The Critical Role of Galectin-12 in Modulating Lipid Metabolism in Sebaceous Glands

Sebaceous glands play an important role in maintaining the skin barrier function by producing lipids. Dysregulated lipid production in these glands may contribute to the pathogenesis of human skin diseases. Galectin-12, a member of the β-galactoside‒binding lectin family, is preferentially expressed in adipocytes, where it regulates adipogenesis and functions as an intrinsic negative regulator of lipolysis. It is also expressed by sebocytes and contributes to the proliferation of this cell type. In this study, we show the association between galectin-12 expression and sebocyte differentiation. Galectin-12 knockdown in a human sebocyte cell line reduced lipogenesis and decreased the production of cholesteryl esters, triglycerides, free fatty acids, and cholesterol. Metabolomic analysis of skin surface lipids showed that the levels of the lipids mentioned earlier decreased in sebaceous gland‒specific galectin-12‒knockout mice compared with that in wild-type mice. In addition, galectin-12 positively regulated peroxisome proliferator‒activated receptor-γ transcriptional activity in sebocytes stimulated with fatty acids. Downregulating galectin-12 suppressed the expression of peroxisome proliferator‒activated receptor-γ target genes—acetyl-coenzyme A synthetase 2 gene ACS2 and diacylglycerol O-acyltransferase 1 gene DGAT1—that are required for fatty acid activation and cholesterol and triglyceride biosynthesis. In conclusion, galectin-12 is a positive regulator of sebaceous lipid metabolism with a potential role in the maintenance of skin homeostasis. Sebaceous glands play an important role in maintaining the skin barrier function by producing lipids. Dysregulated lipid production in these glands may contribute to the pathogenesis of human skin diseases. Galectin-12, a member of the β-galactoside‒binding lectin family, is preferentially expressed in adipocytes, where it regulates adipogenesis and functions as an intrinsic negative regulator of lipolysis. It is also expressed by sebocytes and contributes to the proliferation of this cell type. In this study, we show the association between galectin-12 expression and sebocyte differentiation. Galectin-12 knockdown in a human sebocyte cell line reduced lipogenesis and decreased the production of cholesteryl esters, triglycerides, free fatty acids, and cholesterol. Metabolomic analysis of skin surface lipids showed that the levels of the lipids mentioned earlier decreased in sebaceous gland‒specific galectin-12‒knockout mice compared with that in wild-type mice. In addition, galectin-12 positively regulated peroxisome proliferator‒activated receptor-γ transcriptional activity in sebocytes stimulated with fatty acids. Downregulating galectin-12 suppressed the expression of peroxisome proliferator‒activated receptor-γ target genes—acetyl-coenzyme A synthetase 2 gene ACS2 and diacylglycerol O-acyltransferase 1 gene DGAT1—that are required for fatty acid activation and cholesterol and triglyceride biosynthesis. In conclusion, galectin-12 is a positive regulator of sebaceous lipid metabolism with a potential role in the maintenance of skin homeostasis.