Long-term insulin treatment of 3T3-L1 adipocytes results in mis-targeting of GLUT4: implications for insulin-stimulated glucose transport
Long-term insulin treatment of 3T3-L1 adipocytes results in mis-targeting of GLUT4: implications for insulin-stimulated glucose transport
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DOI：
10.1007/s001250051523
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发表时间：
2000-10-01
期刊：
影响因子：
8.2
通讯作者：
Gould, GW
中科院分区：
文献类型：
--
作者：
Maier, VH;Gould, GW
目的/假设。胰岛素刺激脂肪和肌肉组织中的葡萄糖转运，通过将细胞内含有GLUT 4的囊泡的专门库易位到细胞表面。已经确定，胰岛素刺激的GLUT 4易位缺陷与胰岛素抵抗相关。3 T3-L1脂肪细胞的长期胰岛素处理（500 nmol/l，持续24 h）先前已显示降低细胞GLUT 4含量并减少胰岛素刺激的GLUT 4易位。在这里，我们测试的假设，长期胰岛素治疗后观察到的胰岛素抵抗产生的选择性损失GLUT 4从一个特定的细胞内compart. Methods。使用碘克沙醇梯度离心，我们已经将细胞内含有GLUT 4的膜分离成两个不同的群体，对应于再循环内体和一个不同的细胞内室，其可能代表GLUT 4储存囊泡（GSV）。短期胰岛素刺激降低了GSV组分中GLUT 4的含量（51 +/- 3.5%），仅比内体组分（23 +/- 2.6%）略有降低。长期胰岛素治疗使细胞GLUT 4含量降低约40%，并降低了短期胰岛素激发促进GLUT 4易位的能力。我们进一步表明，这种细胞GLUT 4的消耗选择性地来自GSV组分（与未处理的细胞相比减少68 +/- 7%）。这些数据表明，长期胰岛素治疗导致GLUT 4靶向错误，使其不再进入GSV隔室。这些数据表明，GLUT 4远离GSV隔室的缺陷靶向在胰岛素抵抗的病因学中起重要作用。
Aims/hypothesis. Insulin stimulates glucose transport in adipose and muscle tissue by the translocation of a specialised pool of intracellular GLUT4-containing vesicles to the cell surface. It is well established that defective insulin-stimulated GLUT4 translocation is associated with insulin resistance. Long-term insulin treatment (500 nmol/l for 24 h) of 3T3-L1 adipocytes has previously been shown to decrease cellular GLUT4 content and reduce insulin-stimulated GLUT4 translocation. Here, we test the hypothesis that the insulin resistance observed after long-term insulin treatment arises by the selective loss of GLUT4 from a specific intracellular compartment.Methods. Using iodixanol gradient centrifugation we have separated intracellular GLUT4 containing membranes into two distinct populations corresponding to recycling endosomes and a distinct intracellular compartment which probably represents GLUT4 storage vesicles (GSVs).Results. A short-term insulin stimulation reduced the content of GLUT4 in the GSV fraction (51 +/- 3.5%) with only a modest decrease from the endosomal fraction (23 +/- 2.6%). Long-term insulin treatment decreased cellular GLUT4 content by about 40% and diminished the ability of a short-term insulin challenge to promote GLUT4 translocation. We further show that this depletion of cellular GLUT4 is selectively from the GSV fraction (68 +/- 7% decrease compared to untreated cells).Conclusions/interpretation. Such data argue that long-term insulin treatment results in the mis-targe ting of GLUT4 such that it no longer accesses the GSV compartment. These data imply that defective targeting of GLUT4 away from the GSV compartment plays an important role in the aetiology of insulin resistance.