Regulation of cell and organ size in vivo

描述(由申请人提供)：本提案中描述的实验旨在描述调节单个细胞大小以及整个器官大小的机制。我们已经对果蝇进行了基因筛查，并确定了至少16个不同基因的突变，这些突变要么导致细胞大小增加，要么导致眼睛整体大小增加。在之前的资助期间，我们证明了果蝇结节性硬化症基因的同源基因，在体内具有限制细胞生长的功能。我们还鉴定了几种新的细胞和组织生长调节剂，包括群岛以及由萨尔瓦多、疣和河马蛋白组成的复合体。在这一应用中，建议进行实验来表征几种调节组织生长但仍知之甚少的途径。我们的实验室最近发现，HMG-box蛋白Capicua在EGF受体和RAS下游发挥作用，调节细胞生长。具体目标1详细介绍了有助于确定Capicua在这一途径中的确切作用的实验。首先，我们建议通过实验来研究EGFR/RAS通路激活下调Capicua水平的机制。其次，利用寡核苷酸芯片和染色质免疫沉淀，我们将识别其表达直接受Capicua调控的基因。特定目标2提出了一种通过非细胞自主机制增加组织生长的突变分析。在这些突变体中，突变细胞生长不良，但它们的存在会导致邻近野生型组织的过度生长。我们的实验将通过表征突变细胞产生的促进生长信号的性质来帮助确定这种过度生长发生的机制。总之，这些研究将帮助我们了解在生物体的正常发育过程中，体内生长是如何受到调节的。 我们的发现也将有助于理解人类癌症中发生的扰动生长。

DESCRIPTION (provided by applicant): The experiments described in this proposal are aimed at characterizing the mechanisms that regulate the size of individual cells as well as the size of whole organs. We have conducted a genetic screen in the fruit fly, Drosophila, and identified mutations in at least sixteen different genes that result either in increased cell size or an increase in the overall size of the eye. In the previous funding period, we showed that the Drosophila orthologs of the tuberous sclerosis genes, function to restrict cell growth in vivo. We have also identified and characterized several novel regulators of cell and tissue growth including Archipelago as well as a complex composed of the Salvador, Warts and Hippo proteins. In this application, experiments are proposed to characterize several pathways that regulate tissue growth but that are still poorly understood. Our laboratory has recently shown that the HMG-box protein Capicua functions downstream of the EGF receptor and Ras to regulate cell growth. Specific Aim 1 details experiments that will help define the precise role of Capicua in this pathway. First, experiments are proposed that wil investigate the mechansim by which activtton of the Egfr/Ras pathway downregulates Capicua levels. Second, using oligonucleotide microarrays and chromatin immunopreciptiation, we will identify genes whose expression is directly regulated by Capicua. Specific Aim 2 proposes an analysis of mutations that increase tissue growth by a non-cellautonomous mechanism. In these mutants, the mutant cells grow poorly but their presence leads to the overgrowth of adjacent wild-type tissue. Our experiments will help define the mechansim by which this overgrowth occurs by characterizing the nature of the growth promoting signals produced by the mutant cells. Together, these studies will help us understand how growth is regulated in vivo during the normal development of an organism. Our findings will also be relevant for understanding the perturbed growth that occurs in human cancers.