秀丽线虫daf-2 rsks-1双突变体长达五倍寿命延长的分子机制研究

Aging can be modulated by highly conserved pathways, such as insulin/insulin-like growth factor-1 (IGF-1), TOR (target of rapamycin) and germline signaling pathways. We previously reported that double mutations in DAF-2 (IGF-1 receptor) and RSKS-1 (S6K), which block both the IGF-1 and TOR pathways, led to 5-fold, synergistic lifespan extension in C. elegans. Further studies demonstrated that AMPK-mediated positive feedback regulation of the DAF-16 (FOXO) transcription factor is required for the synergistic lifespan extension by the daf-2 rsks-1 double mutant, and the germline tissue plays an important role in modulating the synergistic longevity through cell-non-autonomous regulation of DAF-16. Using functional genomics approaches, we have identified hundreds of genes that are differentially expressed in the super long-lived daf-2 rsks-1 double mutant. We hypothesized that some of these genes play important roles in aging. Preliminary genetic screenings helped us identify novel lifespan determinant genes. In order to gain better understanding of the molecular mechanisms of the significantly prolonged longevity by daf-2 rsks-1, we propose to analyze genes that are differentially expressed in daf-2 rsks-1 for their functions in aging in the tissue-specific context, and for their expression patterns and transcriptional regulation. The completion of this proposal will help to elucidate the network of transcriptional control downstream of the highly conserved insulin/IGF-1 and TOR pathways, which will be of broad interests to the research fields of development, metabolism, diseases and aging.

衰老受高度保守的胰岛素类生长因子（IGF-1）和雷帕霉素受体（TOR）信号通路调节。申请人发现在秀丽线虫中同时抑制这两条通路的daf-2 rsks-1双突变体表现出长达近五倍的协同性寿命延长。进一步的研究表明这种长寿表型是由AMPK介导的正反馈激活DAF-16（FOXO）转录因子而实现的。我们已有的工作基础显示，在daf-2 rsks-1双突变体中存在大量表达发生特异性改变的基因。初步的研究表明这些基因中存在新颖的调控衰老的因子。本申请拟通过功能性基因组学手段，分析在daf-2 rsks-1双突变体中表达发生改变的基因是如何以组织特异性的方式调节衰老以及它们是如何在转录水平上被调控的，从而阐明秀丽线虫daf-2 rsks-1双突变体长达近五倍的寿命延长的分子机制。本申请的实施将有助于理解高度保守的IGF-1和TOR通路下游的转录调控网络，对于发育、代谢、疾病与衰老等研究领域有着广泛的意义。

衰老受遗传和环境因素的调节。抑制进化中高度保守的胰岛素类信号（insulin-like signaling）或雷帕霉素靶蛋白（TOR，target of rapamycin）通路均能显著延缓衰老。然而，这两条通路如何相互作用从而影响衰老的机制尚不明确。本课题组发现，同时抑制秀丽线虫中编码胰岛素类生长因子受体的daf-2基因和编码TOR下游核糖体S6激酶的rsks-1基因造成长达近五倍的寿命延长。进一步研究显示，在daf-2 rsks-1双突变体中存在由能量代谢关键因子AMPK介导的正反馈激活DAF-16（FOXO）转录因子这一作用机制。为了更加深入的研究daf-2 rsks-1双突变体超级长寿表型的分子机制，本研究通过转录组分析，识别在daf-2 rsks-1双突变体中表达发生特异性改变的基因。功能分析显示，编码酪氨酸蛋白激酶的drdk-1基因作用于DAF-16转录因子下游，通过组织特异性方式抑制衰老。通过遗传筛选，发现在daf-2 rsks-1双突变体中转录水平下调的基因中存在大量衰老负调控因子。在野生型线虫中抑制这些基因的表达能够显著的延长寿命。生物信息学分析辅以遗传筛选帮助我们找到了daf-2 rsks-1双突变体中调控衰老的多个转录因子，从而加深了对于insulin-like signaling和TOR通路下游的转录调控网络的理解。本研究通过功能性基因组学手段，系统的阐明了秀丽线虫daf-2 rsks-1双突变体超级长寿表型的分子机制，对于衰老的基础生物学研究有重要意义。