线粒体与内质网互作在生殖细胞发育中的建立、维持及其机制研究

During spermatogenesis, germ cells undergo dramatic changes which require tight coordinated actions of subcellular organelles such as mitochondria and endoplasmic reticulum (ER) in response to developmental signals, substrate availability, and metabolic need. Mitochondria are now increasingly recognized as a key player in multiple cellular and biological processes such as cell signaling, proliferation, lineage commitment, and apoptosis, rather than being originally considered as a static subcellular powerhouse. It remains largely unknown how mitochondria interact with ER to response to extracellular stimuli to regulate germ cell development. Our preliminary data demonstrate that regulators in mitochondrial dynamics regulate spermatogenesis. In addition, germline protein Asz1 is localized at mitochondria. We found that Asz1 interacts with mitochondrial modulators to regulate both mitochondrial and ER homeostasis. In this study, we will systematically delineate the regulators in mitochondrion-ER juxtaposition and coordination in spermatogenesis. We will determine the functional mechanisms how these factors respond to developmental cues and metabolic needs to regulate germ cell fate specification during spermatogenesis. Knowledge gleaned from this study will help understand novel roles and functional mechanisms of mitochondrial dynamics and their coordination with ER during spermatogenesis, but also contribute to future development of drugs targeting male infertility due to metabolic deficits.

生殖细胞的功能及代谢需求在精子发生中发生巨大的变化，需要多种细胞器间的协同作用，传递发育和代谢信号。线粒体的生物学功能已不再局限于最初的能量代谢，在细胞命运形成方面亦发挥重要的作用，而其与内质网的互作在生殖细胞发育及疾病发生中的影响尚不清楚；而线粒体功能及其与内质网的互作如何受到组织特异性因子的调控，也是一个亟待回答的重要科学问题。我们前期工作发现调控线粒体融合的重要因子在生殖细胞分化及成熟中起重要作用，且生殖特异性基因Asz1定位于线粒体，与之相互作用，调控线粒体与内质网的功能，影响精子发生。因而，该课题将聚焦于线粒体及内质网的互作，揭示它们对生殖细胞发育过程中的调控作用，确定生殖细胞中线粒体-内质网耦联的关键蛋白，研究它们如何响应发育和代谢信号，影响生殖细胞命运决定的分子机制，为精子发生机制及男性不育的治疗提供新的理论及实验依据。

生殖细胞的功能及代谢需求在精子发生中发生巨大的变化，需要多种细胞器间的协同作用，传递发育和代谢信号。线粒体的生物学功能已不再局限于最初的能量代谢，在细胞命运形成方面亦发挥重要的作用，而其与内质网的互作在生殖细胞发育及疾病发生中的影响尚不清楚；而线粒体功能及其与内质网的互作如何受到组织特异性因子的调控，也是一个亟待回答的重要科学问题。我们发现在精原干细胞分化过程中，线粒体代谢升高，调控线粒体融合的重要因子MFN1及MFN2表达上调，敲除后影响精原细胞分化。同时，MFN2与MFN1的作用不同，在调控线粒体融合之外，MFN2亦调控内质网的稳态，其敲除导致内质网应激反应，胞质内及线粒体Ca2+升高，分化的精原细胞死亡。另外，MFN1及MFN2在精子发育的不同过程中作用不同，在成熟精子中不起作用。总之，该课题将聚焦于线粒体及内质网的互作，揭示了MFN1/2对生殖细胞发育过程中的调控作用，及其影响生殖细胞命运决定的分子机制，为精子发生机制及男性不育的治疗提供新的理论及实验依据。