This study aims to investigate the role of calreticulin in (CRT) pressure overload induced cardiac hypertrophy. In our study, cardiac hypertrophy was induced by left ventricular pressure overload in male SD rats subjected to transverse aortic constriction (TAC) operation. Expression of gene and protein of calreticulin, markers of cardiac hypertrophy and endoplasmic reticulum stress (ERS) were measured with real-time qPCR and Western blot respectively. Meanwhile, atorvastatin (a known ERS inhibitor) and calreticulin-specific small interference ribonucleic acid (siRNA) were used to inhibit the expression of ERS and calreticulin respectively. The experimental data demonstrated that the gene and protein levels of calreticulin, hypertrophic and ERS markers were increased significantly in the heart tissues of TAC rat models after 4 weeks. Moreover, atorvastatin administration improved the cardiac function and reduced the expression of calreticulin and ERS markers in TAC rats. In addition, cultured primary neonatal rat cardiomyocytes (NCMs) were treated with norepinephrine (NE), angiotensionⅡ (AngⅡ) or isoprenaline (ISO) to induce hypertrophic phenotype and ERS. The expression of hypertrophic markers was reduced in NCMs transfected with calreticulin-siRNA. The results suggested that calreticulin might be a promising target for the treatment of cardiac hypertrophy.
The aim of the current study is to investigate the effect of visfatin on cardiomyocyte hypertrophy. Cultured H9c2 cardiomyocytes were exposed to visfatin at different concentrations for different periods of time, and the markers of cardiomyocyte hypertrophy were detected. Moreover, pravastatin, the inhibitor of endoplasmic reticulum stress (ERS) or thapsigargin, an ERS agonist was used respectively to pre-treat the cells before visfatin stimulation. F-actin staining was performed to measure the cell surface change. The mRNA expressions of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP)and ERS markers including glucose-regulated protein 78(GRP78), C/EPB homologous protein (CHOP) and activating transcription factor 6 (ATF6) were assessed by real time RT-PCR. The change of protein level of GRP78 and CHOP was detected by Western blot. The experimental data demonstrated that exposure to 100 or 150 ng/mL concentrations of visfatin for 24 h, or 100 ng/mL of visfatin for 24 or 48 h, significantly increased the expression of markers for cardiomyocyte hypertrophy. Visfatin stimulation provoked ERS in H9c2 cells. Furthermore, pre-treatment with pravastatin partially inhibited the visfatin-induced mRNA expression of ANP and BNP in H9c2 cells, whereas thapsigargin promoted the visfatin-induced expression of cardiomyocyte hypertrophy markers. The results suggest that visfatin might induce cardiomyocyte hypertrophy via ERS -dependent pathways.
ObjectiveTo investigate the role of endoplasmic reticulum stress in liver regeneration after associating liver partition and portal vein ligation for staged hepatectomy (ALPPS).MethodsSeventy-two C57bl/6 mice were randomly divided into ALPPS group, portal vein ligation group (PVL group), and sham operation group (Sham group), 24 mice in each group. And then one-stage ALPPS operation, simple PVL, and sham operation will be performed. Six mice were randomized selected of the three groups on the 1st, 2nd, 4th, and 7th day after surgery, respectively, the liver weight to body weight ratio (FLR/BW) of each group was measured, and the liver tissues were taken for immunohistochemical staining to calculate the proportion of Ki-67 positive cells, Western blot was used to detect the expression levels of X-box binding protein 1 (XBP1) and inositol-requiring enzyme 1α (IRE1α) proteins.Results① FLR/BW: On the 4th day and the 7th day after operation, the FLR/BW of the Sham group, PVL group, and ALPPS group increased in sequence at the same time, and the difference between the three groups was statistically significant (P<0.05). ② Ki-67 positive cell ratio: On the 2nd day after operation, the ratio of Ki-67 positive cells in the Sham group, PVL group, and ALPPS group increased sequentially, and the difference between the two groups was statistically significant (P<0.05). On the 4th day after operation, the ratio of Ki-67 positive cells in the PVL group and the ALPPS group were still higher than that of the Sham group (P<0.05). ③ Expression levels of XBP1 and IRE1α: On the 2nd and 4th postoperative day, the expression levels of XBP1 and IRE1α in the ALPPS group were higher than those in the Sham group and the PVL group (P<0.05). On the 7th day after surgery, the expression levels of XBP1 and IRE1α in the ALPPS group were higher than those in the Sham group (P<0.05), while compared with the PVL group, the expression level of XBP1 in the ALPPS group was still higher (P<0.05).ConclusionsALPPS-induced liver regeneration is more advantageous than traditional PVL in mice. It may be attributed to the obvious endoplasmic reticulum stress activation after ALPPS leading to the up-regulation of IRE1α-XBP1 expression, which is involved in the regulation of hepatocyte cell cycle and promotes hepatocyte proliferation, thus promoting rapid liver regeneration.
