A Small-RNA-Mediated Feedback Loop Maintains Proper Levels of 22G-RNAs in C. elegans

ERI-6/7 is a negative regulator of exogenous RNAi, however the function of SOSI-1 has never previously been characterized. We noticed that expression of sosi-1 and eri-6/7 are mutually exclusive. Due to its genomic locus being nested within the eri-6 locus, we hypothesized that sosi-1 could be acting as a regulator of ERI-6/7 function by disrupting eri-6/7 expression upon sensing changes in the production of MUT-16-dependent 22G siRNAs. Our data confirms that expression of the sosi-1 mRNA is regulated by MUT-16-dependent 22G siRNAs. In addition, we show here that the expression of the eri-6 and eri-7 pre-mRNAs, and thus the eri-6/7 trans-spliced mRNA, are mis-regulated upon loss of sosi-1-targeting and eri-6[e-f]-targeting MUT-16-dependent 22G siRNAs, suggesting that sosi-1 and eri-6[e-f] act as a feedback sensor for small RNA function. 24 mRNA-seq libraries and 30 small RNA-seq libraries were generated and analyzed. Each genotype per condition were generated in triplicate.