Pathways governing survival of neural crest derivatives

描述（由申请人提供）：在发育过程中促进细胞存活的遗传途径定义不清，但代表了抗癌药物的潜在靶点。促进黑素细胞存活的基因，特别是那些独立于以受体酪氨酸激酶C-kit为首的充分表征的抗凋亡途径而运作的基因，在很大程度上是未知的。通过对斑马鱼的正向和反向遗传学研究，我们已经确定了两个独立于C-kit调节胚胎黑素细胞数量的基因。一种是Touchtone（Tct），它似乎可以防止黑素细胞中的坏死细胞死亡，但其分子身份尚不清楚。另一个是转录因子AP-2 α，人们早就知道它在神经嵴中表达，但由于冗余，它在那里的功能仍然不清楚。有趣的是，我们有证据表明，Tct和AP-2也需要在神经嵴衍生的Rohon-Beard感觉神经元（RB）。我们的总体假设是Tct和AP-2调节神经嵴衍生物的存活，并且它们可能作为单一调节途径的一部分这样做。在目的1中，为了深入了解可能的新Tct途径，我们建议通过定位克隆来鉴定Tct基因并鉴定新的等位基因。目的2：为了了解AP-2型活性在神经嵴和黑素细胞中的功能，我们提出用细胞类型特异性启动子对AP-2型活性进行时间和空间调节。在目的3中，为了确定Tct和AP-2在RB中的功能，我们提出了Tct突变体中RB的超微结构分析，以及RB特异性启动子对AP-2型活性的时空调节。最后，我们建议用双突变体实验来测试Tct和AP-2型活性的可能相互作用。这些实验利用了斑马鱼模型的优势，解剖了知之甚少的神经嵴调节通路。这些途径是治疗恶性黑色素瘤和其他神经嵴疾病的潜在切入点。

DESCRIPTION (provided by applicant): Genetic pathways that promote cell-survival during development are poorly defined, yet represent potential targets for anti-cancer drugs. The genes that promote survival of melanocytes, in particular those that operate independently of the well-characterized anti-apoptotic pathway headed by the receptor tyrosine kinase, C-kit, are largely unknown. Through forward and reverse genetic studies in zebrafish, we have identified two genes that regulate the number of embryonic melanocytes independently of C-kit. One is Touchtone (Tct), which appears to prevent necrotic cell death in melanocytes, but whose molecular identity is unknown. The other is transcription factor AP-2alpha, which has long been known to be expressed in neural crest, but whose function there has remained obscure because of redundancy. Interestingly we have evidence that Tct and AP-2 are also required within neural crest-derived Rohon-Beard sensory neurons (RBs). Our overall hypothesis is that Tct and AP-2 regulate survival of neural crest derivatives, and that they may do so as part of a single regulatory pathway. In Aim 1, to gain insight into the possibly novel Tct pathway, we propose to identify the Tct gene by positional cloning and identify new alleles. In Aim 2, to learn the function of AP-2-type activity in neural crest and melanocytes, we propose temporal and spatial modulation of AP-2-type activity with cell-type-specific promoters. In Aim 3, to determine the function of Tct and AP-2 in RBs, we propose ultrastructural analysis of RBs in the Tct mutant, and temporal and spatial modulation of AP-2-type activity with RB-specific promoters. Finally we propose to test for possible interaction of Tct and AP-2 type activity with double mutant experiments. These experiments exploit the advantages of the zebrafish model to dissect poorly understood neural crest regulatory pathways. These pathways are potential entry points for therapies against malignant melanoma and other neural crest diseases.