The occurrence and development of myopia is closely related to scleral remodeling. Therefore, in order to effectively prevent and cure myopia, it is very important to clarify the mechanism of scleral remodeling. In recent years, Chinese scholars have found that endoplasmic reticulum stress can regulate the expression of apoptotic proteins through the inositol demand protein-1/X box binding protein-1 pathway in the unfolded protein response, thus it is involved in regulating the state of scleral fibroblasts under hypoxia and regulating the occurrence and development of scleral remodeling. At the same time, some studies have found that inhibiting and knocking out protein kinase RNA-like endoplasmic reticulum kinase and activated transcription factor 6 in endoplasmic reticulum stress can effectively inhibit the growth of ocular axis. This proves that endoplasmic reticulum stress plays an important role in the occurrence and development of scleral remodeling. However, the comprehensive analysis of endoplasmic reticulum stress and scleral remodeling has not been reported at home and abroad. In-depth analysis of the relationship between endoplasmic reticulum and scleral remodeling is of great significance for the follow-up analysis and study of the mechanism of scleral remodeling.
ObjectiveTo investigate the influence of endoplasmic reticulum stress (ERS) on smoking-induced nucleus pulposus cells apoptosis and inflammatory response.MethodsBetween October 2016 and October 2018, 25 patients with cervical disc herniation receiving discectomy were collected and divided into smoking group (14 cases) and non-smoking group (11 cases). The baseline data of age, gender, herniated segment, and Pfirrmann grading showed no significant difference between the two groups (P>0.05). The obtained nucelus pulposus tissues were harvested to observe the cell apoptosis via detecting the apoptosis-related proteins (Caspase-3 and PRAP) by TUNEL staining and Western blot test. The nucleus pulposus cells were isolated and cultured with enzyme digestion, of which the third generation cells were used in follow-up experiments. Then, the expressions of inflammatory factors [interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α)] were detected by ELISA; the nuclear translocation of P65 was monitored by cell immunofluorescence staining. Furthermore, ERS-related proteins (GRP78 and CHOP) were detected by Western blot; and endoplasmic reticulum ultrastructure was observed under transmission electron microscope. To verify the regulatory effect of ERS, cells were pretreated by ERS specific inhibitor (4-PBA), then cell apoptosis and inflammatory response were tested.ResultsThe nucleus pulposus tissue observation showed that the cell apoptotic rate and the expressions of apoptosis-related proteins (Caspase-3 and PARP) were obviously higher in smoking group than in non-smoking group (P<0.05). The nucleus pulposus cells observation indicated that the expressions of the inflammatory factors (IL-1β and TNF-α) and the ERS-related proteins (GRP78 and CHOP) were also higher in smoking group than in non-smoking group (P<0.05). The results of cell immunofluorescence staining further confirmed that smoking stimulated nuclear translocation of P65 in nucleus pulposus cells. The ERS injury was much more serious in smoking group than in non-smoking group. Furthermore, after 4-PBA inhibiting ERS, the expressions of GRP78, CHOP, IL-1β, TNF-α, and P65 were significantly decreased (P<0.05), and flow cytometry results showed that cell apoptotic rate in smoking group was decreased, showing significant difference compared with the non-smoking group (P<0.05).ConclusionSomking can stimulate cell apoptosis and inflammatory response in nucleus pulposus cells via ESR pathway. Suppressing ESR may be a novel target to suspend smoking-induced intervertebral disc degeneration.
