Characterization of the interaction between Mmp2 Frac and during axon guidance

描述（由申请人提供）：癌症和神经退行性疾病通常以基质金属蛋白酶（MMPs）表达的显著变化为特征。这些蛋白酶已被研究作为治疗多种疾病的潜在治疗靶点。不幸的是，对于24种不同的脊椎动物MMPs，临床试验一直受到副作用的阻碍，这表明MMPs对正常生理功能很重要。果蝇只有两个mmmp，这使得它成为研究MMP函数的一个很好的模型系统，因为它在很大程度上消除了冗余和补偿问题。我们最近报道了果蝇MMPs在胚胎发育过程中对轴突的束控/捆绑很重要。为了了解Frac在神经元发育过程中的功能，鉴定其蛋白水解底物至关重要。一个候选靶点，致命吸引力（Frac），已经在酵母双杂交筛选中被确定。在本提案中，我们提出表征Frac在轴突引导中的功能，并确定其是否受Mmp2的调节。Frac蛋白与脊椎动物的基质蛋白和原纤维蛋白同源。人类纤维蛋白的丢失导致马凡氏综合征或比尔斯综合征，表明这些研究可能具有临床相关性。初步结果表明，断裂RNA定位于胚胎肌肉，这与轴突引导的作用一致。肌肉中Frac的错误表达导致轴突引导缺陷，这与Mmp2功能丧失（LOF）突变体中报道的去血循环表型难以区分，有力地支持Frac和Mmp2之间的功能联系。我们假设Frac作为肌肉中的粘附分子，将轴突吸引到目标肌肉，远离神经分支。然后Mmp2负责裂解和灭活压裂。在具体目标1中，我们将通过分析Frac LOF突变表型和Frac与Mmp2之间的遗传相互作用来表征Frac在轴突引导中的功能。特异性Aim 2测试Frac是否被加工，如果是，这个切割是否依赖于mmp2。由于这一提议解决了一种可能参与轴突引导决策的新型Mmp2底物的特征，它可能会揭示MMPs及其底物在脊椎动物神经元发育中的正常生理功能。

DESCRIPTION (provided by applicant): Cancers and neurodegenerative disorders are often marked by dramatic changes in the expression of matrix metalloproteinases (MMPs). These proteases have been investigated as potential therapeutic targets to treat a variety of diseases. Unfortunately, with 24 different vertebrate MMPs, clinical trials have been hindered by side effects, suggesting that MMPs are important for normal physiological functions. There are only two MMPs in Drosophila, making it an excellent model system to study MMP function as the problems of redundancy and compensation are largely eliminated. We recently reported that Drosophila MMPs are important for the fasciculation/bundling of axons during embryonic development. To understand Frac function during neuronal development, it is critical to identify its proteolytic substrate(s). A candidate target, Fatal Attraction (Frac), has been identified in a yeast two-hybrid screen. In this proposal, we propose to characterize the function of Frac in axon guidance and determine whether it is regulated by Mmp2. Frac protein is homologous to the vertebrate Matrilin and Fibrillin protein. Loss of fibrillin in humans leads to Marfan or Beals syndrome indicating that these studies are likely to be relevant clinically. Preliminary results indicate that frac RNA is localized to embryonic muscle, a position consistent with a role in axon guidance. Frac misexpression in muscle results in axon guidance defects that are indistinguishable from the defasciculation phenotype reported in Mmp2 loss-of-function (LOF) mutants strongly supporting a functional link between Frac and Mmp2. We hypothesize that Frac acts as an adhesive molecule in muscle to attract axons to their target muscles and away from nerve branches. Mmp2 would then be responsible for cleaving and inactivating Frac. In Specific Aim 1, we will characterize the function of Frac in axon guidance by assaying the frac LOF mutant phenotype and genetic interactions between frac and Mmp2. Specific Aim 2 tests whether Frac is processed and, if so, whether this cleavge is Mmp2-dependent. As this proposal addresses the characterization of a novel Mmp2 substrate likely involved in axon guidance decisions, it may shed light on the normal physiological functions of MMPs and their substrates in vertebrate neuronal development.