Expression Of Glucose-regulated Protein 78 Protein Research Articles

Endoplasmic Reticulum Stress in Myometrial Smooth Muscle Cells and Spontaneous Contraction Changes in the Uterus of Dehydroepiandrosterone-induced Polycystic Ovary Syndrome Rats.

Myometrial changes in polycystic ovary syndrome (PCOS) are poorly investigated. Thus, we aimed to investigate endoplasmic reticulum (ER) stress in myometrial smooth muscle cells and changes in spontaneous uterine contraction in PCOS. Twenty-one female Sprague-Dawley rats (21 days old) were divided into control (n = 7), vehicle (n = 7) and PCOS (n = 7) groups. While the control group was not injected subcutaneously, the vehicle group was injected subcutaneously with sesame oil (0.2 ml/day) for 20 consecutive days. The PCOS group was injected subcutaneously with dehydroepiandrosterone (6 mg/100 g/day dissolved in 0.2 ml sesame oil) for 20 consecutive days. Blood samples were collected for the measurement of follicle stimulating-hormone (FSH), luteinizing hormone (LH), testosterone (T), estradiol (E2) and glucose-regulated protein 78 (GRP78). The mRNA expression of GRP78 in the uterine tissue samples was analysed by quantitative real-time polymerase chain reaction. GRP78 protein expression was assessed by immunohistochemistry. Myometrial smooth muscle cells were examined by transmission electron microscopy. Uterine contractions were evaluated with isolated organ bath experiments. In the PCOS group, T and LH levels increased significantly, although FSH and E2 levels decreased, but this decrease was not statistically significant. Additionally, GRP78 levels increased significantly in the PCOS group. In the PCOS group, the mRNA level, immunostaining intensity of GRP78, and ER damage grade increased, but the uterine tissue calcium levels, and the frequency and amplitude of spontaneous uterine contractions decreased. The results indicated that increased ER stress in myometrial smooth muscle cells may play a causative role in the decreased spontaneous uterine contractions in PCOS.

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.

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.

β-Sitosterol attenuates anlotinib resistance in non-small cell lung cancer cells by inhibiting miR-181a-3p/SHQ1 signaling.

Anlotinib is used for the treatment of advanced non-small cell lung cancer; however, the emergence of drug resistance limits its clinical application. β-sitosterol may also be used to treat lung cancer, but there have been no studies evaluating β-sitosterol against anlotinib-resistant lung cancer. The purpose of this study was to determine the mechanism by which β-sitosterol enhances the sensitivity of lung cancer cells to anlotinib. A549 cells were treated with different concentrations of anlotinib to generate anlotinib-resistant cells (A549/anlotinib cells). miR-181a-3p mimics were transfected into A549/anlotinib cells. A549 and A549/anlotinib cells were treated with β-sitosterol at various concentrations. The Cell Counting Kit-8 (CCK-8) assay was used to measure cell proliferation. Apoptosis was assessed by flow cytometry. Real-time quantitative PCR was used to measure the expression of miR-181a-3p. The interaction of miR-181a-3p with the H/ACA ribonucleoprotein assembly factor (SHQ1) was predicted using the miRDB and TargetScan Human databases and verified with a luciferase reporter assay. The expression of SHQ1, activating transcription factor 6 (ATF6), and glucose-regulated protein 78 (GRP78) were measured by western blot analysis. β-Sitosterol effectively suppressed A549/anlotinib cell proliferation and promoted apoptosis. SHQ1 is a downstream target of miR-181a-3p. The expression of miR-181a-3p was inhibited; however, SHQ1 expression was increased by β-sitosterol treatment of A549/anlotinib cells. The inhibition of SHQ1, ATF6, and GRP78 protein expression by β-sitosterol in A549/anlotinib cells was rescued by increased miR-181a-3p. β-Sitosterol markedly promotes anlotinib-resistant A549 cell apoptosis and inhibits cell proliferation by activating SHQ1/UPR signaling through miR-181a-3p inhibition.

Mechanism of Qili Qiangxin Capsule for Heart Failure Based on miR133a-Endoplasmic Reticulum Stress.

To investigate the pharmacological mechanism of Qili Qiangxin Capsule (QLQX) improvement of heart failure (HF) based on miR133a-endoplasmic reticulum stress (ERS) pathway. A left coronary artery ligation-induced HF after myocardial infarction model was used in this study. Rats were randomly assigned to the sham group, the model group, the QLQX group [0.32 g/(kg·d)], and the captopril group [2.25 mg/(kg·d)], 15 rats per group, followed by 4 weeks of medication. Cardiac function such as left ventricular ejection fraction (EF), fractional shortening (FS), left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), the maximal rate of increase of left ventricular pressure (+dp/dt max), and the maximal rate of decrease of left ventricular pressure (-dp/dt max) were monitored by echocardiography and hemodynamics. Hematoxylin and eosin (HE) and Masson stainings were used to visualize pathological changes in myocardial tissue. The mRNA expression of miR133a, glucose-regulated protein78 (GRP78), inositol-requiring enzyme 1 (IRE1), activating transcription factor 6 (ATF6), X-box binding protein1 (XBP1), C/EBP homologous protein (CHOP) and Caspase 12 were detected by RT-PCR. The protein expression of GRP78, p-IRE1/IRE1 ratio, cleaved-ATF6, XBP1-s (the spliced form of XBP1), CHOP and Caspase 12 were detected by Western blot. TdT-mediated dUTP nick-end labeling (TUNEL) staining was used to detect the rate of apoptosis. QLQX significantly improved cardiac function as evidenced by increased EF, FS, LVSP, +dp/dt max, -dp/dt max, and decreased LVEDP (P<0.05, P<0.01). HE staining showed that QLQX ameliorated cardiac pathologic damage to some extent. Masson staining indicated that QLQX significantly reduced collagen volume fraction in myocardial tissue (P<0.01). Results from RT-PCR and Western blot showed that QLQX significantly increased the expression of miR133a and inhibited the mRNA expressions of GRP78, IRE1, ATF6 and XBP1, as well as decreased the protein expressions of GRP78, cleaved-ATF6 and XBP1-s and decreased p-IRE1/IRE1 ratio (P<0.05, P<0.01). Further studies showed that QLQX significantly reduced the expression of CHOP and Caspase12, resulting in a significant reduction in apoptosis rate (P<0.05, P<0.01). The pharmacological mechanism of QLQX in improving HF is partly attributed to its regulatory effect on the miR133a-IRE1/XBP1 pathway.

