Original article
G-protein-coupled receptor 40 mediates the effects of free fatty acid on proliferation in mouse islet beta-cell line NIT-1
Ying ZHANG, Zhao-fan LUO, Hong-li ZHAO, Ming-tong XU, Wei-wen LIANG, Hua CHENG
Published 2010-02-27
Cite as Chin J Diabetes Mellitus, 2010, 02(1): 58-63. DOI: 10.3760/cma.j.issn.1674-5809.2010.01.015
Abstract
ObjectiveTo investigate whether G-pretein-couple receptor 40 (GPR40) mediates the effects of free fatty acid (FFA) on proliferation of mouse insulin NIT-1cells.
MethodsThe expression of GPR40 in NIT-1 cells was inhibited by siRNA, and the effects of 12 or 48 h incubation with saturated fatty acid (SFA) and unsaturated fatty acid (UFA)on proliferation of NIT-1 cell transfected with GPR40 siRNA were observed. Cell proliferation was detected by cell counting kit-8 and Brdu-ELISA methods. The expression of Egr-1 in NIT-1 cells transfected with GPR40 siRNA or treated with FFAs was examined by Western blot. Analysis of variance was used for data analysis.
ResultsA 12-h exposure to different groups of FFA and 48-h exposure to oleate or linoleic acid stimulated the proliferation of NIT-1 cells, whereas 48-h exposure to palmitate or sterate inhibited the proliferation of NIT-1 cells. After co-incubation with palmitate and oleate for 48 h, the proliferation of NIT-1 cells was significantly increased when compared with that in palmitate or sterate treated cells. The mock-, control siRNA-, and GPR40 siRNA-transfected cells were supplemented with saturated fatty acids (palmitate or sterate), no significant difference in the absorbance values was indicated between the GPR40 siRNA tranfected cells and mock. Incubated with oleate or linoleic acid for 12 and 48 h, the absorbance values of GPR40 siRNA tranfected cells were less than that of the mock. After co-incubation with palmitate and oleate for 12 and 48 h, the absorbance values of GPR40 siRNA tranfected cells were less than that of mock (CCK-8: q was 7.834 and 8.236, P<0.05; Brdu-ELISA: q was 7.981 and 5.376, P<0.05). Western blot showed that Egr-1 was markedly activated by oleate, which was significantly inhibited by transfection with GPR40 siRNA.
ConclusionThe bilateral effects of SFA may be GPR40 independent. UFA promotes islet beta-cell proliferation, and counteracts the negative effects of SFA, which is mediated at least in part through GPR40; the process is accompanied by increased expression of Egr-1. Our data suggest that GPR40 might be implicated in the control of beta-cell compensation and GPR40 probably provide a link between obesity and type 2 diabetes mellitus.
Key words:
G-protein-coupled receptor 40; Type 2 diabetes mellitus; Free fatty acids; Islet beta-cells; Proliferation
Contributor Information
Ying ZHANG
Department of Endocrinology, the Third Affiliated Hospital of Guangzhou Medical College, Guangzhou 510150, China
Zhao-fan LUO
Hong-li ZHAO
Ming-tong XU
Wei-wen LIANG
Hua CHENG
