Structural recognition of the mRNA 3' UTR by PUF-8 restricts the lifespan of C. elegans

The molecular mechanisms of aging are unsolved and fascinating fundamental biological questions. Caenorhabditis elegans is an ideal model organism for investigating aging. PUF-8, a PUF (Pumilio and FBF) protein in C. elegans, is crucial for germline development through binding to the 3' untranslated regions (3' UTR) in the mRNA of target genes. Recently, PUF-8 was reported to alter mitochondrial dynamics and mitophagy by regulating MFF, a mitochondrial fission factor, and subsequently regulate longevity. Here, we determined the crystal structure of the PUF domain of PUF-8 with an RNA substrate. Mutagenesis experiments were performed to alter PUF-8 recognition of its target mRNAs. We generate these mutations in C. elegans, those mutations reduced the fertility and extended the lifespan. We deep sequenced total mRNAs from wild-type and puf-8 mutant worms and conducted in vitro RNA pull-down experiments. Six PUF-8 regulated genes were identified, in which their mRNA 3' UTRs contain at least one PUF-binding element (PBE). One of the six genes, pqm-1, is crucial for lipid storage and aging process. Knockdown of pqm-1 could revert the lifespan extension of puf-8(-) animals. Therefore, PUF-8 may regulate the lifespan of C. elegans via modulating pqm-1-related pathways Overall design: In this study, we compared total mRNAs from (1) control animals; (2) puf-8(ust221) mutant; (3) puf-8(ust222) mutant; (4) puf-8(ust223) mutant; (5) puf-8(ok302).