Pathology-induced NG2 proteoglycan expression in microglia

Abstract

Oligodendrocyte precursor cells (OPCs) and microglia are two very fascinating cell types with a multitude of important but different functions. At a first glance, they appear not to share many cellular properties, nor are directly related to one another or derived from a common ancestor. Despite all differences, emerging data show that both cell types express the protein nerve/glial antigen 2 (NG2) after pathological insults (Figure 1). For years, it remained controversial whether microglia really could express NG2 upon injury, with contradictory results reported among different disease models. Addressing this question, we could recently show by using triple transgenic knock-in mice and either an acute injury model (stab wound injury) or the middle cerebral artery occlusion combined with immunohistochemistry that a subset of microglia activates the cspg4 gene in a disease dependent manner leading to a bonafide microglia-specific NG2 protein expression besides OPCs and pericytes. Our data show that the cspg4 gene not only gets transcribed in microglia based on reporter expression after recombination, but also the protein itself is expressed (Huang et al., 2020).