Poster abstracts
Poster number 113 submitted by Benjamin Pastore
Determination of the mechanisms governing piRNA degradation
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:
Organisms are constantly under attack by foreign nucleic acids from viruses and transposons that cause genome damage and an array of genetic diseases. To combat these foreign genetic elements organisms evolved RNA- and DNA- directed immune pathways such as RNA-interference (RNAi) and CRISPR/CAS. One of the most ancient and evolutionarily conserved RNA-directed immune pathways is the PIWI/piRNA pathway. In animal germlines piRNAs, together with effector PIWI proteins, suppress transposons and are indispensable for fertility. Since their discovery, piRNA biogenesis and function have been well studied, yet until recently the mechanisms governing piRNA degradation were largely unexplored. In a recent work, we identified a piRNA quality control mechanism that is mediated by 3' nontemplated nucleotide additions (3' tailing) of RNA nucleotides. Moreso, we found that piRNA::target interactions have the capacity to induce 3' uridine (U) tailing of piRNAs and their degradation. Using genetics, high-throughput RNA sequencing, and bioinformatics, we have expanded our understanding of piRNA degradation by identifying and characterizing the terminal nucleotidyltransferase (TENT) and exonuclease required for piRNA 3' U tailing and degradation. Additionally, to specifically interrogate factors mediating piRNA turnover, we designed an assay to measure global piRNA turnover rates by shutting of piRNA transcription via auxin inducible degron of the piRNA transcription factor TOFU-5. In all we find that piRNA 3' U tailing is concurrent, yet not required for decay. Additionally, we report that piRNAs have a broad range of half-lives ranging from less than 1 hour to greater than 16 hours. Intriguingly, we find that in general, piRNAs with 3' terminal U nts are turned over at rates faster than those with 3' G or C, suggesting 3' U nts make piRNAs susceptible to exonucleolytic degradation. In all this highly systematic work greatly expands our understanding of the mechanisms of piRNA decay by identifying the TENT, and exonuclease mediating piRNA tailing and degradation, as well as measuring, and determining factors that influence, piRNA half-life.
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 Rep 36, 109640. 10.1016/j.celrep.2021.109640.
Gainetdinov, I., Colpan, C., Cecchini, K., Arif, A., Jouravleva, K., Albosta, P., Vega-Badillo, J., Lee, Y., Ozata, D.M., and Zamore, P.D. (2021). Terminal modification, sequence, length, and PIWI-protein identity determine piRNA stability. Mol Cell 81, 4826-4842 e4828. 10.1016/j.molcel.2021.09.012.
Ozata, D.M., Gainetdinov, I., Zoch, A., O'Carroll, D., and Zamore, P.D. (2019). PIWI-interacting RNAs: small RNAs with big functions. Nature Reviews Genetics 20, 89-108. 10.1038/s41576-018-0073-3.
Keywords: piRNA, C elegans, RNA decay