ERS-related Proteins Research Articles

Role of HMGB1 in Post-traumatic Endoplasmic Reticulum Stress in Rat Lung Tissues.

To explore the role of high mobility group B1 （HMGB1） protein in the post-traumatic endoplasmic reticulum stress （ERS） in rat lung tissues. The rat model of acute lung injury was established by crushing the hind limbs of rats with standard weight. The first experiment was to divide rats into postural control group and crush groups （6 h, 18 h and 30 h after crushing）. The second experiment was to divide rats into postural control group, 18 h crush group, HMGB1 inhibitor sodium butyrate （SB） group and 18 h crush+SB group. The protein expression changes of HMGB1 and ERS- related proteins （GRP78, caspase-12, CHOP and IRE1α） in rat lung tissues were detected with Western blotting. Meanwhile, the pathological changes of rat lungs were observed by HE stain. Compared with the postural control group, the expression levels of ERS-related proteins （GRP78, caspase-12, CHOP and IRE1α） and HMGB1 protein in rat lung tissues by crushing the hind limbs of rats were obviously increased. The protein levels reduced at 30 h after crushing but were still higher than those of postural control group and obvious pathological changes of acute lung injury were observed simultaneously in rats. Compared with the 18 h crush group, the expression levels of the ERS-related proteins and HMGB1 protein in rat lung tissues were attenuated in 18 h crush+SB group, and the pathological changes of rat lung injury began to alleviate. HMGB1-ERS pathway activated by traumatic stress can lead to acute lung injury in rats.

Effect and mechanisms of celastrol on the apoptosis of HOS osteosarcoma cells.

Osteosarcoma is the most common primary malignant tumor of the bone found predominantly in children and teenagers and results in early metastasis and poor prognosis. The present study primarily focused on the impact of celastrol on apoptosis and autophagy of osteosarcoma HOS cells, as well as the related mechanisms. Following the appropriate treatment, the human osteosarcoma cell line HOS was assessed for viability, Ca2+ in cells, apoptosis and changes in cell morphology using Cell Counting Kit-8, flow cytometry, inverted phase contrast microscope, Hoechst staining and transmission electron microscopy. The expression levels of various proteins, including endoplasmic reticulum stress (ERS)-related proteins (Bip, PERK, p-PERK, IRE1α, calnexin, PDI and Erol‑Lα), apoptosis-related proteins (CHOP, cleaved caspase‑12), mitochondrial apoptosis-related proteins (Bax, Bcl-2 and cytochromec), cleaved caspase-3, and autophagy-related proteins (LC3-Ⅰ, LC3-Ⅱ and P62) and β-actin, were assessed with western blotting. Celastrol significantly inhibited the viability of HOS cells in a dose-dependent manner and promoted the expression of ERS-related, apoptosis-related and mitochondrial apoptosis-related proteins. The ERS inhibitor tauroursodeoxycholate promoted celastrol-induced autophagy and apoptosis of HOS cells. Pretreatment with the PERK inhibitor GSK2656157 significantly promoted celastrol-induced death and attenuated HOS cell autophagy. Our results indicated that the ERS pathway and the mitochondrial pathway were involved in celastrol-induced apoptosis of HOS cells. The ERS/PERK pathway may protect HOS cells from apoptosis by celastrol and may play a complicated role in the process of autophagy.

Effects of insulin-like growth factor-1 on endoplasmic reticulum stress and autophagy in rat gastric smooth muscle cells cultured at different glucose concentrations in vitro.

