TGFb Signaling in Vertebrate Mesoderm Induction

描述(申请人提供)：这项建议的总体目标是阐明转化生长因子-B(转化生长因子-B)途径在非洲爪哇中胚层诱导和形成中胚层中的生物化学和胚胎学功能。通过结合非洲爪哇胚胎中的表达克隆、全球转录图谱和上一轮资助中的生化方法，我们已经在多个水平上确定了在初级胚轴的发生和离散细胞命运的建立中调节转化生长因子-β途径的关键因素。在这一进展的基础上，我们将重点研究其中两个不寻常的调节TGFb途径的因素：COCO，作用于细胞外，以及SCP2，第一个被发现的Smad磷酸酶，作用于细胞核。我有两个主要目标。第一个是在非常早期的胚胎背景下剖析椰子生化功能的分子机制。这将通过从受精卵中去除可可，并评估这种功能丧失对胚胎发育的后果来实现。根据这一机制分析，将识别与可可蛋白相互作用的胚胎因子，以揭示可可合作伙伴。第二个目标，旨在解开期待已久的TGFb途径的生物化学、细胞和胚胎学功能，Smad磷酸酶，我们最终确定了它。我们还将通过比较他们的生化和胚胎学功能，将这一分析扩展到这一组的个别家庭成员。从线虫到人类，TGFb途径在进化上都是保守的，涵盖了胚胎发育和成体生活中一系列令人惊讶的生物学活动。这一途径的突变是各种疾病的原因，包括发育障碍和人类癌症。因此，从这一应用中提出的研究结果超出了它们与我们对胚胎学事件的基本分子理解的相关性，并达到了我们对这一重要信号通路的了解，在一生中不同组织和细胞类型中反复重复这一重要信号通路。

DESCRIPTION (provided by applicant): The overall goal of this proposal is to elucidate the biochemical and embryological function of the Transforming Growth Factor-B (TGF-B) pathway in the induction and patterning of the mesodermal embryonic germ layer in Xenopus. By combining expression cloning in Xenopus embryos, global transcriptional profiling, and biochemical approaches during the last round of funding, we have identified key factors which modulate the TGF-B pathway at multiple levels in the generation of the primary embryonic axis and the establishment of discrete cell fates. Building on this progress, we will focus on two of these factors that are unusual regulators of the TGFB pathway: Coco, acting outside of the cell, and SCP2, the first identified Smad phosphatase, acting in the nucleus. I have two main objectives. The first is to dissect the molecular mechanism underlying the biochemical function of coco in the context of the very early embryo. This will be done by eliminating Coco from the fertilized eggs and assess the consequence of this loss of function on the development of the embryo. In line with this mechanistic analysis, embryonic factors that interact with Coco protein will be identified to unveil Coco-partners. The second aim, targets the unraveling of the biochemical, cellular and embryological function of long awaited players in the TGFB pathway, Smad phosphatases, which we have finally identified. We will also extend this analysis to individual family members of this group by addressing comparatively their biochemical and embryological functions. The TGFB pathway has been evolutionarily conserved from C. elegans to human, covering an amazing range of biological activities both in embryogenesis and adult life. Mutations in this pathway are the causes of various diseases including developmental disorders and human cancer. Therefore, the findings derived from the studies presented in this application extend beyond their relevance to our basic molecular understanding of embryological events, and reach our knowledge about this important signaling pathway, reiterated again and again in different tissues and cell type throughout life.