Diabetic retinopathy (DR), a neurovascular complication of diabetes, presents a multifaceted pathogenesis that encompasses numerous biological processes and molecular mechanisms. Endoplasmic reticulum stress (ERS) plays a critical role in the maintenance of cellular homeostasis, and diabetic neuro-microangiopathy is driven by high glucose, which activated ERS through the promotion of protein misfolding, oxidative stress, and disturbances in calcium homeostasis. ERS activates the unfolded protein response, thereby influencing the onset and progression of DR through modulating mitochondria-associated endoplasmic reticulum membranes, autophagy, apoptosis, microvascular function, oxidative stress, and inflammation pathways. Currently, the principal interventions against ERS comprise the modulation of the ERS signalling axis and its interactions with associated pathological processes such as autophagy, oxidative stress, and inflammation, through pharmacological and molecular mechanisms. These interventions are directly or indirectly shown to inhibit persistent ERS and are demonstrated to ameliorate DR. With the in-depth study of ERS and the research and development of various drugs for ERS, it is expected to bring novel insights and strategies for DR management in the future.
Objective To investigate the protective effect of 4-phenylbutyric acid (PBA) on liver injury induced by severe acute pancreatitis (SAP) in rats and its possible mechanism. Methods Twenty-four SPF adult male Sprague Dawley rats were randomly divided into three groups: shame operation group (SO group,n=8), SAP group (n=8), and PBA group (n=8). SAP model was induced by retrograde injection of 5% sodium taurocholate (1 mL/kg) in biliopancreatic duct in SAP group and PBA group. PBA solution (50 mg/kg) was administeredvia intraperitoneal injection for 3 days prior to establishing models in PBA group. Rats were injected equivalent saline solution instead of PBA solution in SAP group and SO group. All rats were sacrificed at 12 h after modeling. Blood samples were collected by inferior vena cava puncture, and serum levels of amylase (AMY), alanine aminotransferase (ALT), and aspartate transaminase (AST) were measured using a fully automatic chemistry analyzer. The head of pancreas and right lobe of hepatic tissues were harvested and pathological examination was observed under the light microscope. Expressions of glucose-regulated protein 78 (GRP78), CCAAT/enhancer binding protein homologous protein (CHOP) and Caspase-3 in hepatic tissues were evaluated by immunohistochemistry assay. Results Compared with SO group, the serum levels of AMY, ALT and AST were significantly increased in SAP group (P＜0.05). The serum levels of ALT and AST in PBA group were significantly lower than those in SAP group (P＜0.05). There was no difference of the serum levels of AMY between in PBA group and SAP group (P＞0.05). Compared with SO group, the damages of the pancreas and liver tissues and the expressions of GRP78, CHOP and Caspase-3 in hepatic tissues were significantly increased in SAP group (P＜0.05). And the above indices in PBA group were significantly decreased when compared with SAP group. Conclusions PBA can alleviate severe acute pancreatitis-induced liver injury, and the mechanism may be associated with inhibition of endoplasmic reticulum stress (ERS) and reduction of hepatocyte apoptosis.