The purpose of the study was to observe changes in endoplasmic reticulum stress (ERS)- and autophagy-related proteins in gastric smooth muscle tissues of diabetic rats with gastroparesis, investigate the effect of insulin-like growth factor 1 (IGF-1) on ERS and autophagy in rat gastric smooth muscle cells cultured under different glucose concentrations, and explore the influence of IGF-1 on development of diabetic gastroparesis (DGP). After establishing a rat model of DGP, rats were divided into normal control (NC) and 6-week diabetic model (DM6W) groups. Expression of ERS-related and autophagy-related proteins was detected by western blot analysis and immunofluorescence assay in rat gastric smooth muscle tissue and in vitro-cultured rat gastric smooth muscle cells exposed to different glucose concentrations and treatment with IGF-1 for 24 or 48h. Changes in glucose-regulated-protein-78 (GRP78), growth arrest and DNA damage-inducible gene 153 (CHOP), and microtubule-associated protein 1A/1B light chain 3B (LC3) expression levels were detected by western blot analysis, and GRP78 and LC3 expression were examined by confocal laser-scanning microscopy. In vivo expression levels of GRP78, CHOP, and LC3 were significantly higher in the DM6W group compared with the NC group (p < 0.001). Twenty-four hours after cells were cultured at different glucose concentrations in vitro, expression of GRP78, CHOP, and LC3II/Iwas significantly higher in the high glucose-treated group compared with the normal glucose group (p < 0.05). After IGF-1 intervention, CHOP and GRP78 expression were significantly higher in the normal glucose + IGF-1 group compared with the normal glucose group (p < 0.01), while no significant difference was found between high glucose and high glucose + IGF-1 groups. LC3II/Iexpression was significantly lower in the normal glucose + IGF-1 group compared with the normal glucose group, and was significantly lower in the high glucose and high glucose + IGF-1 groups (p < 0.05). After 48h of culture, CHOP expression was significantly higher and LC3II/I expression was significantly lower in the high glucose group compared with the normal glucose group (p < 0.05), but no significant change in GRP78 expression was observed between these two groups. After IGF-1 intervention, there was no difference in CHOP or GRP78 expression between normal glucose + IGF-1 and normal glucose groups. However, CHOP and GRP78 expression were significantly lower in the high glucose + IGF-1 group compared with the high glucose group (p < 0.05). There was no significant difference in LC3II/I expression between normal glucose + IGF-1 and normal glucose groups, or high glucose + IGF-1 and high glucose groups. Results of confocal laser-scanning microscopy showed significantly lower expression of LC3II/Iin the high glucose + IGF-1 group compared with the high glucose group (p < 0.05). ERS and autophagy were involved in the occurrence of DGP. IGF-1 exerted an inhibitory effect on ERS in rat gastric smooth muscle cells cultured under high glucose conditions, and this inhibitory effect increased with time. IGF-1 inhibited the level of autophagy in rat gastric smooth muscle cells cultured under high glucose conditions at early stages, which may be achieved through inhibition of ERS.

High mobility group box 1 contributes to the endoplasmic reticulum stress of liver in rats with trauma

To investigate the role of high mobility group box 1 (HMGB1) in hepatic endoplasmic reticulum stress (ERS) in rats with trauma. Sixty SPF Sprague-Dawley (SD) rats were randomly divided into groups (n = 6). The rat model of liver injury following traumatic stress was established by continuous compressing the bilateral hind-limbs of rats for 3 hours and then intermittent compressing and decompressing for 30 minutes respectively three times with standard weight of 15 kg. The experiment 1 was divided into two groups: control group and 6, 18, 30 hours after crush. The experiment 2 was divided into control group, crush model group (18 hours after crush), HMGB1 inhibitor sodium butyrate (SB) or ethyl pyruvate (EP) groups, and SB or EP treatment groups (500 mg/kg SB solution or 40 mg/kg EP solution was injected intraperitoneally after 3 hours crush). The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum were measured with automatic biochemistry analyzer. Histopathological severity of liver injury was assessed by hematoxylin and eosin (HE) staining. The expressions of HMGB1 and ERS-related proteins were detected with Western Blot. The expression and translocation of HMGB1 in liver tissue were evaluated by immuno-histochemical technique. (1) Compared with the control group, the pathological changes of liver injury, the levels of AST and ALT in serum and protein expression of HMGB1 as well as ERS-related proteins such as glucose regulated protein 78 (GRP78), caspase-12, and inositol-requiring enzyme 1α (IRE1α) in liver tissue were significantly increased after traumatic stress, and reached the peak at 18 hours. The expression of C/EBP-homologous protein (CHOP) was increased in a time-dependent manner and peaked at 30 hours after crush. Immunohistochemistry showed that HMGB1 expression increased at 6 hours after crush, some HMGB1 shifted from nucleus to cytoplasm, and the expression was more obvious at 18 hours. (2) Compared with crush model group, the expressions of HMGB1 and ERS-related proteins were significantly decreased following the administration of HMGB1 inhibitors SB or EP (HMGB1/β-actin: 0.703±0.213, 0.512±0.075 vs. 1.041±0.186; GRP78/β-actin: 0.614±0.052, 0.450±0.115 vs. 0.847±0.120; caspase-12/β-actin: 0.636±0.066, 0.812±0.142 vs. 1.086±0.130; CHOP/β-actin: 0.314±0.046, 0.621±0.123 vs. 0.996±0.764; IRE1α/β-actin: 0.473±0.033, 0.519±0.094 vs. 0.742±0.054, all P < 0.05), the levels of serum AST and ALT were significantly decreased [AST (U/L): 1 030.50±427.73, 1 414.50±347.86 vs. 2 122.20±322.76; ALT (U/L): 285.75±11.30, 368.50±80.58 vs. 473.80±33.54, all P < 0.01], the degree of acute liver injury was reduced. Only SB or EP could not affect the parameters mentioned above. HMGB1-ERS pathway was involved in mediating traumatic stress-induced acute liver injury in rats.

