title: Ablation of a galectin preferentially expressed in adipocytes increases lipolysis, reduces adiposity, and improves insulin sensitivity in mice.
abstract: The breakdown of triglycerides, or lipolysis, is a tightly controlled process that regulates fat mobilization in accord with an animal's energy needs. It is well established that lipolysis is stimulated by hormones that signal energy demand and is suppressed by the antilipolytic hormone insulin. However, much still remains to be learned about regulation of lipolysis by intracellular signaling pathways in adipocytes. Here we show that galectin-12, a member of a β-galactoside-binding lectin family preferentially expressed by adipocytes, functions as an intrinsic negative regulator of lipolysis. Galectin-12 is primarily localized on lipid droplets and regulates lipolytic protein kinase A signaling by acting upstream of phosphodiesterase activity to control cAMP levels. Ablation of galectin-12 in mice results in increased adipocyte mitochondrial respiration, reduced adiposity, and ameliorated insulin resistance/glucose intolerance. This study identifies unique properties of this intracellular galectin that is localized to an organelle and performs a critical function in lipid metabolism. These findings add to the significant functions exhibited by intracellular galectins, and have important therapeutic implications for human metabolic disorders.
authors.affiliation: Department of Dermatology, School of Medicine, University of California, Davis, Sacramento, CA 95817, USA.
authors.forename: Ri-Yao
authors.initials: RY
authors.lastname: Yang
authors.forename: Lan
authors.initials: L
authors.lastname: Yu
authors.forename: James L
authors.initials: JL
authors.lastname: Graham
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Hsu
authors.forename: K C Kent
authors.initials: KC
authors.lastname: Lloyd
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Havel
authors.forename: Fu-Tong
authors.initials: FT
authors.lastname: Liu
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D037161:Galectins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D037102:Lectins / Q000737:chemistry; D050356:Lipid Metabolism; D008066:Lipolysis / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D018797:Cell Cycle Proteins; D037161:Galectins; D007328:Insulin; D037102:Lectins; C503649:Lgals12 protein, mouse; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D010727:Phosphoric Diester Hydrolases