Danial Nika N, Gramm Colette F, Scorrano Luca, Zhang Chen-Yu, Krauss Stefan, Ranger Ann M, Datta Sandeep Robert, Greenberg Michael E, Licklider Lawrence J, Lowell Bradford B, Gygi Steven P, Korsmeyer Stanley J
Howard Hughes Medical Institute, Dana-Faber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.
Nature. 2003 Aug 21;424(6951):952-6. doi: 10.1038/nature01825.
Glycolysis and apoptosis are considered major but independent pathways that are critical for cell survival. The activity of BAD, a pro-apoptotic BCL-2 family member, is regulated by phosphorylation in response to growth/survival factors. Here we undertook a proteomic analysis to assess whether BAD might also participate in mitochondrial physiology. In liver mitochondria, BAD resides in a functional holoenzyme complex together with protein kinase A and protein phosphatase 1 (PP1) catalytic units, Wiskott-Aldrich family member WAVE-1 as an A kinase anchoring protein, and glucokinase (hexokinase IV). BAD is required to assemble the complex in that Bad-deficient hepatocytes lack this complex, resulting in diminished mitochondria-based glucokinase activity and blunted mitochondrial respiration in response to glucose. Glucose deprivation results in dephosphorylation of BAD, and BAD-dependent cell death. Moreover, the phosphorylation status of BAD helps regulate glucokinase activity. Mice deficient for BAD or bearing a non-phosphorylatable BAD(3SA) mutant display abnormal glucose homeostasis including profound defects in glucose tolerance. This combination of proteomics, genetics and physiology indicates an unanticipated role for BAD in integrating pathways of glucose metabolism and apoptosis.
糖酵解和细胞凋亡被认为是对细胞存活至关重要的主要但相互独立的途径。促凋亡的BCL-2家族成员BAD的活性受生长/存活因子响应下的磷酸化调节。在此，我们进行了一项蛋白质组学分析，以评估BAD是否也可能参与线粒体生理过程。在肝线粒体中，BAD与蛋白激酶A、蛋白磷酸酶1（PP1）催化亚基、作为A激酶锚定蛋白的威斯科特-奥尔德里奇家族成员WAVE-1以及葡萄糖激酶（己糖激酶IV）共同存在于一个功能性全酶复合物中。BAD是组装该复合物所必需的，因为缺乏Bad的肝细胞缺少这种复合物，导致基于线粒体的葡萄糖激酶活性降低以及对葡萄糖的线粒体呼吸减弱。葡萄糖剥夺导致BAD去磷酸化以及依赖BAD的细胞死亡。此外，BAD的磷酸化状态有助于调节葡萄糖激酶活性。缺乏BAD或携带不可磷酸化的BAD(3SA)突变体的小鼠表现出异常的葡萄糖稳态，包括葡萄糖耐量的严重缺陷。这种蛋白质组学、遗传学和生理学的结合表明BAD在整合葡萄糖代谢和细胞凋亡途径中具有意想不到的作用。
