Browsing by Subject "Endoplasmic reticulum stress"

Now showing 1 - 4 of 4
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    Bone biology in postnatal Wistar rats following hypoxia-reoxygenation
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2020) Hameister, Rita; Lohmann, Christoph H.; Dheen, Thameem; Singh, Gurpal; Kaur, Charanjit
    Hypoxia response pathways have a central role in normal and abnormal bone biology but the effect of systemic hypoxia-reoxygenation on bone is not clear. Following hypoxic exposure, aberrant synthesis, folding and trafficking of proteins has been reported to occur, which can result in endoplasmic reticulum (ER) stress and may finally cause cell death. This study aimed to examine the effect of systemic hypoxia-reoxygenation injury on bone biology in postnatal rats. Immunoexpression of HIF-1α and VEGF was upregulated in femurs of newborn Wistar rats in response to systemic hypoxia-reoxygenation. Along with that, increased apoptosis of osteoblast precursors, osteoblasts, osteocytes and endothelial cells was observed in comparison to femurs of control animals by transmission electron microscopy, TUNEL staining and immunoexpression of cleaved caspase-3. The viability of osteoclasts was not affected. After hypoxia- reoxygenation, ER stress was observed in the osteoblasts and osteocytes as indicated by dilatation of the ER and enhanced immunoexpression of the ER stress marker GRP78. Localisation of collagen α1 immunoreaction was widespread in the bone matrix of control femurs but was confined to the osteoblasts and osteocytes in response to hypoxia-reoxygenation. In support of these findings, in vitro work showed reduced viability of osteoblast-like SaOs-2 cells and upregulation of GRP78 protein expression in them by western blotting following exposure to hypoxia. This suggests that systemic hypoxia-reoxygenation may disturb bone biology in postnatal Wistar rats by inducing ER stress and apoptosis in osteoblasts and osteocytes, without affecting the viability of osteoclasts. More in-depth research is needed to confirm causality between ER stress and apoptosis of osteoblasts and osteocytes
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    Protective effect of 2-deoxy-D-glucose on the brain tissue in rat cerebral ischemia-reperfusion models by inhibiting caspase-apoptotic pathway
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2017) Min, He-ming; Wang, Yan; Ren, Da Yong; Cheng, Xue; Li, Jian; Jiang, Xing qian; Min, Lian qiu; Bao, Cui fen
    We observed the effect of 2-deoxy-D-glucose (2-DG) on the brain tissue in rat cerebral ischemiareperfusion (I/R) and explored its mechanism. After observing the effect of 2-DG on endoplasmic reticulum stress (ERS), rats were randomly divided into shamoperation group, I/R group and I/R+2-DG group (each group with 60 rats). I/R models were prepared by middle cerebral artery occlusion. In I/R+2-DG group, each rat was given intraperitoneal 2-DG of 100 mg/kg once a day for 7 days before brain ischemia. According to different time points (3 h, 6 h, 12 h, 24 h and 48 h) after I/R, each group was divided into 5 subgroups (each subgroup with 12 rats). Nerve cell apoptosis, and the expressions of mRNA and protein of glucose regulated protein 78 (GRP78), cleaved-caspase-9 and cleaved-caspase-3 were determined with TUNEL, Western blotting and RT-PCR, respectively, in rat cerebral hippocampal CA1 area at each time point. TUNEL-positive cells were significantly less in I/R+2-DG group than in I/R group at each time point (all P<0.01). In I/R and I/R+2-DG groups, the expressions of mRNA and protein of GRP78 reached the maximum 12 h after I/R, and cleavedcaspase-9 and cleaved-caspase-3 reached the maximum 24 h after I/R. Compared with sham-operation group, the expressions of mRNA and protein of GRP78, cleavedcaspase-9 and cleaved-caspase-3 were all significantly increased (all P<0.01) in I/R and I/R+2-DG groups. However, the expressions of mRNA and protein of GRP78 were significantly higher in I/R+2-DG group than in I/R group (all P<0.05), but the expressions of mRNA and protein of cleaved-caspase-9 and cleavedcaspase-3 were all significantly lower in I/R+2-DG group than in I/R group (all P<0.05). We conclude that 2-DG has a neuroprotective effect on the brain tissue in rat cerebral ischemia-reperfusion models. The mechanism may be that 2-DG starts ERS followed by up-regulation of mRNA and protein of GRP78 and down-regulation of mRNA and protein of cleavedcaspase-9 and cleaved-caspase-3, which blocks the apoptotic pathway.
