加拿大和美国科学家的一项研究,阐述了蛋白质ephrin如何控制神经从脊髓到肢体肌肉的连接。相关论文发表在12月26日的《神经元》(Neuron)上。
神经系统是高精度且极其复杂的神经网络,主要功能是分析外界刺激并通过协调运动对外界刺激进行反应。这一高精度来自神经细胞和肌肉之间神经连接的高准确度。加拿大蒙特利尔临床研究所(IRCM)神经网络发育研究部主任Artur Kania解释说:“为了了解这是如何发生的,我们研究了一个简单的系统,在这个系统中,神经从脊髓延伸到肌肉,不仅连接了如二头肌这样的屈肌,也连接了像三头肌这样的伸肌。”之前的研究曾发现,出现在发育中的肢体内的一种蛋白质ephrin-A指引着连接伸肌的神经指向特定的目标。
研究人员用鸡和小鼠胚胎作为模型,发现了一个近亲蛋白质家族ephrin-B,它指引神经连接到拮抗肌群屈肌。这些研究共同构成了一副完整图像,表述了肢体神经如何准确地将神经系统与肌肉相连。而且,通过研究相对简单的神经连接网络,研究人员发现一个很可能在神经系统中广泛采用的分子策略,这一分子策略将更复杂的神经回路连接起来,学习、记忆和协调运动需要的神经回路就属于这类更复杂的类型。
神经系统的错误连线被认为是造成像癫痫和智力缺陷等的因素之一。通过研究肢体神经发育的过程,科学家能帮助发展新的疗法来治疗神经系统受损的病人。
加拿大健康研究所(CIHR)科学主管Rémi Quirion表示:“对ephrin蛋白质的研究应该有助于我们理解像孤独症和精神分裂症这类疾病,以及很多神经失调问题。我们很骄傲能够为这一研究提供支持,并且希望这一研究能够提高相关患者的生活质量。”(生物谷Bioon.com)
生物谷推荐原始出处:
Neuron,26 December 2008 doi:10.1016/j.neuron.2008.11.011
Specification of Motor Axon Trajectory by Ephrin-B:EphB Signaling: Symmetrical Control of Axonal Patterning in the Developing Limb
Victor Luria1,6,Dayana Krawchuk9,Thomas M. Jessell2,3,4,6,Ed Laufer1,5,6,10,,andArtur Kania2,3,7,8,9,,
1 Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032, USA
2 Department of Neuroscience, Columbia University Medical Center, New York, NY 10032, USA
3 Department of Biochemistry and Molecular Biophysics, Columbia University Medical Center, New York, NY 10032, USA
4 Howard Hughes Medical Institute, Columbia University Medical Center, New York, NY 10032, USA
5 Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
6 Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, NY 10032, USA
7 Faculty of Medicine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
8 Department of Anatomy and Cell Biology and Division of Experimental Medicine, McGill University, Montréal, QC, H3A 2T5, Canada
9 Institut de recherches cliniques de Montréal (IRCM), Montréal, QC, H2W 1R7, Canada
10 Present address: Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
Studies of the innervation of limb muscles by spinal motor neurons have helped to define mechanisms by which axons establish trajectories to their targets. Related motor axons select dorsal or ventral pathways at the base of the limb, raising the question of how these alternate trajectories are specified. EphA signaling has been proposed to control the dorsal trajectory of motor axons in conjunction with other signaling systems, although the respective contributions of each system to motor axon guidance are unclear. We show that the expression of EphB receptors by motor axons, and ephrin-B ligands by limb mesenchymal cells, directs the ventral trajectory of motor axons. Our findings reveal symmetry in the molecular strategies that establish this aspect of nerve-muscle connectivity. The involvement of ephrin:Eph signaling in guiding both sets of motor axons raises the possibility that other signaling systems function primarily to refine or modulate a core Eph signaling program.