8月21日,东京医科齿科大学的研究人员美国《神经科学期刊》(Journal of Neuroscience)上报告说,他们在对实验鼠的神经回路进行分析的过程中,发现导致手脚和头部震颤的致病基因。
特发性震颤是临床常见的运动障碍疾病,其临床表现是“姿势性震颤”,即肢体维持一定姿势时引发的震颤,在肢体完全放松时震颤自然消失。
日本的统计数据显示,在超过40岁的人群中,每20人当中有1人患特发性震颤,65岁以上人群中则每5人就有1人患此病。特发性震颤被认为是基因原因所致,但与此相关的具体基因及其引发症状的详细机制此前一直不明。
研究人员分析了行走时下半身出现强烈震颤症状的实验鼠的基因及其中枢神经系统,发现实验鼠的“Teneurin-4”基因出现变异,导致神经细胞的轴突外没有形成髓鞘。神经类似电线,轴突相当于电线中的导线,而髓鞘如同覆盖在导线外的绝缘层。
另外,研究人员确认“Teneurin-4”基因功能受到抑制的转基因实验鼠也存在髓鞘发育不全的状况。
研究人员认为,实验鼠是由于髓鞘没有正常形成,导致神经回路“短路”,才出现震颤症状。人类也有功能相同的基因,所以发生这种震颤的原因很可能也一样。
该研究小组带头人、东京医科齿科大学讲师铃木喜晴认为,如果能控制上述致病基因,就有可能开发出治疗特发性震颤的药物。(生物谷Bioon.com)
doi:10.1523/JNEUROSCI.2045-11.2012
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Teneurin-4 Is a Novel Regulator of Oligodendrocyte Differentiation and Myelination of Small-Diameter Axons in the CNS
Nobuharu Suzuki1,2, Masaya Fukushi1, Keisuke Kosaki1, Andrew D. Doyle1, Susana de Vega1,3, Keigo Yoshizaki1, Chihiro Akazawa2, Eri Arikawa-Hirasawa3, and Yoshihiko Yamada1
Myelination is essential for proper functioning of the CNS. In this study, we have identified a mouse mutation, designated furue, which causes tremors and hypomyelination in the CNS, particularly in the spinal cord, but not in the sciatic nerve of the PNS. In the spinal cord of the furue mice, myelination of small-diameter axons was dramatically reduced, and differentiation of oligodendrocytes, the myelin-forming cells in the CNS, was inhibited. We subsequently found that the furue mutation was associated with a transgene insertion into the teneurin-4 (Ten-4, Ten-m4/Odz4) gene, encoding a transmembrane protein of unknown function. Ten-4 was strongly expressed in the spinal cord of wild-type mice and was induced during normal oligodendrocyte differentiation. In contrast, in the furue mice, the expression of Ten-4 was absent. Differentiation and cellular process formation of oligodendrocytes were inhibited in primary cell culture from the furue mice. Cell differentiation and process formation were also inhibited in the oligodendrocyte progenitor cell line CG-4 after suppression of Ten-4 expression by shRNA. Furthermore, Ten-4 positively regulated focal adhesion kinase, an essential signaling molecule for oligodendrocyte process formation and myelination of small-diameter axons. These findings suggest that Ten-4 is a novel regulator of oligodendrocyte differentiation and that it plays a critical role in the myelination of small-diameter axons in the CNS.