in a PC-3 xenograft tumor model in nude mice, showing superior blockade than that of docetaxel. RM-581 was also able to stop the progression of PC-3 cells when they had become resistant to docetaxel treatment. Concomitantly, we observed a decrease in gene markers of mevalonate and fatty acid pathways, and intratumoral levels of cholesterol by 19% and fatty acids by 22%. Overall, this work demonstrates the potential of an ER stress inducer as an anticancer agent for the treatment of prostate cancers that are refractory to commonly used chemotherapy treatments.

Natural Thiols, but Not Thioethers, Attenuate Patulin-Induced Endoplasmic Reticulum Stress in HepG2 Cells.

Patulin, a mycotoxin, is known to have cytotoxic effects, but few studies have focused on the involvement of the endoplasmic reticulum (ER) stress response in patulin toxicity and the natural compounds that attenuate it in HepG2 cells. This study tested the ability of patulin to induce ER stress, and that of four thiols and three thioethers to attenuate patulin-induced ER stress in HepG2 cells. Patulin dose-dependently inhibited cell proliferation (IC50, 8.43 μM). Additionally, patulin was found to increase the expression levels of ER stress-related genes and/or protein markers, including BiP, CHOP, and spliced XBP1, in HepG2 cells compared to the vehicle control, indicating its potential in ER stress induction. Patulin-induced cytotoxicity in HepG2 cells was reduced by naturally occurring thiol compounds (glutathione, L-acetyl-L-cysteine, cysteine, and captopril), but not by thioether compounds (sulforaphane, sulforaphene, and S-allyl-L-cysteine). Patulin-thiol co-treatment decreased CHOP expression and BiP and CHOP levels in HepG2 cells but did not alter BiP expression. Spliced XBP1 expression was decreased by patulin-thiol co-treatment. Thus, patulin induced ER stress in HepG2 cells and thiols, but not in thioethers, attenuated patulin-induced ER stress.

Imoxin inhibits tunicamycin-induced endoplasmic reticulum stress and restores insulin signaling in C2C12 myotubes.

Prolonged endoplasmic reticulum (ER) stress can mediate inflammatory myopathies and insulin signaling pathways. The double-stranded RNA (dsRNA)-activated protein kinase R (PKR) has been implicated in skeletal muscle dysfunction. However, pathological roles of PKR in ER stress in muscle are not fully understood. The current study aimed to investigate the effect of imoxin (IMX), a selective PKR inhibitor, on tunicamycin (TN)-induced promotion of ER stress and suppression of insulin signaling in C2C12 myotubes. Cells were pretreated with 5 µM IMX for 1 h and exposed to 0.5 µg/mL TN for 23 h. A subset of cells was stimulated with 100 nM insulin for the last 15 min. mRNA expression and protein levels involved in ER stress were measured by RT-PCR and Western blotting, respectively. TN significantly augmented PKR phosphorylation by 231%, which was prevented by IMX. In addition, IMX reduced mRNA and protein levels of ER stress-related markers, including CCAAT-enhancer-binding protein homologous protein (CHOP, mRNA: 95% decrease; protein: 98% decrease), activating transcription factor 4 (ATF4, mRNA: 69% decrease; protein: 99% decrease), cleavage of ATF6, and spliced X-box-binding protein 1 (XBP-1s, mRNA: 88% decrease; protein: 79% decrease), which were induced by TN. Furthermore, IMX ameliorated TN-induced suppression of phospho-insulin receptor β (317% increase) and Akt phosphorylation (by 36% at Ser473 and 30% at Thr308) in myotubes, while augmenting insulin-stimulated AS160 phosphorylation and glucose uptake (by ∼30%). These findings suggest that IMX may protect against TN-induced skeletal muscle ER stress and insulin resistance, which are potentially mediated by PKR.

Melatonin Improves Endoplasmic Reticulum Stress-Mediated IRE1α Pathway in Zücker Diabetic Fatty Rat.

