Functional identification of Api5 as a suppressor of E2F-dependent apoptosis in vivo.
Functional identification of Api5 as a suppressor of E2F-dependent apoptosis in vivo.
复制标题
API5作为E2F依赖性凋亡的抑制剂的功能鉴定。
DOI：
10.1371/journal.pgen.0020196
复制
发表时间：
2006-11-17
期刊：
影响因子：
4.5
通讯作者：
Dyson NJ
中科院分区：
文献类型：
--
作者：
Morris EJ;Michaud WA;Ji JY;Moon NS;Rocco JW;Dyson NJ
视网膜母细胞瘤蛋白和 E2 启动子结合因子 (E2F) 家族成员是 G1-S 期进展的重要调节因子。 E2F 失调也会使细胞对细胞凋亡敏感，但人们对 E2F 功能的这一方面知之甚少。 E2F诱导细胞凋亡的研究大多在组织培养细胞中进行，对该过程重要因素的分析仅限于少数候选基因的测试。使用果蝇作为模型系统，我们开发了一些工具，可以在体内鉴定 E2F 依赖性细胞凋亡的遗传修饰剂，并开发了可以在培养细胞中研究 E2F 诱导的细胞凋亡影响的测定方法。遗传相互作用表明，体内 dE2F1 依赖性细胞凋亡涉及 dArk/Apaf1 凋亡体依赖性启动子和效应子 caspase 的激活，并且对果蝇凋亡抑制剂 1 (dIAP1) 的水平敏感。使用这些方法，我们报告了令人惊讶的发现，即凋亡抑制剂 5/抗凋亡克隆 11 (Api5/Aac11) 是体内和体外 dE2F1 诱导细胞凋亡的关键决定因素。这种功能性相互作用发生在多个组织中，是 E2F 诱导的细胞凋亡所特有的，并且从果蝇到人类都是保守的。有趣的是，Api5/Aac11 在 E2F 下游发挥作用，抑制 E2F 依赖性细胞凋亡，但通常不会阻断 E2F 依赖性转录。 Api5/Aac11 表达在肿瘤细胞中通常上调，特别是在转移细胞中。我们发现 Api5 的缺失会导致肿瘤细胞死亡。 E2F 和 Api5/Aac11 之间强烈的遗传相互作用表明，在肿瘤发生过程中可能会选择升高水平的 Api5，从而使 E2F 活性失调的细胞能够在次优条件下生存。因此，抑制 Api5 功能可能为抗肿瘤开发提供一种可能的机制。视网膜母细胞瘤蛋白 (pRB) 是第一个被描述的人类肿瘤抑制因子，它通过限制 E2F 转录因子的活性发挥作用。 pRB 通路在大多数形式的癌症中失活，因此，大多数肿瘤细胞的 E2F 失调。不受控制的 E2F 会促进细胞增殖，但也会使细胞更加敏感地死亡（细胞凋亡）。 E2F 诱导的细胞凋亡尚不清楚，但它会影响癌症的发展，并有可能用于癌症治疗。然而迄今为止，在动物模型中E2F诱导细胞凋亡的研究还很少。作者描述了一系列遗传工具，可用于系统研究 E2F 诱导的果蝇细胞凋亡。作为验证，该方法鉴定了一些已知的 E2F 依赖性细胞凋亡调节因子，并鉴定了 Api5（一种此前未与 E2F 关联的很少被研究的基因），作为 E2F 诱导的细胞死亡的有效抑制因子。 Api5 对 E2F 的影响发生在几种不同的组织中，并且从果蝇到人类都是保守的。最后一点很重要，因为 Api5 在癌细胞中表达上调。 E2F-Api5 相互作用的发现表明，E2F 诱导的细胞凋亡的重要调节剂有待发现，并且可以使用果蝇来发现它们。
Retinoblastoma protein and E2-promoter binding factor (E2F) family members are important regulators of G1-S phase progression. Deregulated E2F also sensitizes cells to apoptosis, but this aspect of E2F function is poorly understood. Studies of E2F-induced apoptosis have mostly been carried out in tissue culture cells, and the analysis of the factors that are important for this process has been restricted to the testing of a few candidate genes. Using Drosophila as a model system, we have generated tools that allow genetic modifiers of E2F-dependent apoptosis to be identified in vivo and developed assays that allow effects on E2F-induced apoptosis to be studied in cultured cells. Genetic interactions show that dE2F1-dependent apoptosis in vivo involves dArk/Apaf1 apoptosome-dependent activation of both initiator and effector caspases and is sensitive to levels of Drosophila inhibitor of apoptosis-1 (dIAP1). Using these approaches, we report the surprising finding that apoptosis inhibitor-5/antiapoptosis clone-11 (Api5/Aac11) is a critical determinant of dE2F1-induced apoptosis in vivo and in vitro. This functional interaction occurs in multiple tissues, is specific to E2F-induced apoptosis, and is conserved from flies to humans. Interestingly, Api5/Aac11 acts downstream of E2F and suppresses E2F-dependent apoptosis without generally blocking E2F-dependent transcription. Api5/Aac11 expression is often upregulated in tumor cells, particularly in metastatic cells. We find that depletion of Api5 is tumor cell lethal. The strong genetic interaction between E2F and Api5/Aac11 suggests that elevated levels of Api5 may be selected during tumorigenesis to allow cells with deregulated E2F activity to survive under suboptimal conditions. Therefore, inhibition of Api5 function might offer a possible mechanism for antitumor exploitation. The retinoblastoma protein (pRB) was the first human tumor suppressor to be described, and it works by limiting the activity of the E2F transcription factor. The pRB pathway is inactivated in most forms of cancer, and, accordingly, most tumor cells have deregulated E2F. Uncontrolled E2F drives cell proliferation, but it also sensitizes cells to die (apoptosis). E2F-induced apoptosis is not well understood, but it affects the development of cancer and, potentially, could be exploited for cancer treatment. To date, however, there have been very few studies of E2F-induced apoptosis in animal models. The authors describe a series of genetic tools that allow systematic studies of E2F-induced apoptosis in Drosophila. As validation, this approach identified some known regulators of E2F-dependent apoptosis and also identified Api5, a little-studied gene that had not previously been linked to E2F, as a potent suppressor of E2F-induced cell death. The effects of Api5 on E2F occur in several different tissues and are conserved from flies to humans. This last point is significant since Api5 is upregulated in cancer cells. The discovery of the E2F–Api5 interaction demonstrates that important modulators of E2F-induced apoptosis are waiting to be discovered and that they can be found using Drosophila.
登录
查看更多内容
影响因子：
8.8
作者：
Forozan, F;Veldman, R;Ammerman, CA;Parsa, NZ;Kallioniemi, A;Kallioniemi, OP;Ethier, SP
通讯作者：
Ethier, SP
影响因子：
4.6
作者：
Kimura, KI;Kodama, A;Ohta, T
通讯作者：
Ohta, T
影响因子：
3.3
作者：
Delalle, I;Pfleger, CM;Hariharan, IK
通讯作者：
Hariharan, IK
影响因子：
10.5
作者：
Frolov, MV;Stevaux, O;Dyson, NJ
通讯作者：
Dyson, NJ
DOI：
10.1073/pnas.1831408100
发表时间：
2003-09-16
影响因子：
11.1
作者：
Hallstrom, TC;Nevins, JR
通讯作者：
Nevins, JR