Metabolic regulation of stem cell behavior and longevity

描述（由申请人提供）：衰老与生物体水平的功能下降相关，其起源于细胞退化和组织稳态丧失。线粒体能量代谢和干细胞功能的变化被广泛报道;然而，线粒体动力学，衰老和干细胞行为之间的相互作用几乎被忽视了。PI的实验室使用果蝇Drosophila melanogaster的强大遗传学来阐明干细胞行为和寿命的代谢调节机制。在哺乳动物中，过氧化物酶体增殖物激活受体γ共激活因子-1（PGC-1）家族的转录共激活因子调节几个关键的代谢过程，包括线粒体生物发生和能量代谢。此外，PGC-1表达和线粒体生物发生的增加与包括人类在内的许多物种的饮食限制的寿命延长机制有关。这些实验室已经发现果蝇PGC-1家族同源物（dPGC-1）是线粒体生物发生的有效诱导物，并且dPGC-1在肠道中的靶向表达足以延长寿命。此外，过表达dPGC-1的长寿果蝇显示出肠道和生殖系干细胞的稳健维持。这些发现对于理解代谢、干细胞生物学和寿命决定之间的关系具有深远的意义。本提案将通过解决三个具体目标建立在这些研究的基础上：1）检查果蝇PGC-1（dPGC-1）同源物的过表达对代谢和寿命的影响2）表征干细胞行为和线粒体代谢之间的关系3）表征dPGC-1介导的寿命的机制。果蝇PGC-1的表达将在多个组织和不同的时间点被诱导，然后分析代谢、行为和寿命的变化。同时，将使用充分表征的标记物结合免疫荧光显微镜来表征肠和格尔线中的干细胞数量、活性和分化潜力。最后，dPGC-1过表达导致寿命延长的机制将通过研究衰老苍蝇的肠道功能和进行遗传上位性实验与先前表征的长寿途径进行研究。

DESCRIPTION (provided by applicant): Aging is associated with a decline of function at the organismal level that has origins in cellular deterioration and the loss of tissue homeostasis. Age-related changes in both mitochondrial energy metabolism and stem cell function are widely reported; however, the interplay between mitochondrial dynamics, aging, and stem cell behavior has been virtually neglected. The PIs' laboratories use the powerful genetics of the fruit fly Drosophila melanogaster to elucidate the mechanisms underlying metabolic regulation of stem cell behavior and lifespan. In mammals, the peroxisome proliferator-activated receptor gamma co-activator-1 (PGC-1) family of transcription co-activators regulates several key metabolic processes, including mitochondrial biogenesis and energy metabolism. Moreover, increases in PGC-1 expression and mitochondrial biogenesis have been implicated in the life-extending mechanism of dietary restriction in a number of species, including humans. These laboratories have discovered that the Drosophila PGC-1 family homolog (dPGC-1) is a potent inducer of mitochondrial biogenesis, and targeted expression of dPGC-1 in the intestine is sufficient to extend lifespan. Furthermore, long-lived flies overexpressing dPGC-1 display robust maintenance of intestinal and germline stem cells. These findings have profound implications for the understanding of the relationship between metabolism, stem cell biology and lifespan determination. This proposal will build upon these studies by addressing three Specific Aims: 1) To examine the impact of overexpression of the Drosophila PGC-1 (dPGC-1) homolog on metabolism and lifespan 2) To characterize the relationship between stem cell behavior and mitochondrial metabolism 3) To characterize the mechanisms of dPGC-1-mediated longevity. Drosophila PGC-1 expression will be induced in multiple tissues and at different time-points, followed by analysis of changes in metabolism, behavior and longevity. Simultaneously, stem cell number, activity, and differentiation potential will be characterized in the intestine and ger line using well-characterized markers in combination with immunofluorescence microscopy. Lastly, the mechanism by which dPGC-1 overexpression leads to lifespan extension will be examined by studying intestinal function in aging flies and conducting genetic epistasis experiments with previously characterized longevity pathways.