Mettl3 is required for germline function during Drosophila spermatogenesis.

The m6A modification is responsible for regulating several aspects of RNA metabolism. The enzyme that catalyzes this modification Mettl3, is highly conserved and required for numerous biological processes such as spermatogenesis. Here we examine the role of Mettl3 in germline function during Drosophila spermatogenesis. We find that depletion of Mettl3 in the germline results in errors in late-stage spermatogenesis, the process known as spermiogenesis. In germline knockdowns, actin cones bound to spermatids fail to remain tightly packed during the individualization process. Issues with actin cone assembly appear to disrupt progression through spermiogenesis resulting in waste bag deficiency, an indicator of abnormal spermatid individualization. These errors result in little to no sperm in seminal vesicles culminating in reduced fertility in germline knockdowns. Furthermore, our findings suggest Hsp60B is misregulated in knockdowns, which potentially explains at least some observed phenotypes. Collectively, the data presented in this investigation suggests Mettl3 has a prominent role in regulating spermatid differentiation during Drosophila spermatogenesis.