Obesity and diabetes are linked to an increased prevalence of kidney disease. Endoplasmic reticulum stress has recently gained growing importance in the pathogenesis of obesity and diabetes-related kidney disease. Melatonin, is an important anti-obesogenic natural bioactive compound. Previously, our research group showed that the renoprotective effect of melatonin administration was associated with restoring mitochondrial fission/fusion balance and function in a rat model of diabesity-induced kidney injury. This study was carried out to further investigate whether melatonin could suppress renal endoplasmic reticulum (ER) stress response and the downstream unfolded protein response activation under obese and diabetic conditions. Zücker diabetic fatty (ZDF) rats and lean littermates (ZL) were orally supplemented either with melatonin (10 mg/kg body weight (BW)/day) (M–ZDF and M–ZL) or vehicle (C–ZDF and C–ZL) for 17 weeks. Western blot analysis of ER stress-related markers and renal morphology were assessed. Compared to C–ZL rats, higher ER stress response associated with impaired renal morphology was observed in C–ZDF rats. Melatonin supplementation alleviated renal ER stress response in ZDF rats, by decreasing glucose-regulated protein 78 (GRP78), phosphoinositol-requiring enzyme1α (IRE1α), and ATF6 levels but had no effect on phospho–protein kinase RNA–like endoplasmic reticulum kinase (PERK) level. In addition, melatonin supplementation also restrained the ER stress-mediated apoptotic pathway, as indicated by decreased pro-apoptotic proteins phospho–c–jun amino terminal kinase (JNK), Bax, and cleaved caspase-3, as well as by upregulation of B cell lymphoma (Bcl)-2 protein. These improvements were associated with renal structural recovery. Taken together, our findings revealed that melatonin play a renoprotective role, at least in part, by suppressing ER stress and related pro-apoptotic IRE1α/JNK signaling pathway.

JAK2/STAT3 inhibitor reduced 5-FU resistance and autophagy through ATF6-mediated ER stress

Drug resistance seriously limits the efficacy of chemotherapy drugs and hinders successful treatment in patients with gastric cancer. Endoplasmic reticulum (ER) and autophagy are recognized to be one of the mechanisms involving the drug resistance of gastric cancer. The mechanisms of action of JAK2/STAT3 pathway were investigated in AGS cells with drug resistance of 5-fluorouracil (5-FU) by corresponding inhibitors. We firstly analyzed the effects of JAK2/STAT3 inhibitor on the expression of drug resistance genes, autophagy markers, and ER stress-related markers on AGS/5-FU cells by Western blot. Whether JAK2/STAT3 pathway regulated the transcription of ATF6 was investigated through luciferase reporter assay. The expression of LC3B was detected by immunofluorescence assay. Next, ER stress inhibitor and ATF6 overexpression plasmid were respectively used to treat AGS/5-FU cells for analyzing whether JAK2/STAT3 pathway regulated ER stress. The results showed that JAK2 inhibitor or STAT3 inhibitor significantly altered the expression of these proteins and suppressed the activities of ATF6 promoter. Intriguingly, ATP6 overexpression could markedly reverse their effects. Moreover, similar effects to JAK2 inhibitor or STAT3 inhibitor appeared in ER stress inhibitor-treated group. These findings indicated that the involvement of JAK2/STAT3 pathway in regulating ER stress affected the 5-FU resistance of AGS cells and autophagy, which was mediated by ATF6. Targeting JAK2/STAT3 pathway could be a potential approach to decrease the 5-FU resistance of gastric cancer and enhance the sensitivity of gastric cancer to 5-FU. Additionally, our study offers new insights into the molecular mechanisms underlying the resistance of gastric cancer to 5-FU.

Effects of eccentric exercise-induced delayed onset muscle soreness on endoplasmic reticulum stress-related markers

Abstract Short Communications Apelin, pentraxin3 (PTX3), and interleukin6 (IL6) parameters are known as inflammation markers and found to be related to endoplasmic reticulum (ER) stress. The aim of the study was to investigate the effect of eccentric exercise-induced delayed onset muscle soreness (DOMS) on ER stress-related markers in young athletes. Objectives and Methods ER stress and DOMS-related blood markers, maximal strength level, and rate of perceived exertion using the visual analog scale (VAS) were assessed before, immediately after, 24, 48, and 72 h after the muscle damage protocol. Results IL6 peaked 24 h after while creatine kinase and lactate dehydrogenase enzyme levels reached their peaks at 72 h after the protocol. The level of apelin continued to increase throughout the four measurements, and PTX3 peaked at 24 h, and then declined to the levels before the protocol but the differences were not significant. The significant decrease in the strength and the significant increase in VAS continued 48 h after the protocol. Conclusion ER is activated and ER stress occurred, due to increases in IL6, PTX3 and apelin levels after the test protocol concluded that a single vigorous eccentric exercise should be avoided in harmful effect on health as parallel with Physical Activity Guidelines.

