Small RNAs regulate spermatogenesis ranging from Caenorhabditis elegans to mammals. In C. elegans, two Argonaute proteins, ALG-3 and ALG-4, and their associated alg-3/4 26G-small RNAs are essential for spermatogenesis at 25°C. The alg-3/4 26G-small RNAs are antisense to their target mRNAs and are known to be produced by the RNA-dependent RNA polymerase, RRF-3. However, it remains unclear how the RNA templates for RRF-3 are generated and which cellular processes are affected by alg-3/4 26G-small RNAs. Here, we demonstrate a key role for the conserved zc3h12a-ribonuclease-like protein, NYN-3, in spermatogenesis. Our small RNA sequencing revealed that NYN-3 is required for alg-3/4 26G-small RNAs presence. We further identified NYN-3 binding/cleavage sites were downstream of the binding sites for alg-3/4 26G-small RNAs on targeted mRNAs. Finally, a bioinformatics analysis parsed the ALG-3-targeted genes into functional subclasses (e.g., signaling, chromatin defects). Collectively, these findings reveal NYN-3 as an initiator of alg-3/4 26G-small RNA generation.
Dr. Hsin-Yue Tsai is currently an assistant professor in the Institute of Molecular Medicine in National Taiwan University. She started her Ph.D. training as a RNA biochemist by studying Ribonuclease P, a ribozyme, in Dr. Venkat Gopalan’s laboratory in The Ohio State University. She then continued her RNA journey by joining Dr. Craig Mello’s group, the Nobel laureate for RNA interference (RNAi) discovery, to study the mechanism of the amplification processes of RNAi and endogenous small RNAs. The current focus in her lab is the zc3h12a ribonuclease domain containing proteins in various biological processes.