Effects and mechanism of diammonium glycyrrhizinate on liver injury in severely scalded rats

Objective: To investigate the effects and mechanism of diammonium glycyrrhizinate (DG) on liver injury in severely scalded rats. Methods: The experimental research method was used. Fifty-four female Sprague-Dawley rats aged 7-9 weeks were divided into sham injury group with simulated injury on the back, and simple scald group and scald+DG group with scald of 30% total body surface area on the back, with 18 rats in each group. Rats in sham injury group were not specially treated after injury, and rats in simple scald group and scald+DG group were rehydrated for antishock. Besides, rats in scald+DG group were injected intraperitoneally with 50 mg/kg DG at post injury hour (PIH) 1, 25, and 49. Rats in the three groups were collected, the serum content of liver function injury related indexes including aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), total protein, and albumin was measured by automatic biochemical assay analyzer, and serum content of ornithine carbamoyl transferase (OCT) was measured by enzyme-linked immunosorbent assay method at PIH 24, 48, and 72; hepatic histopathological changes at PIH 72 were observed by hematoxylin-eosin staining; the mRNA expressions of B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), glucose regulated protein 78 (GRP78), activating transcription factor 4 (ATF4), and protein kinase R-like endoplasmic reticulum kinase (PERK) in liver tissue were detected by real-time fluorescent quantitative reverse transcription polymerase chain reaction at PIH 24, 48, and 72. The protein expressions of Bcl-2, Bax, GRP78, PERK, and ATF4 in liver tissue were detected by Western blotting at PIH 72 in sham injury group and PIH 24, 48, and 72 in simple scald group and scald+DG group. The number of samples was 6 in each group at each time point. Data were statistically analyzed with analysis of variance for factorial design, one-way analysis of variance, and Bonferroni test. Results: Compared with that in sham injury group, the serum content of AST, ALT, and LDH was significantly increased (P<0.01), and the serum content of total protein and albumin was significantly decreased (P<0.05 or P<0.01) of rats in simple scald group at all post-injury time points. Compared with those in simple scald group, the serum AST content of rats in scald+DG group at PIH 24 was decreased significantly (P<0.05); the serum AST, ALT, and LDH content of rats in scald+DG group at PIH 48 was decreased significantly (P<0.01), and the serum total protein content was increased significantly (P<0.01); the serum AST, ALT, and LDH content of rats in scald+DG group at PIH 72 was decreased significantly (P<0.01), and the serum total protein and albumin content was increased significantly (P<0.01). At PIH 24, 48, and 72, the serum OCT content of rats in simple scald group was (48.5±3.9), (40.8±2.4), and (38.7±2.0) U/L, which was significantly higher than (15.1±2.5), (15.7±2.6), and (16.4±3.7) U/L in sham injury group (P<0.01), and (39.0±4.5), (31.8±2.0), and (22.1±2.6) U/L in scald+DG group (P<0.05 or P<0.01). At PIH 72, the cells in liver tissue of rats in sham injury group had normal morphology and regular arrangement, with no obvious inflammatory cell infiltration; the cells in liver tissue of rats in simple scald group had disordered arrangement, diffuse steatosis, and moderate inflammatory cell infiltration; the cells in liver tissue of rats in scald+DG group arranged regularly, with scattered steatosis and a small amount of inflammatory cell infiltration. Compared with those in sham injury group, the Bcl-2 mRNA (P<0.05 or P<0.01) and protein expressions of liver tissue were significantly decreased, and the mRNA (P<0.01) and protein expressions of Bax were significantly increased in rats in simple scald group at PIH 24, 48, and 72. Compared with those in simple scald group, the mRNA (P<0.05) and protein expressions of Bax in liver tissue of rats in scald+DG group were decreased significantly at PIH 48; the mRNA (P<0.01) and protein expressions of Bax in liver tissue of rats in scald+DG group were significantly decreased, and the mRNA (P<0.01) and protein expressions of Bcl-2 were significantly increased at PIH 72. Compared with those in sham injury group, the mRNA (P<0.05 or P<0.01) and protein expressions of ATF4, GRP78, and PERK in liver tissue were significantly increased in rats in simple scald group at all post-injury time points. Compared with those in simple scald group, the mRNA (P<0.01) and protein expressions of ATF4 in liver tissue of rats in scald+DG group at PIH 48 were significantly decreased, and the mRNA (P<0.05 or P<0.01) and protein expressions of ATF4, GRP78, and PERK were significantly decreased in liver tissue of rats in scald+DG group at PIH 72. Conclusions: DG can effectively reduce the degree of liver injury in rats after severe scald, and the mechanism may involve alleviating endoplasmic reticulum stress and mitigating mitochondrial damage.

Ubiquitin-conjugating enzyme E2T promotes tumor stem cell characteristics and migration of cervical cancer cells by regulating the GRP78/FAK pathway.

