Pancreatic agenesis and altered m6A methylation in the pancreas of PDX1-mutant cynomolgus macaques

As a transcriptional activator, PDX1 plays a crucial role in pancreatic development and β cell function. Mutations in the PDX1 gene may lead to type 4 maturity-onset diabetes in the young (MODY4) or neonatal diabetes mellitus. However, the mechanism underlying MODY4 remains elusive due to a paucity of clinical samples and pronounced differences in pancreatic architecture and genomic composition between humans and existing animal models. In this study, three PDX1-mutant cynomolgus macaques were generated using CRISPR/Cas9, all of which died shortly postpartum, displaying pancreatic agenesis. Notably, the one tri-allelic PDX1-mutant cynomolgus macaques (designated M4) possessed a pancreas, whereas the two mono-allelic PDX1-mutant cynomolgus macaques exhibited no anatomical evidence of a pancreas. RNA sequencing analysis of the M4 pancreas revealed substantial molecular changes in both endocrine and exocrine functions, suggesting a developmental delay and PDX1-haploinsufficiency. Of note, a marked alteration in m6A methylation was observed in the M4 pancreas, as verified through cultured PDX1-mutant islet organoids. Importantly, the m6A modulator METTL3 restored the function of heterozygous PDX1-mutant islet organoids when overexpressed. This study highlights a novel role of m6A methylation modification in the progression of MODY4 and provides important molecular reference values for preclinical investigations.