Mitochondrial RNA Modifications in Pancreatic β-Cells: A Novel Axis in Early Diabetes Pathogenesis

Mitochondrial RNA (mtRNA) modifications have emerged as critical regulators of pancreatic β-cell bioenergetics, influencing glucose-stimulated insulin secretion (GSIS) and the early pathogenesis of diabetes mellitus (DM). This review synthesizes current evidence on the diversity, mechanisms, and functional implications of mtRNA modifications—such as N6-methyladenosine (m6A), 5-methylcytosine (m5C), pseudouridine (Ψ), and 5-formylcytosine (f5C)—within β-cell mitochondria. These chemical marks, installed and recognized by specific writer, eraser, and reader proteins, regulate mitochondrial translation, oxidative phosphorylation (OXPHOS) complex assembly, and redox balance. Defects in mtRNA modification machinery, exemplified by β-cell-specific knockout of TFB1M, MRM2, or PUS1, impair ribosome biogenesis, disrupt ATP production, and precipitate insulin secretory failure, as demonstrated in human islets, rodent models, and monogenic diabetes syndromes. Advances in epitranscriptomic mapping technologies—including nanopore direct RNA sequencing, RNA immunoprecipitation (RIP)-seq, and mass spectrometry—have enabled high-resolution profiling of mtRNA modification landscapes under physiological and diabetic conditions, revealing their dynamic regulation in response to metabolic stress. Furthermore, mtRNA modifications interact with environmental stressors, such as oxidative damage and toxic metals, modulating β-cell vulnerability via pathways like the mitochondrial unfolded protein response (UPRmt). Therapeutically, modulation of RNA-modifying enzymes or restoration of specific chemical marks holds promise for preserving β-cell function, with potential applications in early diagnosis, risk stratification, and precision medicine approaches for DM. Despite substantial progress, critical gaps remain in understanding the interplay between mtRNA modifications, mitochondrial-nuclear crosstalk, and β-cell plasticity. Addressing these gaps will be pivotal for translating mtRNA biology into novel biomarkers and targeted interventions for early-stage diabetes.