Cardioprotective effect of Rosa canina L. methanolic extract on heat shock induced cardiomyocyte injury: An experimental study.

Introduction: Overexposure to heat conditions can affect the functioning of the cardiovascular system and may promote cardiovascular disorders. Heat shock induced myocardial injury via increasing endoplasmic reticulum response-mediated apoptosis. This study investigated the impact of pretreatment with Rosa canina (RC), a natural antioxidant, on myocardial damage induced by heat stress exposure and underlying mechanisms in cardiomyocytes in rats. Methods: Sixty adult male Wistar rats were allocated into five groups, including Control: received normal saline (NS), Heat Stress (HS), and HS+RC groups. Animals in the HS groups were subjected to heat stress (43 ºC) for 15 minutes once a day for two weeks. Animals in the HS+RC groups received three doses of RC (250, 500, and 1000 mg/mL) one hour before being subjected to heat shock. The endoplasmic reticulum (ER) transmembrane kinases, including PKR-like endoplasmic reticulum kinase (PERK), immunoreactivity of CCAAT/enhancer-binding protein homologous protein (CHOP), and eukaryotic translation initiation factor 2-alpha (eIF2α) as well as caspase 8 were detected by Western blot. The levels of reactive oxygen species (ROS) were assessed. Moreover, histopathological changes and apoptosis were also assayed in the heart tissue by using histopathological and TUNEL assays. Results: Heat exposure increased the level of ROS and induced oxidative damage in the heart tissue. The results demonstrated that RC administration decreased the overproduction of ROS induced by heat stress in cardiomyocytes. Moreover, heat stress up regulated the expression of p-PERK, p-eIF2α,and CHOP protein while pretreatment with RC decreased expression of ER stress-related markers in cardiomyocytes. Besides, RC diminished heat stress-induced cellular damage and apoptosis associated with inhibition of caspase 8 activation, a pro-apoptotic protein in cardiomyocytes. Conclusion: These findings indicate that RC exerts a protective effect on heart tissue, at least in part,through inactivation of PERK/eIF2α/CHOP pathway or inhibition of ER stress and oxidative stress triggeredapoptosis in cardiomyocytes induced by heat stress.

Pharmacological blockade of PCAF ameliorates osteoarthritis development via dual inhibition of TNF-α-driven inflammation and ER stress.

BackgroundEpigenetic mechanisms have been reported to play key roles in osteoarthritis (OA) development. P300/CBP-associated factor (PCAF) is a member of the histone acetyltransferases, which exhibits a strong relationship with endoplasmic reticulum (ER) stress and transcription factor nuclear factor kappa B (NF-κB) signals. Salidroside, a natural histone acetylation inhibitor, showed its anti-inflammatory and anti-apoptotic effects in lipopolysaccharide (LPS)-stimulated microglia cells in our previous study. However, whether Sal has a protective effect against OA remains unknown, and its relationships to PCAF, NF-κB, and the ER stress pathway should be explored further.MethodsWe identified the role of PCAF in the pathogenesis of OA and determined the chondroprotective effect of Sal on both tumor necrosis factor alpha (TNF-α)-treated human chondrocytes and a destabilized medial meniscus (DMM) mouse OA model.FindingsWe found increased PCAF expression in human OA cartilage and TNF-α-driven chondrocytes. Meanwhile, silencing of PCAF attenuated nuclear p65 and C/EBP homologous protein levels in chondrocytes upon TNF-α stimulation. Furthermore, Sal was found to specifically bind to the inhibitory site of the PCAF protein structure, which subsequently reversed the TNF-α-induced activation of NF-κB signal and ER stress-related apoptosis in chondrocytes. In addition, the protective effect of Sal and its inhibitory effects on PCAF as well as inflammatory- and ER stress-related markers were also observed in the mouse DMM model.InterpretationPharmacological blockade of PCAF by Sal ameliorates OA development via inhibition of inflammation and ER stress, which makes Sal a promising therapeutic agents for the treatment of OA.

