title: G-protein coupled receptor 120 is involved in glucose metabolism in fat cells.
abstract: Free fatty acids (FFA) are closely related to insulin resistance in which proteins such as insulin receptor substrate 1 (IRS-1), phosphatidylinositol 3 kinase (PI3K) and glucose transporter type 4 (GLUT4) are involved. Recent researches have shown that G-protein coupled receptor 120 (GPR120) is a receptor for medium and long chain FFA. This study aimed to evaluate the relationship between GPR120 and proteins related to the glucose metabolism. We used siRNA technique to down-regulate the GPR120 expression in 3T3-L1 cells before incubation with palmitic acid (PA), and evaluated the effect of GPR120 expression on the levels of IRS-1, PI3K and GLUT4 after PA induction. RT-PCR and western blot were performed to detect gene and protein levels in differentiated cells. RT-PCR result showed that GPR120 mRNA significantly increased in differentiated cells. GPR120-SiRNA transfection significantly down-regulated GPR120 gene and protein level in differentiated 3T3-L1 cells on day 5 after PA-induced and also decreased lipid droplets accumulated within the cells. SiRNA-mediated decreased of GRP120 was associated with significant reductions in gene and protein levels of IRS-1 and GLUT4. Our results showed that the expression level of GPR120 affected the expression of proteins related to the glucose metabolism, suggesting a contribution of GPR120 in the insulin resistance.
authors.affiliation: Department of Endocrinology, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China.
authors.forename: D
authors.initials: D
authors.lastname: Liu
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.forename: Q
authors.initials: Q
authors.lastname: Meng
authors.forename: H
authors.initials: H
authors.lastname: Kuang
authors.forename: X
authors.initials: X
authors.lastname: Liu
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D015536:Down-Regulation / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D055504:Insulin Receptor Substrate Proteins / Q000235:genetics / Q000378:metabolism; D007333:Insulin Resistance; D051379:Mice; D019308:Palmitic Acid / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D005947:Glucose; D051275:Glucose Transporter Type 4; D055504:Insulin Receptor Substrate Proteins; D019308:Palmitic Acid; D019869:Phosphatidylinositol 3-Kinases; D034741:RNA, Small Interfering; D043562:Receptors, G-Protein-Coupled; C498007:FFAR4 protein, mouse