Maternal obesity imprints methylation marks in oocytes to drive intergenerational metabolic dysfunction.

Maternal obesity predisposes offspring to metabolic disease, yet how oocytes transmit this risk remains unclear. Here, we show that maternal obesity induces locus-specific DNA methylation changes in oocytes to drive intergenerational metabolic dysfunction in a tissue-specific and sex-specific manner. Among these, a subset of metabolic genes, notably Hnf1α, Thra and Pdk4, exhibited persistent intergenerational methylation and transcriptional dysregulation. Although these methylation marks were erased during embryogenesis, H3K36me2 enrichment was retained at the loci, suggesting a potential chromatin-associated cue for methylation re-establishment. Single-CpG analysis identified regulatory landmarks correlating with gene expression, and conserved hypermethylation of HNF1A and THRA was also detected in oocytes from women with obesity. Using methylation-edited mouse models, we further demonstrated that targeted oocyte hypermethylation at Hnf1α enhanced hepatic gluconeogenesis in offspring, whereas Pdk4 hypermethylation impaired glucose tolerance, both in a female-biased manner. Together, our findings provide direct causal evidence that germline methylation at defined loci can programme intergenerational metabolic dysfunction, highlighting the preconception period as a critical window for potential intervention in humans.