Chaudhuri A G, Sen P C, Ganguly U
National Institute of Cholera and Enteric Diseases, Beliaghata, Calcutta, India.
FEMS Microbiol Lett. 1993 Jun 15;110(2):185-9. doi: 10.1111/j.1574-6968.1993.tb06318.x.
Rat intestinal epithelial cells were isolated and the activity of the calcium- and phospholipid-dependent protein kinase C (PKC) was investigated. The stimulation of activity by Escherichia coli heat stable enterotoxin (STa) was about 5-fold compared to control activity (16.91 +/- 1.69 vs 93.56 +/- 10.40 nmol/mg protein/min) and was dose dependent. Maximum enzyme activity was observed after incubation for 1 min with 6 ng of purified STa. The synergistic effects of calcium, phosphatidylserine and diolein on the enzyme activity were noted both in control and STa-treated cells. Staurosporine, a potent PKC inhibitor, significantly reduced the enzyme activity. Autoradiographic analysis of polyacrylamide gel electrophoresis revealed that pretreatment of the cells with STa also resulted in the phosphorylation of specific membrane proteins each with a molecular mass of 37 kDa, 100 kDa and 140 kDa. However, STa had no direct role on the enzyme activity. Our results, therefore, provide evidence for the involvement of PKC in STa-induced signal transduction in rat enterocytes.
分离大鼠肠上皮细胞并研究钙和磷脂依赖性蛋白激酶C（PKC）的活性。与对照活性相比，大肠杆菌热稳定肠毒素（STa）对活性的刺激约为5倍（16.91±1.69对93.56±10.40 nmol/mg蛋白质/分钟），且呈剂量依赖性。用6 ng纯化的STa孵育1分钟后观察到最大酶活性。在对照细胞和经STa处理的细胞中均注意到钙、磷脂酰丝氨酸和二油精对酶活性的协同作用。强效PKC抑制剂星形孢菌素显著降低了酶活性。聚丙烯酰胺凝胶电泳的放射自显影分析表明，用STa预处理细胞还导致分子量分别为37 kDa、100 kDa和140 kDa的特定膜蛋白磷酸化。然而，STa对酶活性没有直接作用。因此，我们的结果为PKC参与STa诱导的大鼠肠上皮细胞信号转导提供了证据。
