Ways D K, Messer B R, Garris T O, Qin W, Cook P P, Parker P J
Department of Medicine, East Carolina University, School of Medicine, Greenville, North Carolina 27858-4354.
Cancer Res. 1992 Oct 15;52(20):5604-9.
Expression of protein kinase C-epsilon was examined in the human monoblastoid U937 cell. This cell type contained the alpha, beta, and epsilon isoforms of protein kinase C (PKC). While PKC-epsilon content was slightly higher in the cytosolic than in the particulate fraction, the amount contained in the particulate fraction was higher than the alpha and beta isoforms which were predominantly localized to the cytosol. After an acute exposure to tetradecanoyl-13-phorbol acetate (TPA), PKC-epsilon translocated to the particulate fraction. Acute or chronic exposure to ionomycin did not alter content of the epsilon isoform. Longer exposures to TPA decreased PKC-epsilon in both cellular fractions. PKC-epsilon displayed a similar sensitivity to TPA-induced down-regulation as did PKC-beta while PKC-alpha was more resistant to this effect. After a 72-h exposure to 0.1 nM TPA, increases in the alpha and beta isoforms but not in PKC-epsilon were observed. However, 1,25-dihydroxy vitamin D3 and dibutyryl cyclic AMP which induce U937 differentiation enhanced PKC-epsilon expression.
在人单核细胞样U937细胞中检测了蛋白激酶C-ε的表达。这种细胞类型含有蛋白激酶C（PKC）的α、β和ε亚型。虽然PKC-ε在胞质溶胶中的含量略高于颗粒部分，但颗粒部分中的含量高于主要定位于胞质溶胶中的α和β亚型。急性暴露于十四烷酰-13-佛波醇乙酸酯（TPA）后，PKC-ε易位至颗粒部分。急性或慢性暴露于离子霉素不会改变ε亚型的含量。长时间暴露于TPA会降低两个细胞部分中的PKC-ε。PKC-ε对TPA诱导的下调表现出与PKC-β相似的敏感性，而PKC-α对这种作用更具抗性。在暴露于0.1 nM TPA 72小时后，观察到α和β亚型增加，但PKC-ε没有增加。然而，诱导U937分化的1,25-二羟基维生素D3和二丁酰环磷酸腺苷增强了PKC-ε的表达。
