Regulation of Cell-Cell Interactions by Matrix Metalloproteases

描述（申请人提供）：信号分子，细胞外基质成分和分泌蛋白酶之间的复杂相互作用调节组织结构，功能和稳态。这一建议是基于最近建立的范例，即通过基质金属蛋白酶（MMP）介导的机制调节细胞外信号传导。果蝇Mmp2可切割硫酸肝素蛋白多糖（HSPG） Dally，将其从支持FGF- r信号的细胞表面结合的co受体转化为FGF的可溶性抑制剂。这种机制控制果蝇幼虫的分支形态发生，但也可能调节其他依赖FGF的过程，包括上皮-间质相互作用、发育组织者的模式和组织重塑。除FGF外，许多细胞外信号分子受与HSPGs（肝素结合生长因子，VEGF, HIV-TAT, Wnt, Hh, TGF-2）的相互作用调节。可以想象，这些蛋白质的功能也可能受到本文提出的机制的影响。该实验计划将利用申请人建立的细胞培养方法探索Mmp2和Dally之间相互作用的机制基础。这些实验将深入了解细胞表面结合基质金属蛋白酶的结构-功能关系，并可能提供有关MMPs调节特异性机制的一般信息。体内实验将探索MMPs、HSPGs和FGF之间的调节相互作用，并将验证Dally蛋白水解片段可以作为细胞外信号、模式和器官形成的特定调节因子的假设。在最后的目标中，在细胞培养和果蝇中的发现将被纳入两个哺乳动物系统，以询问是否可以利用基于蛋白质水解的调节机制来逆转致癌FGF信号的作用。该提案的实验计划得益于强大的遗传和成像工具在果蝇中可用。果蝇系统的另一个优势是MMPs的遗传冗余度大大降低（果蝇中有2个mmp基因，而哺乳动物中有26个）。果蝇的实验优势与fgf依赖性肿瘤形成的哺乳动物模型提供的癌症相关性相辅相成。

DESCRIPTION (provided by applicant): Complex interactions between signaling molecules, extracellular matrix components and secreted proteases regulate tissue structure, function and homeostasis. This proposal is founded on a recently established paradigm for the regulation of extra cellular signaling by matrix metalloprotease (MMP) - mediated mechanisms. Drosophila Mmp2 cleaves the heparin sulfate proteoglycan (HSPG) Dally, to convert it from a cell surface bound co receptor that supports FGF-R signaling to a soluble inhibitor of FGF. This mechanism controls branching morphogenesis in Drosophila larvae, but may also modulate other FGF- dependent processes, including epithelial-mesenchymal interactions, patterning by developmental organizers, and tissue remodeling. Many extracellular signaling molecules in addition to FGF are regulated by interactions with HSPGs, (Heparin binding growth factors, VEGF, HIV-TAT, Wnt, Hh, TGF-2). It is conceivable that the function of these proteins might also be influenced by the mechanism proposed here. The experimental plan will explore the mechanistic basis of the interaction between Mmp2 and Dally using cell culture assays established by the applicant. These experiments will provide insight into the structure-function relationships in cell surface bound matrix metalloproteases and may yield general information on the mechanisms governing the regulatory specificity of MMPs. In vivo experiments will explore the regulatory interplay between MMPs, HSPGs, and FGF and will test the hypothesis that proteolytic fragments of Dally can act as specific regulators of extracellular signaling, patterning and organ formation. In a final aim the findings made in cell culture and in fruit flies will be taken into two mammalian systems to ask whether the proteolysis- based regulatory mechanism characterized here might be exploited to reverse the effects of oncogenic FGF signaling. The experimental plan of the proposal benefits from the powerful genetic and imaging tools available in Drosophila. A further advantage of the fruit fly system is the much-reduced genetic redundancy of MMPs (2 mmp genes in Drosophila vs. 26 in mammals). The experimental advantages of Drosophila are complemented by the cancer relevance provided by the mammalian models of FGF-dependent tumor formation. PUBLIC HEALTH RELEVANCE: Deregulation of Matrix metalloproteases (MMPs) and FGF signaling has been implicated in tumor-stroma interactions, metastasis formation and tumor angiogenesis. This project will study a recently discovered functional connection between MMP activity and FGF signaling that might be relevant in malignancy. The potential tumor suppressive function of a specific inhibitor of FGF signaling, which is generated by MMP, will be tested.