Control of caspase activation in apoptosis

描述（由申请人提供）：细胞凋亡导致的细胞死亡导致单个细胞从活组织中移除，而不会损害周围组织。近年来，人们认识到对细胞凋亡的抵抗是癌症的一个标志，对化疗的抵抗可能源于细胞凋亡信号传递的失败。我们已经发现，高水平的葡萄糖代谢，就像在癌细胞中看到的那样，可以有效地抑制细胞凋亡。特别是，我们发现引发剂caspase， caspase 2 (C2)，在对许多化疗药物的反应中被激活，当戊糖磷酸途径（PPP）活性高时被抑制。我们发现，大量的NADPH，由PPP产生，促进激酶CaMKII活化磷酸化和抑制C2。小酸性蛋白14-3-3？阻止C2去磷酸化、二聚化和活化。相反，当葡萄糖或其他营养物质稀缺时，14-3-3 ？从C2释放，允许去磷酸化和激活。我们最近发现14- 3-3 ？当营养物质耗尽时，与C2的结合受到乙酰化的阻碍（因此PPP不能运作），14-3-3 ？在营养充足的条件下，由Sirt1催化的去乙酰化受到刺激。该基金的目的是：1)描绘连接NADPH和CaMKII的分子途径；2)确定Sirt1如何被调节以控制14-3-3 ？3)确定乳腺癌细胞的化学反应性是否可以通过操纵连接代谢和C2的途径来改变。

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. PUBLIC HEALTH RELEVANCE: The goal of this grant is to determine how metabolism regulates the apoptotic protease, caspase 2 and to determine how metabolic manipulation might be used to enhance caspase-2 activation. As caspase 2 has been implicated in the response to some chemotherapeutic agents, this work may provide avenues for enhancing the response to cancer chemotherapy.