Epac介导环磷酸腺苷(cAMP)依赖性轴突生长、导向和再生。

Epac mediates cyclic AMP-dependent axon growth, guidance and regeneration.

作者信息

Murray Andrew J, Shewan Derryck A

机构信息

School of Medical Sciences, College of Life Sciences and Medicine, University of Aberdeen, Institute of Medical Sciences, Forresterhill, Aberdeen AB25 2ZD, UK.

出版信息

Mol Cell Neurosci. 2008 Aug;38(4):578-88. doi: 10.1016/j.mcn.2008.05.006. Epub 2008 May 20.

Abstract

A decline in developing neuronal cAMP levels appears to render mammalian axons susceptible to growth inhibitory factors in the damaged CNS. cAMP elevation enhances axon regeneration, but the cellular mechanisms involved have yet to be fully elucidated. Epac has been identified as a signaling protein that can be activated by cAMP independently of PKA, but little is known of its expression or role in the nervous system. We report that Epac expression is developmentally regulated in the rat nervous system, and that activation of Epac promotes DRG neurite outgrowth and is as effective as cAMP elevation in promoting neurite regeneration on spinal cord tissue. Additionally, siRNA mediated knockdown of Epac reduces DRG neurite outgrowth, prevents the increased growth promoted by cAMP elevation and also diminishes the ability of embryonic neurons to grow processes on spinal cord tissue. Furthermore, we show that asymmetric activation of Epac promotes attractive growth cone turning in a similar manner to cAMP activation. We propose that Epac plays a role in mediating cAMP-dependent axon growth and guidance, and may provide an important target for inducing axon regeneration in vivo.

摘要

发育中的神经元cAMP水平下降似乎使哺乳动物轴突易受受损中枢神经系统中生长抑制因子的影响。cAMP水平升高可促进轴突再生,但其中涉及的细胞机制尚未完全阐明。Epac已被确定为一种信号蛋白,它可被cAMP独立于PKA激活,但对其在神经系统中的表达或作用知之甚少。我们报告称,Epac在大鼠神经系统中的表达受发育调控,并且Epac的激活促进背根神经节(DRG)神经突生长,在促进脊髓组织上的神经突再生方面与cAMP升高一样有效。此外,siRNA介导的Epac敲低减少了DRG神经突生长,阻止了cAMP升高所促进的生长增加,并且还削弱了胚胎神经元在脊髓组织上生长突起的能力。此外,我们表明Epac的不对称激活以与cAMP激活类似的方式促进有吸引力的生长锥转向。我们提出,Epac在介导cAMP依赖性轴突生长和导向中起作用,并且可能为体内诱导轴突再生提供一个重要靶点。

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