Maternal diabetes causes embryonic cranial neural tube defects is associated with elevated H3K18cr and reduced AKT/PIKFYVE

Neural tube defects (NTDs) are severe congenital malformations resulting from incomplete neural tube closure during embryogenesis, with maternal diabetes mellitus being a well-established risk factor. However, the underlying epigenetic mechanisms remain poorly understood. In this study, we established a maternal diabetes mouse model by intraperitoneal injection of streptozotocin at embryonic day (E) 5.5 and examined embryos during the critical neural tube closure period (E8.5–E10.5). Embryos from diabetic dams developed both cranial and spinal NTDs, with a marked predominance of cranial defects; we therefore focused our analyses on cranial neural tissues from affected embryos. In the cranial neural tissue of NTD-affected embryos, we observed significant accumulation of crotonyl-coenzyme A (Cro-CoA), accompanied by elevated levels of lysine crotonylation (Kcr) and histone H3 lysine 18 crotonylation (H3K18cr). Notably, maternal hyperglycemia-induced downregulation of HDAC1 and HDAC2, together with crotonyl-CoA accumulation, promoted a global increase in H3K18cr in cranial neural tissues. However, despite this global elevation, H3K18cr enrichment was paradoxically reduced at the promoters of AKT and PIKFYVE in cranial NTD embryos, correlating with their transcriptional silencing and contributing to cranial NTD pathogenesis. In HT-22 hippocampal neurons, exogenous glucose and crotonate recapitulated the metabolic and epigenetic alterations, leading to Cro-CoA accumulation and a global increase in H3K18cr. However, at the promoters of AKT and PIKFYVE , H3K18cr levels were decreased and consequently suppressed cell proliferation. Our findings demonstrate that maternal diabetes induces NTDs, at least in part, through aberrant elevation of H3K18cr, which suppresses the expression of AKT and PIKFYVE and impairs neural cell proliferation. Our findings reveal a potential regulatory mechanism by which abnormal H3K18cr elevation contributes to the occurrence of cranial NTDs induced by maternal diabetes.