Transcriptional Heterogeneity of Oligodendrocytes: Molecular Basis of Diversity Across Development, Brain Regions, and Neurological Diseases.

Oligodendrocytes (OLs) are specialized glial cells essential for the formation and maintenance of the myelin sheath within the central nervous system (CNS). Historically, OLs were considered a functionally homogeneous population. However, the advent and widespread application of single-cell and single-nucleus RNA sequencing (scRNA-seq/snRNA-seq) technologies since 2015 have revealed substantial transcriptional heterogeneity, varying according to developmental stage, anatomical region, and disease state. In this review, we synthesized current advances in the understanding of OL heterogeneity. Nine OL cell classes have been identified in the mouse somatosensory cortex and hippocampal CA1 region, later expanding to 13 distinct subpopulations across ten CNS regions. Furthermore, we characterized disease-associated oligodendrocytes (DAOs)/disease-associated oligodendrocyte lineages (DOLs), identified in various neurological diseases, including multiple sclerosis (MS), Alzheimer's disease (AD), and spinal cord injury, focusing on their molecular markers, spatial distribution, and pathophysiological roles. We summarized key transcriptional regulatory networks underlying DAO induction, including the signal transducer and activator of transcription (STAT)/interferon regulatory factor (IRF) family, the Yin Yang 1 (YY1)/nuclear factor kappa B (NF-κB) axis, and the SOX9/SOX10 regulatory system. The utility of region-specific brain analyses using spatial transcriptomics (ST) in conjunction with these approaches was also discussed. Finally, we compiled the implications of patient stratification according to white matter glial response patterns derived from large-scale snRNA-seq analyses of patients with progressive MS. Our synthesis shows that oligodendrocytes consist of multiple distinct subtypes that vary across development, brain regions, and disease conditions. In pathological states, they adopt specific disease-associated programs that reflect context-dependent responses and may influence disease progression and repair. This work provides a framework for understanding how oligodendrocyte diversity contributes to neurological disease and may support the development of targeted remyelination therapies.