Ubiquitin-conjugating enzyme E2T (UBE2T) functions as an E2 ubiquitin-conjugating enzyme in the ubiquitin-proteasome degradation system and mediates cellular processes, such as cell cycle, proliferation, and differentiation. UBE2T has been considered to be an oncogene in a variety of tumors. However, the oncogenic role of UBE2T in cervical cancer remains unclear. In this study, our results first showed that the expression of UBE2T was higher in both of cervical cancer tissues and cells than that in the normal tissues and cells. Knockdown of UBE2T reduced cervical cancer cell viability and suppressed the proliferation, invasion, and migration. However, overexpression of UBE2T contributed to cervical cancer cell growth and metastasis. Moreover, UBE2T overexpression cervical cancer cells demonstrated enhanced self-renewal capacity with upregulation of SOX2, Oct-4, and Nanog protein. Silencing of UBE2T downregulated protein expression of SOX2, Oct-4, and Nanog in cervical cancer cells reduced self-renewal capacity. Furthermore, ectopic UBE2T expression promoted protein expression of glucose-regulated protein 78 (GRP78) and focal adhesion kinase (FAK) phosphorylation in cervical cancer cells. The knockdown of UBE2T reduced protein expression of GRP78 and FAK phosphorylation. Collectively, UBE2T promoted cervical cancer stem cell traits and exerted an oncogenic role through activation of the GRP78/FAK pathway.

Enhanced GRP78 protein expression via the IRE1α/ASK1/p38 MAPK pathway during As2O3-induced endoplasmic reticulum stress in BEAS-2B cells

Inorganic arsenic is widely present in the environment. Exposure to moderate to high concentrations of arsenic from drinking water or air can cause various cancers and multisystem dysfunction. Glucose-regulated protein 78 (GRP78) is an endoplasmic reticulum (ER) stress sensor of unfolded protein response (UPR) under stress conditions and it enhances cell survival. The aim of this study is to investigate molecular mechanisms of arsenic-induced GRP78 expression in BEAS-2B cells model. We found that GRP78 protein expression was enhanced, while the level of GRP78 mRNA expression did not change under arsenic trioxide (As2O3)-induced ER stress condition in BEAS-2B cells. Cycloheximide, a protein synthesis inhibitor, completely inhibited As2O3-induced GRP78 protein expression. GRP78 mRNA expression was inhibited by actinomycin-D (Act-D). However, GRP78 protein expression was upregulated in the presence of Act-D under As2O3-induced ER stress condition. These data indicated that the upregulation of GRP78 protein under As2O3-induced UPR condition was possibly due to the increased biosynthesis of GRP78 protein. Moreover, both inositol-requiring enzyme 1α (IRE1α) RNase and kinase inhibitor KIRA6 and IRE1α kinase inhibitor APY29 completely inhibited As2O3-induced GRP78 protein expression and phosphorylation of JNK, ERK and p38 MAPK. Activation of apoptotic signaling kinase 1 (ASK1) is a downstream effector of IRE1α kinase. ASK1 inhibitor selonsertib and p38 MAPK inhibitor SB203580 partially inhibited As2O3-induced GRP78 protein expression, respectively. Our results suggested that As2O3 enhanced GRP78 protein expression in BEAS-2B cells via IRE1α kinase/ASK1/p38 MAPK signaling pathway. To our knowledge, this is the first report on illuminating the related mechanisms of increased GRP78 protein expression in As2O3-induced ER stress condition through a novel IRE1α pathway.

Glucose- regulated protein 78 (GRP78) in renal cell carcinoma: A novel biomarker for predicting tumor behavior

ObjectiveTo study the mRNA and protein expression of GRP78 in tumor and serum of the RCC patients and compare with the controls and to correlate the expression with the grade and stage of RCC. Materials and methodsA prospective cohort study involving 60 patients planned for radical/partial nephrectomy for primary RCC between July 2017 to June 2019. The RCC and adjacent non-tumorous renal tissues (Control) along with serum samples of patients were collected. Control for the serum samples is from the patients undergoing simple nephrectomy for non-functioning kidney due to benign etiology. The GRP78 expression was studied using RT-PCR for mRNA expression, Western blot analysis and immunohistochemistry (IHC) for protein expression and using ELISA in serum for both the subjects and controls. ResultsMean age of patients was 50.3 years. The mRNA and protein expression of GRP78 in tissue samples were significantly higher in RCC patients as compared to controls (p < 0.001). IHC also demonstrated significantly higher expression in tumour samples as compared to controls (p < 0.001). Circulatory levels of GRP78 in serum samples were also significantly increased (p < 0.0001) in RCC patients in comparison to control subjects. The expression of GRP78 in circulation significantly correlated with the pathological tumor stage (p = 0.03), grade of disease (p < 0.001). ConclusionThe GRP78 in RCC is significantly upregulated both at molecular and protein level expression. The overexpression of GRP78 correlates with the stage and grade of disease, thereby, highlighting its prognostic ability.

6-Formylindolo[3,2-b]carbazole alleviates lipopolysaccharide-induced acute lung injury via suppressing endoplasmic reticulum stress

