Bjłrndal B, Helleland C, Lillehaug J R
Department of Molecular Biology, University of Bergen, Norway.
Anticancer Res. 2000 Jul-Aug;20(4):2633-40.
60-75% of PKC alpha and 30-40% of PKC beta I++ protein was located to the membranes and nuclear/nuclear associated endoplasmatic reticulum fractions of resting 10T1/2CI 8 mouse embryo fibroblasts. On average, 35% of the PKC alpha and 65% of the PKC beta I++ isoforms existed in a soluble state. Maximum PDGF-BB-mediated Erk1 activation was obtained without significant changes in soluble PKC alpha- or PKC beta I++- levels. The subcellular localisation of PKC alpha and PKC beta I was not affected by PDGF-BB treatment. 12-O-tetradecanoyl phorbol-13-acetate (TPA) caused translocation of cytoplasmic PKC alpha and beta I to the nucleus/nuclear associated endoplasmatic reticulum fraction. Down-regulation of PKC and bisindolylmaleimide I inhibited both TPA and PDGF-BB stimulated Erk1 activity. We are the first to show that PDGF-mediated activation of Erk1 involves a PKC-dependent step in 10T1/2CI 8 cells. We also provide novel evidence that PDGF-BB mediated Erk1 activation can take place in these cells without apparent recruitment of soluble PKC alpha/beta I to the particulate cell fractions.
在静止的10T1/2CI 8小鼠胚胎成纤维细胞中，60 - 75%的蛋白激酶Cα（PKCα）和30 - 40%的蛋白激酶CβI++蛋白定位于细胞膜以及细胞核/与细胞核相关的内质网部分。平均而言，35%的PKCα和65%的PKCβI++亚型以可溶状态存在。在可溶性PKCα或PKCβI++水平无显著变化的情况下，可获得血小板衍生生长因子BB（PDGF - BB）介导的细胞外信号调节激酶1（Erk1）激活的最大值。PKCα和PKCβI的亚细胞定位不受PDGF - BB处理的影响。12 - O - 十四酰佛波醇 - 13 - 乙酸酯（TPA）导致细胞质中的PKCα和βI转位至细胞核/与细胞核相关的内质网部分。PKC的下调和双吲哚马来酰亚胺I抑制了TPA和PDGF - BB刺激的Erk1活性。我们首次表明，在10T1/2CI 8细胞中，PDGF介导的Erk1激活涉及一个PKC依赖性步骤。我们还提供了新的证据，即PDGF - BB介导的Erk1激活可以在这些细胞中发生，而无需明显地将可溶性PKCα/βI募集到颗粒细胞部分。
