Molecular mechanism of Caenorhabditis elegans insulin-like peptides that regulate diapause and longevity positively or negatively

作为对不利生长条件的反应，秀丽隐杆线虫停止发育并进入滞育阶段。秀丽隐杆线虫利用诱导滞育的信息素作为一种化学介质来检测种群过剩。秀丽隐杆线虫的胰岛素/胰岛素样生长因子- 1信号通路不仅通过受体DAF-2调控幼虫滞育，还通过DAF-2调控成虫寿命。最近有报道称，敲除in -7 RNAi可延长寿命。在我们之前的研究中，我们发现了胰岛素样基因In -17和In -18，并对它们进行了干扰，以阐明它们的生理功能。在上述信息素存在的情况下，这些基因破坏导致幼虫滞育显著减少。相比之下，干扰对寿命的影响一直不明确。在上述背景下，我们试图对诱导滞育的信息素进行表征。此外，我们还阐明了这些胰岛素样基因在诱导滞育和延长寿命条件下的生理功能。我们首先从化学和生物学的角度对滞育诱导信息素进行了表征。我们尝试用HPLC等多种色谱方法纯化信息素。虽然提纯尚未完成，但信息素似乎是一种中性或碱性化合物，分子量在1000左右。非常有趣的是，原始信息素以剂量依赖的方式延长了寿命。此外，寿命延长依赖于DAF-2下游的转录因子DAF-16，提示信息素通过IIS途径调节成体寿命。接下来，我们破坏了7号和11号胰岛素样基因。正如预期的那样，缺乏in -7的突变动物表现出更长的寿命。该动物还显示，在信息素存在下，幼虫滞育增加。相反，in11基因的破坏对幼虫滞育和成虫寿命没有影响。然后，为了阐明ins基因的冗余功能，我们对基因破坏的动物进行了杂交。ins-11、ins-17、ins-18基因的破坏抑制了ins-7基因的破坏引起的幼虫滞育，说明ins-11、ins-17、ins-18基因与ins-7具有相反的功能。此外，只有ins-18的破坏才能抵消ins-7的破坏所导致的寿命延长，这表明只有ins-18在寿命调节方面具有与ins-7相反的功能。简而言之，INS-7对受体DAF-2起激动作用，INS-11、-17和-18在幼虫滞育方面起拮抗剂作用。另一方面，就成年寿命而言，只有INS-18具有DAF-2的拮抗剂作用。少

In a response to unfavorable growth conditions, the nematode Caenorhabditis elegans ceases development and enters a diapause stage. C.elegans utilizes the diapause-inducing pheromone as a chemical mediator to detect overpopulation. The insulin/insulin-like growth factor-I signaling (IIS) pathway of C.elegans regulates not only larval diapause but also adult lifespan via the receptor DAF-2. Recently, it was reported that ins-7 RNAi knockdown causes an extended lifespan. In our previous study, we identified insulin-like genes ins-17 and ins-18 and disrupted them to elucidate their physiological functions. In the presence of the pheromone described above, these gene-disruptions caused a significant decrease in larval diapause. In contrast, effect of the disruptions on lifespan has been ambiguous. Under the background described above, we attempted to characterize the diapause-inducing pheromone. In addition, we elucidated physiological functions of these insulin-like genes in diapause-indu … More cing and lifespan-extending conditions.We first characterized the diapause-inducing pheromone chemically and biologically. We tried purifying the pheromone with several chromatographic methods including HPLC. Although the purification has not yet completed, the pheromone seems a neutral or basic compound of which molecular weight is around 1,000. Quite interestingly, the crude pheromone caused an extended lifespan in a dose-dependent manner. In addition, the lifespan extension depended on the transcription factor DAF-16 downstream of DAF-2, suggesting that the pheromone regulates adult lifespan via the IIS pathway.Next, we disrupted insulin-like genes ins-7 and ins-11. As expected, the mutant animal lacking ins-7 showed an extended lifespan. The animal also revealed an increase in larval diapause in the presence of the pheromone. In contract, the gene-disruption of ins-11 showed no influence in larval diapause and adult lifespan. Then in order to elucidate redundant function of ins genes, we crossed the gene-disrupted animals. Disruption of ins-11, ins-17, or ins-18 suppressed the larval diapause caused by that of ins-7, indicating that ins-11, -17, and -18 genes have an opposite function to ins-7. Moreover, only disruption of ins-18 canceled the lifespan extension caused by that of ins-7, indicating that only ins-18 has an opposite function to ins-7 in lifespan regulation. In short, INS-7 functions as an agonist to the receptor DAF-2, and INS-11, -17, and -18 function as an antagonist in terms of larval diapause. On the other hand, only INS-18 functions as an antagonist to DAF-2 in terms of adult lifespan. Less