To investigate the effect and mechanism of 6-formylindolo[3,2-b]carbazole (FICZ) on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. Male C57BL/6J mice aged 8-12 weeks were divided into 4 groups with 8 mice in each group, according to the method of simple random sampling. Sepsis-induced ALI mice model was established by intraperitoneal injection of LPS 5 mg/kg (LPS group), and phosphate buffer saline (PBS) control group (PBS group) was injected with equal volume of PBS. The LPS+FICZ group was intervened by intraperitoneal injection of 1 μg FICZ 1 hour after LPS stimuli, while the FICZ control group (FICZ group) was given the same amount of FICZ 1 hour after intraperitoneal injection of PBS. Serum and lung tissue were collected 24 hours after LPS stimuli, and the pathological changes of lung tissue were analyzed by hematoxylin-eosin (HE) staining and wet/dry weight (W/D) ratio of lung tissue. The concentrations of inflammatory factors in serum and lung tissue were detected by enzyme linked immunosorbent assay (ELISA). The expression levels of endoplasmic reticulum stress signaling pathway related molecules were detected by real-time fluorescent quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Compared with PBS group, inflammatory cell infiltration, alveolar collapse and obvious alveolar exudative lesions had increased, lung tissue W/D ratio was significantly increased, serum interleukin-6 (IL-6) level, lung tissue IL-6 mRNA expression, and the mRNA expressions of glucose-regulated protein 78 (GRP78), protein kinase R-like endoplasmic reticulum kinase (PERK), CCAAT/EBP homologous protein (CHOP), and the protein expressions of GRP78, PERK, activating transcription factor 6 (ATF6), CHOP in lung tissue were significantly increased in LPS group. However, the indexes of FICZ group were not affected. Compared with LPS group, LPS+FICZ group had less inflammatory cell infiltration, relatively intact alveolar structure. Lung W/D weight ratio in LPS+FICZ group was significantly decreased (5.38±0.10 vs. 6.60±0.30, P < 0.01), so as serum IL-6 (ng/L: 15.55±3.77 vs. 32.22±3.84) and lung IL-6 mRNA expression (2-ΔΔCt: 0.79±0.21 vs. 6.89±0.92, both P < 0.01). The mRNA expressions of GRP78, PERK and CHOP were also significantly decreased [GRP78 mRNA (2-ΔΔCt): 1.90±0.16 vs. 7.55±1.29, PERK mRNA (2-ΔΔCt): 1.68±0.20 vs. 4.54±0.89, CHOP mRNA (2-ΔΔCt): 1.13±0.24 vs. 4.44±1.13, all P < 0.05], and the protein expressions of GRP78, PERK, ATF6 and CHOP were significantly decreased (GRP78/GAPDH: 0.59±0.02 vs. 0.77±0.01, PERK/GAPDH: 0.48±0.03 vs. 1.04±0.05, ATF6/GAPDH: 0.51±0.03 vs. 0.65±0.01, CHOP/GAPDH: 0.91±0.05 vs. 1.11±0.07, all P < 0.05). FICZ protects LPS-induced ALI possibly via suppressing endoplasmic reticulum stress and reducing IL-6 expression in blood and lung tissue.

Kuanoniamine C stimulates bortezomib-induced cell death via suppression of glucose-regulated protein 78 in osteosarcoma

Osteosarcoma is the most frequent and intractable malignancy of the bone in children and young adults. Surgical operation requires extensive excision of the cancer tissue and neighboring normal tissues. In addition, anticancer drugs and radiation therapy are thought to be almost ineffective. Glucose-regulated protein 78 (GRP78), a cell-protective endoplasmic reticulum (ER) chaperone protein, is one of the most promising anticancer targets for osteosarcoma. Here, by analyzing the molecular mechanisms of kuanoniamine C, we report that kuanoniamine C suppresses GRP78 expression via GRP78 mRNA degradation in an ER stress response-independent manner. Interestingly, kuanoniamine C-induced cell death and downregulation of GRP78 expression was regulated by p53 signaling. Moreover, co-treatment with bortezomib, which is a newly identified anticancer drug for osteosarcoma, and kuanoniamine C suppressed GRP78 protein expression, which is essential for the stimulation of bortezomib-induced cell death. These results suggest that co-treatment with bortezomib and kuanoniamine C is a novel therapeutic strategy for the treatment of osteosarcoma that enhances bortezomib-dependent cell death by the downregulation of GRP78, and this combination selectively targets the major cell population of osteosarcoma, which expresses wild-type p53.

Effects of bergapten on damages of osteocytes MLO-Y4 induced by TCP wear particles and its mechanism

To study the effects of bergapten (BP) on damages of osteocytes MLO-Y4 induced by tricalcium phosphate (TCP) wear particles and its mechanism. ;Methods: MLO-Y4 cells were treated with TCP wear particles for 48 h to establish the model of osteocytes injuries in vitro. The MLO-Y4 cells were divided into the following five groups: control group, TCP wear particles treated (0.1 mg/ml) group, bergapten (1, 5 and 20 μmol/L) treated groups. MTT assay and Calcein-AM staining were used to determine the viability of MLO-Y4 cells; Hoechst 33342 staining and the flow cytometry were applied to detect the apoptosis of MLO-Y4; real-time PCR was performed to examine the mRNA levels of dentin matrix protein1 (DMP-1), sclerostin (SOST) and fibroblast growth factor23 (FGF23); Western blot was performed to examine protein expressions of glucose-regulated protein 78 (GRP78), protein kinase R-like ER kinase (PERK) phospho-PERK (p-PERK), eukaryotic initiation factor 2α (eIF2α), phospho-eIF2α (p-eIF2α), activating transcription factor 4 (AFT4), C/EBP homologous protein (CHOP) and caspase-3 in MLO-Y4 cells. ;Results: Compared with control group, the MLO-Y4 viability and DMP-1 mRNA level in TCP group were decreased significantly (P＜0.05), while the percentage of apoptosis and mRNA levels of SOST and FGF23 were obviously increased (P＜0.05), and protein expressions of GRP78, AFT4, CHOP, p-PERK/PERK and p-eIF2α/eIF2α were up-regulated significantly in MLO-Y4 cells (P＜0.05). Compared with TCP group, the damages of MLO-Y4 and cell apoptosis in bergapten treated groups were decrease obviously (P＜0.05), the expressions of GRP78, AFT4, CHOP, p-PERK/PERK and p-eIF2α/eIF2α were down-regulated remarkably (P＜0.05). ;Conclusion: Bergapten can inhibit osteocytes damages induced by TCP wear particles, which may be related to reducing ER stress and PERK pathway activation.

