Nuclear Hormone Receptor LXRα Inhibits Adipocyte Differentiation of Mesenchymal Stem Cells with Wnt/beta-catenin Signaling

Nuclear hormone receptor liver X receptor-alpha (LXRα) plays a vital role in cholesterol homeostasis and is reported to play a role in adipose function and obesity although this is controversial. Conversely, mesenchymal stem cells (MSCs) are suggested to be a major source of adipocyte generation. Accordingly, we examined the role of LXRα in adipogenesis of MSCs. Adult murine MSCs (mMSCs) were isolated from wild type (WT) and LXR-null mice. Using WT mMSCs, we further generated cell lines stably overexpressing GFP-LXRα (mMSC/LXRα/GFP) or GFP alone (mMSC/GFP) by retroviral infection. Confluent mMSCs were differentiated into adipocytes by the established protocol. Compared with MSCs isolated from WT mice, MSCs from LXR-null mice showed significantly increased adipogenesis, as determined by lipid droplet accumulation and adipogenesis-related gene expression. Moreover, mMSCs stably overexpressing GFP-LXRα (mMSC/LXRα/GFP) exhibited significantly decreased adipogenesis compared with mMSCs overexpressing GFP alone (mMSC/GFP). Since Wnt/beta-catenin signaling is reported to inhibit adipogenesis, we further examined it. The LXR-null group showed significantly decreased Wnt expression accompanied by a decrease of cellular beta-catenin (vs. WT). The mMSC/LXRα/GFP group exhibited significantly increased Wnt expression accompanied by an increase of cellular beta-catenin (vs. mMSC/GFP). These data demonstrate that LXRα has an inhibitory effect on adipogenic differentiation in murine mesenchymal stem cells with Wnt/beta-catenin signaling. These results provide important insights into the pathophysiology of obesity and obesity related consequences such as metabolic syndrome and may identify potential therapeutic targets.