Tazi K A, Moreau R, Heller J, Poirel O, Lebrec D
Laboratoire d'Hémodynamique Splanchnique et de Biologie Vasculaire, INSERM Unité 481, Hôpital Beaujon, Clichy, France.
Gastroenterology. 2000 Jul;119(1):201-10. doi: 10.1053/gast.2000.8522.
BACKGROUND & AIMS: Although protein kinase C (PKC) alterations may play a role in the abnormal reactivity of cirrhotic rat aortas, its isoforms and cellular distribution are unknown. We therefore studied the protein expression and cellular distribution of PKC isoforms and their activation in cirrhotic rat aortas.
Endothelium-denuded aortas from control and cirrhotic rats were examined. Immunoblots were performed with PKC isoform-specific antibodies. Aortic reactivity was determined for phorbol myristate acetate and phenylephrine after PKC down-regulation.
PKC-alpha expression was reduced in both the cytosolic and membrane fractions in cirrhotic aortas. Trace amounts of PKC-beta were detected in cirrhotic aortas. PKC-delta was detected in the cytosolic fraction of control and cirrhotic aortas. PKC-zeta was detected in the membrane fraction in control aortas and in the cytosolic fraction in cirrhotic aortas. Phorbol myristate acetate and phenylephrine triggered translocation of PKC-alpha and PKC-delta isoforms from the cytosol to the membrane in control aortas; in cirrhotic aortas, only PKC-alpha was translocated. Aortic reactivities were reduced after PKC down-regulation. PKC-alpha and -delta activities were reduced in cirrhotic aortas.
These results suggest that a change in PKC isoforms may be responsible in part for the abnormal reactivity and intracellular transduction through the PKC pathway in cirrhotic rat aortas.
尽管蛋白激酶C（PKC）改变可能在肝硬化大鼠主动脉的异常反应性中起作用，但其亚型及细胞分布尚不清楚。因此，我们研究了PKC亚型在肝硬化大鼠主动脉中的蛋白表达、细胞分布及其激活情况。
检测对照大鼠和肝硬化大鼠去内皮的主动脉。用PKC亚型特异性抗体进行免疫印迹分析。PKC下调后，测定主动脉对佛波醇肉豆蔻酸酯和去氧肾上腺素的反应性。
肝硬化主动脉的细胞溶质和膜部分中PKC-α表达均降低。在肝硬化主动脉中检测到痕量的PKC-β。在对照和肝硬化主动脉的细胞溶质部分中检测到PKC-δ。在对照主动脉的膜部分和肝硬化主动脉的细胞溶质部分中检测到PKC-ζ。在对照主动脉中，佛波醇肉豆蔻酸酯和去氧肾上腺素可触发PKC-α和PKC-δ亚型从细胞溶质向膜的转位；在肝硬化主动脉中，只有PKC-α发生转位。PKC下调后主动脉反应性降低。肝硬化主动脉中PKC-α和PKC-δ活性降低。
这些结果表明，PKC亚型的改变可能部分导致了肝硬化大鼠主动脉的异常反应性及通过PKC途径的细胞内转导。