Pro-inflammatory effect induced by endoplasmic reticulum stress in placental trophoblast cells participates in genesis of gestational diabetes mellitus

Objective To explore whether the pro-inflammatory effect of endoplasmic reticulum stress in placental tissues involves in the genesis of gestational diabetes mellitus (GDM). Methods Forty gravidas who underwent regular prenatal examinations and delivered at Tongji Hospital were recruited from January to December, 2016. Among them, 20 were GDM women (GDM group), and the remaining twenty were served as the control, which were selected from those without GDM and matched for age and gestational weeks to the GDM group. Placental tissues were collected from the two groups. The ultrastructure of endoplasmic reticulum in trophoblast cells was observed under transmission electron microscope. The expression of glucose-regulated protein-78 (GRP-78), a marker protein for endoplasmic reticulum stress, and C/EBP homologous protein (CHOP) were detected using Western blotting. Five placental tissue samples were collected from normal gravidas for explant culture. Three subgroups were set up according to different culturing methods including culturing with IL-1β (5 ng/ml) for 20 h (IL-1β model group), 30 μmol/L thapsigargin (TG, an endoplasmic reticulum stress agonist) for 2 h after treating with IL-1β (5 ng/ml) for 18 h (IL-1β+TG intervention group) or with no stimulation (blank control group). Western blotting was used to detect the expressions of GRP-78, CHOP and glucose transporter 4 (GLUT4) in placenta explants. The mRNA expressions of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were determined by real-time fluorescence quantitative polymerase chain reaction (RT-PCR). Statistical analysis was performed using one-way analysis of variance, LSD and t test. Results (1) In the GDM group, increased number and size of endoplasmic reticulum cisternae were observed in trophoblast cells. Moreover, obviously dilated endoplasmic reticulum and different size of fragments and vesicles were also seen under electron microscope. While the endoplasmic reticulum in the placental tissues of the control group showed no obvious swelling. (2) The expression of GRP-78 and CHOP protein in the GDM group were higher than those in the control group (0.90±0.17 vs 0.48±0.08, t=2.24; 0.85±0.13 vs 0.46±0.12, t=2.10; both P<0.05). (3) Compared with the blank control group, the expression of GRP-78 and CHOP protein in the IL-1β model group increased significantly (0.87±0.18 vs 0.36±0.07, t=2.67; 1.14±0.09 vs 0.78±0.06, t=3.20; both P<0.05); but the expression of GLUT4 protein significantly decreased (1.00±0.14 vs 2.21±0.49, t=2.40, P<0.05); the expressions of IL-6 and TNF-α mRNA significantly increased (0.89±0.23 vs 0.30±0.06, t=2.31; 0.62±0.16 vs 0.17±0.09, t=2.29; both P<0.05). Compared with the IL-1β model group, the expression of GRP-78 and CHOP protein significantly increased in IL-1β+TG group (2.02±0.32 vs 0.87±0.18, t=3.11; 2.18±0.31 vs 1.14±0.09, t=3.16; both P<0.05); the expression of GLUT4 protein significantly decreased (0.39±0.19 vs 1.00±0.14, t=2.66, P<0.05); the expression of IL-6 and TNF-α mRNA increased significantly (1.67±0.25 vs 0.89±0.23, t=2.26; 1.42±0.27 vs 0.62±0.16, t=2.51; both P<0.05). Conclusions Endoplasmic reticulum stress may be associated with increased release of pro-inflammatory cytokines in placental tissues of some GDM women and involved in the onset and development of GDM. Key words: Diabetes, gestational; Endoplasmic reticulum stress; Placenta; Cytokines; Inflammation

Effect of granulocyte-colony stimulating factor on endoplasmic reticulum stress in neonatal rats after hypoxic-ischemic brain damage

Objective To evaluate the protective effect of granulocyte-colony stimulating factor(G-CSF) on neonatal rats after hypoxic-ischemic brain damage(HIBD)and its effect on endoplasmic reticulum (ER) stress. Methods According to the random number table, a total of 54 Sprague-Dawley (SD) rats aged 7 days were divided into 3 groups(18 rats in each group): Sham group, HIBD group and G-CSF group, and the improved Rice method was used to establish a neonatal rat model of HIBD.A dose of 50 μg/kg of G-CSF was administered intraperitoneally 1 hour after HIBD (G-CSF group), while the rats in HIBD group and Sham group received saline only.At 24 hours of HIBD, pups were euthanized to quantify brain infarct volume by using 2, 3, 5-Triphenyltetrazolium chloride.Hematoxylin-Eosin (HE) staining was used to observe the changes of brain structure.Neuronal cell death was determined by using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). Then the expressions of glucose-regulated protein 78 (GRP78), cysteinyl aspartate specific proteinase 12 (Caspase-12), CCAAT/enhancer binding-protein homologous protein (CHOP) were assessed by Western blot and immunofluorescence staining. Results Twenty-four hours after operation, HE staining showed that no significant neuronal damage was observed in Sham group.The brain tissue structure of rats in the HIBD group was significantly damaged, while some improvement was observed in the G-CSF group.The infarction volume in HIBD group[(25.40±5.15)%] increased compared with that in the Sham group[(0.31±0.15)%] and the G-CSF group[(16.36±4.97)%], and the differences were statistically significant(all P<0.05). There was increased positive expression of GRP78 protein in HIBD group, compared with that in the Sham group and the G-CSF group[(49.38±10.06)% vs.(9.12±4.50)%, (30.61±6.35)%], and the differences were statistically significant (all P<0.05). The percentage of apoptosis in the hippocampal CA1 region and conex in HIBD group [(44.84±11.54)%, (48.23±14.07)%] were higher than those in the G-CSF group [(17.87±7.20)%, (26.18±9.96)%], and the differences were statistically significant (all P<0.05). The expression of GRP78, CHOP and Caspase-12 in the HIBD group (0.63±0.24, 0.72±0.21, 0.68±0.25) were higher than those in the Sham group (0.20±0.08, 0.28±0.08, 0.23±0.07), and the G-CSF group (0.39±0.13, 0.51±0.18, 0.48±0.16), and the differences were statistically significant (all P<0.05). Conclusions G-CSF exerts neuroprotective effect on the neonatal rats after HIBD.G-CSF may be an effective treatment of HIBD by reducing ER stress-induced neuronal apoptosis. Key words: Infant, newborn; Hypoxic-ischemic brain damage; Granulocyte-colony stimulating factor; Endoplasmic reticulum stress

Effects of glutamine on skeletal muscle membrane repair in severely burned mice and the functional mechanism

