Insulin increases the association of akt-2 with Glut4-containing vesicles
Insulin increases the association of akt-2 with Glut4-containing vesicles
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DOI：
10.1074/jbc.273.13.7201
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发表时间：
1998-03-27
影响因子：
4.8
通讯作者：
Pilch, PF
中科院分区：
文献类型：
--
作者：
Calera, MR;Martinez, C;Pilch, PF
在3 T3 L1脂肪细胞中，组成型活性的膜相关Akt-1（PKB α）构建体的表达显示在不存在胰岛素的情况下通过刺激Glut 4易位至质膜来诱导葡萄糖摄取（Kohn，A.D.，萨默斯，S.A.，Birnbaum，M.J.，和Roth，R.A.（1996）J.Biol.Chem.271，31372-31378）。然而，在大鼠脂肪细胞中，绝大多数Akt-1是胞质的，并且没有显示响应于胰岛素而重新分布到质膜。另一方面，对于Akt家族的其他成员如Akt-2（PKB beta）或Akt-3（PKB gamma）的研究很少。在这份报告中，Akt-2在大鼠脂肪细胞中的亚细胞分布的分析表明，Akt-2是存在于各种膜隔室中的显着量，以及在胞质溶胶中，前者包括轻微粒体中的Glut 4是存在于基础状态。Akt-2在静息脂肪细胞中的分布被发现与Glut 4的分布基本重叠，当轻微粒体被蔗糖速度梯度细分时，表明可能的共定位。我们通过Glut 4囊泡的免疫纯化证实了Akt-2和Glut 4在基础状态下的共定位，相对于Glut 4的量，Akt-2响应于胰岛素表现出5.5倍的增加。这些结果与Akt-2可能参与Glut 4囊泡易位的可能性一致。
Expression of a constitutively active, membrane-associated Akt-1 (PKB alpha) construct in 3T3L1 adipocytes was shown to induce glucose uptake in the absence of insulin by stimulating Glut4 translocation to the plasma membrane (Kohn, A.D., Summers, S.A., Birnbaum, M.J., and Roth, R.A. (1996) J. Biol. Chem. 271, 31372-31378). However, in rat fat cell the vast majority of Akt-1 is cytosolic and shows no re-distribution to the plasma membrane in response to insulin. On the other hand, little work has been done with other Akt family members such as Akt-2 (PKB beta) or Akt-3 (PKB gamma). In this report, an analysis of the subcellular distribution of Akt-2 in rat adipocytes shows that Akt-2 is present in significant amounts in various membrane compartments, as well as in the cytosol, and the former include the light microsomes where Glut4 is present in the basal state. The distribution of Akt-2 in resting adipocytes was found to substantially overlap with that of Glut4 when light microsomes were subfractionated by a sucrose velocity gradient indicating possible co-localization. We confirmed co-localization of Akt-2 and Glut4 in the basal state by immunopurification of Glut4 vesicles, which exhibited a 5.5-fold increase in Akt-2 in response to insulin relative to the amount of Glut4. These results are consistent with the possibility that Akt-2 may be involved in Glut4 vesicle translocation.