Studies have confirmed a strong association between activation of the endoplasmic reticulum stress pathway and cerebral ischemia/reperfusion(I/R) injury.In this study,three key proteins in the endoplasmic reticulum st...Studies have confirmed a strong association between activation of the endoplasmic reticulum stress pathway and cerebral ischemia/reperfusion(I/R) injury.In this study,three key proteins in the endoplasmic reticulum stress pathway(glucose-regulated protein 78,caspase-12,and C/EBP homologous protein) were selected to examine the potential mechanism of endoplasmic reticulum stress in the neuroprotective effect of G protein-coupled estrogen receptor.Female Sprague-Dawley rats received ovariectomy(OVX),and then cerebral I/R rat models(OVX+ I/R) were established by middle cerebral artery occlusion.Immediately after I/R,rat models were injected with 100 μg/kg E2(OVX + I/R +E2),or 100 μg/kg G protein-coupled estrogen receptor agonist G1(OVX + I/R + G1) in the lateral ventricle.Longa scoring was used to detect neurobehavioral changes in each group.Infarct volumes were measured by 2,3,5-triphenyltetrazolium chloride staining.Morphological changes in neurons were observed by Nissl staining.Terminal dexynucleotidyl transferase-mediated nick end-labeling staining revealed that compared with the OVX + I/R group,neurological function was remarkably improved,infarct volume was reduced,number of normal Nissl bodies was dramatically increased,and number of apoptotic neurons in the hippocampus was decreased after E2 and G1 intervention.To detect the expression and distribution of endoplasmic reticulum stress-related proteins in the endoplasmic reticulum,caspase-12 distribution and expression were detected by immunofluorescence,and mRNA and protein levels of glucose-regulated protein 78,caspase-12,and C/EBP homologous protein were determined by polymerase chain reaction and western blot assay.The results showed that compared with the OVX+ I/R group,E2 and G1 treatment obviously decreased mRNA and protein expression levels of glucose-regulated protein 78,C/EBP homologous protein,and caspase-12.However,the G protein-coupled estrogen receptor antagonist G15(OVX + I/R + E2 + G15) could eliminate the effect of E2 on cerebral I/R injury展开更多
AIM To investigate the protective effect of prostaglandin E1(PGE1) against endoplasmic reticulum(ER) stressinduced hepatocyte apoptosis, and to explore its underlying mechanisms.METHODS Thapsigargin(TG) was used to in...AIM To investigate the protective effect of prostaglandin E1(PGE1) against endoplasmic reticulum(ER) stressinduced hepatocyte apoptosis, and to explore its underlying mechanisms.METHODS Thapsigargin(TG) was used to induce ER stress in the human hepatic cell line L02 and hepatocarcinomaderived cell line Hep G2. To evaluate the effects of PGE1 on TG-induced apoptosis, PGE1 was used an hour prior to TG treatment. Activation of unfolded protein response signaling pathways were detected by western blotting and quantitative real-time RTPCR. Apoptotic index and cell viability of L02 cells and Hep G2 cells were determined with flow cytometry and MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium] assay. RESULTS Pretreatment with 1 μmol/L PGE1 protected against TG-induced apoptosis in both L02 cells and Hep G2 cells. PGE1 enhanced the TG-induced expression of C/EBP homologous protein(CHOP), glucose-regulated protein(GRP) 78 and spliced X box-binding protein 1 at 6 h. However, it attenuated their expressions after 24 h. PGE1 alone induced protein and m RNA expressions of GRP78; PGE1 also induced protein expression of DNA damage-inducible gene 34 and inhibited the expressions of phospho-PKR-like ER kinase, phosphoeukaryotic initiation factor 2α and CHOP. Treatment with protein kinase A(PKA)-inhibitor H89 or KT5720 blocked PGE1-induced up-regulation of GRP78. Further, the cytoprotective effect of PGE1 on hepatocytes was not observed after blockade of GRP78 expression by H89 or small interfering RNA specifically targeted against human GRP78.CONCLUSION Our study demonstrates that PGE1 protects against ER stress-induced hepatocyte apoptosis via PKA pathwaydependent induction of GRP78 expression.展开更多
Numerous studies have shown that topical application of mitomycin C after surgical decompression effectively reduces scar adhesion. However, the underlying mechanisms remain unclear. In this study, we investigated the...Numerous studies have shown that topical application of mitomycin C after surgical decompression effectively reduces scar adhesion. However, the underlying mechanisms remain unclear. In this study, we investigated the effect of mitomycin C on the proliferation and apoptosis of human epidural scar fibroblasts. Human epidural scar fibroblasts were treated with various concentrations of mitomycin C （1, 5, 10, 20, 40 μg/mL） for 12, 24 and 48 hours. Mitomycin C suppressed the growth of these cells in a dose- and time-dependent manner. Mitomycin C upregulated the expression levels of Fas, DR4, DR5, cleaved caspase-8/9, Bax, Bim and cleaved caspase-3 proteins, and it downregulated Bcl-2 and Bcl-xL expression. In addition, inhibitors of caspase-8 and caspase-9 （Z-IETD-FMK and Z-LEHD-FMK, respectively） did not fully inhibit mitomycin C-induced apoptosis. Furthermore, mitomycin C induced endoplasmic reticulum stress by increasing the expression of glucose-regulated protein 78, CAAT/enhancer-binding protein homologous protein （CHOP） and caspase 4 in a dose-dependent manner. Salubrinal significantly inhibited the mitomycin C-induced cell viability loss and apoptosis, and these effects were accompanied by a reduction in CHOP expression. Our results support the hypothesis that mitomycin C induces human epidural scar fibroblast apoptosis, at least in part, via the endoplasmic reticulum stress pathway.展开更多