Immunocompetence and mechanism of the DRibble-DCs vaccine for oral squamous cell carcinoma.

BackgroundDue to the high-quality immunogenicity of tumor-derived autophagosomes (DRibbles), we aimed to explore the antitumor ability and mechanism of DRibble-loaded dendritic cells (DRibble-DCs).Materials and methodsDRibbles extracted from the oral squamous cell carcinoma cell line SCC7 express specific LC3-II and ubiquitination marker. Immunization of mice with the DRibble-DCs vaccine led to the proliferation and differentiation of CD3+CD4+IFN-γ+ and CD3+CD8+IFN-γ+ T cells. The expression of proteins in endoplasmic reticulum stress (ERS) pathways was determined by Western blotting. Additionally, the functional properties of the DRibble-DCs were examined in mice, and regulatory T cells were measured by flow cytometry.ResultsExcellent biocompatibility was observed in vitro when DCs were loaded with DRibbles. T cells of lymph nodes and spleens from mice immunized with DRibble-DCs had cytotoxic effects on SCC7 cells. DCs homeostasis and ERS-related proteins were affected by DRibbles. Moreover, the DRibble-DCs vaccine achieved significantly better antitumor efficacy than DRibbles and tumor cell lysate-loaded DCs.ConclusionThe results validated the antitumor immune responses to the DRibble-DCs vaccine in vivo and in vitro. The ERS pathway can be affected by DRibbles.

Gecko Active Components Regulates Endoplasmic Reticulum Stress to Induce the Apoptosis of KYSE150 Cells through PERK Pathway

Objective: Gecko active components (GACs), extracted from the powder of whole Gecko, have been reported to be effective against esophageal squamous cell carcinoma (ESCC). Endoplasmic reticulum stress (ERs) has been regarded as an important cause for pathogenesis of esophageal squamous cell carcinoma (ESCC). In this paper, we aimed to study the effect of GACS on apoptosis of human esophageal carcinoma KYSE150 cells and to analyze the underlying signaling pathway. Methods: MTT assay was used to detect the viability of KYSE150 cells, and Flow cytometry was applied to detect reactive oxygen species (ROS), calcium generation, and the level of mitochondrial membrane potential (MMP). Western blot analysis was applied to observe the expression of apoptosis-related proteins and endoplasmic reticulum stress (ERs)-related proteins in KYSE150 cells. Results: The results showed that GACs inhibited KYSE150 cell vitality in a dose- and time-dependent manner. Not only that, GACs could up-regulated ERs-related and apoptosis-related proteins expression, and the content of ROS and calcium were significantly increased, and also, the level of MMP was significantly decreased. Conclusion: The results of this report suggested that induction of apoptosis occurs through the ERs dependent signaling pathways.

Progesterone inhibited endoplasmic reticulum stress associated apoptosis induced by interleukin-1β via the GRP78/PERK/CHOP pathway in BeWo cells.

Pre-eclampsia (PE) is a pregnancy complication characterized by new onset maternal hypertension and proteinuria. Its underlying mechanisms are unclear. This study investigated the relationship between progesterone and endoplasmic reticulum stress (ERS) associated apoptosis induced by interleukin (IL)-1β via the glucose regulated protein 78 (GRP78)/protein kinase RNA-like endoplasmic reticulum kinase (PERK)/C/EBP-homologous protein (CHOP) pathway in BeWo cells. Venous blood and placental tissues were collected from PE patients, normal pregnancy and preterm delivery cases, respectively. Progesterone serum levels were detected by enzyme-linked immunosorbent assay and ERS-related protein expression in placentas was examined by immunohistochemistry, reverse transcriptase-polymerase chain reaction and Western blot. BeWo cells were stimulated by IL-1β to induce ERS associated apoptosis in vitro. The apoptotic rate was measured by flow cytometry. The mechanism of progesterone acting on IL-1β induced ERS associated apoptosis was investigated by reverse transcriptase-polymerase chain reaction, Western blot and PERK small interfering RNA, with RU486 used as a receptor inhibitor. PE patients exhibited decreased serum levels of progesterone and activated ERS and increased ERS-related protein expression. IL-1β could induce ERS and associated cell apoptosis by activating the GRP78/PERK/CHOP signal pathway, which could be inhibited by progesterone. PERK could be upregulated and phosphorylation activated in ERS. The protective effects of progesterone could be attenuated by RU486. IL-1β could induce ERS associated cell apoptosis by activating the GRP78/PERK/CHOP signal pathway in BeWo cells and may play an important role in PE occurrence. Progesterone levels were decreased in patients with PE and seemed to have a protective effect by inhibiting ERS associated cell apoptosis.

