Cell Clearance in Urogenital Tract

描述(由申请人提供)：死亡/凋亡细胞被清除的机制及其清除如何影响男性泌尿生殖道的生理和病理是重要的，但仍是一个研究不足的领域。生精上皮是研究细胞凋亡清除的独特模型系统，从这些研究中吸取的经验教训将对泌尿生殖道的发育和动态平衡具有重要的意义。生殖细胞的增殖和分化与“不适合”的生殖细胞的死亡和移除密切相关。这项拨款申请的两个首席研究人员的实验室对男性生殖道内的细胞清除问题以及这与男性性腺功能之间的关系感兴趣。我们之前已经报道了吞噬蛋白ELMO1和支持细胞介导的生精上皮中死亡/凋亡生殖细胞的清除的关键作用。我们最近发现，线粒体蛋白UCP2缺乏的小鼠细胞间隙的扰动会恶化睾丸扭转的病理结果。这项工作明确了生精上皮内细胞清除的重要性，并强调了进一步了解男性泌尿生殖道细胞身体清除的生理后果的必要性。我们的总体假设是，特定的信号通路关键地调节TH去除凋亡细胞，并影响正常的睾丸发育、生理和泌尿生殖道的病理。在本提案的目的1中，对调节睾丸细胞清除的ELMO1上游和下游成分进行了研究。具体地说，我们研究了ELMO1上游的受体BAI1和ELMO1下游激活的GTP酶RAC1是如何调节细胞清除的，使用了可诱导的和组织特异性的基因敲除小鼠。在这项建议的AIM2中，我们讨论了泌尿生殖道中的细胞清除如何调节血液睾丸屏障，这对于建立生精上皮的完整性和防止对睾丸抗原的自身免疫是重要的。我们还讨论了增强吞噬(通过在Sertoli细胞中转基因过表达吞噬受体BAI1，以及通过降低线粒体膜电位的化合物)是否会改善睾丸扭转的临床结果。重要的是，在睾丸扭转后收集的人类睾丸活检数据将与小鼠模型的数据相关联。总而言之， 体外研究和整体动物研究相结合，集中在特定的分子和途径上，将提供关于男性泌尿生殖道细胞身体清除和动态平衡的机械性见解。此外，这些研究可能指向加强细胞清除，作为一种潜在的治疗方式的某些病理的泌尿生殖道。

DESCRIPTION (provided by applicant): The mechanism by which dying/apoptotic cells are cleared and how their clearance impacts the physiology and pathology of the male urogenital tract are important, yet is an understudied area. The seminiferous epithelium is a unique model system to study apoptotic cell clearance, and lessons learned from these studies will have important relevance in urogenital tract development and homeostasis. The proliferation and differentiation of germ cells is intimately tied to the death and removal of "unfit" germ cells. Th laboratories of the two Principal Investigators on this grant application are interested in the problem of cell clearance within the male tract and how this relates to the male gonadal function. We have previously reported a critical role for the engulfment protein ELMO1 and the Sertoli cell-mediated clearance of dying/apoptotic germ cells in the seminiferous epithelium. And we recently uncovered that perturbation of cell clearance in mice deficient in the mitochondrial protein UCP2 worsens the pathologic outcome of testicular torsion. This work defined the importance of cell clearance within the seminiferous epithelium and also underscored the need for further understanding the physiologic consequences of cell corpse clearance in the male urogenital tract. Our overall hypothesis is that specific signaling pathways critically regulate th removal apoptotic cells, and impacts normal testicular development, physiology, and pathology of the urogenital tract. In Aim1 of this proposal, components upstream and downstream of ELMO1 that regulate cell clearance in the testes are investigated. Specifically, we address how BAI1, the receptor upstream of ELMO1, and RAC1 (the GTPase that is activated downstream of ELMO1), regulate cell clearance, using inducible and tissue specific knockout mice. In Aim2 of this proposal, we address how the cell clearance in the urogenital tract regulates the blood testes barrier, which is important for establishing the integrity of the seminiferous epithelium an in preventing autoimmunity to testicular antigens. We also address whether enhancing engulfment (through transgenic overexpression of the engulfment receptor BAI1 in the Sertoli cells, and by compounds that decrease the mitochondrial membrane potential) would improve the clinical outcome from testicular torsion. Importantly, data from human testis biopsies collected after testicular torsion will be correlated with data from the mouse model. Collectively, the combination of in vitro and whole animal studies, focusing on specific molecules and pathways, will provide mechanistic insights governing cell corpse clearance and homeostasis in the male urogenital tract. Additionally, these studies could point toward enhancing cell clearance as a potential therapeutic modality for certain pathologies of the urogenital tract.