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）表达的显著变化为标志。这些蛋白酶已被研究为治疗多种疾病的潜在治疗靶标。不幸的是，对于24种不同的脊椎动物MMPs，临床试验受到副作用的阻碍，这表明MMPs对正常的生理功能很重要。果蝇中只有两种MMP，这使其成为研究MMP功能的极好模型系统，因为冗余和补偿的问题在很大程度上被消除。我们最近报道，果蝇MMPs是重要的fasciculation/捆绑的轴突在胚胎发育。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是至关重要的。一个候选目标，致命吸引力（Frac），已确定在酵母双杂交筛选。在这个建议中，我们建议表征Frac在轴突引导中的功能，并确定它是否受Mmp 2的调节。Frac蛋白与脊椎动物Matrilin和Fibrilin蛋白同源。人体中的马凡氏蛋白缺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意义。初步结果表明，断裂RNA定位于胚胎肌肉，位置与轴突指导的作用一致。Frac在肌肉中的错误表达导致轴突导向缺陷，其与Mmp 2功能丧失（LOF）突变体中报道的去束表型难以区分，这强烈支持Frac和Mmp 2之间的功能联系。我们假设Frac作为肌肉中的粘附分子，将轴突吸引到其靶肌肉并远离神经分支。Mmp 2则负责裂解和灭活Frac。在具体目标1中，我们将通过分析Frac LOF突变体表型和Frac与Mmp 2之间的遗传相互作用来表征Frac在轴突引导中的功能。特异性目的2测试Frac是否被加工，如果是，则该切割是否是Mmp 2依赖性的。由于这一建议解决了一种新的Mmp 2底物可能参与轴突导向决策的表征，它可能揭示了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.