Necrostatin-1 Mitigates Endoplasmic Reticulum Stress After Spinal Cord Injury

Necrostatin-1 (Nec-1) has been shown to inhibit necroptosis and convey a significant protective effect after spinal cord injury (SCI). This small molecule inhibitor may reduce tissue damage and restore neurological function by lessening mitochondrial injury after SCI and preserving energy homeostasis. However, the effects of Nec-1 on endoplasmic reticulum stress (ERS)-an important pathological consequence of SCI-are still not clear. The present study investigates the relationship between necroptosis and ERS in a rat model of SCI. Electron microscopy was employed to observe ultra-structural changes in the endoplasmic reticulum and mitochondria after lesioning. Real-time quantitative PCR was used to measure the mRNA levels of ERS-related pro-apoptotic molecules such as C/EBP homologous protein (CHOP), immunoglobulin-binding protein (BiP/GRP78) and X box-binding protein-1 (XBP-1). Western blot and immunofluorescence were conducted to analyze CHOP, GRP78 and XBP-1 protein expression after lesioning. Results demonstrated that applying Nec-1 in SCI reduces ultra-structural damage to the endoplasmic reticulum and mitochondria and inhibits expression of ERS-related genes and proteins after lesioning. Immunofluorescence also shows ERS-related proteins mainly expressed in the cytoplasm of nerve cells. Taken together, these results demonstrate that Nec-1 has protective effect on the endoplasmic reticulum and mitochondria and alleviates ERS after SCI.

β-elemene regulates endoplasmic reticulum stress to induce the apoptosis of NSCLC cells through PERK/IRE1α/ATF6 pathway

Endoplasmic reticulum stress (ERs) has been regarded as an important cause for the pathogenesis of non-small-cell lung cancer (NSCLC). β-elemene is an active component in the essential oil extracted from a medicinal herb, Curcuma wenyujin, and has been reported to be effective against non-small-cell lung cancer (NSCLC). However, the potential effect and underlying mechanisms of β-elemene on regulating ERs to inhibit NSCLC are still unclear. In the present study, A549 cells and Lewis tumor-bearing C57BL/6J mice were established to evaluate this effect. Visualsonics Vevo 2100 Small Animal Dedicated High-frequency Color Ultrasound was performed to observe tumor volume in vivo. 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) was used to evaluate cell vitality of A549 cells. Furthermore, western blotting (WB), immunohistochemistry (IHC) and quantitative reverse transcription polymerase chain reaction (q-PCR) were applied to detect the ERs-related proteins. Flow cytometry was also applied to detect cell apoptosis and assay kit for reactive oxygen species (ROS) generation. Our results showed that β-elemene inhibited lung cancer tumor growth and cell vitality in a dose- and time-dependent manner. Not only that, β-elemene could up-regulate ERs-related proteins like PERK, IRE1α, ATF6, ATF4, CHOP and down-regulate the Bcl-2 expression. More importantly, ERs inhibitor 4-PBA, IRE1α inhibitor STF-083010, ATF6 inhibitor Anti-ATF6 and PERK inhibitor GSK2656157 can all reduce the amplitude of protein expression changes and apoptosis rates, then weaken the anti-tumor effect of β-elemene. Therefore, the present in vivo and in vitro study revealed that the anti-NSCLC effect of β-elemene is closely related to the activation of ERs through PERK/IRE1α/ATF6 pathway, and this might be beneficial for clinical therapy of NSCLC.

Endoplasmic reticulum stress induces autophagy and apoptosis while inhibiting proliferation and drug resistance in multiple myeloma through the PI3K/Akt/mTOR signaling pathway.

We investigated the effects of endoplasmic reticulum stress (ERS) on autophagy, proliferation, apoptosis, and drug resistance in multiple myeloma (MM). MM patients enrolled in our study (n = 268) were classified into sensitive and resistant groups based on chemotherapy efficacy, and their serum levels of β2-MG, albumin (ALB), lactic dehydrogenase (LDH), Ca2+ and hemoglobin were determined. In addition, human MM U266 and MOLP-2/R cells were divided into blank, tunicamycin (TM), TM + insulin-like growth factor-1 (IGF-1), and TM + rapamycin groups, and measured expression of ERS-related, PI3K/Akt/mTOR pathway-related, and autophagy-related mRNA and proteins. Serum levels of β2-MG, LDH and Ca2+, and expression of PI3K, Akt, and mTOR were higher in the resistant than sensitive group. Serum levels of ALB and hemoglobin, and expression of glucose-regulated protein 78 (GRP78), GRP94, microtubule associated protein 1 light chain 3 (LC3), and Beclin1, were lower in the resistant than sensitive group. In U266 cells treated with TM and IGF-1 or rapamycin, ERS promoted autophagy and apoptosis while inhibiting proliferation through inhibition of PI3K/Akt/mTOR signaling. ERS also reversed drug resistance in MOLP-2/R cells via the PI3K/Akt/mTOR signaling pathway. These data suggest that ERS activation could be exploited for therapeutic benefits in the treatment of MM.