Objective: To observe how glutamine affect the skeletal muscle membrane repair in severely burned mice through promoting the mitsugumin 53 (MG53) dimerization in skeletal muscle and to explore its functional mechanism. Methods: (1) Animal experiments. A total of 179 BALB/c male mice aged 6 to 8 weeks were divided into sham injury group (n=43), burn group (n=73) and burn+ glutamine group (n=63) according to the random number table (the same grouping method below). Mice in sham injury group were sham injured on the back, and mice in burn group and burn+ glutamine group were inflicted with 30% total body surface area full-thickness scald (hereinafter referred to as burn) on the back. Mice in burn+ glutamine group were intragastrically administered with glutamine (1 mg/kg), and the other two groups were given the same amount of amino acid solution once per day for 14 days. On post burn hour 12, 10 mice from burn group were taken for preparation of burn serum, which is used in the following cell experiments. Blood samples were collected from the hearts to prepare serum from 10 mice in sham injury group immediately after burn and from 10 mice in burn group and burn+ glutamine group on post burn day (PBD) 5, 10, and 14, respectively. And then the whole gastrocnemius muscle was harvested after the mice were sacrificed. On PBD 10, the whole flexor brevis digitorum was harvested from 6 mice in the 3 groups respectively after the mice were sacrificed. On PBD 5, 10, and 14, the whole gastrocnemius muscle tissue was harvested from another 9 mice in the 3 groups respectively after the mice were sacrificed. The mass of the whole gastrocnemius muscle of mice was weighed. The total protein content of gastrocnemius muscle of mice was detected by coomassie brilliant blue method. The repair function of myolemma of flexor brevis digitorum of mice was detected by two-photon laser fiber membrane perforating. The serum content of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) of mice was determined with radioimmunoassay. The expressions of MG53 dimer and monomer in gastrocnemius of mice were determined with non-reductive electrophoresis-Western blotting. The protein expressions of endoplasmic reticulum stress sign proteins CCAAT/enhancer binding protein homologous protein (CHOP) and glucose-regulated protein 78 (GRP78) in gastrocnemius of mice were determined with Western blotting. (2) Cell experiments. Mice skeletal muscle precursor cells C2C12 were cultured in vitro, and cells of the second passage were selected for the experiments. The cells were divided into normal control group, burn serum group, and burn serum+ glutamine group, with 3 dishes in each group and 1×10(3) cells in each dish. Cells in normal control group were cultured with 1 mL Dulbecco's modified Eagle medium (DMEM) with fetal bovine serum of volume fraction 10%, cells in burn serum group were cultured with 1 mL DMEM with burn serum of volume fraction 10%, and cells in burn serum+ glutamine group were cultured with 1 mL DMEM with burn serum of volume fraction 10% and 4 μL glutamine with a final molar concentration of 8 mmol/L. After 24 hours of culturing, the repair function of myocyte membrane after differentiation of skeletal muscle precursor cells in mice was detected with the same method before. Another cells were grouped and cultured as before, with 3 wells in each group and 1×10(5) cells in each well. After 24 hours of culturing, the expressions of MG53 dimer and monomer and endoplasmic reticulum stress marker proteins in the cells were detected as before. Data were processed with analysis of variance of factorial design, one-way analysis of variance, least significant difference t test, and Student Newman Keuls test. Results: Animal experiments. (1) Compared with those in sham injury group, the mass and total protein content of gastrocnemius muscle of mice in burn group were significantly decreased on PBD 5, 10, and 14 (P 0.05). Compared with 58.5±1.8 in normal control group, the expression of MG53 dimer of cells in burn serum group was significantly decreased after 24 hours of culturing (14.1±1.4, P<0.05). Compared with that in burn serum group, the expression of MG53 dimer of cells in burn serum+ glutamine group was significantly increased after 24 hours of culturing (30.9±0.6, P<0.05). Compared with those in normal control group, the protein expressions of CHOP and GRP78 of cells were significantly elevated in burn serum group after 24 hours of culturing (P<0.05). Compared with those in burn serum group, the protein expressions of CHOP and GRP78 of cells were significantly reduced in burn serum+ glutamine group after 24 hours of culturing (P<0.05). Conclusions: Glutamine can promote MG53 dimerization by alleviating endoplasmic reticulum stress in severely burned mice. Thus it can accelerate skeletal muscle membrane repair, reduce the local inflammatory reaction of skeletal muscle and consumption of skeletal muscle.

Effects of insulin therapy on skeletal muscle wasting in severely scalded rats and its related mechanism

