MMP regulation of stem cell proliferation in the Drosophila ovary

描述（由申请人提供）：在果蝇卵巢中，发育中的卵泡是由体细胞卵泡细胞围绕生殖系囊肿组成的，生殖系囊肿将成为卵子。卵泡细胞来源于体细胞干细胞，体细胞干细胞产生卵泡细胞前体，后者分化为成熟的卵泡细胞。据报道，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，因为这些通路的过度激活导致卵泡细胞过剩。这些信号是由距离干细胞3-5个细胞直径的细胞产生的，这就提出了信号是如何传递到应答干细胞的问题。在我们对细胞外基质降解MMP蛋白酶家族的持续研究中，我们观察到，当成年女性的Mmp2功能有条件地丧失时，卵泡干细胞在卵巢中过度增殖。这种表型与Mmp2抑制Wg和/或Hh信号通路一致。这项R03提案描述了一项确定Mmp2如何调节体细胞干细胞增殖的小型研究。在ai1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、Hh或两种通路是否发生改变。在Aim 2中，我们将通过询问Mmp2- gfp本身是否运输，并测试候选运输模型，包括脂质颗粒运输、HSPG运输和gpi锚定介导的运输，来确定Mmp2如何介导几种细胞直径的远程信号传导。我们很适合进行这些研究，因为PI已经研究果蝇MMPs十年了，并且最初在果蝇卵巢中接受过培训，并且进行实验的博士后具有果蝇卵巢中干细胞增殖的经验。此外，我们的实验室毗邻研究脊椎动物中wnt和hh信号的实验室。我们的研究具有很高的意义，因为所有这三种通路- MMP， Wg和Hh -都与肿瘤进展有关，Wnt信号传导是皮肤和肠道等上皮细胞干细胞调控的核心。我们的发现提出了一种新的模型，即MMPs限制了这些促进生长的信号进入干细胞。我们希望这里提出的小型研究将为MMPs在发育和癌症中如何调节干细胞增殖的更大机制分析奠定基础。

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.