LincRNA
Long intergenic non-coding RNAs (lincRNAs) genes express transcripts that are over 200 nucleotides long, do code for proteins and do not overlap with coding sequences. The biogenesis of lincRNAs is similar to mRNAs, and they are often capped, poly-adenylated and spliced. LincRNAs are highly expressed in both mammalian and C. elegans testis, suggesting they have important role in fertility. Unlike mammals, which have tens of thousands lincRNA genes, C. elegans has only hundreds to a few thousands lincRNA genes, thus facilitating systematic studies.
We have previously published an analysis of the roles of six highly expressed lincRNAs in oogenesis. We used CRISPR to create strains with deletion of the entire lincRNA gene from the genome:
We then performed a thorough meiotic analysis on those strains. You can read about those in our recent paper. Surprisingly, deletion of linc-4 led to slower growth recovery, which a somatic and not a germline process:
A: Images of WT and linc-4 worms 48 hours after the release from 7 days at L1 starvation arrest. B: Quantification of the size of WT and linc-4 worms after the release from 7 days at L1 starvation arrest
Even more surprising was to find that only soma and only germline RNAi depletion showed that linc-4 exerts its role from its germline expression:
Quantification of the size of ppw-1 (soma RNAi) and rrf-1 (mostly germline RNAi) worms following linc-4 or control RNAi depletion after the release from 4 days at L1 starvation arrest
In line with this, RNASeq indicated that differentially expressed genes in linc-4 worms compared to WT, are enriched with genes with roles in the cuticle and germline functions.
Open questions and current work:
1. How can linc-4 affect growth from the germline?
2. Is linc-4 expression required for normal growth happens in the oocyte or the primordial germ cells?
3. Can linc-4 expression in the germline change transcription in the soma?
