Fructose uptake in rat adipocytes: GLUT5 expression and the effects of streptozotocin-induced diabetes
Fructose uptake in rat adipocytes: GLUT5 expression and the effects of streptozotocin-induced diabetes
复制标题
DOI：
10.1007/s001250050993
复制
发表时间：
1998-07-01
期刊：
影响因子：
8.2
通讯作者：
Hundal, HS
中科院分区：
文献类型：
--
作者：
Hajduch, E;Darakhshan, F;Hundal, HS
先前的研究表明，大鼠脂肪细胞具有通过与葡萄糖转运不同的机制摄取果糖的能力。在这项调查中，我们报告说，大鼠脂肪细胞表达GLUTS果糖转运蛋白，它是负责介导的一个重要组成部分（类似于80%）的总细胞果糖摄取。该提议基于以下发现：仅21%的总果糖摄取是细胞松弛素B（CB）敏感的，这最可能反映了经由GLUT 1和/或GLUT 4的转运。与该建议一致，我们发现（i）胰岛素引起果糖摄取的小但显著的刺激（类似于35%），其在CB存在下被消除，和（ii）3-O-甲基葡萄糖抑制果糖摄取至与CB存在下观察到的水平相当的水平。发现GLUTS仅定位于脂肪细胞质膜中，并且与GLUT 4或GLUT 1不同，其细胞表面丰度不受胰岛素调节。在链脲佐菌素糖尿病大鼠的脂肪细胞中，GLUTS表达大幅下降（接近75%），并伴有果糖摄取减少约50%。用原钒酸钠治疗链脲佐菌素糖尿病大鼠3天，导致血肌酐显著降低约40%，GLUTS表达和脂肪细胞果糖摄取部分恢复。我们认为，大鼠脂肪细胞中的果糖摄取主要是由葡萄糖转运蛋白介导的胰岛素和CB不敏感的方式和大鼠脂肪细胞中的葡萄糖转运蛋白的表达可能会受到血液中葡萄糖血症的变化。
Previous studies have shown that rat adipocytes possess the capacity to take up fructose by a mechanism that is distinct from that involved in the transport of glucose. In this investigation we report that rat adipocytes express the GLUTS fructose transporter and that it is responsible for mediating a substantial component (similar to 80%) of the total cellular fructose uptake. This proposition is based on the finding that only 21 % of the total fructose uptake was cytochalasin B (CB) sensitive which most likely reflects transport via GLUT1 and/or GLUT4. Consistent with this suggestion we found (i) that insulin caused a small, but significant stimulation in fructose uptake (similar to 35 %) which was abolished in the presence of CB and (ii) that 3-O-methyl glucose inhibited fructose uptake to a level comparable with that observed in the presence of CB. GLUTS was found to be localised only in the adipocyte plasma membrane and, unlike GLUT4 or GLUT1, its cell surface abundance was not modulated by insulin. GLUTS expression fell substantially (by similar to 75 %) in adipocytes of streptozotocin-diabetic rats and was accompanied by a reduction in fructose uptake by approximately 50%. Treatment of streptozotocin-diabetic rats with sodium orthovanadate for a period of 3 days led to a significant reduction in blood glycaemia by approximately 40% and a partial restoration in both GLUTS expression and adipocyte fructose uptake. We suggest that fructose uptake in rat adipocytes is principally mediated by GLUTS in an insulin- and CB-insensitive manner and that expression of GLUTS in rat adipocytes may be regulated by changes in blood glycaemia.