Objective: To explore the effects of insulin therapy on skeletal muscle wasting (SMW) in severely scalded rats and its related mechanism. Methods: Totally 48 male Wistar rats aged 7-8 weeks were divided into simple scald (SS) group and insulin therapy (IT) group according to the random number table, with 24 rats in each group. After weighing the body mass and measuring the blood glycemic level of the tail end with a glucometer, the rats in the two groups were immersed in hot water at 94 ℃ for 12 seconds to make a full-thickness dorsal scald model involving 30% total body surface area. Rats in group IT were subcutaneously injected with 1 U/kg insulin glargine at 8: 00 a day from post injury day (PID) 1 to 7, whilst rats in group SS were given the same amount of normal saline. Rats in the two groups were given 10 mL/kg enteral nutritional emulsion by intragastric infusion at 8: 00 (after insulin administration), 13: 00, and 18: 00 a day respectively from PID 1 to 7. The blood glycemic levels of tail end of rats in the two groups were measured by glucometer before insulin administration on PID 1-4, 6, and 7 and on every morning of PID 8, 9, 11, 12, and 14. The body mass of rats in the two groups on PID 14 without any treatment was weighed. Eight rats from each group were collected respectively on PID 4, 7, and 14 to harvest tibialis anterior muscle (TAM) samples. The mass of TAM on PID 14 was weighed. The ultrastructural changes of TAM myocytes on PID 7 were observed with transmission electron microscope. The apoptotic rates of TAM myocytes on PID 4, 7, and 14 were assessed by the assay of terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphate-biotin nick end labeling, the expressions of cysteine-aspartic protease-3 (caspase-3) of TAM on PID 4, 7, and 14 were detected with immunohistochemistry, and protein expressions of endoplasmic reticulum (ER) stress (ERS) associated proteins glucose-regulated protein 78 (GRP78), CCAAT/enhancer binding protein-homologous protein (CHOP), and activated caspase-12 of TAM on PID 4, 7, and 14 were detected with Western blotting. Data were processed with completely random design t test, analysis of variance for repeated measurement, analysis of variance for factorial design, t test, and Bonferroni correction. Results: The blood glycemic level and body mass of rats in the two groups before injury were similar (t=0.204, 0.405, P>0.05). There were no statistically significant differences in blood glycemic levels of rats between the two groups on PID 1, 6, 9, 11, 12, and 14 (t=0.229, 3.339, 1.610, 0.178, 0.181, 0.079, P>0.05). Compared with those of group SS, blood glycemic levels of rats in group IT were significantly lower on PID 2, 3, 4, 7, and 8 (t=7.245, 4.165, 4.609, 4.018, 3.995, P<0.05 or P<0.01). On PID 14, the body mass and TAM mass of rats in group IT were (271±19) g and (0.47±0.05) g respectively, both obviously higher than (254±12) g and (0.43±0.04) g of group SS (t=2.159, 2.375, P<0.05). On PID 7, nuclear pyknosis and deformation, chromosome misdistribution, and ER swelling in TAM myocytes of rats in group SS were observed; the apoptotic alterations and ER swelling of TAM myocytes were alleviated in rats of group IT as compared with those of group SS. The apoptotic rates of TAM myocytes of rats in group IT were obviously lower than those of group SS on PID 4, 7, and 14 (t=4.262, 9.153, 9.799, P<0.01). The expressions of caspase-3 in TAM of rats in group IT were obviously lower than those of group SS on PID 7 and 14 (t=10.429, 7.617, P<0.01). Compared with those of group SS, the protein expressions of GRP78 were obviously increased on PID 4 and 14 (t=4.172, 4.437, P<0.05), the protein expressions of activated caspase-12 were obviously decreased on PID 7 and 14 (t=11.049, 11.181, P<0.01), and the protein expressions of CHOP were obviously decreased on PID 4, 7, and 14 (t=13.837, 9.572, 6.930, P<0.01) in TAM of rats in group IT. Conclusions: Insulin therapy may reduce skeletal muscle myocytes apoptosis and SMW by alleviating ERS in rats with severe scald.

Strontium Alleviates Endoplasmic Reticulum Stress in a Nonalcoholic Fatty Liver Disease Model.

The purpose of this study was to explore the effects of strontium on fatty liver, and to clarify the possible mechanisms by which strontium improves nonalcoholic fatty liver disease (NAFLD). We also evaluated how strontium affected the endoplasmic reticulum stress (ERS) pathways. We established an in vitro model of NAFLD using a human hepatocyte cell line (L02) treated with 0.2 mM palmitic acid. The Sprague-Dawley rats were fed with a high-fat diet (HFD) to establish NAFLD model in vivo. After strontium treatment, the total cholesterol (TC), triglyceride (TG), and lipid deposition in L02 cells and liver tissues were determined. Strontium treatment suppressed intracellular TC and TG levels and lipid accumulation in L02 cells, and the effect of high concentrations of strontium were more obvious. Strontium significantly reduced the mRNA and protein expression of glucose-regulated protein 78 (GRP78), activating transcription factor 6 (ATF6), inositol requiring enzyme 1 (IRE1), SREBP cleavage activator protein (SCAP), sterol regulatory element binding protein 1c (SREBP-1c), and SREBP-2 in L02 cells. In HFD-fed rats, strontium treatment reduced serum TC, TG, and low density lipoprotein cholesterol (LDL-C) levels, concurrent with a decrease in hepatic lipid accumulation. Furthermore, strontium treatment reduced the expression of GRP78 and SREBP-2 protein in liver tissues. Overall, strontium alleviated hepatic steatosis by decreasing ERS-related protein expression in vivo and in vitro models. The results indicated that strontium has the potential to become a new therapy for the prevention and treatment of NAFLD.

Jiangtang Xiaoke granule attenuates glucose metabolism disorder via regulating endoplasmic reticulum stress in the liver of type 2 diabetes mellitus mice

OBJECTIVETo observe the effect of Jiangtang Xiaoke (JTXK) granule on endoplasmic reticulum (ER) stress in high fat diet (HFD)-induced type 2 diabetes mellitus (T2DM) KK-Ay mice. METHODSKK-Ay mice were fed with HFD to induce the T2DM model, while normal control C57BL/6J mice were given standard feed. Fasting blood glucose (FBG) in all mice was measured weekly and oral glucose tolerance tests (OGTTs) were performed at 4 and 10 weeks after start of treatment to determine glucose metabolism. Serum fasting insulin (FINS) and insulin sensitivity index (ISI) were measured to determine insulin sensitivity. mRNA expressions of eukaryotic initiation factor-2 alpha (eIF2α), glucose regulated protein 78 (GRP78), activating transcription factor 4 (ATF4), and C/EBP homology protein (CHOP) were assessed by reverse transcription polymerase chain reaction and the protein expressions of p-eIF2α, GRP78, and CHOP were assessed by Western blotting. RESULTSJTXK granule significantly reduced FBG and free fatty acid levels and improved OGTT at the 120 min of the 10-week treatment in T2DM KK-Ay mice. FINS and HbAlc levels were reduced and insulin sensitivities were increased in KK-Ay diabetic mice, which were improved with the treatment of JTXK granule, especially at the 7 and 3.5 g/kg doses. JTXK granule at the 3.5 g/kg dose was most effective in reducing both gene and protein expressions of eIF2α, GRP78, and CHOP. CONCLUSIONER stress response is increased in T2DM KK-Ay mice. Treatment with JTXK granule attenuates glucose disorders, improves insulin sensitivity, and reduces serum FFA in T2DM KK-Ay mice. The mechanisms may be attributed to regulation of the signaling ER stress pathway via decreasing eIF2α phosphorylation and suppressing eIF2α-ATF4-CHOP activation.

