title: Glycerol kinase deficiency alters expression of genes involved in lipid metabolism, carbohydrate metabolism, and insulin signaling.
abstract: Glycerol kinase (GK) is at the interface of fat and carbohydrate metabolism and has been implicated in insulin resistance and type 2 diabetes mellitus. To define GK's role in insulin resistance, we examined gene expression in brown adipose tissue in a glycerol kinase knockout (KO) mouse model using microarray analysis. Global gene expression profiles of KO mice were distinct from wild type with 668 differentially expressed genes. These include genes involved in lipid metabolism, carbohydrate metabolism, insulin signaling, and insulin resistance. Real-time polymerase chain reaction analysis confirmed the differential expression of selected genes involved in lipid and carbohydrate metabolism. PathwayAssist analysis confirmed direct and indirect connections between glycerol kinase and genes in lipid metabolism, carbohydrate metabolism, insulin signaling, and insulin resistance. Network component analysis (NCA) showed that the transcription factors (TFs) PPAR-gamma, SREBP-1, SREBP-2, STAT3, STAT5, SP1, CEBPalpha, CREB, GR and PPAR-alpha have altered activity in the KO mice. NCA also revealed the individual contribution of these TFs on the expression of genes altered in the microarray data. This study elucidates the complex network of glycerol kinase and further confirms a possible role for glycerol kinase deficiency, a simple Mendelian disorder, in insulin resistance, and type 2 diabetes mellitus, a common complex genetic disorder.
authors.affiliation: Biomedical Engineering, Interdepartmental Program, Henry Samueli School of Engineering and Applied Science at UCLA, Los Angeles, CA 90095, USA.
authors.forename: Lola
authors.initials: L
authors.lastname: Rahib
authors.forename: Nicole K
authors.initials: NK
authors.lastname: MacLennan
authors.forename: Steve
authors.initials: S
authors.lastname: Horvath
authors.forename: James C
authors.initials: JC
authors.lastname: Liao
authors.forename: Katrina M
authors.initials: KM
authors.lastname: Dipple
mesh_terms: D002001:Adipose Tissue, Brown / Q000201:enzymology / Q000378:metabolism; D000818:Animals; D050260:Carbohydrate Metabolism / Q000235:genetics*; D020869:Gene Expression Profiling; D005991:Glycerol Kinase / Q000172:deficiency*; D007328:Insulin / Q000502:physiology*; D050356:Lipid Metabolism / Q000235:genetics*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D047492:Peroxisome Proliferator-Activated Receptors / Q000502:physiology; D016133:Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics*; D014157:Transcription Factors / Q000502:physiology
chemical_list: D007328:Insulin; D047492:Peroxisome Proliferator-Activated Receptors; D014157:Transcription Factors; D005991:Glycerol Kinase