Abstract
Although NG2 is known to be selectively expressed in oligodendrocyte precursor cells (OPCs) for many years, its expressional regulation and functional involvement in oligodendrocyte differentiation have remained elusive. Here, we report that the surface-bound NG2 proteoglycan can physically bind to PDGF-AA and enhances PDGF receptor alpha (PDGFRα) activation of downstream signaling. During differentiation stage, NG2 protein is cleaved by A disintegrin and metalloproteinase with thrombospondin motifs type 4 (Adamts4), which is highly upregulated in differentiating OPCs but gradually downregulated in mature myelinating oligodendrocytes. Genetic ablation of Adamts4 gene impedes NG2 proteolysis, leading to elevated PDGFRα signaling but impaired oligodendrocyte differentiation and axonal myelination in both sexes of mice. Moreover, Adamts4 deficiency also lessens myelin repair in adult brain tissue following Lysophosphatidylcholine-induced demyelination. Thus, Adamts4 could be a potential therapeutic target for enhancing oligodendrocyte differentiation and axonal remyelination in demyelinating diseases.
SIGNIFICANCE STATEMENT NG2 is selectively expressed in OPCs and downregulated during differentiation stage. To date, the molecular mechanism underlying the progressive removal of NG2 surface proteoglycan in differentiating OPCs has been unknown. In this study, we demonstrate that ADAMTS4 released by differentiating OPCs cleaves surface NG2 proteoglycan, attenuates PDGFRα signaling, and accelerates oligodendrocyte differentiation. In addition, our study also suggests ADAMTS4 as a potential therapeutic target for promoting myelin recovery in demyelinating diseases.
