Anderson L E, Seybold V S
Graduate Program in Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, USA.
J Neurochem. 2004 Dec;91(6):1417-29. doi: 10.1111/j.1471-4159.2004.02833.x.
Although primary afferent neurons express receptors for calcitonin gene-related peptide (CGRP), understanding of the cellular effects of these receptors is limited. We determined that CGRP receptors regulate gene transcription in primary afferent neurons through a cyclic AMP (cAMP)-dependent pathway. CGRP increased cAMP in neonatal dorsal root ganglion (DRG) neurons in a concentration-dependent manner that was blocked by the receptor antagonist CGRP(8-37). The response to CGRP also occurred in adult DRG cells. In contrast, CGRP did not alter the concentration of free intracellular calcium in neonatal or adult DRG neurons. Immunohistochemical data showed that one downstream effect of the cAMP signaling pathway was phosphorylation of cAMP response element binding (CREB) protein, suggesting that CGRP regulates gene expression. This interpretation was supported by evidence that CGRP increased CRE-dependent gene transcription in neurons transiently transfected with a CRE-luciferase DNA reporter construct. The effect of CGRP on gene transcription was inhibited by H89, myristoylated-protein kinase A inhibitor(14-22)-amide and U0126, indicating that protein kinase A and mitogen-activated protein kinase/extracellular receptor kinase kinase are enzymes that mediate effects of CGRP on gene transcription. Therefore, CGRP receptors may regulate expression of proteins by primary afferent neurons during development and in response to tissue-damaging stimuli.
尽管初级传入神经元表达降钙素基因相关肽(CGRP)的受体,但对这些受体的细胞效应了解有限。我们确定CGRP受体通过环磷酸腺苷(cAMP)依赖性途径调节初级传入神经元中的基因转录。CGRP以浓度依赖性方式增加新生背根神经节(DRG)神经元中的cAMP,该作用被受体拮抗剂CGRP(8 - 37)阻断。对CGRP的反应在成年DRG细胞中也会出现。相比之下,CGRP不会改变新生或成年DRG神经元中细胞内游离钙的浓度。免疫组织化学数据表明,cAMP信号通路的一个下游效应是cAMP反应元件结合(CREB)蛋白的磷酸化,这表明CGRP调节基因表达。用CRE - 荧光素酶DNA报告构建体瞬时转染的神经元中,CGRP增加CRE依赖性基因转录的证据支持了这一解释。CGRP对基因转录的作用被H89、肉豆蔻酰化蛋白激酶A抑制剂(14 - 22) - 酰胺和U0126抑制,表明蛋白激酶A和丝裂原活化蛋白激酶/细胞外受体激酶激酶是介导CGRP对基因转录作用的酶。因此,CGRP受体可能在发育过程中以及对组织损伤刺激的反应中调节初级传入神经元的蛋白质表达。