Transcriptional Regulation by the Wnt Effector POP-1

Wnt 效应子 POP-1 的转录调控

• 批准号: 6987849
• 负责人: Rueyling Lin
• 金额: $ 34.28万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-01 至 2009-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6987849
• 关键词: Caenorhabditis elegans; biological signal transduction; developmental genetics; early embryonic stage; endoderm; gene induction /repression; gene mutation; genetic regulation; histogenesis; immunofluorescence technique; invertebrate embryology; lasers; molecular asymmetry; molecular cloning; phenotype; polymerase chain reaction; transcription factor

DESCRIPTION (provided by applicant): The long-term objective of my laboratory is to achieve a detailed understanding of the molecular mechanism(s) by which cell fates are specified via cell-cell interactions. In C. elegans embryos, Wnt signaling induces the E blastomere to produce endoderm. Without this induction, E adopts the fate of its sister, MS. Because POP-1 represses 2 known E-specific genes in MS, and POP-1 level in E is lowered by Wnt signal, it has been proposed that Wnt signal promotes endoderm fate by downregulating POP-1 activity in E. Our recent results force a reevaluation of this model. We show that POP-1 has a positive role in the expression of E-specific, Wnt-responsive genes in E, and a negative role for them in MS. In addition, we have identified POP-1-dependent, Wnt non-responsive genes in MS. The overall goal of this proposal is to determine how POP-1 activates E-specific genes in response to Wnt signaling but represses them in the absence of Wnt signaling, and how POP-1 can promote the expression of MS-specific genes but repress E-specific genes, all in the same cell. Specific Aims for this proposal are: (1) Genetic dissection for factors regulating POP-1 transcriptional activity in the E blastomere. We will revisit established genetic interactions using the expression of E-specific and MS-specific genes as readouts. We will also identify positive regulators of E-specific gene expression by way of a genetic screen. (2) To determine the effect of phosphorylation by Wnt signaling on POP-1 transcriptional regulation of E-specific genes. We will determine the domain(s) and residues of POP-1 phosphorylated upon Wnt signaling important for its ability to activate E-specific genes. (3) To investigate the mechanism by which phosphorylation of POP-1 can alter POP-1 transcriptional activity. We will investigate the effect of POP-1 phosphorylation in E on interactions of POP-1 with corepressors and coactivators and with DNA. (4) To characterize transcriptional activation of MS-specific genes by POP-1. POP-1 must regulate E-specific and MS-specific genes differently. We will analyze how POP-1 regulates target genes in MS, and will examine the role of POP-1 characteristics shown to be important for E-specific gene activation on MS-specific gene expression. Deregulation of the Wnt signaling pathway has been found in various cancers. It is our hope that understanding how Wnt regulates the expression of target genes via TCF proteins could someday help target identification for anticancer drug design.

描述（由申请人提供）：我实验室的长期目标是对通过细胞 - 细胞相互作用指定细胞命运的分子机制进行详细的理解。在秀丽隐杆线虫的胚胎中，Wnt信号传导诱导E骨基瘤产生内胚层。没有这种归纳，E会采用其姐姐MS的命运。由于POP-1在MS中抑制2个已知的E特异性基因，并且E中的POP-1水平通过Wnt信号降低，因此已提出WNT信号通过下调E.中的POP-1活性来促进内胚层命运E。我们最近的结果将其重新评估该模型。我们表明，POP-1在E中E特异性，WNT响应基因的表达中具有积极作用，而在MS中对它们具有负面作用。此外，我们已经确定了MS中的POP-1依赖性WNT无反应基因。该提案的总体目标是确定POP-1如何激活E特异性基因，以响应Wnt信号传导，但在没有Wnt信号的情况下抑制它们，以及POP-1如何促进MS特异性基因的表达，但抑制了E特异性基因，所有这些基因均在同一细胞中。该提案的具体目的是：（1）调节E胚瘤中POP-1转录活性的因素的遗传解剖。我们将使用E特异性和MS特异性基因作为读数的表达来重新访问已建立的遗传相互作用。我们还将通过遗传筛选来鉴定电子特异性基因表达的阳性调节剂。 （2）确定Wnt信号传导对磷酸化的影响对E特异性基因的POP-1转录调控。我们将确定在Wnt信号传导上对其激活E特异性基因的能力很重要的POP-1磷酸化的域和残基。 （3）研究POP-1磷酸化的机制可以改变POP-1的转录活性。我们将研究E POP-1磷酸化在E中对POP-1与核压子和共激活因子以及与DNA相互作用的影响。 （4）通过POP-1表征MS特异性基因的转录激活。 POP-1必须以不同的方式调节电子特异性和MS特异性基因。我们将分析POP-1如何调节MS中的靶基因，并将检查对MS特异性基因表达中E特异性基因激活显示的POP-1特征的作用。在各种癌症中发现了Wnt信号通路的放松管制。我们希望，了解Wnt如何通过TCF蛋白来调节靶基因的表达，有一天可以帮助靶向抗癌药物设计鉴定。