Endoplasmic reticulum stress promotes autophagy and apoptosis and reverses chemoresistance in human ovarian cancer cells.

Ovarian cancer presents the highest mortality rate among gynecological tumors. Here, we measured cell viability, proliferation, apoptosis, autophagy, and expression of endoplasmic reticulum stress (ERS)-related proteins, PI3K/AKT/mTOR pathway-related proteins, and apoptosis- and autophagy-related proteins in SKOV3 and SKOV3/CDDP cells treated with combinations of CDDP, tunicamycin, and BEZ235 (blank control, CDDP, CDDP + tunicamycin, CDDP + BEZ235, and CDDP + tunicamycin + BEZ235). Increasing concentrations of tunicamycin and CDDP activated ERS in SKOV3 cells, reduced cell viability and proliferation, increased apoptosis and autophagy, enhanced expression of ERS-related proteins, and inhibited expression of PI3K/AKT/mTOR pathway-related proteins. CDDP, tunicamycin, and BEZ235 acted synergistically to enhance these effects. We also detected lower expression of the ERS-related proteins caspase-3, LC3 II and Beclin 1 in ovarian cancer tissues than adjacent normal tissues. By contrast, expression of Bcl-2 and PI3K/AKT/mTOR pathway-related proteins was higher in ovarian cancer tissues than adjacent normal tissues. Lastly, expression of the ERS-related proteins Beclin 1, caspase-3 and LC3 II was higher in the sensitive group than the resistant group, while expression of Bcl-2, LC3 I, P62 and PI3K/AKT/mTOR pathway-related proteins was decreased. These results show that ERS promotes cell autophagy and apoptosis while reversing chemoresistance in ovarian cancer cells by inhibiting activation of the PI3K/AKT/mTOR signaling pathway.

Glutamine supplementation provides neuroprotection by inhibiting endoplasmic reticulum stress response after traumatic brain injury in rats

Objective To investigate the effects of glutamine (Gln) supplementation on neurologica severity score, brain edema, neuron apoptosis, and endoplasmic reticulum stress (ERS) response after traumatic brain injury (TBI) in rats. Methods TBI rat models were established using modified Feeney's method. Eighty Sprague-Dawley rats were divided into 4 groups with a random number table: sham operation group (Sham group), TBI group, Gln supplementation group (TBI+ Gln group) and ERS inducer 2-deoxy-D-glucose group (TBI+ Gln+ 2-DG group). We measured the rats' neurobehavioral outcomes by modified neurologic severity score (mNSS) on day 1, 3, 7 and 14 after TBI. Neuron apoptosis was detected using TUNEL staining. Brain water content was measured with wet-dry weight method.The apoptosis-related protein (caspase-12, caspase-3, and Bcl-2) and ERS-related cytokines [inositol-requiring enzyme 1(IRE-1), C/EBP homologous protein (CHOP)] expressions in TBI cerebral cortex were determined by immunohistochemistry staining and Western blot. Results Compared with the Sham group, the levels of brain edema, mNSS, apoptosis-related protein (caspase-12, caspase-3, Bcl-2) and ERS-related proteins (IRE-1, CHOP) were significantly increased in the other three groups(all P=0.00). Compared with the TBl group, the TBI+ Gln group showed significant lower brain water content[3 d: (81.39±0.59)% vs.(83.54±0.52)%, P=0.04; 7 d: (74.86±0.38)% vs. (77.32±0.66)%, P=0.03], improved mNSS(8.63±0.22 vs. 10.37±0.29, P=0.03), suppressed expressions of apoptosis- and ERS-related proteins (caspase-12, caspase-3, IRE-1, and CHOP)(P=0.01, P<0.01), and increased expression of anti-apoptotic protein Bcl-2 (P=0.02). Compared with the TBI+ Gln group, the expression of ERS-related factors (IRE-1 and CHOP), brain edema level, and neurological severity were increased in the TBI+ Glu+ 2-DG group. Conclusion Glutamine supplementation may have neuroprotection function, demonstrated as reducing brain edema and neuron apoptosis, and improving neurobehaviroal outcomes after TBI, possibly mediated by inhibiting TBI-induced ERS response. Key words: Traumatic brain injury; Glutamine; Endoplasmic reticulum stress; Neuroprotection

Effects of the Activin A-Follistatin System on Myocardial Cell Apoptosis through the Endoplasmic Reticulum Stress Pathway in Heart Failure.

