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.
The endoplasmic reticulum (ER) is physically connected to mitochondria through the specific sub-domain,called mitochondria-associated endoplasmic reticulum membranes (MAMs). These contacts are involved in calcium signaling,lipid transferring,mitochondrial fission and fusion and energy metabolism. Recently,MAMs alterations have been identified to associate with some diseases,including neurodegenerative diseases,obesity,cardiovascular diseases and cancer. Therefore,in this paper,we introduce the structure,function and detection methods of MAMs. Besides,we also summarize the potential role of MAMs in these diseases. In any case,the signaling at the MAMs might be a promising pharmacological target for several diseases.
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.
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 study effects of oxymatrine on proliferation and apoptosis of gastric cancer cell line BGC-823 and explore role of endoplasmic reticulum stress in apoptosis of gastric cancer cells induced by oxymatrine and elucidate its mechanism.MethodsThe gastric cancer BGC-823 cells at the logarithmic phase were divided into a control group, oxymatrine alone group (oxymatrine at 10, 30, 60 and 90 μmol/L concentrations), and combination group (oxymatrine at various concentrations combined with 2 μmol/L endoplasmic reticulum stress inhibitor salubrinal). The MTT assay was used to observe the inhibitory effect of the oxymatrine on the growth of BGC-823 cells. The flow cytometry was used to analyze the apoptosis and cell cycle. The Western blot and RT-PCR methods were used to detect the expressions of GRP78/Bip and the caspase-12 protein and gene, respectively.Results① Compared with the control group, the oxymatrine could significantly inhibit the growth of gastric cancer BGC-823 cells in a concentration-time dependent manner (P<0.05) and its IC50 (48 h) value was (59.5±0.5) μmol/L. The inhibitory effect of the combination group of 30, 60, and 90 μmol/L oxymatrine was significantly weakened as compared with the the corresponding oxymatrine alone group (P<0.05). ② The oxymatrine could significantly induce the apoptosis and arrest the G2/M phase in the gastric cancer BGC-823 cells in a concentration-dependent manner (P<0.05). The combination group of 60 μmol/L oxymatrine could significantly decreased the apoptosis rate and the number of cells in the G2/M phase in the gastric cancer BGC-823 cells after treating 48 h (P<0.05). ③ The protein and gene levels of GRP78/Bip and caspase-12 showed significant increases with the increase of oxymatrine concentrations in the oxymatrine alone group (except the protein and gene levels of caspase-12 at 10 μmol/L oxymatrine) as compared with the control group (P<0.05), which in the combination group of 60 μmol/L and 90 μmol/L oxymatrines were significantly decreased as compared with the corresponding oxymatrine alone group (P<0.05).ConclusionOxymatrine can inhibit growth of human gastric cancer cell line BGC-823, which maybe related to caspase-12-dependent induction of apoptosis and up-regulation of GRP78/Bip expression, which needs further experimental verification.
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.
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.
ObjectiveTo summarize the progress of study on the relationship between endoplasmic reticulum stress and cell proliferation and provide evidence with reliable evidence-based data to the experiment on the field of tissue damage repair, organ proliferation, and regeneration.MethodThe relevant literatures about the progress of multiple signaling pathways related to the endoplasmic reticulum stress in the cell proliferation and injury repair in recent years were reviewed.ResultsThe endoplasmic reticulum stress participated in the process of proliferation and regeneration in the intestinal epithelial cells, skeletal muscle cells, islet cells, and hepatocytes through different pathways, which involved the three pathways of unfolded protein reaction that interacted with interleukin-6, tumor necrosis factor-α, vascular endothelial growth factor, Wnt, etc.ConclusionsAlthough endoplasmic reticulum stress has been widely debated in the field of determining cell fate, after we reviewed recent studies on endoplasmic reticulum stress in maintaining cell survival and promoting cell proliferation, the complexity, diversity, and importance of the endoplasmic reticulum stress in promoting cell proliferation have been presented in front of us. It not only promotes cell proliferation through the classical signaling pathway with Wnt protein, but also acts to repair tissue and promote proliferation by interacting with Musashi protein independently of the Notch pathway. The complex reaction pathway interacts with different stimulating factors in different cells, providing research directions and exploration possibilities for cell proliferation, injury repair, and organ regeneration, reveales the critical role of endoplasmic reticulum stress in cell proliferation.
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.
ObjectiveTo investigate the effects of phenethyl isothiocyanate (PEITC) on apoptosis and proliferation of breast cancer SK-BR-3 cells. MethodsSK-BR-3 cells were treated with different concentrations (0, 10, 30, 50 μmol/L) of PEITC respectively. The proliferation capacity of SK-BR-3 cells was detected by MTT and BrdU staining methods. The cell apoptosis was detected by TUNEL and flow cytometry methods. The protein and mRNA expressions levels of indexes related apoptosis such as Bcl-2, Bax, and MCL-1 and indexes related endoplasmic reticulum stress (ERS) such as PERK, eIF2α, CHOP, IRE1α, ATF6α were detected by Western blot and quantitative real-time PCR (qRT-PCR), respectively. ResultsCompared with the control group (0 μmol/L PEITC treatment group), the results of MTT and BrdU staining methods showed that the proliferations of SK-BR-3 cells in the 10, 30 and 50 μmol/L PEITC treatment group were decreased in turn with the increase of concentration. The results of TUNEL and flow cytometry methods showed that the apoptosis rates of SK-BR-3 cells in the 10, 30 and 50 μmol/L PEITC treatment group were increased in turn with the increase of concentration. The results of Western blot and qRT-PCR methods showed that the protein and mRNA expression levels of anti-apoptotic indexes (Bcl-2, MCL-1) were decreased with the increase of concentration, while the expression levels of protein and mRNA of the pro-apoptotic index (Bax) and ERS-related indexes (PERK, eIF2α, CHOP, IRE1α, ATF6α) increased with the increase of concentration. ConclusionFrom the preliminary results of this study, PEITC can promote the apoptosis of breast cancer SK-BR-3 cells and inhibit cell proliferation, which might be achieved by regulating the expression levels of indexes related apoptosis and ERS.