SSAO酶抑制剂对脂肪细胞内GLUT4转运作用的研究

The effect of SSAO inhibitor on GLUT4 translocation in adipocytes

SSAO酶在脂肪细胞中的含量较多,位于细胞膜上的SSAO酶的活性和其蛋白质的免疫反应性都是最大的。对于体内葡萄糖的运输和葡萄糖转运蛋白的转运,此酶起到了一定的促进作用,当它与底物在膜上反应后会引起信号传导刺激细胞内葡萄糖转运蛋白(GLUT4)从内部囊泡转移到细胞表面程,从而促进葡萄糖的运输和细胞对葡萄糖的吸收。如果有SSAO酶抑制剂存在,如氨基脲,二溴乙胺等,这种对GLUT4转运的促进作用就会被削弱。本研究的目的在于建立一种新的定量方法—竞争ELISA法来测试脂肪细胞膜上GLUT4的含量,从而确定SSAO酶抑制剂对GLUT4转运的作用。实验结果说明当SSAO醇抑制剂和脂肪细胞预温育一段时间后,质膜上GLUT4的含量发生下降,钒盐使得这种下降的程度加大,证明GLUT4由细胞内囊泡向细胞质膜转运的易位过程受到了抑制。此种竞争性ELISA的测试方法优点在于只需要少量的细胞膜样品就可以确定GLUT4的含量,灵敏度较高。

Adipocytes membrane had substantial levels of semicarbazide-sensitive amine oxidase (SSAO). Its activity and im-munoreactive protein were maximal in plasma membranes. The combination of SSAO substrates and alow concentration of vanadate stimulate glucose transport and glucose transporter (GLUT4) translocation from intracellular compartment to the cell surface in rat adipocytes. This synergistic effect on GLUT4 translocation was totally abolished in the presence of semicarbazide or 2-bromoethylamine, the specific inhibitors for SSAO. The purpose of this study was to apply a novel quantitative method-competitive ELISA assay to measure the GLUT4 content in plasma membrane of rat adipocytes. The experimental result showed that after inhibitor's injection into the cell suspension, GLUT4 level in plasma membrane is decreased, and the administration of a low concentration of vanadate made this reduction seriously. As a result, the GLUT4 recruitment from intracellular vesicle to plasma membrane is prevented. In addition, the ELISA method allows for the use of small quantities of membrane protein in order to quantitate GLUT4, and it has good sensitivity.