Objective To investigate the subcellular distribution of glucose transporter GLUT4 and adiponectin in 3T3-L1 adipocytes.Methods 3T3-L1 preadiocytes were differentiated in medium containing 10% FBS,5pg/ml insulin,1μmol/L dexamethasone and 0.5mmol/L IBMX.Western blot was used to examine the expression levels of GLUT4 and adiponectin before and after cell differentiation.The densities of GLUT4 vesicles and adiponectin vesicles were compared by sucrose gradient centrifugation.The subcellular distributions of GLUT4 and adiponectin were investigated by three-dimensional structured illumination microscopy (3D-SIM).Results As 3T3-L1 adipocytes matured,the cell shape changcd noticeably,from fibroblastic to spherical with numerous oil droplets in the cytoplasm.GLUT4 and adiponectin were not expressed in 3T3-L1 preadipocytes,but highly expressed in mature adipocytes.GLUT4 and adiponectin distribution overlapped in the sucrose gradient,suggesting that GLUT4 vesicels and adiponectin vesicles have similar densities.Furthermore,3D-SIM revealed that the endogenous GLUT4 in the steady state was co-localized with adiponectin,which was supported by a value of pearson coefficient of correlation of (0.842 ± 0.021) (mean ± SEM).Conclusion GLUT4 and adiponectin are present in the same membranous cellular compartment and share similar intracellular trafficking pathways.%目的 观察葡萄糖转运蛋白GLUT4和脂联素在3T3-L1细胞中的亚细胞分布.方法 诱导3T3-L1前脂肪细胞分化,比较细胞分化前后GLUT4和脂联素的表达情况;通过蔗糖密度梯度离心比较GLUT4囊泡和脂联素囊泡的密度;采用结构照明超高分辨率显微镜(3D-SIM)观察GLUT4和脂联素在3T3-L1脂肪细胞内的分布情况.结果 3T3-L1前脂肪细胞呈梭形,胞质内无脂滴,细胞分化成熟后呈圆形,胞质内含有大量脂滴;GLUT4和脂联素在3T3-L1前脂肪细胞中不表达,在分化成熟的脂肪细胞中高表达;GLUT4囊泡和脂联素囊泡具有相似的密度;GLUT4和脂联素在细胞中共定位.结论 GLUT4和脂联素在3T3-L1脂肪细胞中分布于相似的细胞囊泡结构,共享转运机制.
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