Programmed Cell Death (Apoptosis) in Drosophila

细胞凋亡是细胞死亡的一个生理过程，对正常发育和组织动态平衡至关重要。细胞凋亡机制调控的缺陷导致多种疾病的发生，包括细胞凋亡率降低(癌症、自身免疫)或细胞过度死亡(神经变性、中风、心肌梗死)。这项建议的主要焦点是阐明在发育中的有机体中调节和执行细胞死亡的遗传机制。 我们正在利用高度可及的遗传模式生物黑腹果蝇。在果蝇中，细胞死亡机制的基本组成部分是保守的。Caspase、Ced-4/APAF-1和LAPS的同源物已经被鉴定。我们已经进行了基因突变筛选，目的是识别果蝇细胞死亡机制组件中的突变。这些突变体为果蝇细胞死亡途径的遗传解剖提供了极其丰富的信息。例如，对这些突变体的一个子集的遗传分析表明，ras/mapk通路是hid的重要负调控因子，hid是诱导细胞死亡的途径之一。 苍蝇的基因。这一发现意义重大，因为30%的人类肿瘤与致癌有关 RAS的形式。因此，我们花了两个具体的目标来分析这种互动。我们将确定RAS/MAPK抑制HID的生化基础，并从分子上鉴定另一个控制MAPK/HID相互作用的基因shes。 半胱氨酸天冬氨酸酶是细胞凋亡的主要效应因子，受到严格的遗传控制，LAPS抑制半胱氨酸天冬氨酸蛋白酶的活性，而Ced-4/APAF-L样蛋白需要激活。LAPS和Ced-4/APAF-1样蛋白是如何协调caspase激活的还知之甚少。利用果蝇LAPS和Ced-4/APAF-1同源基因的突变体，我们将剖析这些基因对控制caspase激活的遗传需求。最后，我们提出了一种新的方法，它将使我们能够分离出果蝇细胞死亡途径中其他尚未确定的成分。在这些实验中获得的信息将为人类疾病提供新的见解，在这些疾病中，已知的是细胞凋亡的放松调控，并可能导致新的治疗干预策略。

Apoptosis is a physiological process of cell death that is critical for normal development and tissue homeostasis. Defects in the regulation of apoptotic mechanisms contribute to the pathogenesis of multiple diseases, including those with reduced rates of apoptosis (cancer, autoimmunity) or with excessive cell death (neurodegeneration, stroke, myocardial infarction). The primary focus of this proposal is to elucidate the genetic mechanisms that regulate and execute cell death in the context of a developing organism. We are utilizing the highly accessible genetic model organism Drosophila melanogaster. In Drosophila, the basic components of the cell death machinery are conserved. Homologs of caspases, ced-4/Apaf-1, and lAPs have been identified. We have performed a genetic mutagenesis screen aimed at identifying mutants in components of the cell death machinery in Drosophila. These mutants are extremely informative for the genetic dissection of the Drosophila cell death pathway. For instance, genetic analysis of a subset of these mutants identified the Ras/MAPK pathway as important negative regulator of Hid, one of the cell death-inducing genes in flies. This finding is significant as 30% of human tumors are associated with oncogenic forms of Ras. Therefore, we devote two specific aims to analyze this interaction. We will determine the biochemical basis of Ras/MAPK-induced inhibition of Hid, and we will molecularly identify an additional gene, shes, that appears to control the MAPK/Hid interaction. Caspases, the principal effectors of apoptosis, are under tight genetic control, lAPs inhibit the activity of caspases, whereas Ced-4/Apaf-l-like proteins are required for their activation. How lAPs and Ced-4/Apaf-1- like proteins coordinate caspase activation is poorly understood. Using mutants of the Drosophila homologs of lAPs and Ced-4/Apaf-1 we will dissect the genetic requirement of these genes for the control of caspase activation. Finally, we propose a novel approach that will permit us to isolate additional as yet uncharacterized components of the Drosophila cell death pathway. The information obtained in these experiments will provide new insights into human diseases where deregulation of apoptosis is known to occur and may lead to new strategies for therapeutic intervention.