Chd7 Collaborates with Sox2 to Regulate Activation of Oligodendrocyte Precursor Cells after Spinal Cord Injury

Oligodendrocyte precursor cells (OPCs) act as a reservoir of new oligodendrocytes (OLs) in homeostatic and pathological conditions. OPCs are activated in response to injury to generate myelinating OLs, but the underlying mechanisms remain poorly understood. Here, we show that chromodomain helicase DNA binding protein 7 (Chd7) regulates OPC activation after spinal cord injury (SCI). Chd7 is expressed in OPCs in the adult spinal cord and its expression is upregulated with a concomitant increase in Sox2 expression after SCI. OPC-specific ablation of Chd7 in injured mice leads to reduced OPC proliferation, the loss of OPC identity, and impaired OPC differentiation. Ablation of Chd7 or Sox2 in cultured OPCs shows similar phenotypes to those observed in Chd7 knock-out mice. Chd7 and Sox2 form a complex in OPCs and bind to the promoters or enhancers of the regulator of cell cycle (Rgcc) and protein kinase C theta (PKC theta) genes, thereby inducing their expression. The expression of Rgcc and PKC theta is reduced in the OPCs of the injured Chd7 knock-out mice. In cultured OPCs, overexpression and knock-down of Rgcc or PKC theta promote and suppress OPC proliferation, respectively. Furthermore, overexpression of both Rgcc and PKC theta rescues the Chd7 deletion phenotypes. Chd7 is thus a key regulator of OPC activation, in which it cooperates with Sox2 and acts via direct induction of Rgcc and PKC theta expression.