Glucosamine protects neonatal cardiomyocytes from ischemia-reperfusion injury via increased protein O-GlcNAc and increased mitochondrial Bcl-2
Glucosamine protects neonatal cardiomyocytes from ischemia-reperfusion injury via increased protein O-GlcNAc and increased mitochondrial Bcl-2
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DOI：
10.1152/ajpcell.00456.2007
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发表时间：
2008-06-01
影响因子：
5.5
通讯作者：
Chatham, John C.
中科院分区：
文献类型：
--
作者：
Champattanachai, Voraratt;Marchase, Richard B.;Chatham, John C.
我们以前曾报道，葡萄糖胺保护新生大鼠心室肌细胞对缺血-再灌注（I/R）损伤，这是与蛋白质O-连接-N-乙酰葡萄糖胺（O-GlcNAc）水平的增加。然而，葡糖胺的保护作用可以通过O-GlcNAc形成以外的途径介导;因此，本研究的最初目标是确定增加催化O-GlcNAc形成的O-GlcNAc转移酶（OGT）表达是否具有与葡糖胺类似的保护作用。为了更好地了解潜在的机制O-GlcNAc介导的细胞保护，我们检查是否增加O-GlcNAc水平改变Bcl-2蛋白家族成员的表达和易位。葡萄糖胺（5 mM）和OGT过表达增加基础和I/R诱导的O-GlcNAc水平，显着降低细胞损伤，并减弱细胞色素c的损失。这两种干预措施也减弱了H2 O2诱导的线粒体膜电位的损失，也与线粒体Bcl-2水平的增加有关，但对Bad或Bax水平没有影响。与葡萄糖胺和OGT过表达相比，NButGT（100 μ M），O-GlcNAc酶的抑制剂，对I/R和H2 O2的保护作用较小，并且不影响Bcl-2的表达，尽管总体O-GlcNAc水平增加了5- 10倍。OGT表达减少导致基础O-GlcNAc水平降低，阻止I/R诱导的O-GlcNAc和线粒体Bcl-2增加，并增加细胞损伤。这些结果表明，葡糖胺的保护作用是通过增加O-GlcNAc的形成介导的，并表明这部分是由于线粒体Bcl-2易位增强。
We have previously reported that glucosamine protected neonatal rat ventricular myocytes against ischemia-reperfusion (I/R) injury, and this was associated with an increase in protein O-linked-N-acetylglucosamine (O-GlcNAc) levels. However, the protective effect of glucosamine could be mediated via pathways other that O-GlcNAc formation; thus the initial goal of the present study was to determine whether increasing O-GlcNAc transferase (OGT) expression, which catalyzes the formation of O-GlcNAc, had a protective effect similar to that of glucosamine. To better understand the potential mechanism underlying O-GlcNAc-mediated cytoprotection, we examined whether increased O-GlcNAc levels altered the expression and translocation of members of the Bcl-2 protein family. Both glucosamine (5 mM) and OGT overexpression increased basal and I/R-induced O-GlcNAc levels, significantly decreased cellular injury, and attenuated loss of cytochrome c. Both interventions also attenuated the loss of mitochondrial membrane potential induced by H2O2 and were also associated with an increase in mitochondrial Bcl-2 levels but had no effect on Bad or Bax levels. Compared with glucosamine and OGT overexpression, NButGT (100 mu M), an inhibitor of O-GlcNAcase, was less protective against I/R and H2O2 and did not affect Bcl-2 expression, despite a 5- to 10-fold greater increase in overall O-GlcNAc levels. Decreased OGT expression resulted in lower basal O-GlcNAc levels, prevented the I/R-induced increase in O-GlcNAc and mitochondrial Bcl-2, and increased cellular injury. These results demonstrate that the protective effects of glucosamine are mediated via increased formation of O-GlcNAc and suggest that this is due, in part, to enhanced mitochondrial Bcl-2 translocation.