Psoralen induces hepatic toxicity through PERK and ATF6 related ER stress pathways in HepG2 cells

Psoralen has potential hepatotoxicity and has a certain promoting effect on the clinical liver injury of Psoralea corylifolia L (Fructus Psoraleae). This study investigated the underlying mechanisms of psoralen-induced hepatotoxicity in vitro. HepG2 cells were treated with psoralen for 6, 12, 24, or 48 h, and an endoplasmic reticulum (ER) stress-specific inhibitor, 4-PBA, was employed to investigate the mechanism of psoralen on ER stress and unfolded protein response (UPR). Cell viability was tested by MTT assay, ATP assay, and cell death by LDH. The apoptosis was reflected by the flow cytometry, caspase-8, and caspase-3 activates. The expression of ER stress-related markers was determined by RT-PCR and western blot. We found that psoralen significantly decreased cell viability, increased activities of caspase-8 and caspase-3, and upregulated expression of CHOP and BAX in a time- and dose-dependent manner. Moreover, psoralen significantly increased the expression and transcription levels of ER stress-related markers, including Grp78, PERK, eIF2α, ATF4, and ATF6, while IRE1α was not significantly affected. And 4-PBA could effectively inhibit psoralen-induced cell death and apoptosis along with the inhibition of ER stress responses. These results suggested that psoralen causes liver injury due to the induction of the ER stress-mediated apoptosis via PERK-eIF2α-ATF4-CHOP and ATF6-CHOP related pathways.

Pharmacological Blockade of PCAF Ameliorates Osteoarthritis Development via Dual Inhibition of TNF-α-Driven Inflammation and ER Stress

Epigenetic mechanisms have been reported to play key roles in osteoarthritis (OA) development. Here, we identified the role of histone acetyltransferase p300/CBP-associated factor (PCAF) in the pathogenesis of OA and determined that the chondroprotective effect of specific pharmacological inhibition of PCAF by a natural compound salidroside (Sal) in Tumor Necrosis Factor Alpha (TNF-α) treated human chondrocytes and a destabilized medial meniscus (DMM) mouse OA model.In vitro, we found increased PCAF expression and activity in human OA cartilage and TNF-α-driven chondrocytes. Meanwhile, silencing PCAF attenuates the nuclear p65 and C/EBP Homologous Protein (CHOP) level in human chondrocytes under TNF-α stimulation. Furthermore, Sal was found to bind the inhibitory site of PCAF protein structure specifically according to docking analysis, which subsequently reversed the TNF-α induced activation of transcription factor nuclear factor kappa B (NF-κB) signals and Endoplasmic Reticulum (ER) stress related apoptosis in chondrocytes. In addition, the protective effect of Sal and its inhibitory effect on PCAF as well as inflammatory and ER stress related markers were also found in mouse DMM model. Our studies have uncovered that aberrant PCAF accumulation contributes to the OA development and the mechanism underlying the anti-inflammatory and anti-apoptotic effect of Sal is in relation to the cross-talk between PCAF and NF-κB and ER stress cascades. Funding Statement: Financial supports from National Natural Science Foundation of China (NO. 81601983, NO.81501869). Declaration of Interests: The authors report no conflicts of interest. Ethics Approval Statement: The experimental protocols, animal use and postoperative animal care procedures were performed in line with the guidelines and principles of the Animal Care and Use Committee of Wenzhou Medical University (ethic code: wydw2014-0129). The whole study was approved by the medical ethics committee of The Second Affiliated Hospital of Wenzhou Medical University (number: LCKY-2017-36) and in accordance with the guidelines of the Declaration of Helsinki. Informed consent was obtained from every participant.

Gastric Sleeve Surgery Alleviates Obesity-Associated Insulin Resistance and Suppresses Endoplasmic Reticulum Stress in Adipose Tissue of db/db Mice.