Background: A previous study suggested that activin A inhibited myocardial cell apoptosis. This study thus aimed to explore the effects of the activin A–follistatin system on myocardial cell apoptosis in heart failure (HF) rats in order to determine whether or not the mechanism operates through the endoplasmic reticulum stress (ERS) pathway. Methods: Myocardial infarction (MI) by vascular deprivation was used to induce HF. The enzyme-linked immunosorbent assay was used to detect activin A, follistatin and brain natriuretic peptide (BNP) contents in serum. Immunohistochemical staining for activin A, follistatin, CCAAT-enhancer-binding protein (C/EBP) homologous protein (CHOP) and caspase-3 was performed on the myocardial tissue. The activin A-stimulated apoptosis of H9c2 cells was tested by flow cytometry. Western blot was used to detect the expression levels of activin A, follistatin and ERS-related proteins. Results: It was found that the high expression of activin A could cause activin A–follistatin system imbalance, inducing myocardial cell apoptosis via ERS in vivo. When HF developed to a certain stage, the expression of follistatin was upregulated to antagonize the expression of activin A. Activin A inhibited cardiomyocyte apoptosis with a low concentration and promoted apoptosis with a high concentration in vitro, also via ERS. Conclusion: Activin A–follistatin system participated in ERS-mediated myocardial cell apoptosis in HF.

Melatonin Relieves Busulfan-Induced Spermatogonial Stem Cell Apoptosis of Mouse Testis by Inhibiting Endoplasmic Reticulum Stress

Background/Aims: Busulfan is commonly used for cancer chemotherapy. Although it has the advantage of increasing the survival rate of patients, it can cause male infertility via damaging the testes and reducing sperm counts. Therefore, the underlying mechanism should be explored, and new agents should be developed to protect the male reproductive system from busulfan-induced damage. Endoplasmic reticulum stress (ERS) is considered a key contributor to numerous pathologies. Despite several studies linking ERS to toxicants, studies have yet to determine whether ERS is a contributing factor to busulfan-induced testicular damage. Melatonin is a well-known broad-spectrum antioxidant, anti-inflammatory and antitumour agent, but the effects of melatonin on busulfan-induced ERS in mouse testes damage are less documented. Methods: The effects of melatonin were measured by immunofluorescence staining, Western blot, qRT-PCR analysis and flow cytometry assay. The underlying mechanism was investigated by measuring ERS. Results: We found that ERS was strongly activated in mouse testes (in vivo) and the C18-4 cell line (in vitro) after busulfan administration. ERS-related apoptosis proteins such as caspase-12, CHOP and caspase-3 were activated, and the expression of apoptotic proteins such as P53 and PUMA were upregulated. Furthermore, we investigated whether melatonin reduced the extent of damage to mouse testes and improved the survival rates of busulfan-treated mice. When exploring the underlying mechanisms, we found melatonin could counteract ERS by decreasing the expression levels of the ERS markers GRP78, ATF6, pIRE1 and XBP1 in mouse testes and mouse SSCs (C18-4 cells). Moreover, it blocked the activation of ERS-related apoptosis proteins caspase-12, CHOP and caspase-3 and suppressed P53 and PUMA expression stimulated by busulfan both in vivo and in vitro. Conclusion: Our results demonstrate that ERS is an important mediator for busulfan-induced apoptosis. The attenuation of ERS by melatonin can prevent busulfan-treated SSCs apoptosis and protect busulfan-treated testes from damage. Thus, this study suggests that melatonin may alleviate the side effects of busulfan for male patients during clinical treatment.

Activation of endoplasmic reticulum stress promotes autophagy and apoptosis and reverses chemoresistance of human small cell lung cancer cells by inhibiting the PI3K/AKT/mTOR signaling pathway.

