Effects of nuclear translocation of tissue transglutaminase and the release of cytochrome C on hepatocyte apoptosis

Objective To assess the effects of nuclear translocation of tissue transglutaminase (TTG) and the release of cytochrome C on hepatocyte apoptosis and to reveal the mechanism of signal transcluction of early apoptosis in injured hepatocytes.Methods Hepatocytes isolated from tissue transglutaminase gene knock-out mice and rats were stimulated with ethanol. Proteins from whole cell, cytoplasm and nuclei were extracted for determination of TTG activity by ^14C-putrescine incorporation. Distribution of TTG throughout the entire cell, as well as just nucleus was observed under a confocal scanning microscope. The amount of cytochrome C released from mitochonclria was determined by ELISA. Cell apoptosis was observed by fluorescent cytochemistry.Results TTG activity in whole cells and nuclei was significantly increased after the hepatocytes were treated with ethanol. Cytochrome C release was remarkably increased in the cells isolated from rat and wild-type mouse after treatment with ethanol but not in TTG gene knock-out mice. Cellular apoptosis appeared in hepatocytes isolated from rats and wild-type mice but not in the hepatocytes from TTG gene knock-out mice after stimulation with ethanol.Conclusions Increased TTG in hepatocytes can be translocated into the nucleus and promote release of mitochonclrial cytochrome C into the cytoplasm. Passing through a series of signal pathways, hepatocyte apoptosis is induced eventually.     

体外诱导成体大鼠骨骼肌组织来源的干细胞向神经干细胞的转化

目的研究成体Sprague-Dawley(SD)大鼠骨骼肌来源的干细胞(MDSCs)体外诱导向神经干细胞(NSCs)分化的可行性。方法通过酶消化和连续贴壁的方法体外分离成年SD大鼠腓肠肌中的MDSCs。当传代至4-6代时,加入神经干细胞的特殊培养基Neurobasal-A和细胞因子进行诱导分化。用免疫细胞化学、Western blot以及realtime-PCR方法进行鉴定。结果MDSCs在神经干细胞特殊培养基中培养7~10 d后可形成类似神经球的细胞聚集物。运用免疫细胞化学、Western blot以及realtime-PCR检测发现MDSCs的标记蛋白结蛋白(desmin)表达下调,NSCs的特异性抗原神经巢蛋白(Nestin)开始表达。结论在神经干细胞的特殊培养基培养7~10 d后,MDSCs能够向神经干细胞转化。这种现象提示MDSCs有可能作为治疗神经系统疾病尤其是神经退行性疾病的一种新的干细胞来源。