Control of caspase activation in apoptosis

描述(申请人提供)：通过细胞凋亡导致的细胞死亡导致从活组织中移走单个细胞，而不损害周围组织。近年来，人们已经认识到，抗凋亡是癌症的一个标志，而化疗耐药可能源于细胞凋亡信号传递的失败。我们发现，高水平的葡萄糖代谢，就像在癌细胞中常见的那样，可以有效地抑制细胞凋亡。特别是，我们发现当磷酸戊糖途径(PPP)活性较高时，启动子caspase，caspase 2(C2)被一些化疗药物激活，受到抑制。我们已经发现，由PPP产生的丰富的NADPH促进激酶CaMKII的激活，使其磷酸化并抑制C2。小分子酸性蛋白14-3-3与磷酸化C2的结合？防止C2去磷酸化、二聚化和激活。相反，当葡萄糖或其他营养素缺乏时，14-3-3？从C2释放，以允许去磷酸化和激活。我们最近发现14-3-3？当营养耗尽时，与C2的结合被乙酰化所阻碍(因此PPP不能运行)，并且14-3-3？在营养充足的条件下，由sirtuin，Sirt1催化的脱乙酰基被刺激。这项拨款的目的是1)描绘连接NADPH和CaMKII的分子通路，2)确定Sirt1是如何调控14-3-3-C2相互作用的，以及3)确定是否可以通过操纵连接新陈代谢和C2的通路来改变乳腺癌细胞的化学反应性。

DESCRIPTION (provided by applicant): Cell death by apoptosis results in the removal of individual cells from the midst of a living tissue without damage to surrounding tissue. In recent years, it has been recognized that resistance to apoptosis is a hallmark of cancers and that resistance to chemotherapy can stem from a failure in apoptotic signal transmission. We have found that high levels of glucose metabolism, as is typically seen in cancer cells, can potently suppress apoptosis. In particular, we have found that the initiator caspase, caspase 2 (C2), activated in response to a number of chemotherapeutic agents, is suppressed when pentose phosphate pathway (PPP) activity is high. We have found that abundant NADPH, produced by the PPP, promotes activation of the kinase CaMKII to phosphorylate and suppress C2. Binding of phosphorylated C2 by the small acidic protein 14-3-3? prevents C2 dephosphorylation, dimerization, and activation. Conversely, when glucose or other nutrients are scarce, 14-3-3 ? is released from C2 to allow dephosphorylation and activation. We have recently found that 14- 3-3 ? binding to C2 is impeded by acetylation when nutrients are depleted (so that the PPP cannot operate) and that 14-3-3 ? deacetylation, catalyzed by the sirtuin, Sirt1, is stimulated under nutrient replete conditions. The aims of this grant are 1) to delineate the molecular pathways linking NADPH and CaMKII, 2) to determine how Sirt1 is regulated to control 14-3-3 ?-C2 interactions and 3) to determine whether chemoresponsiveness of breast cancer cells can be altered by manipulating the pathways linking metabolism and C2.