Poster abstracts
Poster number 105 submitted by Benjamin Pastore
Pre-piRNA trimming prevents piRNAs from being erroneously targeted by RNA dependent RNA polymerase
Benjamin Pastore (Department of Biological Chemistry and Pharmacology, The Center for RNA Biology, The Ohio State Biochemistry Program, The Ohio State University), Hannah L. Hertz (Department of Biological Chemistry and Pharmacology, The Center for RNA Biology, The Ohio State University), Wen Tang (Department of Biological Chemistry and Pharmacology, The Center for RNA Biology, The Ohio State University)
Abstract:
In animal germ lines, the Piwi/piRNA pathway suppresses transposable elements, thereby preserving genome integrity and promoting fertility. After transcription from discrete genomic loci, piRNA precursors undergo nucleolytic processing at both 5’ and 3’ ends. The ribonuclease PARN-1 and its orthologs mediate piRNA 3' trimming in worms, insects and mammals. Yet, the significance of this evolutionarily conserved processing step remains poorly understood. Our previous work utilizing C. elegans as a model organism demonstrated that 3' trimming is essential for protecting piRNAs against nontemplated nucleotide addition and degradation. In this study, we present an unexpected finding that C. elegans deficient for PARN-1 accumulate a heretofore unrecognized RNA species termed anti-piRNAs, which are antisense to piRNAs. These anti-piRNAs associate with Piwi protein and display the propensity for a length of 17-19 nucleotides and 5’ guanine and adenine residues. Furthermore, we show that untrimmed pre-piRNAs in parn-1 mutants are modified by the terminal nucleotidyl transferase RDE-3 and erroneously targeted by the RNA dependent RNA polymerase EGO-1 to generate anti-piRNAs. Taken together, our work identifies a previously unknown class of small RNAs upon loss of parn-1 and provides mechanistic insight to the enzymatic activity of RDE-3 and EGO-1.
References:
Pastore, B., Hertz, H.L., Price, I.F., and Tang, W. (2021). pre-piRNA trimming and 2'-O-methylation protect piRNAs from 3' tailing and degradation in C. elegans. Cell reports 36, 109640.
Shukla, A., Yan, J., Pagano, D.J., Dodson, A.E., Fei, Y., Gorham, J., Seidman, J.G., Wickens, M., and Kennedy, S. (2020). poly(UG)-tailed RNAs in genome protection and epigenetic inheritance. Nature 582, 283-288.
Tang, W., Tu, S., Lee, H.C., Weng, Z., and Mello, C.C. (2016). The RNase PARN-1 Trims piRNA 3' Ends to Promote Transcriptome Surveillance in C. elegans. Cell 164, 974-984.
Keywords: piRNA, RdRP, parn-1