The conserved microRNA‐229 family controls low‐insulin signaling and dietary restriction induced longevity through interactions with SKN‐1/NRF2

Several microRNAs have emerged as regulators of pathways that control aging. For example, miR‐228 is required for normal lifespan and dietary restriction (DR) mediated longevity through interaction with PHA‐4 and SKN‐1 transcription factors in Caenorhabditis elegans. miR‐229,64,65, and 66, a cluster of microRNAs located adjacent to each other on chromosome III, are in the same family as miR‐228, albeit with slight differences in the miR‐228 seed sequence. We demonstrate that, in contrast to the anti‐longevity role of miR‐228, the miR‐229‐66 cluster is required for normal C. elegans lifespan and for the longevity observed in mir‐228 mutants. miR‐229‐66 is also critical for lifespan extension observed under DR and reduced insulin signaling (IIS) and by constitutive nuclear SKN‐1. Both DR and low‐IIS upregulate the expression of the miRNA cluster, which is dependent on transcription factors PHA‐4, SKN‐1, and DAF‐16. In turn, the expression of SKN‐1 and DAF‐16 requires mir‐229,64,65,66. miR‐229‐66 targets the odd‐skipped‐related transcription factor, odd‐2 to regulate lifespan. Knockdown of odd‐2 increases lifespan, suppresses the short lifespan of mir‐229,64,65,66(nDf63) III mutants, and alters levels of SKN‐1 in the ASI neurons. Together with SKN‐1, the miRNA cluster also indirectly regulates several genes in the xenobiotic detoxification pathway which increases wild‐type lifespan and significantly rescues the short lifespan of mir‐229,64,65,66(nDf63) III mutants. Thus, by interacting with SKN‐1, miR‐229‐66 transduces the effects of DR and low‐IIS in lifespan extension in C. elegans. Given that this pathway is conserved, it is possible that a similar mechanism regulates aging in more complex organisms.