The 18S rRNA Methyltransferase DIMT-1 Regulates Lifespan in the Germline Later in Life.

Ribosome heterogeneity has emerged as an important regulatory control feature for determining which proteins are synthesized, however, the influence of age on ribosome heterogeneity is not fully understood. Whether mRNA transcripts are selectively translated in young versus old cells and whether dysregulation of this process drives organismal aging is unknown. Here we examined the role of ribosomal RNA (rRNA) methylation in maintaining appropriate translation as organisms age. In a directed RNAi screen, we identified the 18S rRNA N6'-dimethyl adenosine (mA) methyltransferase, as a regulator of lifespan and stress resistance. Lifespan extension induced by deficiency required a functional germline and was dependent on the known regulator of protein translation, the Rag GTPase, which links amino acid sensing to the mechanistic target of rapamycin complex (mTORC)1. Using an auxin-inducible degron tagged version of we demonstrate that DIMT-1 functions in the germline after mid-life to regulate lifespan. We further found that knock-down of leads to selective translation of transcripts important for stress resistance and lifespan regulation in the germline in mid-life including the cytochrome P450 which synthesizes a steroid that signals from the germline to the soma to regulate lifespan. We found that induced lifespan extension was dependent on the signaling pathway. This finding reveals a new layer of proteome dysfunction, beyond protein synthesis and degradation, as an important regulator of aging. Our findings highlight a new role for ribosome heterogeneity, and specific rRNA modifications, in maintaining appropriate translation later in life to promote healthy aging.