Karl P I, Divald A
Department of Pediatrics, Boas-Marks Biomedical Science Research Center, North Shore University Hospital-New York University School of Medicine, Manhasset 11030, USA.
Biochem J. 1996 Dec 15;320 ( Pt 3)(Pt 3):831-6. doi: 10.1042/bj3200831.
The protein kinase C (PKC) superfamily is a family of serine/threonine kinases involved in the regulation of many cell functions. The objective of the present work was to identify the PKC isoenzymes present in human placental trophoblasts and to compare their relative responses to acute and chronic phorbol 12-myristate 13-acetate (PMA) treatment. In addition, the effect of PMA treatment on ligand-stimulated cAMP production was determined. In total extracts prepared from cultured or freshly purified trophoblasts, PKC isoforms alpha, epsilon and zeta were detected. Following acute treatment with PMA, PKC alpha and PKC epsilon were translocated from the cytosol to the particulate fraction. Prolonged treatment (up to 36 h) with PMA resulted in the temporal down-regulation of PKC alpha and PKC epsilon. PKC zeta did not respond to either acute or chronic treatment with PMA. An acute 10 min treatment of the cells with PMA (10(-10)-10(-6) M) enhanced isoprenaline- and adrenaline-stimulated cAMP production. An enhanced response was observed at all concentrations of isoprenaline tested (10(-9)-10(-4) M), suggesting an increased capacity to respond. The acute PMA effect was evident within 2 min and near maximal by 5 min. The acute response to PMA was lost in cells where PKC was down-regulated by prior PMA treatment. Epidermal growth factor, a potential ligand for the activation of PKC in trophoblasts, enhanced isoprenaline-stimulated cAMP production. In summary, activation of PMA-responsive PKCs (PKC alpha or PKC epsilon) appears to enhance ligand-stimulated cAMP production in trophoblasts. This may be a physiologically important example of 'cross-talk' between various signalling pathways in human placental trophoblasts.
蛋白激酶C（PKC）超家族是一类丝氨酸/苏氨酸激酶家族，参与多种细胞功能的调节。本研究的目的是鉴定人胎盘滋养层细胞中存在的PKC同工酶，并比较它们对急性和慢性佛波酯12 -肉豆蔻酸酯13 -乙酸酯（PMA）处理的相对反应。此外，还确定了PMA处理对配体刺激的cAMP产生的影响。在从培养的或新鲜纯化的滋养层细胞制备的总提取物中，检测到PKC同工型α、ε和ζ。用PMA急性处理后，PKCα和PKCε从细胞质转移到颗粒部分。用PMA长时间处理（长达36小时）导致PKCα和PKCε的时间性下调。PKCζ对PMA的急性或慢性处理均无反应。用PMA（10^-10 - 10^-6 M）对细胞进行急性10分钟处理可增强异丙肾上腺素和肾上腺素刺激的cAMP产生。在所有测试的异丙肾上腺素浓度（10^-9 - 10^-4 M）下均观察到增强反应，表明反应能力增强。PMA的急性作用在2分钟内明显，5分钟时接近最大值。在先前用PMA处理使PKC下调的细胞中，对PMA的急性反应消失。表皮生长因子是滋养层细胞中PKC激活的潜在配体，可增强异丙肾上腺素刺激的cAMP产生。总之，PMA反应性PKC（PKCα或PKCε）的激活似乎增强了滋养层细胞中配体刺激的cAMP产生。这可能是人类胎盘滋养层细胞中各种信号通路之间“串扰”的一个生理上重要的例子。
