Nematode telomerase RNA hitchhikes on introns of germline-up-regulated genes.

Abstract

Telomerase is a ribonucleoprotein complex that elongates telomeric DNA, ensuring germline immortality. In this study, we identified the <i>Caenorhabditis elegans</i> telomerase RNA component 1 (<i>terc-1</i>), as the first known telomerase RNA expressed as an intronic long noncoding RNA (lncRNA), embedded in an intron of germline-up-regulated gene <i>nmy-2</i>. <i>terc-1</i> undergoes splicing, polyadenylation, and nuclear RNA exosome-dependent maturation, stabilized by H/ACA small nucleolar ribonucleoproteins, thus co-opting the H/ACA small nucleolar RNA (snoRNA) biogenesis machinery. Mutations in <i>terc-1</i> led to progressive telomere shortening and sterility in successive generations. Artificially transplanting the <i>nmy-2</i> intron into the introns of germline-expressed genes but not non-germline-expressed genes restored germline immortality, highlighting the importance of genomic context. Our findings suggest that nematode telomerase RNA is a snoRNA-like intronic lncRNA that exploits the introns of germline-up-regulated genes to ensure species survival.