来自MIT的Picower学习和记忆研究所的科学家最近发现了一种常见蛋白在大脑中出人意料的功能，这一发现将可能带来治疗阿兹海默症和帕金森氏症等疾病的新方法。
神经科学教授、Howard Hughes医学研究所科学家Morgan H. Sheng以及同事将他们的研究结果发表在10月23日的《当代生物学》（Current Biology）上，文章表示，帮助酵母细胞出芽生殖成两个后代酵母菌的蛋白同样也能帮助神经萌芽出突起，这能用来与周围神经元交流。
科学家早在1970年代就已经知道这种septin蛋白对于酵母菌细胞质的分裂过程很关键。Sheng表示：“在酵母中，septin位于母细胞和芽体之间的狭窄位置。令人惊讶的是我们发现septin还存在于神经树突棘的同样位置以及树突的支点。”
哺乳动物中发现的14种septin有9种存在于大脑中。其中之一Sept7最常出现，但它的功能却并不清楚。Septin形成长长的细丝，并利用其它蛋白来构建细胞的基础结构。尽管神经元不会分裂，但是它们能形成突起，并最终延长成为树突。树突负责将其它神经元的电刺激传递到所属的神经胞体。
电刺激通过突触传播，突触位于树突上的不同位置。树突对于接受突触信号很重要。合作者之一的Tomoko Tada说：“由于树突棘对于突触功能和记忆形成很重要，了解septin能帮助防止很多神经退化疾病导致的树突棘和突触损失。Septin可能是治疗以上疾病的目标之一。”
此外在科学家培养的海马体神经元中，septin对于正常的突起和棘形成很关键。充足的septin能帮助树突生长增生，而缺少septin则使它们变得很小、畸形。Sheng说：“提高septin的表达和功能将增加棘和突触的稳定性，这对于学习和记忆等认知功能有好处。”实验室目前正在探索防止septin退化和损失的方法。（教育部科技发展中心 ）
原文链接：http://www.physorg.com/news112020162.html
原始出处:
Current Biology, Vol 17, 1752-1758, 23 October 2007
Report
Role of Septin Cytoskeleton in Spine Morphogenesis and Dendrite Development in Neurons
Tomoko Tada,1 Alyson Simonetta,1 Matthew Batterton,1 Makoto Kinoshita,2 Dieter Edbauer,1 and Morgan Sheng1,
1 The Picower Institute for Learning and Memory, RIKEN-MIT Neuroscience Research Center, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
2 Biochemistry and Cell Biology Unit, Horizontal Medical Research Organization, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo, Kyoto 606-8501, Japan
Corresponding author
Morgan Sheng
msheng@mit.edu
Septins are GTP-binding proteins that polymerize into heteromeric filaments and form microscopic bundles or ring structures in vitro and in vivo. Because of these properties and their ability to associate with membrane, F-actin, and microtubules, septins have been generally regarded as cytoskeletal components [1, 2]. Septins are known to play roles in cytokinesis, in membrane trafficking, and as structural scaffolds; however, their function in neurons is poorly understood. Many members of the septin family, including Septin 7 (Sept7), were found by mass-spectrometry analysis of postsynaptic density (PSD) fractions of the brain [3, 4], suggesting a possible postsynaptic function of septins in neurons. We report that Sept7 is localized at the base of dendritic protrusions and at dendritic branch points in cultured hippocampal neurons—a distribution reminiscent of septin localization in the bud neck of budding yeast. Overexpression of Sept7 increased dendrite branching and the density of dendritic protrusions, whereas RNA interference (RNAi)-mediated knockdown of Sept7 led to reduced dendrite arborization and a greater proportion of immature protrusions. These data suggest that Sept7 is critical for spine morphogenesis and dendrite development during neuronal maturation.
