Romano Simona, Muscella Antonella, Storelli Carlo, Marsigliante Santo
Department of Biological and Environmental Sciences and Technologies, Ecotekne, Via Prov.le per Monteroni, 73100 Lecce, Italy.
J Endocrinol. 2006 Dec;191(3):727-35. doi: 10.1677/joe.1.06653.
In PC Cl3 cells, a rat thyroid cell line, angiotensin (Ang II) activates the atypical protein kinase C-zeta (PKC-zeta) and the extracellular signal-regulated kinase (ERK) pathways. We here studied the Ang II effects on PC Cl3 cell proliferation. It was found that Ang II: (1) induced the phosphorylation of protein kinase B (PKB), (2) induced the growth-related early gene c-fos expression, (3) enhanced the cyclin E and p27(kip) expression, (4) had no effects on Cdk2, and (5) did not affect the transition from G0/G1 to S phase. Inhibition of phosphoinositide-3kinase by LY294002 further increased the effect of Ang II on p27(kip) induction, whilst PKCs inhibition by GF109203X decreased such effect. The role of PKC-zeta was recognized by the use of a synthetic myristoylated peptide with sequences based on the endogenous PKC-zeta pseudosubstrate and by PKC-zeta downregulation using the small interfering RNA (siRNA). Insulin had a replicating effect on PC Cl3 cells, induced the phosphorylation of PKB, decreased p27(kip) expression and had no effect on the PKC-zeta cytosol-to-membrane translocation. PC Cl3 cell proliferation was induced more potently by simultaneous stimulation with insulin and Ang II than by stimulation with insulin alone, and the effect on p27(kip) expression was similar to that obtained with insulin only. These observations demonstrate that in PC Cl3 cells Ang II causes a block in G1 phase, although both ERK and PKB pathways are activated, and this effect may be due to the upregulation of p27(kip) and PKC-zeta operativity.
在大鼠甲状腺细胞系PC Cl3细胞中，血管紧张素（Ang II）激活非典型蛋白激酶C-ζ（PKC-ζ）和细胞外信号调节激酶（ERK）通路。我们在此研究了Ang II对PC Cl3细胞增殖的影响。结果发现，Ang II：（1）诱导蛋白激酶B（PKB）磷酸化，（2）诱导生长相关早期基因c-fos表达，（3）增强细胞周期蛋白E和p27（kip）表达，（4）对细胞周期蛋白依赖性激酶2（Cdk2）无影响，（5）不影响从G0/G1期到S期的转换。LY294002抑制磷酸肌醇-3激酶进一步增强了Ang II对p27（kip）诱导的作用，而GF109203X抑制蛋白激酶C则降低了这种作用。通过使用基于内源性PKC-ζ假底物序列的合成肉豆蔻酰化肽以及使用小干扰RNA（siRNA）下调PKC-ζ，确定了PKC-ζ的作用。胰岛素对PC Cl3细胞有增殖作用，诱导PKB磷酸化，降低p27（kip）表达，且对PKC-ζ从胞质到膜的转位无影响。与单独用胰岛素刺激相比，同时用胰岛素和Ang II刺激更有效地诱导PC Cl3细胞增殖，且对p27（kip）表达的影响与仅用胰岛素时相似。这些观察结果表明，在PC Cl3细胞中，尽管ERK和PKB通路均被激活，但Ang II导致G1期阻滞，这种作用可能归因于p27（kip）上调和PKC-ζ活性。
