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

As an essential 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 of the young (MODY4) and neonatal diabetes mellitus. However, the precise mechanisms underlying MODY4 remain elusive due to the 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 technology, all of which succumbed shortly postpartum, exhibiting pancreatic agenesis. Notably, one tri-allelic PDX1-mutant cynomolgus macaque (designated as M4) developed a pancreas, whereas the two mono-allelic PDX1-mutant cynomolgus macaques displayed no anatomical evidence of pancreatic formation. RNA sequencing of the M4 pancreas revealed substantial molecular changes in both endocrine and exocrine functions, indicating developmental delay and PDX1 haploinsufficiency. A marked change in m6A methylation was identified in the M4 pancreas, confirmed through cultured PDX1-mutant islet organoids. Notably, overexpression of the m6A modulator METTL3 restored function in heterozygous PDX1-mutant islet organoids. This study highlights a novel role of m6A methylation modification in the progression of MODY4 and provides valuable molecular insights for preclinical research.