高糖通过线粒体途径诱导成骨细胞凋亡

线粒体途径是细胞凋亡的重要途径之一. 在特定的刺激下，例如高糖条件，可以通过caspase依赖性和非依赖性两种途径诱导多种细胞凋亡.但线粒体凋亡途径在高糖引起成骨细胞凋亡中所起的作用，目前尚不清楚.本研究证明，高糖可以通过线粒体凋亡途径诱导成骨细胞凋亡.Annexin V-FITC/PI流式细胞学检测显示,高糖可诱导MC3T3-E1细胞凋亡.Western印迹检测发现,不同浓度D-葡萄糖（11，22，33 mmol/L）可以引起线粒体中Bax蛋白表达的增加，使Bax蛋白由细胞质中易位到线粒体，激活了线粒体凋亡途径.JC-1荧光探针检测证实，高糖处理成骨细胞后,线粒体膜电位明显降低，表明线粒体途径被激活.而细胞质中的细胞色素c、凋亡诱导因子（AIF）表达增加，细胞色素c和AIF从线粒体中释放到细胞质中，释放到细胞质中的细胞色素c使caspase-3、caspase-9剪切活化，从而激活了caspase依赖性凋亡途径.因此，线粒体凋亡途径可能是高糖诱导成骨细胞凋亡过程中一个重要的途径.

Cell Apoptosis Induced by HighGlucose in Osteoblastic Cells via a Mitochondrial Mediated Pathway

Mitochondria-mediated pathway plays an important role in the apoptosis induced by some specific stimulation, such as high glucose. Mitochondria-mediated pathway includes caspase-dependent and caspase-independent apoptosis processes. However, the exact role of mitochondria-mediated apoptotic pathway in high glucose induced osteoblast apoptosis remained unclear. This study demonstrated that high glucose induced osteoblast apoptosis via a mitochondria-mediated pathway. Apoptosis was measured by Annexin V-FITC/PI. Western blotting results showed that different concentrations of D-glucose (11, 22, 33 mmol/L) increased the expression level of Bax in mitochondrial protein fraction, suggesting that Bax translocated from the cytoplasm to the mitochondria and then activated the mitochondrial apoptotic pathways. The decrease of mitochondrial membrane potential measured by JC-1 fluorescence probe, confirmed that the mitochondrial pathway was activated in high sugar processing osteoblasts. Western blotting also found that the expression of cytochrome c, apoptosis-inducing factor (AIF) in cytoplasm fraction significantly increased, suggesting that cytochrome c and AIF were released from the mitochondria to cytoplasm. The increase of cytochrome c in cytoplasm fraction could activate caspase-3 and caspase-9, and finally activate the caspase-dependent apoptosis pathway. Therefore, the mitochondrial apoptotic pathway may play an important role in the apoptosis induced by high glucose in osteoblastic MC3T3-E1 cells.