ObjectiveThis study aims to investigate the effects of endoplasmic reticulum stress (ERS) on autophagy, apoptosis and chemoresistance of human small cell lung cancer (SCLC) cells via the PI3K/AKT/mTOR signaling pathway.ResultsThe expressions of ERS-related proteins (PEAK, eIF2α and CHOP) up-regulated, autophagy-related proteins (LC3, LC3-II and Beclin1) and apoptosis-related proteins (Bax and procaspase-3) down-regulated in NCI-H446 and H69 cells after tunicamycin treatment for 24 h. Compared with the blank group, the tunicamycin, BEZ235 and tunicamycin + BEZ235 groups exhibited decreased expressions of p-PI3K, p-AKT and p-mTOR, and increased expressions of autophagy-related proteins (LC3, LC3-II and Beclin1) and apoptosis proteins (Bax and procaspase-3), and the most obvious changes were observed in the tunicamycin + BEZ235 group.Materials and MethodsCCK-8 assay was applied to select the best cell line from five SCLC cell lines (NCI-H446, H69, H526, H146 and H209). Finally, NCI-H446 and H69 cells were selected for further experiments. NCI-H446/CDDP and H69/CDDP were selected and divided into the blank group, tunicamycin (an ESR inducer) group, BEZ235 (inhibitors of PI3K/AKT/mTOR pathway) group and tunicamycin + BEZ235 group. Cell apoptosis was detected by flow cytometry. Autophagy was observed by fluorescence microscopy and flow cytometry. Western blotting was used to detect the expressions of ERS-related proteins, autophagy-related proteins, apoptosis-related proteins and PI3K/AKT/mTOR pathway-related proteins.ConclusionsOur findings provide evidence that the activation of ERS could promote autophagy and apoptosis and reverse chemoresistance of human SCLC cells by inhibiting the PI3K/AKT/mTOR pathway.

The protective effect of the earthworm active ingredients on hepatocellular injury induced by endoplasmic reticulum stress.

The earthworm is a widely used Chinese herbal medicine. There are more than 40 prescriptions including earthworms in the "Compendium of Materia Medica". TCM theory holds that earthworms exert antispasmodic and antipyretic effects through the liver meridian to calm the liver. However, the clinical effect of earthworms on liver injury has not been clearly demonstrated. We have previously established a method to extract the active ingredients from earthworms (hereinafter referred to as EWAs) [1]. In the present study, we observed protective effect of the EWAs on tunicamycin-induced ERS (endoplasmic reticulum stress) model in human hepatic L02 cells. The results showed that the EWAs promote proliferation and reduced apoptosis of ERS model in L02 cells (P<0.01). The up-regulation of ERS-related proteins, including PERK (protein kinase RNA-like endoplasmic reticulum kinase), eIF2a (eukaryotic translation initiation factor 2a), ATF4 (activating transcription factor 4) and CHOP (CCAAT/enhancer binding protein homologous protein), in L02 cell under ERS was inhibited by treatment of the EWAs (P<0.01). In summary, our data suggest the EWAs can significant attenuate ERS-induced hepatocyte injury via PERK-eIF2a-ATF4 pathway.

Involvement of Endoplasmic Reticulum Stress in Uremic Cardiomyopathy: Protective Effects of Tauroursodeoxycholic Acid

Background/Aims: Uremic cardiomyopathy (UCM) is a complication in chronic kidney disease. We investigated if endoplasmic reticulum stress (ERS) is involved in UCM, and determined the efficacy of tauroursodeoxycholic acid (TUDCA) in UCM prevention. Methods: Mice were divided randomly into three groups: sham (saline, i.p), 5/6 nephrectomized (Nx) (saline, i.p) and Nx+TUDCA (250 mg/kg/day, i.p.). Renal function was assessed by measuring serum creatinine, blood urea nitrogen and by periodic acid-Schiff reagent staining. Histologic examination of cardiac fibrosis and apoptosis was determined by Masson's trichrome and TUNEL assay. Cardiac function was evaluated by echocardiography. Fibrotic factors (transforming growth factor-β, fibronectin, collagen I/IV) were evaluated by real-time PCR. ERS-related proteins were measured by western blotting. Results: Impaired renal function and cardiac dysfunction were shown in 5/6 nephrectomy mice but were improved significantly by TUDCA. 5/6 nephrectomy mice exhibited marked cardiomyocyte apoptosis, cardiac fibrosis and elevated pro-fibrotic factors. ERS markers (GRP78, GRP94, P-PERK, P-eIF2a) and ERS-induced apoptosis pathways (activation of CHOP and caspase-12) were increased significantly in 5/6 nephrectomy mice, and TUDCA treatment blunted these changes. Conclusions: ERS has a key role in UCM, and the cardioprotective role of TUDCA is related to inhibition of ERS-induced apoptosis by inhibition of CHOP and caspase-12 pathways.

Trinitrotoluene Induces Endoplasmic Reticulum Stress and Apoptosis in HePG2 Cells.

