MMP regulation of stem cell proliferation in the Drosophila ovary

描述(申请人提供)：在果蝇的卵巢中，发育中的卵泡由体细胞卵泡细胞组成，包围着将成为卵子的生殖系包囊。毛囊细胞来自体细胞干细胞，体细胞干细胞产生毛囊细胞前体，我将其分化为成熟的毛囊细胞。已有报道Wnt(Wg)和Hedgehog(HH)信号通路刺激果蝇卵巢中的体细胞干细胞增殖，因为这些信号通路的过度激活导致过多的卵泡细胞。这些信号是由距离干细胞3-5个细胞直径的细胞产生的，这提出了一个问题，即信号是如何传输到做出反应的干细胞的。在我们对降解细胞外基质的基质金属蛋白酶家族的持续研究中，我们观察到，当成年女性MMP2功能发生条件性丧失时，卵泡干细胞在卵子中过度增殖。这种表型与MMP2抑制Wg和/或HH信号通路相一致。这份R03提案描述了一项小型研究，以确定MMP2如何调控体细胞干细胞增殖。在Aim1中，我们将通过分析遗传相互作用和基因表达模式来确定Wg和HH或这两条途径是否发生改变。在目标2中，我们将通过询问MMP2-GFP是否自身运输，并测试候选运输模型，包括脂质颗粒运输、HSPG运输和GPI-锚介导的运输，来确定MMP2如何在几个细胞直径上介导长距离信号传递。我们非常适合进行这些研究，因为PI研究果蝇MMPs已经有十年了，最初是在果蝇卵巢进行培训的，而且进行实验的博士后有果蝇卵巢干细胞增殖的经验。此外，我们的实验室紧邻研究脊椎动物WNT和HH信号的t实验室。我们的研究具有很高的意义，因为这三条途径--基质金属蛋白酶、Wg和HH--都与肿瘤的进展有关，而Wnt信号在皮肤和肠道等上皮细胞的干细胞调控中起着中心作用。我们的发现提出了一种新的模型，即MMPs将这些促进生长的信号限制在干细胞中。我们希望这里提出的小型研究将为更大范围的MMPs如何在发育和癌症中调控干细胞增殖的机制分析奠定基础。

DESCRIPTION (provided by applicant): In the Drosophila ovary, developing follicles are composed of somatic follicle cells surrounding germline cysts that will become the egg. The follicle cells derive from somatic stem cells, which give rise to follicle cell precursors, which i turn differentiate into mature follicle cells. It has been reported that the Wnt (Wg) and Hedgehog (Hh) signaling pathways stimulate somatic stem cell proliferation in the Drosophila ovary, as the hyper-activation of these pathways results in excess follicle cells. These signals are produced by cells that are 3-5 cell diameters away from the stem cells, raising the question of how the signals are transported to the responding stem cells. In our continuing studies of the extracellular matrix-degrading MMP family of proteases, we have observed that when Mmp2 function is lost conditionally in adult females, the follicle stem cells over-proliferate in the ovry. This phenotype is consistent with Mmp2 inhibiting the Wg and/or Hh signaling pathway. This R03 proposal describes a small study to determine how Mmp2 regulates somatic stem cell proliferation. In Aim1, we will determine if Wg, Hh, or both pathways are altered, through analysis of genetic interactions and gene expression patterns. In Aim 2, we will determine how Mmp2 mediates long-range signaling over several cell diameters, by asking if Mmp2-GFP is itself transported, and testing candidate transport models including lipid particle transport, HSPG transport, and GPI-anchor mediated transport. We are well situated to perform these studies, as the PI has been investigating Drosophila MMPs for a decade and originally trained in the Drosophila ovary, and the postdoc performing the experiments has experience with stem cell proliferation in the Drosophila ovary. Additionally, our lab is located immediately adjacent t labs that study wnt and hh signaling in vertebrates. Our studies have high significance, as all three of these pathways - MMP, Wg, and Hh - have been implicated in tumor progression, and Wnt signaling is central to stem cell regulation in epithelia such as skin and intestine. Our findings propose a new model that MMPs limit these growth-promoting signals to stem cells. We expect the small study proposed here will lay the foundation for a larger mechanistic analysis of how MMPs regulate stem cell proliferation, in both development and cancer.