Activation and mitochondrial translocation of protein kinase Cδ are necessary for insulin stimulation of pyruvate dehydrogenase complex activity in muscle and liver cells
Activation and mitochondrial translocation of protein kinase Cδ are necessary for insulin stimulation of pyruvate dehydrogenase complex activity in muscle and liver cells
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DOI：
10.1074/jbc.m105451200
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发表时间：
2001-11-30
影响因子：
4.8
通讯作者：
Beguinot, F
中科院分区：
文献类型：
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作者：
Caruso, M;Maitan, MA;Beguinot, F
在L 6骨骼肌细胞和永生化肝细胞中，胰岛素诱导丙酮酸脱氢酶（PDH）复合物活性增加2倍。这种作用几乎完全被蛋白激酶C（PKC）delta抑制剂Rottlerin和PKC delta反义寡核苷酸阻断。在变异，野生型PKC δ或活性PKC δ突变体的过度表达诱导PDH复合物的活性在L 6和肝细胞。胰岛素刺激PDH复合物的活性伴随着PDH磷酸酶1和2（PDP 1/2）活性的2.5倍增加，而PDH激酶的活性没有变化。PKC δ反义阻断胰岛素对PDP 1/2的激活，与PDH相同。在胰岛素暴露的细胞中，PDP 1/2激活被PKC 8 δ的激活和线粒体易位所抑制，正如细胞亚分级和共聚焦显微镜研究所揭示的那样。PKC δ的线粒体易位，如其激活，被Rottlerin阻止。在胰岛素刺激细胞的提取物中，PKC δ与PDP 1/2共沉淀。在重叠印迹中，PKC δ也与PDP 1/2结合，这表明直接的PKC δ-PDP相互作用也可能在体内发生。在完整的细胞中，胰岛素暴露决定了PDP 1/2磷酸化，这是专门防止PKC δ反义。PKC δ也在体外磷酸化PDP，随后激活PDP 1/2。因此，在肌肉和肝细胞中，胰岛素引起PKC δ的活化和线粒体易位，伴随着PDP磷酸化和活化。这些事件对于这些细胞中PDH复合物的胰岛素活化是必需的。
In L6 skeletal muscle cells and immortalized hepatocytes, insulin induced a 2-fold increase in the activity of the pyruvate dehydrogenase (PDH) complex. This effect was almost completely blocked by the protein kinase C (PKC) delta inhibitor Rottlerin and by PKC delta antisense oligonucleotides. At variance, overexpression of wild-type PKC delta or of an active PKC delta mutant induced PDH complex activity in both L6 and liver cells. Insulin stimulation of the activity of the PDH complex was accompanied by a 2.5-fold increase in PDH phosphatases 1 and 2 (PDP1/2) activity with no change in the activity of PDH kinase. PKC delta antisense blocked insulin activation of PDP1/2, the same as with PDH. In insulin-exposed cells, PDP1/2 activation was paralleled by activation and mitochondrial translocation of PKC8 delta, as revealed by cell subfractionation and confocal microscopy studies. The mitochondrial translocation of PKC delta, like its activation, was prevented by Rottlerin. In extracts from insulin-stimulated cells, PKC delta co-precipitated with PDP1/2. PKC delta also bound to PDP1/2 in overlay blots, suggesting that direct PKC delta -PDP interaction may occur in vivo as well. In intact cells, insulin exposure determined PDP1/2 phosphorylation, which was specifically prevented by PKC delta antisense. PKC delta also phosphorylated PDP in vitro, followed by PDP1/2 activation. Thus, in muscle and liver cells, insulin causes activation and mitochondrial translocation of PKC delta, accompanied by PDP phosphorylation and activation. These events are necessary for insulin activation of the PDH complex in these cells.