ins-7 Gene Expression Is Partially Regulated by the DAF-16/IIS Signaling Pathway in Caenorhabditis elegans under Celecoxib Intervention

DAF-16 target genes are employed as reporters of the insulin/IGF-1 like signal pathway (IIS), and this is notably true when Caenorhabditis elegans (C. elegans) is used to study the action of anti-aging compounds on IIS activity. However, some of these genes may not be specific to DAF-16, even if their expression levels are altered when DAF-16 is activated. Celecoxib was reported to extend the lifespan of C. elegans through activation of DAF-16. Our results confirmed the function of celecoxib on aging; however, we found that the expression of ins-7, a DAF-16 target gene, was abnormally regulated by celecoxib. ins-7 plays an important role in regulating aging, and its expression is suppressed in C. elegans when DAF-16 is activated. However, we found that celecoxib upregulated the expression of ins-7 in contrast to its role in DAF-16 activation. Our subsequent analysis indicated that the expression level of ins-7 in C. elegans was negatively regulated by DAF-16 activity. Additionally, its expression was also positively regulated by DAF-16-independent mechanisms, at least following external pharmacological intervention. Our study suggests that ins-7 is not a specific target gene of DAF-16, and should not be chosen as a reporter for IIS activity. This conclusion is important in the study of INSs on aging in C. elegans, especially under the circumstance of drug intervention.

DAF-16靶基因常被用作胰岛素/胰岛素样生长因子1信号通路（IIS）的报告基因，在以秀丽隐杆线虫（C. elegans）为模式生物研究抗衰老化合物对IIS活性的调控作用时，该应用尤为典型。然而，部分此类基因并非DAF-16特异性靶基因，即便DAF-16激活时其表达水平会发生变化。已有研究显示，塞来昔布可通过激活DAF-16延长秀丽隐杆线虫的寿命。本研究验证了塞来昔布的抗衰老功效，但同时发现，作为DAF-16靶基因的ins-7，其表达竟被塞来昔布异常调控。ins-7在衰老调控中发挥关键作用，且当DAF-16激活时，秀丽隐杆线虫体内的ins-7表达会被抑制。但本研究观察到，塞来昔布反而上调了ins-7的表达，这与DAF-16激活时的表达趋势相悖。后续分析表明，秀丽隐杆线虫体内ins-7的表达水平受DAF-16活性的负向调控。此外，至少在施加外源性药物干预的条件下，ins-7的表达同时还受到不依赖DAF-16的正向调控机制的影响。本研究提示，ins-7并非DAF-16的特异性靶基因，不应被选作IIS活性的报告基因。这一结论在以秀丽隐杆线虫为模型开展的胰岛素样肽（INSs）衰老相关研究中具有重要价值，尤其在药物干预条件下的相关研究中。