Grape seed proanthocyanidins protect against streptozotocin‑induced diabetic nephropathy by attenuating endoplasmic reticulum stress‑induced apoptosis.

Diabetic nephropathy (DN) is by far the most common cause of end-stage renal disease (ESRD) in industrial countries, accounting for ~45% of all new ESRD cases in the United States. Grape seed proanthocyanidin extracts (GSPE) are powerful antioxidants, with an antioxidant ability 50-fold greater than that of vitamin E and 20-fold greater than that of vitamin C. The present study investigated whether GSPE can protect against streptozotocin (STZ)-induced DN and aimed to elucidate a possible mechanism. Male Sprague Dawley rats were randomly divided into three groups: Control group (N), diabetes mellitus group (DM) injected with 40 mg/kg STZ, and the GSPE treatment group (intragastric administration of 250 mg/kg/day GSPE for 16 weeks after diabetes was induced in the rats). Blood and kidney samples were collected after treatment. The renal pathological changes were determined with periodic acid-Schiff (PAS) staining, while the protein expression levels of glucose-regulated protein 78 (GRP78), phosphorylated-extracellular signal-regulated kinase (p-ERK) and Caspase-12 were determined by western blotting and immunohistochemical staining. Apoptosis was determined with a terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Compared with the DM group, the GSPE group had no significant changes in the blood urea nitrogen (BUN) level and serum creatinine (Scr) level, but showed a significant decline in the renal index (RI) level and 24-h urinary albumin level (P<0.05). The histopathology results indicated very little pathological damage in the GSPE group. Compared with the DM group, the GSPE group had a significantly reduced number of TUNEL-positive cells (P<0.05), and the GSPE group had an obvious reduction in the protein expression of GRP78, p-ERK, and Caspase-12 (P<0.05). In this study, the results indicated that GSPE can protect renal function and attenuate endoplasmic reticulum stress-induced apoptosis via the Caspase-12 pathway in STZ-induced DN.

The effect of L-carnitine on the apoptosis of human lens epithelial cells through endoplasmic reticulum stress

Objective: To investigate the effect of L-carnitine on the apoptosis of human lens epithelial cells through endoplasmic reticulum (ER) stress pathway. Methods: HLE-B3 cell lines were used to set up an oxidative stress model with H(2)O(2) treatment for 12 h, and lead to ER stress. Cells were divided into four groups: H(2)O(2) group, L-carnitine (100 μmol/L) with H(2)O(2) group, phosphate buffered saline (PBS) group and L-carnitine (100 μmol/L) group. Cell counting kit-8 was used to detect the cell viability under the treatment of different concentrations (200, 400, 600 and 800 μmol/L) of H(2)O(2). The apoptosis ratio of HLE-B3 treated by 400 μmol/L H(2)O(2) was tested by flow cytometry. When HLE-B3 was treated by 400 μmol/L H(2)O(2), the expression levels of cysteinyl aspartate specific proteinase 3 (caspase-3) gene and glucose-regulated protein 78 (GRP78) gene were measured by RT-PCR, and the expression levels of caspase-3 protein and GRP78 protein were assayed by Western blotting. Data from groups was analyzed by the one-way analysis of variance, and the LSD-t test was used for the comparison of groups. Results: Cell counting kit-8 assay showed that when H(2)O(2) concentration was 200, 400, 600 and 800 μmol/L, there was significant difference in the H(2)O(2) group(77.6%±0.8%,58.1%±3.1%,39.2%±1.5%,28.1%±2.2%), L-carnitine with H(2)O(2) group(83.3%±4.2%,74.5%±3.1%,46.4%±1.7%,32.4%±1.2%), PBS group(97.6%±2.1%,98.3%±0.2%,96.3%±2.2%,98.5%±1.1%) and L-carnitine group(98.5%±1.3%, 96.1%±2.1%, 98.1%±0.2%, 97.3%±1.4%) (all P<0.05). There was no significant difference between groups (PBS group compared to L-carnitine group, all P>0.05). When the concentration of H(2)O(2) was 400 μmol/L, the survival rate of the L-carnitine with H(2)O(2) group was higher than the H(2)O(2) group. The difference was statistically significant (t=18.14, P=0.020). With increasing of the H(2)O(2) concentration, cell necrosis was increased. The cell survival rate had no significant difference between the L-carnitine with H(2)O(2) group and H(2)O(2) group (both P>0.05). Flow cytometry results of the H(2)O(2) group, L-carnitine with H(2)O(2) group, PBS group and L-carnitine group were 31.4%±4.5%, 16.5%±2.8%, 2.1%±0.2% and 1.9%±1.8%, respectively (F=126.784, P=0.024) . The rate of apoptosis in the L-carnitine with H(2)O(2) group was lower than that in the H(2)O(2) group (t=24.67, P=0.013). There was no significant difference between the PBS group and L-carnitine group (P>0.05). The results of RT-PCR showed that the expression of caspase-3 mRNA in the L-carnitine with H(2)O(2) group was lower than the H(2)O(2) group (0.424±0.041 vs. 0.752±0.203), and the expression of GRP78 mRNA in the L-carnitine with H(2)O(2) group was lower than the H(2)O(2) group (0.521±0.223 vs. 0.821±0.103). The difference was statistically significant (caspase-3: t=27.92, P=0.018;GRP78: t=16.31, P=0.019). Western blotting showed that the protein expression of caspase-3 in the L-carnitine with H(2)O(2) group was lower than the H(2)O(2) group (0.712±0.212 vs. 1.126±0.251), and the GRP78 protein expression in the L-carnitine with H(2)O(2) group was lower than the H(2)O(2) group (0.512±0.012 vs. 0.735±0.051). The difference was statistically significant (caspase-3: t=15.43, P=0.010;GRP78: t=20.62, P=0.018). Conclusion: L-carnitine can reduce the apoptosis rate of HLE-B3 during oxidative stress through ER stress pathway. (Chin J Ophthalmol, 2018, 54: 363-368).