A high-throughput screen identifies RNA binding proteins that affect fertility in Caenorhabditis elegans and reveals a functional relationship between ADR-2 and SQD-1

RNA binding proteins play essential roles in coordinating germline gene expression and development in all organisms. Here, we report that loss of ADR-2, a member of the Adenosine DeAminase acting on RNA (ADAR) family of RNA binding proteins and the sole adenosine-to-inosine RNA editing enzyme in C. elegans, can improve fertility in multiple genetic backgrounds. First, we show that loss of RNA editing by ADR-2 restores normal embryo production to subfertile animals that transgenically express a vitellogenin (yolk protein) fusion to green fluorescent protein. Using this phenotype, a high-throughput screen was designed to identify RNA binding proteins that when depleted yield synthetic phenotypes with loss of adr-2. The screen uncovered a genetic interaction between ADR-2 and SQD-1, a member of the heterogenous nuclear ribonucleoprotein (hnRNP) family of RNA binding proteins. Microscopy, reproductive assays, and high-throughput sequencing reveal that sqd-1 is essential for the onset of oogenesis and oogenic gene expression in young adult animals, and that loss of adr-2 can counteract the effects of loss of sqd-1 on gene expression and rescue the switch from spermatogenesis to oogenesis. Together, these data demonstrate that ADR-2 can contribute to the suppression of fertility and suggest novel roles for both RNA editing-dependent and independent mechanisms in regulating embryogenesis. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/565157v2_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@14a3449org.highwire.dtl.DTLVardef@aead7dorg.highwire.dtl.DTLVardef@1fff947org.highwire.dtl.DTLVardef@46d487_HPS_FORMAT_FIGEXP M_FIG Graphical AbstractFigure created with BioRender. C_FIG Article SummaryThe molecular information that controls early development is RNA. Interactions between RNA and RNA binding proteins (RBPs) are critical for successful reproduction across species. In this study, we uncovered two roles for the RBP ADR-2 in regulating reproduction. First, we demonstrate that the RNA editing activity of ADR-2 regulates fertility. Next, we screened over 250 other RBPs revealed a genetic interaction between ADR-2 and SQD-1. Further analysis revealed that sqd-1 is essential for the onset of oogenesis, and an editing-independent function of ADR-2 influences proper germline gene expression and oocyte fate in these animals.