ObjectiveTo summarize the mechanism of endoplasmic reticulum stress (ERS) in liver diseases. MethodWe sorted out and summarized the studies related to ERS and liver diseases in recent years. ResultsEndoplasmic reticulum plays important roles in protein folding, calcium ion storage, and lipid synthesis in cells. ERS will be induced when the number of misfolded/unfolded proteins in the endoplasmic reticulum increases or the calcium ion homeostasis is unbalanced. The endoplasmic reticulum regulates the unfolded protein response through three transmembrane receptor proteins to initiate corresponding pathways for restoring endoplasmic reticulum homeostasis. Prolonged stress can lead to metabolic disorders. Mild ERS can promote the progression of hepatocellular carcinoma, and continuous ERS will induce cell apoptosis and play an anti-tumor effect; ERS can promote lipid accumulation in non-alcoholic fatty liver disease and aggravate the progression of the disease; in hepatic ischemia reperfusion injury, ERS activation will aggravate liver damage. Meanwhile, ERS activation plays an important pathogenic role in the pathogenesis of drug-induced liver injury. ConclusionERS plays a crucial regulatory role in the occurrence and development of liver-related diseases, providing a theoretical basis and new approach for targeted ERS therapy in liver diseases.
Calnexin is a lectin-like molecular chaperone protein on the endoplasmic reticulum, mediating unfolded protein responses, the endoplasmic reticulum Ca2+ homeostasis, and Ca2+ signals conduction. In recent years, studies have found that calnexin plays a key role in the heart diseases. This study aims to explore the role of calnexin in the activation of cardiac fibroblasts. A transverse aortic constriction (TAC) mouse model was established to observe the activation of cardiac fibroblasts in vivo, and the in vitro cardiac fibroblasts activation model was established by transforming growth factor β1 (TGFβ1) stimulation. The adenovirus was respectively used to gene overexpression and silencing calnexin in cardiac fibroblasts to elucidate the relationship between calnexin and cardiac fibroblasts activation, as well as the possible underlying mechanism. We confirmed the establishment of TAC model by echocardiography, hematoxylin-eosin, Masson, and Sirius red staining, and detecting the expression of cardiac fibrosis markers in cardiac tissues. After TGFβ1 stimulation, markers of the activation of cardiac fibroblast, and proliferation and migration of cardiac fibroblast were detected by quantitative PCR, Western blot, EdU assay, and wound healing assay respectively. The results showed that the calnexin expression was reduced in both the TAC mice model and the activated cardiac fibroblasts. The overexpression of calnexin relieved cardiac fibroblasts activation, in contrast, the silencing of calnexin promoted cardiac fibroblasts activation. Furthermore, we found that the endoplasmic reticulum stress was activated during cardiac fibroblasts activation, and endoplasmic reticulum stress was relieved after overexpression of calnexin. Conversely, after the silencing of calnexin, endoplasmic reticulum stress was further aggravated, accompanying with the activation of cardiac fibroblasts. Our data suggest that the overexpression of calnexin may prevent cardiac fibroblasts against activation by alleviating endoplasmic reticulum stress.
Objective To explore the effects of 4-phenylbutyric acid (4-PBA) on idiopathic pulmonary fibrosis (IPF) using a murine model of bleomycin (BLM)-induced pulmonary fibrosis. Methods Pulmonary fibrosis was induced in C57BL/6 mice by intratracheal injection of BLM. A total of 120 mice were randomly allocated into three groups: BLM group, BLM+4-PBA group, and control group. Pathology of lung tissue was analyzed to evaluate the degree of pulmonary fibrosis, and the survival of the mice was noted. The expression levels of the endoplasmic reticulum stress markers, activating transcription factor 6 (ATF6) and C/EBP homologous protein (CHOP), were analyzed in lung tissues from mice. Results BLM induced significant collagen deposition in the lungs of the mice, which was alleviated by 4-PBA. 4-PBA also dramatically improved the pulmonary function and increased the survival rate in the BLM+4-PBA group compared with that in the BLM group. Both the mRNA and protein expression levels of ATF6 and CHOP were significantly reduced in mouse lung tissue after 2 weeks of 4-PBA treatment. Conclusions 4-PBA treatment could alleviate BLM-induced pulmonary fibrosis in mice via the attenuation of endoplasmic reticulum stress.