Neuronal cell death in a genetic model

描述（由申请人提供）：在许多神经系统疾病如阿尔茨海默病和帕金森病中，细胞凋亡的失调可导致神经元丧失和变性。为了有效地治疗这些疾病，重要的是我们要了解细胞死亡的机制以及它们如何导致人类病理。凋亡通过凋亡体起作用，凋亡体是一种高度保守的分子机器，控制着半胱天冬酶的激活。在后生动物中广泛的进化守恒使我们能够利用强大的遗传模型来剖析细胞凋亡的潜在功能和调控。因为果蝇在遗传学和神经生物学上都是一个非常复杂的模型，我们可以严格地研究神经元发育和神经元病理中凋亡调节因子的功能。在果蝇中，凋亡成分的突变体，暗的和暗的，显示出不同的神经元表型，这是缺陷细胞死亡的表现。利用这些表型，我们开始筛选凋亡的保守调节因子和效应因子。这项倡议的基本原理取决于与黑暗和无人机中功能丧失突变相关的独特表型，以确定可能的凋亡调节因子和效应因子。发现了20余个细胞死亡缺陷突变，表型暗变和暗变。其中包括一个同源结构域相互作用蛋白激酶（HIPK）的等位基因。通过未知的机制，该基因的小鼠对应体指定神经系统的正常发育，并参与神经元细胞死亡的调节。通过在HIPK位点上使用新的零等位基因，我们已经证明HIPK是发育中的动物和神经系统中细胞死亡的重要调节剂。我的第一个目标是1)通过上位性研究确定HIPK相对于已知凋亡参与者的功能，2)进一步了解HIPK在凋亡中的作用机制，3)将HIPK的作用置于包括背侧/NFKB在内的典型信号网络中。我的第二个目标是研究另一种PCD缺陷突变，pcdnI2，从我们的筛选中分离出来，但尚未涉及细胞死亡。通过生成pcdnI2的一个新的零等位基因，我将确定所涉及的基因座CG31522是否与细胞死亡缺陷表型有关，描述其在发育和神经元细胞死亡中的作用，并将其作用与凋亡途径的已知成员联系起来。公共卫生相关性：细胞凋亡是许多神经系统疾病的关键组成部分。了解细胞凋亡机制将有助于治疗和理解这些疾病。

DESCRIPTION (provided by applicant): Deregulation of apoptosis can lead to neuronal loss and degeneration as seen in many neurological disorders such as Alzheimer's and Parkinson's disease. In order to effectively treat these diseases, it is important that we understand the mechanisms of cell death and how they contribute to human pathologies. Apoptosis functions through the apoptosome, a highly conserved molecular machine that controls caspase activation. The broad evolutionary conservation among metazoans permits us to take advantage of powerful genetic models to dissect the underlying function and regulation of the apoptosome. Because Drosophila is an exceptionally sophisticated model for both genetics and neurobiology, we can rigorously study the function of putative regulators of the apoptosome in neuronal development and neuronal pathologies. In flies, mutants of the apoptosome components, dark and drone, show distinct neuronal phenotypes that are manifestations of defective cell death. Using these phenotypes, we initiated a screen for conserved regulators and effectors of the apoptosome. The rationale for this initiative hinges on the unique phenotypes associated with loss-of-function mutations in dark and drone to identify putative regulators and effectors of the apoptosome. Over twenty cell death defective mutations that phenocopy dark and drone were recovered. Included among these is an allele of Homeodomain Interacting Protein Kinase (HIPK). Through unknown mechanisms, the mouse counterparts of this gene specify proper development of the nervous system and are implicated in the regulation of neuronal cell death. Through the use of novel null alleles at the HIPK locus, we have shown that HIPK is an important regulator of cell death in the developing animal and in the nervous system. My first aim will work to 1) determine where HIPK functions relative to known apoptotic players with epistasis studies, 2) further our understanding of the mechanism of HIPK action with respect to the apoptosome, and 3) place the action of HIPK in canonical signaling networks including Dorsal/NFKB. My second aim addresses an additional PCD defective mutation, pcdnI2, isolated from our screen but not yet implicated in cell death. By generating a novel null allele of pcdnI2, I will determine whether the implicated locus, CG31522, is responsible for cell death defective phenotypes, describe its role in developmental and neuronal cell death, and place its action relative to known members of the apoptotic pathway. PUBLIC HEALTH RELEVANCE: Apoptosis is a key component of many neurological disorders. Understanding apoptotic mechanisms will aid in treatment and understanding of these conditions.