基金supported by the National Natural Science Foundation of China,No.81560175,81260159(both to LL)
文摘Studies have confirmed a strong association between activation of the endoplasmic reticulum stress pathway and cerebral ischemia/reperfusion(I/R) injury.In this study,three key proteins in the endoplasmic reticulum stress pathway(glucose-regulated protein 78,caspase-12,and C/EBP homologous protein) were selected to examine the potential mechanism of endoplasmic reticulum stress in the neuroprotective effect of G protein-coupled estrogen receptor.Female Sprague-Dawley rats received ovariectomy(OVX),and then cerebral I/R rat models(OVX+ I/R) were established by middle cerebral artery occlusion.Immediately after I/R,rat models were injected with 100 μg/kg E2(OVX + I/R +E2),or 100 μg/kg G protein-coupled estrogen receptor agonist G1(OVX + I/R + G1) in the lateral ventricle.Longa scoring was used to detect neurobehavioral changes in each group.Infarct volumes were measured by 2,3,5-triphenyltetrazolium chloride staining.Morphological changes in neurons were observed by Nissl staining.Terminal dexynucleotidyl transferase-mediated nick end-labeling staining revealed that compared with the OVX + I/R group,neurological function was remarkably improved,infarct volume was reduced,number of normal Nissl bodies was dramatically increased,and number of apoptotic neurons in the hippocampus was decreased after E2 and G1 intervention.To detect the expression and distribution of endoplasmic reticulum stress-related proteins in the endoplasmic reticulum,caspase-12 distribution and expression were detected by immunofluorescence,and mRNA and protein levels of glucose-regulated protein 78,caspase-12,and C/EBP homologous protein were determined by polymerase chain reaction and western blot assay.The results showed that compared with the OVX+ I/R group,E2 and G1 treatment obviously decreased mRNA and protein expression levels of glucose-regulated protein 78,C/EBP homologous protein,and caspase-12.However,the G protein-coupled estrogen receptor antagonist G15(OVX + I/R + E2 + G15) could eliminate the effect of E2 on cerebral I/R injury
基金Supported by the National Natural Science Foundation of China,No.81160067 and No.814600124
文摘AIM To investigate the protective effect of prostaglandin E1(PGE1) against endoplasmic reticulum(ER) stressinduced hepatocyte apoptosis, and to explore its underlying mechanisms.METHODS Thapsigargin(TG) was used to induce ER stress in the human hepatic cell line L02 and hepatocarcinomaderived cell line Hep G2. To evaluate the effects of PGE1 on TG-induced apoptosis, PGE1 was used an hour prior to TG treatment. Activation of unfolded protein response signaling pathways were detected by western blotting and quantitative real-time RTPCR. Apoptotic index and cell viability of L02 cells and Hep G2 cells were determined with flow cytometry and MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium] assay. RESULTS Pretreatment with 1 μmol/L PGE1 protected against TG-induced apoptosis in both L02 cells and Hep G2 cells. PGE1 enhanced the TG-induced expression of C/EBP homologous protein(CHOP), glucose-regulated protein(GRP) 78 and spliced X box-binding protein 1 at 6 h. However, it attenuated their expressions after 24 h. PGE1 alone induced protein and m RNA expressions of GRP78; PGE1 also induced protein expression of DNA damage-inducible gene 34 and inhibited the expressions of phospho-PKR-like ER kinase, phosphoeukaryotic initiation factor 2α and CHOP. Treatment with protein kinase A(PKA)-inhibitor H89 or KT5720 blocked PGE1-induced up-regulation of GRP78. Further, the cytoprotective effect of PGE1 on hepatocytes was not observed after blockade of GRP78 expression by H89 or small interfering RNA specifically targeted against human GRP78.CONCLUSION Our study demonstrates that PGE1 protects against ER stress-induced hepatocyte apoptosis via PKA pathwaydependent induction of GRP78 expression.
基金supported by the National Natural Science Foundation of China,No.81401791,81371968,81672152
文摘Numerous studies have shown that topical application of mitomycin C after surgical decompression effectively reduces scar adhesion. However, the underlying mechanisms remain unclear. In this study, we investigated the effect of mitomycin C on the proliferation and apoptosis of human epidural scar fibroblasts. Human epidural scar fibroblasts were treated with various concentrations of mitomycin C （1, 5, 10, 20, 40 μg/mL） for 12, 24 and 48 hours. Mitomycin C suppressed the growth of these cells in a dose- and time-dependent manner. Mitomycin C upregulated the expression levels of Fas, DR4, DR5, cleaved caspase-8/9, Bax, Bim and cleaved caspase-3 proteins, and it downregulated Bcl-2 and Bcl-xL expression. In addition, inhibitors of caspase-8 and caspase-9 （Z-IETD-FMK and Z-LEHD-FMK, respectively） did not fully inhibit mitomycin C-induced apoptosis. Furthermore, mitomycin C induced endoplasmic reticulum stress by increasing the expression of glucose-regulated protein 78, CAAT/enhancer-binding protein homologous protein （CHOP） and caspase 4 in a dose-dependent manner. Salubrinal significantly inhibited the mitomycin C-induced cell viability loss and apoptosis, and these effects were accompanied by a reduction in CHOP expression. Our results support the hypothesis that mitomycin C induces human epidural scar fibroblast apoptosis, at least in part, via the endoplasmic reticulum stress pathway.
