Xom Proteolysis During Early Vertebrate Embryogenesis

早期脊椎动物胚胎发生过程中的 Xom 蛋白水解

• 批准号: 6959037
• 负责人: ZHENGLUN ZHU
• 金额: $ 8.74万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6959037
• 关键词: DNA binding protein; Xenopus; Xenopus oocyte; active sites; biological signal transduction; bone morphogenetic proteins; early embryonic stage; embryogenic cleavage; enzyme activity; ligase; mass spectrometry; nonmammalian vertebrate embryology; phosphorylation; protein protein interaction; proteolysis; serine threonine protein kinase; transcription factor; DNA binding protein; Xenopus; Xenopus oocyte; active sites; biological signal transduction; bone morphogenetic proteins; early embryonic stage; embryogenic cleavage; enzyme activity; ligase; mass spectrometry; nonmammalian vertebrate embryology; phosphorylation; protein protein interaction; proteolysis; serine threonine protein kinase; transcription factor

DESCRIPTION (provided by applicant): Ubiquitin-mediated proteolysis plays important roles in governing signaling during early embryogenesis. Dysregulation of proteolysis of early developmental pathways often results in tumor formation in adult life. Exploring proteolysis during early embryogenesis, therefore, offers a unique opportunity to unveil mechanisms pertinent to tumorigenesis. During the investigation covered by my K08 award, we found that Xom, a homeobox transcriptional factor of the BMP4 signaling pathway, was degraded in a stage-specific manner at the onset of gastrulation. We have identified the destruction motif of Xom and the critical potential phosphorylation sites (Ser140 and Ser144) of the destruction motif that are important for Xom stability. We have further shown that the SCF-beta-TRCP is most likely the cellular E3 ubiquitin ligase involved in Xom degradation. Expression of non-degradable Xom disrupts dorsoventral pattern formation during early Xenopus embryogenesis, indicating the importance of regulated proteolysis during early embryogenesis. Two important questions remains: 1) how is Xom stabilized during pre-gastrulation phase and 2) what turns on Xom proteolysis at the onset of gastrulation. Based on our preliminary studies, we hypothesized that phosphorylation of the Xom destruction motif plays a regulatory role in determining Xom stability during early development, and a serine/threonine kinase phosphorylates Xom at the onset of gastrulation and triggers Xom degradation. We propose to address the following specific aims to test this hypothesis: 1) Define the function of (Ser140/144) phosphorylation in Xom degradation in vitro; 2) Determine a potential regulatory role of (Ser140/144) phosphorylation in Xom degradation in vivo; 3) Identify the kinase that phosphorylates Ser140/144 of Xom during early embryogenesis. Answers to these questions will present the evidence of how stability of homeobox function is regulated developmentally, which will bear great implications for understanding not only the basic mechanism of embryogenesis but also a broad spectrum of diseases, such as pathogenesis of neoplasm.

描述（由申请人提供）： 泛素介导的蛋白水解在早期胚胎发生过程中的控制信号传导中起着重要作用。早期发育途径的蛋白水解失调通常会导致成人生活中的肿瘤形成。因此，在早期胚胎发生过程中探索蛋白水解提供了与肿瘤发生有关的独特机会。在我的K08奖项涵盖的调查期间，我们发现Xom是BMP4信号通路的同型转录因子，在胃肠道发作时以特定于阶段的方式降解。我们已经确定了XOM的破坏基序以及对XOM稳定性很重要的破坏基序的临界电位磷酸化位点（Ser140和Ser144）。我们进一步表明，SCF-beta-trcp很可能是参与XOM降解的细胞E3泛素连接酶。不可降解的Xom的表达会破坏早期异爪蟾胚胎发生过程中背腹模式的形成，表明在早期胚胎发生过程中调节的蛋白水解的重要性。两个重要的问题仍然存在：1）XOM如何在术前阶段进行稳定，2）在胃结构发作时开启XOM蛋白水解的原因。基于我们的前进研究，我们假设XOM破坏基序的磷酸化在确定早期发育过程中的XOM稳定性方面起着调节作用，而丝氨酸/苏氨酸激酶在胃肠道和触发XOM XOM XOM XOM degradation时会磷酸化XOM。我们建议解决以下特定目的，以检验这一假设： 1）定义（Ser140/144）体外XOM降解中磷酸化的功能； 2）确定（Ser140/144）磷酸化在体内XOM降解中的潜在调节作用； 3）确定在早期胚胎发生过程中磷酸化XOM的Ser140/144的激酶。 这些问题的答案将提供有关同源曲局功能的稳定性如何在发育中调节的证据，这将对不仅理解胚胎发生的基本机制，而且还具有广泛的疾病（例如肿瘤的发病机理）具有很大的影响。