van der Ploeg I, Altiok N, Kvanta A, Nordstedt C, Fredholm B B
Department of Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Naunyn Schmiedebergs Arch Pharmacol. 1991 Nov;344(5):611-7. doi: 10.1007/BF00170660.
In the human T-cell line, Jurkat, the accumulation of cyclic AMP induced by adenosine is enhanced by tumor-promoting phorbol esters, whereas prostaglandin E2 receptor-stimulated cAMP accumulation is antagonized (Nordstedt et al. 1989). In the present study we examine the involvement of pertussis toxin sensitive guanine nucleotide binding proteins (G-proteins) in producing the phorbol ester effects. Pertussis toxin pretreatment of the Jurkat cells invariably caused an ADP ribosylation of two G-proteins that inhibit adenylyl cyclase, tentatively identified as Gi2 and Gi3, using Western blots. Pertussis toxin treatment had little effect on basal cAMP accumulation, but sometimes inhibited, sometimes stimulated agonist and cholera toxin induced cAMP accumulation. The latter effect was not mimicked by the B-oligomer. Irrespective of whether pertussis toxin stimulated or inhibited NECA and cholera toxin-induced cAMP accumulation it could not block the effect of phorbol-12,13-dibutyrate (PDBu). The inhibitory effect of PDBu on prostaglandin E2-induced cAMP accumulation was, however, invariably eliminated by pertussis toxin treatment. In conclusion, activation of protein kinase C by phorbol esters reveals a Gi-mediated prostaglandin E receptor-induced inhibition of adenylate cyclase in addition to the prostaglandin E receptor-mediated stimulation of cAMP accumulation in Jurkat cells. The enhancement of adenosine A2 receptor stimulated cAMP accumulation by PDBu, on the other hand, does not involve a PTX sensitive Gi-protein.
在人T细胞系Jurkat中，肿瘤促进剂佛波酯可增强腺苷诱导的环磷酸腺苷（cAMP）积累，而前列腺素E2受体刺激的cAMP积累则受到拮抗（诺德施泰特等人，1989年）。在本研究中，我们检测了百日咳毒素敏感的鸟嘌呤核苷酸结合蛋白（G蛋白）在产生佛波酯效应中的作用。使用蛋白质免疫印迹法，对Jurkat细胞进行百日咳毒素预处理，总会导致两种抑制腺苷酸环化酶的G蛋白发生ADP核糖基化，初步鉴定为Gi2和Gi3。百日咳毒素处理对基础cAMP积累影响不大，但有时会抑制，有时会刺激激动剂和霍乱毒素诱导的cAMP积累。B寡聚体无法模拟后一种效应。无论百日咳毒素是刺激还是抑制NECA和霍乱毒素诱导的cAMP积累，它都无法阻断佛波醇-12,13-二丁酸酯（PDBu）的作用。然而，百日咳毒素处理总能消除PDBu对前列腺素E2诱导的cAMP积累的抑制作用。总之，佛波酯激活蛋白激酶C揭示了在Jurkat细胞中，除了前列腺素E受体介导的cAMP积累刺激外，还存在Gi介导的前列腺素E受体诱导的腺苷酸环化酶抑制。另一方面，PDBu增强腺苷A2受体刺激的cAMP积累并不涉及对百日咳毒素敏感的Gi蛋白。
