TGFb Signaling in Vertebrate Mesoderm Induction

描述（由申请人提供）：本提案的总体目标是阐明转化生长因子- b （TGF-B）途径在爪蟾中胚层诱导和模式形成中的生化和胚胎学功能。在上一轮融资中，通过结合非洲爪蟾胚胎的表达克隆，全球转录谱和生化方法，我们已经确定了在初级胚胎轴的产生和离散细胞命运的建立中多个水平上调节TGF-B通路的关键因素。在这一进展的基础上，我们将重点关注TGFB途径的两个不同寻常的调节因子：作用于细胞外的Coco和作用于细胞核内的第一个被发现的Smad磷酸酶SCP2。我有两个主要目标。首先是在非常早期胚胎的背景下解剖可可生化功能的分子机制。这将通过从受精卵中去除可可来实现，并评估这种功能丧失对胚胎发育的影响。根据这一机制分析，将确定与Coco蛋白相互作用的胚胎因子，以揭示Coco合作伙伴。第二个目标是揭示TGFB通路中期待已久的Smad磷酸酶的生化、细胞和胚胎学功能，我们最终确定了这些功能。我们还将通过比较处理它们的生化和胚胎学功能，将这种分析扩展到这个群体的单个家庭成员。从秀丽隐杆线虫到人类，TGFB通路在进化上一直是保守的，涵盖了胚胎发生和成年生活中广泛的生物活动。这一途径的突变是多种疾病的原因，包括发育障碍和人类癌症。因此，本应用程序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认识，在生命的不同组织和细胞类型中一再重申。

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.