Muldoon L L, Jamieson G A, Kao A C, Palfrey H C, Villereal M L
Am J Physiol. 1987 Aug;253(2 Pt 1):C219-29. doi: 10.1152/ajpcell.1987.253.2.C219.
The mitogen-induced activation of Na+-H+ exchange was investigated in two cultured human fibroblast strains (HSWP and WI-38 cells) that, based on previous studies, differed in their response to the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) (L. M. Vincentini and M. L. Villereal, Proc. Natl. Acad. Sci. USA 82: 8053-8056, 1985). The role of protein kinase C in the activation of Na+-H+ exchange was investigated by comparing the effects of TPA on Na+ influx, in vitro phosphorylation, and in vivo phosphorylation in both cell types. Although both cell types have significant quantities of protein kinase C activity that can be activated by TPA in intact cells, the addition of TPA to intact cells stimulates Na+ influx in WI-38 cells but not in HSWP cells, indicating that in HSWP cells the stimulation of protein kinase C is not sufficient to activate the Na+-H+ exchanger. Cells were then depleted of protein kinase C activity by chronic treatment with high doses of TPA. Both HSWP and WI-38 cells were rendered protein kinase C deficient by this treatment as determined by in vitro and in vivo phosphorylation studies. Protein kinase C-deficient HSWP cells lose the ability for TPA to inhibit the serum-induced activation of Na+-H+ exchange, but there is no reduction in the stimulation of Na+ influx by serum, bradykinin, vasopressin, melittin, or vanadate, indicating that protein kinase C activity is not necessary for the mitogen-induced activation of Na+-H+ exchange in HSWP cells by agents known to stimulate phosphatidylinositol turnover (G. A. Jamieson and M. Villereal. Arch. Biochem. Biophys. 252: 478-486, 1987). In contrast, depletion of protein kinase C activity in WI-38 cells significantly reduces both the TPA- and the serum-induced activation of the Na+-H+ exchange system, suggesting that protein kinase C activity is necessary for at least a portion of the mitogen-induced activation of the Na+-H+ exchanger in WI-38 cells. These results indicate that the mechanisms for regulating Na+-H+ exchange can differ dramatically between different types of fibroblasts.
在两种培养的人成纤维细胞系（HSWP和WI-38细胞）中研究了丝裂原诱导的Na⁺-H⁺交换激活情况。根据先前的研究，这两种细胞系对促肿瘤佛波酯12-O-十四酰佛波醇-13-乙酸酯（TPA）的反应不同（L.M.文森蒂尼和M.L.维勒雷亚尔，《美国国家科学院院刊》82: 8053 - 8056, 1985）。通过比较TPA对两种细胞类型中Na⁺内流、体外磷酸化和体内磷酸化的影响，研究了蛋白激酶C在Na⁺-H⁺交换激活中的作用。尽管两种细胞类型都有大量可被完整细胞中的TPA激活的蛋白激酶C活性，但向完整细胞中添加TPA可刺激WI-38细胞中的Na⁺内流，而对HSWP细胞则无此作用，这表明在HSWP细胞中，蛋白激酶C的激活不足以激活Na⁺-H⁺交换体。然后通过用高剂量TPA长期处理使细胞耗尽蛋白激酶C活性。通过体外和体内磷酸化研究确定，这种处理使HSWP和WI-38细胞都缺乏蛋白激酶C活性。缺乏蛋白激酶C的HSWP细胞失去了TPA抑制血清诱导的Na⁺-H⁺交换激活的能力，但血清、缓激肽、血管加压素、蜂毒肽或钒酸盐对Na⁺内流的刺激没有减少，这表明蛋白激酶C活性对于已知能刺激磷脂酰肌醇周转的因子在HSWP细胞中诱导的Na⁺-H⁺交换激活不是必需的（G.A.贾米森和M.维勒雷亚尔。《生物化学与生物物理学档案》252: 478 - 486, 1987）。相反，WI-38细胞中蛋白激酶C活性的耗尽显著降低了TPA和血清诱导的Na⁺-H⁺交换系统的激活，这表明蛋白激酶C活性对于WI-38细胞中至少一部分丝裂原诱导的Na⁺-H⁺交换体激活是必需的。这些结果表明，不同类型的成纤维细胞之间调节Na⁺-H⁺交换的机制可能有很大差异。