The aims of this study were to evaluate the effects of gastric sleeve surgery on diabetes remission in db/db mice as well as to determine the underlying mechanisms. Thirty spontaneously obese, diabetic mice (C57BL/Ksj-db/db) were randomly divided into three groups: sleeve gastrectomy group, sham-operated group, and control db/db group. Ten db/m lean mice were used as nondiabetic littermate controls. All mice were sacrificed on day 28. The fasting plasma glucose, serum insulin, lipid profile, and oral glucose tolerance were measured pre- and postoperatively. Inflammatory cytokines (TNF-α and IL-6), endoplasmic reticulum (ER) stress-related markers (GRP78, PERK, IRE-1, and ATF6), and glucose transporter 4 (GLUT4) in the adipose tissue were assayed. Sleeve gastrectomy significantly reduced the body weight and food intake in the db/db mice. This surgery improved glucose and lipid metabolism, as manifested by the decrease in the fasting plasma glucose level and partial restoration of lipid abnormalities. Also, the surgery improved glucose tolerance and alleviated insulin resistance in db/db mice. Sleeve gastrectomy surgery induced downregulation of the inflammatory adipocytokines TNF-α and IL-6; suppressed expression of the ER stress-related markers GRP78, PERK, IRE-1, and ATF-6; and increased the expression and distribution of GLUT4 in adipose tissue of db/db mice. The improvement in glucose tolerance following sleeve gastrectomy is associated with alleviation of insulin resistance, reduction of inflammatory adipocytokine levels, and suppression of ER stress. Further studies are needed to assess whether these effects have a causal role.

Arctigenin ameliorates renal impairment and inhibits endoplasmic reticulum stress in diabetic db/db mice

AimsDiabetic nephropathy (DN) is the most common complication of diabetes mellitus. Endoplasmic reticulum (ER) plays an important role in the development and progression of DN. Arctigenin (ATG), a lignan extract from Fructus Arctii, exhibits anti-inflammatory, anticarcinogenic, anti-oxidative stress and immunomodulatory properties. The present research aimed to investigate whether ATG could protect against diabetes-related renal injury and inhibit ER stress in db/db mice. Main methodsMale db/db mice were randomly divided into two groups: DN group and ATG treatment group (DN + ATG). db/m mice were defined as the normal control group (NC). ATG was dissolved in 0.5% carboxymethyl cellulose sodium salt solution and administered orally at a dose of 80 mg/kg to mice in the DN + ATG group once daily for 8 consecutive weeks. HK2 cells were used to determine the effects of ATG on ER stress and cell apoptosis in vitro. Key findingsATG administration significantly reduced blood glucose, urine albumin excretion, and urine albumin to creatinine ratio, and attenuated renal pathological injury when compared with untreated db/db mice. These changes were accompanied by decreased expression of both ER stress-related markers and caspase 12 level in the kidneys of db/db mice. In vitro, high glucose activated ER stress signal transduction pathway and induced cell apoptosis in HK2 cells, which were blocked by ATG. SignificanceOur results suggest that ATG exerts renoprotective effects on diabetes-related renal injury in db/db mice and cytoprotective effects on high glucose induced cell apoptosis and inhibits ER stress.

Particles-induced osteoblast apoptosis and inflammation mediated by endoplasmic reticulum in a murine model of periprosthestic osteolysis

Macrophage apoptosis and inflammation in interface membrane have been shown to play a significant role in the pathogenesis of osteolysis. However, osteoblasts have not been fully explored as a participant in the process of osteolysis, despite their critical role in bone growth, remodeling and maintenance. The purpose of our study was to identify whether endoplasmic reticulum (ER) stress participates in particle-induced osteolysis (PIO), osteoblasts apoptosis and inflammation within osteolytic bone tissues in PIO animal models. We examined the histopathologic changes of osteolysis and the expression of ER stress-related apoptotic markers (Ca2+, IRE1-α, PERK, GRP78/Bip, CHOP, JNK and Caspase-12) and inflammatory markers (TNF-α, IL-1β, and IL-6; ROS and Ca2+; NF-κB and c-Fos), and analyzed apoptosis and apoptotic regulators (Bcl-2 and Bax) within the osteolytic bone tissues. Our results demonstrated that wear particles were able to induce ER stress, and were associated with the inflammation and apoptosis of osteoblasts in vivo and vitro. Blocking ER stress with 4-PBA dramatically decreased particle-induced osteolysis symptoms, lessened the infiltration of inflammatory cells, reduced the inflammatory response, diminished the capability of osteoclastogenesis, and promoted the differentiation of osteoblasts. However, the ER stress blocker unexpectedly aggravated cell death of osteoblasts, which was of vital importance to the osteanagenesis of the ostolytic and absorptive bone. Given that the ER chaperone conforms to the definition of true moonlighting proteins with two quite distinct roles in nucleus and cell surface, making modulators of ER potentially attractive targets for therapeutics discovery. Thus, a better understanding of the mechanisms that orchestrate the ER may help to devise future strategies of safely modulating this process for therapeutic benefit.