Integrative Analysis of MeRIP-Seq and RNA-Seq Reveals METTL14 as a Core Regulator of Follicular Granulosa Cell Development in Zi Geese

m6A is a ubiquitous and reversible post-transcriptional RNA methylation mark in eukaryotic cells that positively regulates animals follicular development. Profiles in healthy small yellow follicles (HSYF) and atretic small yellow follicles (ASYF) were previously unexplored in poultry. We compared m6A profiles in Zi geese during peak egg-laying. HSYF and ASYF had 23,342 and 25,552 m6A peaks, respectively, mainly in 3′-UTR and stop codon regions. ASYF showed 1174 upregulated and 1250 downregulated differential peak, covering 1141 and 1233 genes, respectively, including METTL14, WTAP, IGF2BP1, and CYTB. Peaks contained the conserved RRACH and DRACH motifs. The follicular transcriptome was extensively methylated, with m6A peaks positively correlated with gene expression. Integrated MeRIP-seq and RNA-seq identified 78 differentially methylated genes (DMGs), including BMP5, PPARGC1A, NGF, and SCD5. mainly involving TGFβ, MAPK, and PPAR signaling pathways and ECM receptor interactions. In vitro. METTL14 knockdown prevented granulosa cell (GCs) apoptosis, promoted proliferation, increased steroid hormone production and secretion, enhanced synthesis-related gene expression and antioxidant enzyme activities (SOD, GSH and CAT),and decreased MDA levels. METTL14 overexpression produced opposite effects These findings indicate widespread follicular m6A methylation and effects of METTL14 on GCs development, providing a theoretical basis for molecular marker-assisted breeding to improving Zi geese egg-laying performance.