GTSF-1 is required for the formation of an RNA-dependent RNA Polymerase complex in C. elegans

ABSTRACT: In every domain of life, Argonaute proteins and their associated small RNAs regulate gene expression. Despite great conservation of Argonaute proteins throughout evolution, there are not many other conserved proteins involved in small RNA pathways. Gametocyte-specific factor 1 (Gtsf1) proteins, characterized by two tandem CHHC zinc fingers and an unstructured, acidic C-terminal tail, represent one such conserved small RNA pathway component. In fly and mouse, they are required for fertility and have been shown to interact with Piwi clade Argonautes. We identified T06A10.3 as the Caenorhabditis elegans Gtsf1 homolog and named it gtsf-1. Given its conserved nature and roles in Piwi-mediated gene silencing, we sought out to characterize GTSF-1 in the context of the small RNA pathways of C. elegans. Surprisingly, we report that GTSF-1 is not required for Piwi-mediated gene silencing. Instead, gtsf-1 mutants lack a class of endogenous small RNAs, known as 26G-RNAs, and fully phenocopy mutants lacking RRF-3, the RNA-dependent RNA Polymerase that synthesizes 26G-RNAs. Like its homologs, GTSF-1 is required for normal fertility. We show, both in vivo and in vitro, that GTSF-1 specifically and robustly interacts with RRF-3 via its tandem CHHC zinc fingers. Furthermore, we demonstrate that GTSF-1 is required for the assembly of a larger RRF-3 and DCR-1-containing complex, also known as ERIC, thereby allowing for 26G-RNA generation. Interestingly, while a GTSF-1-RRF-3 complex exists in the adult, ERIC appears to assemble primarily in embryos, suggesting that 26G-RNA biogenesis mostly occurs after fertilization. We propose that GTSF-1 homologs may similarly act to drive the assembly of larger complexes that subsequently act in small RNA production and/or in imposing small RNA-mediated silencing activities.

ORGANISM(S): Caenorhabditis elegans

PROVIDER: GSE103432 | GEO | 2018/05/11

REPOSITORIES: GEO