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    Sulfur dioxide ameliorates rat myocardial fibrosis by inhibiting endoplasmic reticulum stress
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2018) Wang, Xin Bao; Cui, Hong; Du, Jun Bao
    Myocardial remodeling occurs after myocardial infarction (MI), the leading cause of mortality worldwide. Although myocardial fibrosis plays an important role in the process of myocardial remodeling, there is not yet an effective method of reducing it. The aim of the present study was to determine the effects of sulfur dioxide (SO2) on myocardial fibrosis and the possible mechanisms of these effects. SO2 treatment reduced the extent of myocardial fibrosis and post-MI levels of collagens I and III in the left-ventricular myocardium. SO2 also improved MI-induced thinning of the left ventricular wall while enlarging the left ventricular internal diameter. SO2 was able to reduce matrix metalloproteinase (MMP)-9 activity and increase tissue matrix metalloproteinase inhibitor (TIMP)-1 content in myocardium after MI. However, the mechanism underlying these effects of SO2 on myocardial fibrosis are unknown. Western blot analysis of endoplasmic reticulum (ER) stress-related proteins showed that glucose-regulated protein 78, C/EBP homologous protein, caspase-12, and phosphorylated eukaryotic initiation factor 2α expression levels were significantly increased in MI rats and decreased by SO2 treatment. The ER stress promoter dithiothreitol reversed these effects of SO2. In conclusion, SO2 alleviated myocardial fibrosis in MI rats through a mechanism related to inhibition of excessive ER stress.
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    TROP2 regulates cisplatin sensitivity of triple-negative breast cancer cells by regulating endoplasmic reticulum stress
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2025) Zhang, Mingqi; Xu, Jianzhong; Liu, Qing; Yan, Xi; Li, Ning
    Triple-negative breast cancer (TNBC) is a kind of breast cancer with a high metastasis rate and poor prognosis. As a transmembrane glycoprotein, tumor-associated calcium signal transducer 2 (TROP2) plays a certain role in the cancers. This study aimed to explore the potential mechanism of TROP2 affecting cisplatin (CDDP) resistance in TNBC from endoplasmic reticulum stress (ERS). MDA-MB-231 and CDDP-resistant cell lines MDA-MB-231/CDDP were used in this study, and the expression of TROP2 was detected by western blotting. After transfecting with the interference sequence of siRNA targeting TROP2, cell proliferation and apoptosis were detected by the cell counting kit-8, colony formation, and flow cytometry, and the expression of ERS-marker proteins was detected by western blotting. Furthermore, the effects of ERS in TROP2 on drug resistance of TNBC cells were explored by using ERS inhibitor 4-phenylbutyric acid (4-PBA). Results found that TROP2 expression in MDA-MB-231/CDDP was significantly upregulated compared with MDA-MB-231. The expression of TROP2 in MDA-MB-231/CDDP was significantly decreased after transfection with siRNA-TROP2, and the proliferation of MDA-MB-231 and MDA-MB-231/CDDP cells was significantly decreased after further induction with CDDP. TROP2 significantly affected TNBC cell cloning, apoptosis, and the expression of ERS-related marker proteins, while 4-PBA reversed the promoting effects of siRNA-TROP2 on apoptosis and ERS, as well as the inhibitory effects on cell proliferation, suggesting that TROP2 affected the resistance of TNBC cells to CDDP through ERS. In conclusion, TROP2 inhibited apoptosis of TNBC cells, improved the cell cloning ability, and regulated the sensitivity of TNBC cells to CDDP through ERS.