BackgroundThis study aims to describe trinitrotoluene (TNT)-induced endoplasmic reticulum stress (ERS) and apoptosis in HePG2 cells.Material/MethodsHePG2 cells were cultured in vitro with 0, 6, 12, or 24 μg/ml TNT solution for 12, 24, and 48 h. Western blotting was performed to detect intracellular ERS-related proteins, including glucose-regulated protein (GRP) 78, GRP94, Caspase 4, p-Jun N-terminal kinase (JNK), and C/EBP homologous protein (CHOP). Real-time PCR was used to measure mRNA expression from the respective genes.ResultsThe expressions of ERS-related proteins GRP78 and GRP94 as well as mRNA and protein expression of ERS signaling apoptotic CHOP in the TNT treatment group were significantly increased. In addition, the mRNA and protein expression levels of ERS-induced apoptotic protein Caspase-4 were significantly increased. Flow cytometry revealed that after TNT treatment, the apoptosis rate also significantly increased.ConclusionsTNT could increase the expression levels of GRP78, GRP94, Caspase-4, and CHOP in HePG2 cells; this increase in protein expression might be involved in HePG2 apoptosis through the induction of the ERS pathway.

Pterostilbene exerts an anti-inflammatory effect via regulating endoplasmic reticulum stress in endothelial cells

Pterostilbene (PT), an analog of resveratrol, exerts a potent anti-inflammatory effect. However, the protective effects of PT against inflammation in endothelial cells have not been elucidated. Previous studies have confirmed that endoplasmic reticulum stress (ERS) plays an important role in regulating the pathological process of endothelial cell inflammation. In this study, we explored the effect of PT on the tumor necrosis factor-α (TNF-α)-induced inflammatory response in human umbilical vein endothelial cells (HUVECs) and elaborated the role of ERS in this process. TNF-α treatment significantly upregulated the levels of inflammation-related molecules in cell culture media, increased the adhesion of monocytes to HUVECs, and enhanced the expression of the MMP9 and ICAM proteins in HUVECs. Additionally, TNF-α potently increased ERS-related protein levels, such as GRP78 and p-eIF2α. However, PT treatment reversed the increased production of inflammatory cytokines and the adhesion of monocytes to HUVECs, as well as reduced the TNF-α-induced effects exerted by ERS-related molecules. Furthermore, thapsigargin (THA), an ERS inducer, attenuated the protective effect of PT against TNF-α-induced inflammation and ERS in HUVECs. Additionally, the downregulation of ERS signaling using siRNA targeting eIF2α and IRE1 not only inhibited ERS-related molecules but also simulated the therapeutic effects of PT on TNF-α-induced inflammation. In summary, PT treatment potently attenuates inflammation in vascular endothelial cells, which at least partly depends on the reduction of ERS.

Role of endoplasmic reticulum stress in D-GalN/LPS-induced acute liver failure

To study the role of endoplasmic reticulum stress (ERS) in acute liver failure (ALF) using a mouse model of D-Galactosamine/lipopolysaccharide (D-GalN/LPS)-induced ALF. The ALF model was established by administering intraperitoneal (i.p.) injections of D-Ga1N (700 mg/kg) and LPS (10 mug/kg) to six C57BL/6 mice. Three of the modeled mice were also administered 4-phenylbutyrate (4-PBA; 100 mg/kg i.p.) at 6 hours before the onset of ALF and served as the intervention group. Non-modeled mice served as controls. All mice were analyzed by western blotting and qRT-PCR to determine the expression levels of ERS-related proteins in liver tissue. Liver function was assessed by measuring levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum. Extent of injury to the liver tissue was assessed by hematoxylin-eosin staining and histological analysis. qRT-PCR was also used to detect differences in expression of inflammation-related genes, and western blotting was also used to detect differences in expression of the apoptosis related protein Caspase-3.The extent of apoptosis in liver tissue was assessed by TUNEL assay. The ERS markers GRP78 and GRP94 showed increased expression at both the gene and protein levels which followed progression of ALF. The ERS effector proteins XBP-1, ATF-6 and IRE 1 a involved in the unfolded protein response were activated in the early stages of ALF, and the ERS-induced apoptosis regulators Caspase-12 and CHOP were activated in the late stage of ALF. Inhibition of ERS by 4-PBA intervention protected against injury to liver tissue and function, as evidenced by significantly lower levels of serum ALT and AST and a remarkably decreased extent of histological alterations. Furthermore, the inhibition of ERS suppressed expression of the proinflammatory cytokines TNFa, IL-6 and IL-1 β, and reduced the extent of hepatocyte apoptosis. ERS is activated in the mouse model of D-GalN/LPS-induced ALF. Inhibition of ERS may be protective against liver injury and the mechanism of action may involve reductions in inflammatory and apoptotic factors and/or signaling. Therefore, inhibiting ERS may represent a novel therapeutic approach for treating ALF.