NAT10 Maintains OGA mRNA Stability Through ac4C Modification in Regulating Oocyte Maturation

Abstract

<i>In vitro</i> maturation (IVM) refers to the process of developing immature oocytes into the mature <i>in vitro</i> under the microenvironment analogous to follicle fluid. It is an important technique for patients with polycystic ovary syndrome and, especially, those young patients with the need of fertility preservation. However, as the mechanisms of oocyte maturation have not been fully understood yet, the cultivation efficiency of IVM is not satisfactory. It was confirmed in our previous study that oocyte maturation was impaired after N-acetyltransferase 10 (NAT10) knockdown (KD). In the present study, we further explored the transcriptome alteration of NAT10-depleted oocytes and found that <i>O-GlcNAcase</i>(<i>OGA</i>) was an important target gene for NAT10-mediated ac4C modification in oocyte maturation. NAT10 might regulate <i>OGA</i> stability and expression by suppressing its degradation. To find out whether the influence of NAT10-mediated ac4C on oocyte maturation was mediated by <i>OGA</i>, we further explored the role of <i>OGA</i> in IVM. After knocking down OGA of oocytes, oocyte maturation was inhibited. In addition, as oocytes matured, <i>OGA</i> expression increased and, conversely, O-linked N-acetylglucosamine (O-GlcNAc) level decreased. On the basis of NAT10 KD transcriptome and OGA KD transcriptome data, NAT10-mediated ac4C modification of <i>OGA</i> might play a role through G protein-coupled receptors, molecular transduction, nucleosome DNA binding, and other mechanisms in oocyte maturation. <i>Rsph6a</i>, <i>Gm7788</i>, <i>Gm41780</i>, <i>Trpc7</i>, <i>Gm29036</i>, and <i>Gm47144</i> were potential downstream genes. In conclusion, NAT10 maintained the stability of <i>OGA</i> transcript by ac4C modification on it, thus positively regulating IVM. Moreover, our study revealed the regulation mechanisms of oocytes maturation and provided reference for improving IVM outcomes. At the same time, the interaction between mRNA ac4C modification and protein O-GlcNAc modification was found for the first time, which enriched the regulation network of oocyte maturation.