The transcription factor NKX2-2 regulates oligodendrocyte differentiation through domain-specific interactions with transcriptional co-repressors

The homeodomain protein NK2 homeobox 2 (NKX2-2) is a transcription factor that plays a critical role in the control of cell fate specification and differentiation in many tissues. In the developing central nervous system, this developmentally important transcription factor functions as a transcriptional repressor that governs oligodendrocyte (OL) differentiation and myelin gene expression, but the roles of various NKX2-2 structural domains in this process are unclear. In this study, using in situ hybridization, immunofluorescence, and coimmunoprecipitation, we determined the structural domains that mediate the repressive functions of murine NKX2-2 and identified the transcriptional corepressors that interact with it in OL cells. Through in ovo electroporation in embryonic chicken spinal cords, we demonstrate that the N-terminal Tinman domain and C-terminal domain synergistically promote OL differentiation by recruiting distinct transcriptional corepressors, including enhancer of split Groucho 3 (GRG3), histone deacetylase 1 (HDAC1), and DNA methyltransferase 3 alpha (DNMT3A). We also observed that the NK2-specific domain suppresses the function of the C-terminal domain in OL differentiation. These findings delineate the distinct NKX2-2 domains and their roles in OL differentiation and suggest that NKX2-2 regulates differentiation by repressing gene expression via multiple cofactors and molecular mechanisms.