Neuronal cell death in a genetic model

描述（由申请人提供）：细胞凋亡的失调可导致神经元损失和变性，如在许多神经系统疾病如阿尔茨海默病和帕金森病中所见。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学。细胞凋亡的功能是通过一个高度保守的分子机器，控制半胱天冬酶的激活。后生动物之间广泛的进化保守性使我们能够利用强大的遗传模型来剖析潜在的功能和调节的线粒体。由于果蝇是一个非常复杂的模型，遗传学和神经生物学，我们可以严格研究假定的调节神经元发育和神经元病理学中的调节子的功能。在苍蝇中，突变体的寡聚体组件，黑暗和雄蜂，显示出不同的神经元表型是有缺陷的细胞死亡的表现。使用这些表型，我们开始了一个屏幕上的保守的调节器和效应器的染色体。这一举措的基本原理取决于与黑暗和雄蜂中的功能丧失突变相关的独特表型，以确定推定的调节因子和效应子。发现了20多个细胞死亡缺陷突变，表现型为暗和雄蜂。其中包括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，该基因的小鼠对应物指定神经系统的适当发育，并参与神经元细胞死亡的调节。通过在HIPK基因座上使用新的无效等位基因，我们已经表明HIPK是发育中动物和神经系统中细胞死亡的重要调节因子。我的第一个目标是：1）确定HIPK相对于已知的凋亡参与者的功能，2）进一步理解HIPK对凋亡小体的作用机制，3）将HIPK的作用置于包括Dorsal/NF κ B在内的经典信号网络中。我的第二个目标是解决一个额外的PCD缺陷突变，pcdnI 2，从我们的屏幕上分离，但尚未涉及细胞死亡。通过产生一个新的空等位基因的pcdnI 2，我将确定是否牵连的基因座，CG 31522，是负责细胞死亡缺陷的表型，描述其在发育和神经元细胞死亡的作用，并把它的行动相对于已知的成员的凋亡途径。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条件。

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.