Cumbay Medhane G, Watts Val J
Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, USA.
J Pharmacol Exp Ther. 2004 Jul;310(1):108-15. doi: 10.1124/jpet.104.065748. Epub 2004 Mar 2.
Nine membrane-bound members of the mammalian adenylate cyclase family have been identified. The least characterized and most divergent in sequence of the nine adenylate cyclase isoforms is AC9. Stimulation by Galpha(s) and inhibition by Ca2+/calcineurin are two modes of regulation that have been reported for AC9. We explored the possibility of additional modes of regulation of human AC9. We now report that quinpirole activation of the inhibitory G protein-coupled D2L dopamine receptor inhibits Galpha(s) stimulation of AC9 by approximately 50%. The effects of quinpirole were reversed by the D2 antagonist spiperone and by pertussis toxin pretreatment. We also report the first evidence for regulation of AC9 by protein kinase C (PKC). Specifically, phorbol ester activation of PKC significantly attenuated (approximately 50%) Galpha(s)-stimulated AC9 activity. The effect of PKC activation on AC9 was reversed by the PKC inhibitor bisindolylmaleimide. Galpha(s)-stimulated cyclic accumulation was reduced more by simultaneous addition of both quinpirole and phorbol 12-myristate 13-acetate than by either drug alone. Additional studies investigated the role of glycosylation on AC9 activity. The results show that blocking glycosylation of AC9 significantly attenuates Galpha(s) stimulation. In contrast, the ability of PKC and Galpha(i/o) to negatively regulate AC9 did not seem to be affected by the glycosylation state of AC9. These observations demonstrate the diverse regulatory features of AC9 and the ability of AC9 to integrate multiple signals.
哺乳动物腺苷酸环化酶家族已鉴定出九个膜结合成员。九个腺苷酸环化酶同工型中，特征最少且序列差异最大的是AC9。Gα(s)刺激和Ca2+/钙调神经磷酸酶抑制是已报道的AC9的两种调节模式。我们探索了人类AC9其他调节模式的可能性。我们现在报告，抑制性G蛋白偶联D2L多巴胺受体的喹吡罗激活可使Gα(s)对AC9的刺激抑制约50%。喹吡罗的作用可被D2拮抗剂螺哌隆和百日咳毒素预处理逆转。我们还报告了蛋白激酶C（PKC）调节AC9的首个证据。具体而言，PKC的佛波酯激活显著减弱（约50%）Gα(s)刺激的AC9活性。PKC抑制剂双吲哚马来酰亚胺可逆转PKC激活对AC9的作用。同时添加喹吡罗和佛波醇12-肉豆蔻酸酯13-乙酸酯比单独添加任何一种药物更能降低Gα(s)刺激的环化积累。其他研究调查了糖基化对AC9活性的作用。结果表明，阻断AC9的糖基化显著减弱Gα(s)刺激。相比之下，PKC和Gα(i/o)对AC9负调节的能力似乎不受AC9糖基化状态的影响。这些观察结果证明了AC9多样的调节特征以及AC9整合多种信号的能力。
