WTAP-mediated N6-methyladenosine regulation of the insulin receptor controls ovarian follicle development in mice

N6-methyladenosine (m6A) modification is a major post-transcriptional regulatory mechanism implicated in diverse biological and disease processes. However, its role in controlling ovarian follicle activation and female reproductive disorders remains poorly understood. WTAP, a component of the m6A methyltransferase complex, regulates the nuclear speckle localization of the stable heterodimer core complex. However, the specific role of WTAP in ovarian follicular development remains unclear. This study aimed to investigate the physiological functions and underlying mechanisms by which WTAP regulates oocyte maturation and follicular development. We generated oocyte-specific Wtap knockout mice and performed histological analysis, immunostaining, RNA-seq, and m6A-modified RNA immunoprecipitation sequencing (MeRIP-seq) on germinal vesicle (GV) and growing oocytes (GO). Reverse transcription quantitative real-time PCR (RT-qPCR) and immunostaining assessed primordial follicle activation; MeRIP-qPCR measured m6A enrichment on insulin receptor transcripts. Functional rescue experiments employed pharmacological inhibitors targeting the PI3K-AKT signaling pathway. The findings revealed that oocyte-specific deletion of WTAP impedes oocyte growth and causes female infertility. Loss of WTAP in oocytes triggers the premature activation of primordial follicles. Temporal transcriptome profiling revealed significant maternal RNA accumulation in Wtap knockout oocytes during growth. Analysis of m6A dynamics in GO indicated that WTAP-mediated m6A methylation ensures timely activation of the PI3K-AKT signaling pathway, which regulates the activation of primordial follicles. Moreover, we found that insulin receptor (INSR) is the key target of WTAP-dependent m6A modification. Crucially, pharmacological inhibition of INSR and phosphatidyqinositol‐3 kinase (PI3K) efficiently rescued follicular developmental defects caused by oocyte-specific WTAP deficiency. These findings identify a WTAP-m6A-INSR regulatory axis that links epitranscriptomic regulation to PI3K-AKT signaling during ovarian follicle development and suggest potential biomedical relevance for disorders characterized by abnormal follicle activation and female infertility.