Neuronal cell death in a genetic model

描述(由申请人提供)：放松对细胞凋亡的调控可导致神经元的丢失和退化，如阿尔茨海默氏症和帕金森氏病等许多神经疾病。为了有效地治疗这些疾病，我们必须了解细胞死亡的机制及其对人类病理的影响。细胞凋亡通过凋亡体发挥作用，凋亡体是一种高度保守的分子机器，控制半胱氨酸天冬氨酸酶的激活。后生动物之间广泛的进化保守使我们能够利用强大的遗传模型来剖析凋亡体的潜在功能和调节。由于果蝇在遗传学和神经生物学方面都是一个异常复杂的模型，我们可以严格地研究凋亡体可能的调节因子在神经元发育和神经元病理中的功能。在果蝇中，凋亡体成分的突变，黑色和雄蜂，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，我们启动了对凋亡体保守调控因子和效应子的筛选。这一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，以确定可能的调控者和凋亡体的效应者。恢复了20多个细胞死亡缺陷突变，即表型黑暗和雄蜂。其中包括同源结构域相互作用蛋白激酶(HIPK)的一个等位基因。通过未知的机制，该基因的小鼠对应物指定神经系统的正常发育，并与神经细胞死亡的调节有关。通过利用HIPK基因座上新的零等位基因，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因子。我的第一个目标将致力于1)通过上位性研究确定HIPK相对于已知的凋亡分子的作用位置，2)加深我们对HIPK相对于凋亡体的作用机制的理解，以及3)将HIPK的作用置于包括背部/NFKB在内的规范信号网络中。我的第二个目标是解决另一个PCD缺陷突变，pcdnI2，它是从我们的屏幕上分离出来的，但尚未与细胞死亡有关。通过产生一个新的空等位基因pcdnI2，我将确定相关的基因座CG31522是否与细胞死亡缺陷表型有关，描述其在发育和神经细胞死亡中的作用，并将其作用定位于已知的凋亡途径成员。公共卫生相关性：细胞凋亡是许多神经疾病的关键组成部分。了解细胞凋亡的机制将有助于治疗和了解这些情况。

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.