The RNA-binding protein Adad1 is necessary for germ cell maintenance and meiosis in zebrafish

• Type of Material: Article
• Authors: Kazi Nazrul Islam, University of Massachusetts Boston; Anuoluwapo Ajao, University of Massachusetts Boston; Kavita Venkataramani, University of Massachusetts Boston; Joshua Rivera, University of Massachusetts Boston; Shailja Pathania, University of Massachusetts Boston; Katrin Henke, Emory University; Kellee Renee Siegfried, University of Massachusetts Boston
• Language: English
• Date: 2023-08-01
• Publisher: PLOS
• Publication Version: Final Published Version
• Copyright Statement: © 2023 Islam et al
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pgen.1010589
• Title of Journal or Parent Work: PLoS genetics
• Volume: 19
• Issue: 8
• Start Page: e1010589
• End Page: e1010589
• Grant/Funding Information: This work was supported by NIH-NICHD grant # R15HD107594 awarded to KRS and NIH-NICHD grant# R03HD097433 awarded to KRS and KH. KNI was supported by a Doctoral Dissertation Grant awarded by the University of Massachusetts Boston and a College of Science and Mathematics Doctoral Research Fellowship. AA was supported by the University of Massachusetts Boston – Dana Farber/Harvard Cancer Center U54 Partnership Grant, NCI-NIH #’s U54 CA156734-11 (UMass Boston) and U54 CA156732-11 (DF/HCC). The funders had no role in study design data collection and analysis, decision to publish or preparation of the manuscript.
• Keywords: Mammals; RNA; Animals; Semen; Male; Zebrafish Proteins; Meiosis; RNA-Binding Proteins; Germ Cells; Mice; Adenosine Deaminase; Testis; Zebrafish
• Research Categories: Biology, Genetics; Biology, Cell

Abstract

The double stranded RNA binding protein Adad1 (adenosine deaminase domain containing 1) is a member of the adenosine deaminase acting on RNAs (Adar) protein family with germ cell-specific expression. In mice, Adad1 is necessary for sperm differentiation, however its function outside of mammals has not been investigated. Here, through an N-ethyl-N-nitrosourea (ENU) based forward genetic screen, we identified an adad1 mutant zebrafish line that develops as sterile males. Further histological examination revealed complete lack of germ cells in adult mutant fish, however germ cells populated the gonad, proliferated, and entered meiosis in larval and juvenile fish. Although meiosis was initiated in adad1 mutant testes, the spermatocytes failed to progress beyond the zygotene stage. Thus, Adad1 is essential for meiosis and germline maintenance in zebrafish. We tested if spermatogonial stem cells were affected using nanos2 RNA FISH and a label retaining cell (LRC) assay, and found that the mutant testes had fewer LRCs and nanos2-expressing cells compared to wild-type siblings, suggesting that failure to maintain the spermatogonial stem cells resulted in germ cell loss by adulthood. To identify potential molecular processes regulated by Adad1, we sequenced bulk mRNA from mutants and wild-type testes and found mis-regulation of genes involved in RNA stability and modification, pointing to a potential broader role in post-transcriptional regulation. Our findings suggest that the RNA regulatory protein Adad1 is required for fertility through regulation of spermatogonial stem cell maintenance in zebrafish.