Wnt1 positively regulates CD36 expression via TCF4 and PPAR-γ in macrophages.

BACKGROUND Scavenger receptors including CD36 control the phagocytosis of oxidized low-density lipoprotein and play an important role in macrophage physiology, but the underlying molecular mechanism by which CD36 is regulated in macrophages or during macrophage differentiation from monocytes remains to be determined. METHODS Here, we investigated the relationship between Wnt1 and CD36 during macrophage differentiation. CD36 was suppressed following knockdown of Wnt1 by siRNA, while it was increased by ectopic overexpression of Wnt1 in macrophages. Using a β-catenin inhibitor, peroxisome proliferator-activated receptor gamma (PPAR-γ) siRNA, and transcription factor 4 (TCF4) siRNA, we demonstrated that Wnt1 regulates the expression of CD36 through TCF4 and PPAR-γ. Co-immunoprecipitation, chromatin immunoprecipitation, and immunofluorescence experiments showed that β-catenin interacted with PPAR-γ and that PPAR-γ and TCF4 colocalized in the nucleus. Furthermore, Pax3 regulated Wnt1 via binding to the first binding site in the Wnt1 promoter. RESULTS Our study demonstrated that during macrophage differentiation from monocytes, Wnt1 promotes CD36 expression via activation of PPAR-γ and TCF4. CONCLUSIONS Our findings suggest that Wnt1 plays an important role in macrophage physiology via activation of the canonical Wnt pathway.