Mitochondrial DNA mutation triggers early-onset intestinal epithelial cell dysfunction during acute colitis

Background Mitochondrial DNA (mtDNA) mutations cause multisystem disorders often involving gastrointestinal (GI) dysfunction. However, the mechanisms governing the selection against mutant mtDNA and the specific impact of pathogenic mtDNA mutations on intestinal epithelial cells (IECs) remain poorly understood. Here, we employed mitochondrial single-cell assay for transposase-accessible chromatin with sequencing (mtscATAC-seq) to profile heteroplasmy dynamics in nine subtypes of IECs in m.G5081A (mt-tRNA) and m.G12918A (mt-mRNA) mutant mouse models over a two-year lifespan. Results Our findings reveal an age-dependent decline in mtDNA mutation in all IECs, a process originating within the intestinal stem cell (ISC) compartment. Integrating single-cell RNA sequencing data, we observed that young mice harboring high m.G5081A mutation loads exhibit profound IEC dysfunction, characterized by impaired enterocyte differentiation and defective Paneth cell granule formation. Furthermore, m.G5081A mice displayed increased susceptibility to dextran sulfate sodium (DSS)-induced acute colitis, attributed to impaired intestinal barrier restoration driven by mitochondrial dysfunction. Conclusions Collectively, our study elucidates the heteroplasmy dynamics of mtDNA mutations in IECs during aging and demonstrates the functional consequences of mitochondrial defects on intestinal health, offering critical insights into the pathogenesis and potential management of mitochondrial diseases.