Adiponectin inhibits Wnt co-receptor, Lrp6, phosphorylation and ?-catenin signaling.

ABSTRACT: Adiponectin is a pleiotropic adipokine implicated in obesity, metabolic syndrome and cardiovascular disease. Recent studies have identified adiponectin as a negative regulator of tissue fibrosis. Wnt/?-catenin signaling has also been implicated in metabolic syndrome and can promote tissue fibrosis, but the extent to which adiponectin cross-regulates Wnt/?-catenin signaling is unknown. Using primary human dermal fibroblasts and recombinant purified proteins, we show that adiponectin can limit ?-catenin accumulation and downstream gene activation by inhibiting Lrp6 phosphorylation, a key activation step in canonical Wnt signaling. Inhibition of Wnt3a-mediated Lrp6 phospho-activation is relatively rapid (e.g., by 30 min), and is not dependent on established adiponectin G-protein coupled receptors, AdipoR1 and R2, suggesting a more direct relationship to Lrp6 signaling. In contrast, the ability of adiponectin to limit Wnt-induced and baseline collagen production in fibroblasts requires AdipoR1/R2. These results suggest the possibility that the pleiotropic effects of adiponectin may be mediated through distinct cell surface receptor complexes. Accordingly, we propose that the anti-fibrotic activity of adiponectin may be mediated through AdipoR1/R2 receptors, while the ability of adiponectin to inhibit Lrp6 phospho-activation may be relevant to other recently established roles for Lrp6 signaling in glucose metabolism and metabolic syndrome.

SUBMITTER: Reinke L 

PROVIDER: S-EPMC4747689 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature