Role of a Novel Secreted Protein Tyrosine Kinase in Development

描述(申请人提供)：细胞居住在组织中的微环境，细胞外基质(ECM)，越来越被认为是胚胎形态发生的主要调节因素。我们建议使用非洲爪哇胚胎作为一个模型系统来研究ECM的一种新的调节机制，即分泌蛋白的酪氨酸磷酸化。在我们的初步实验中，我们已经识别出一种蛋白酪氨酸激酶，与 任何已知的酪氨酸激酶，都直接合成到分泌途径中，并使细胞外基质蛋白磷酸化。我们的初步数据表明，这种新的激酶在早期颅面图案中起着关键作用。该激酶的活性和位置为大量已发表的磷酸蛋白质组工作提供了第一个解释，这些工作报告了通过典型信号肽途径分泌的ECM蛋白中保守的酪氨酸磷酸化。我们计划使用青蛙胚胎来研究这种分泌型酪氨酸激酶在早期颅面形态发生中的功能，并在体内识别和表征酪氨酸磷酸化底物。这些研究将为一个全新的研究领域提供基础，即在胚胎发育过程中通过酪氨酸磷酸化对分泌蛋白进行可逆调节。ECM的动态调节和重塑也是许多疾病(如肿瘤转移、纤维化、动脉粥样硬化)的核心，因此，通过酪氨酸磷酸化调节ECM蛋白也可能在疾病发病机制的调控中具有重要意义。

DESCRIPTION (provided by applicant): The microenvironment in which cells reside in tissues, the extracellular matrix (ECM), is increasingly recognized as a major regulator of embryonic morphogenesis. We propose to use the Xenopus embryo as a model system to study a novel mechanism of regulation of ECM, the tyrosine phosphorylation of secreted proteins. In our preliminary experiments, we have identified a protein tyrosine kinase that, unlike any previously known tyrosine kinase, is synthesized directly into the secretory pathway, and which phosphorylates extracellular matrix proteins. Our preliminary data indicate that this novel kinase as a key role in early craniofacial patterning. The activity and location of this kinase provides the first explanation for a large body of published phosphoproteomic work reporting conserved tyrosine phosphorylations in ECM proteins secreted via the canonical signal peptide pathway. We plan to use frog embryos to study the function of this secreted tyrosine kinase in early craniofacial morphogenesis, and identify and characterize tyrosine phosphorylated substrates in an in vivo context. These studies will provide the basis for an entirely new area of study, the reversible regulation of secreted proteins by tyrosine phosphorylation during embryogenesis. Dynamic regulation and remodeling of ECM is also central to a wide range of disease pathologies (e.g. tumor metastasis, fibrosis, atherosclerosis), and therefore the regulation of ECM proteins by tyrosine phosphorylation is likely to also have important implications for the modulation of disease pathogenesis.