Yu Jiang-Zhou, Kuret Jeff, Rasenick Mark M
Department of Physiology and Biophysics, University of Illinois at Chicago College of Medicine, Chicago, Illinois 60612-7342, USA.
J Neurosci Res. 2002 Mar 1;67(5):625-33. doi: 10.1002/jnr.10152.
The neuronal microtubule-associated protein tau promotes microtubule assembly and has been implicated in the development of axonal morphology. In this study, PC12 cells were transiently transfected with constructs coding fusion proteins of human tau with green fluorescent protein (GFP). Expression of tau constructs actively stabilized microtubules. Expression of the C-terminus of tau can mimic this effect in living cells, though to a lesser extent because of the absence of the tau N-terminus. However, tau colocalization with microtubules did not require the presence of the tau N-terminus. Transient expression of tau (including tau24, a four-repeat human tau isoform encoded in 383 residues, and tau23, human fetal tau isoform encoded in 352 residues) stimulated process formation in PC12 cells, and this occurred faster with tau24 than with tau23. The residues (residues 154-172 in tau23) that confer microtubule nucleation activity of tau in vitro are not required for tau-directed process formation. However, when tau induces the formation of cellular processes in response to cortical breakdown by cytochalasin B, residues 154-172 must be present. Thus, it appears that tau may serve to promote cellular process outgrowth in cultured neuronal cells and that C-terminus of tau is essential to this process.
神经元微管相关蛋白tau可促进微管组装，并与轴突形态的发育有关。在本研究中，用编码人tau与绿色荧光蛋白（GFP）融合蛋白的构建体瞬时转染PC12细胞。tau构建体的表达可有效稳定微管。tau C末端的表达可在活细胞中模拟这种作用，尽管由于缺少tau N末端，其作用程度较小。然而，tau与微管的共定位并不需要tau N末端的存在。tau（包括tau24，一种由383个残基编码的四重复人tau异构体，和tau23，一种由352个残基编码的人胎儿tau异构体）的瞬时表达刺激了PC12细胞中突起的形成，且tau24比tau23出现得更快。赋予tau体外微管成核活性的残基（tau23中的154 - 172位残基）对于tau引导的突起形成并非必需。然而，当tau响应细胞松弛素B诱导的皮层崩解而诱导细胞突起形成时，必须存在154 - 172位残基。因此，似乎tau可能有助于促进培养的神经元细胞中细胞突起的生长，并且tau的C末端对于该过程至关重要。
