GTSF ‐1 is required for formation of a functional RNA ‐dependent RNA Polymerase complex in Caenorhabditis elegans

Abstract

Argonaute proteins and their associated small RNAs (sRNAs) are evolutionarily conserved regulators of gene expression. Gametocyte-specific factor 1 (Gtsf1) proteins, characterized by two tandem CHHC zinc fingers and an unstructured C-terminal tail, are conserved in animals and have been shown to interact with Piwi clade Argonautes, thereby assisting their activity. We identified the Gtsf1 homolog, named it and characterized it in the context of the sRNA pathways of We report that GTSF-1 is not required for Piwi-mediated gene silencing. Instead, mutants show a striking depletion of 26G-RNAs, a class of endogenous sRNAs, fully phenocopying mutants. We show, both and , that GTSF-1 interacts with RRF-3 via its CHHC zinc fingers. Furthermore, we demonstrate that GTSF-1 is required for the assembly of a larger RRF-3 and DCR-1-containing complex (ERIC), thereby allowing for 26G-RNA generation. We propose that GTSF-1 homologs may act to drive the assembly of larger complexes that act in sRNA production and/or in imposing sRNA-mediated silencing activities.

Asterix/Gtsf1 links tRNAs and piRNA silencing of retrotransposons

“…Moreover, GTSF-1 in C. elegans has been demonstrated as critical in the formation of a functional RNA-dependent RNA Polymerase Complex (RDRP) where it is believed to aid in the assembly of RNA silencing complexes. 41 These multipartite binding platforms confer enhanced molecular specificity while also allowing flexibility in the repertoire of silencing targets. In this case, our findings suggest that Gtsf1/Asterix exploits a key vulnerability in many retro elements: their dependence on host tRNAs for their replication.…”

The IDR-containing protein PID-2 affects Z granules and is required for piRNA-induced silencing in the embryo

“…Label-free quantitative mass spectrometry has been performed as described in (Almeida et al, 2018). 735…”

“…A third small RNA pathway is driven by so-called 26G RNAs (Billi et al, 2014;Conine et al, 2010;Han et al, 2009;Yigit et al, 2006). These are made by the RdRP enzyme RRF-3, which acts in a large protein complex containing well conserved proteins such as Dicer, GTSF-1 and ERI-1 (Almeida et al, 2018;Billi 105 et al, 2014;Duchaine et al, 2006;Kennedy et al, 2004;Thivierge et al, 2012). These 26G RNAs can be bound by the Argonaute protein ERGO-1, or by two closely related paralogs, the Argonaute proteins ALG-3 and ALG-4 (ALG-3/-4).…”

Systematic Identification of Housekeeping Genes Possibly Used as References in Caenorhabditis elegans by Large-Scale Data Integration

“…Gene expression analysis in this model organism constitutes a powerful tool to discover new roles for different types of molecules. Traditionally, a set of housekeeping genes encoding actin (act-1) [7,8], tubulin (tba-1) [9][10][11], glyceraldehyde-3-phosphate dehydrogenase (gpd-2) [12,13], translation initiation factor 3C (eif-3.C) [14,15], calsequestrin (csq-1) [13,16], Rho GTPase (cdc-42) [17][18][19][20], and peroxisomal membrane protein related (pmp-3) [18,21] were thought to be appropriate reference genes for the normalization of gene expression in C. elegans. However, some reports indicated that the transcription levels of these conserved reference genes may be changed under different conditions, such as developmental stages, drug treatments, and hypoxia [22,23].…”