Wnt activation in mature dermal adipocytes leads to lipodystrophy and skin fibrosis via ATGL-dependent lipolysis.

Abstract

ObjectiveAccumulation of extracellular matrix (ECM) and dermal adipocyte lipodystrophy occurs during skin fibrosis, which compromises the skins flexibility and function. We recently showed that sustained Wnt activation in dermal progenitor cells leads to fibrotic ECM thickening in the dermis and lipodystrophy of dermal white adipose tissue (DWAT). The aim of this study was to test if Wnt/{beta}-catenin signaling in mature dermal adipocytes directly leads to lipodystrophy and impact skin fibrosis. MethodsWe developed a genetically lineage traceable, DWAT specific, inducible and reversible mouse model of Wnt activation (Adipo-{beta}-catistab) in the dorsal skin. We analyzed the DWAT lipid droplet size, cell identity, and affect on ECM accumulation and remodeling in skin fibrosis. Adipocyte triglyceride lipase (ATGL) is the key rate limiting enzyme of the lipolysis pathway, which is a biological process of breaking down triglyceride stores in adipocytes. The Atgl gene was conditionally deleted in mature dermal adipocytes to test the requirement of the lipolysis pathway in the Wnt-induced lipodystrophy (Adipo-{beta}-catistab; Atglfl/fl). ResultsHere, we utilize mouse genetic models with lineage tracing to show that Wnt activation in mature dermal adipocytes is sufficient to induce adipocyte lipodystrophy and fibrotic collagen remodeling. Upon withdrawal of adipocyte-restricted Wnt activation, lipodystrophy and fibrosis were reversed. Mechanistically, we find that Wnt activation stimulates Adipose Triglyceride Lipase (ATGL)-mediated lipolysis pathway. We found Atgl in dermal adipocytes is functionally required for Wnt-induced lipodystrophy in the DWAT and fibrotic remodeling. ConclusionCollectively, this study demonstrates that Wnt activation in dermal adipocytes promotes lipolysis and may be a novel therapeutic avenue for preventing and reversing lipodystrophy and skin fibrosis.