Shen L, Liang F, Walensky L D, Huganir R L
Howard Hughes Medical Institute, Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
J Neurosci. 2000 Nov 1;20(21):7932-40. doi: 10.1523/JNEUROSCI.20-21-07932.2000.
The synaptic localization, clustering, and immobilization of neurotransmitter receptors and ion channels play important roles in synapse formation and synaptic transmission. Although several proteins have been identified that interact with AMPA receptors and that may regulate their synaptic targeting, little is known about the interaction of AMPA receptors with the cytoskeleton. In studies examining the interaction of the AMPA receptor GluR1 subunit with neuronal proteins, we determined that GluR1 interacts with the 4.1G and 4.1N proteins, homologs of the erythrocyte membrane cytoskeletal protein 4.1. Using the yeast two-hybrid system and a heterologous cell system, we demonstrated that both 4.1G and 4.1N bind to a membrane proximal region of the GluR1 C terminus, and that a region within the C-terminal domain of 4.1G or 4.1N is sufficient to mediate the interaction. We also found that 4.1N can associate with GluR1 in vivo and colocalizes with AMPA receptors at excitatory synapses. Disruption of the interaction of GluR1 with 4.1N or disruption of actin filaments decreased the surface expression of GluR1 in heterologous cells. Moreover, disruption of actin filaments in cultured cortical neurons dramatically reduced the level of surface AMPA receptors. These results suggest that protein 4.1N may link AMPA receptors to the actin cytoskeleton.
神经递质受体和离子通道的突触定位、聚集及固定在突触形成和突触传递中发挥着重要作用。尽管已经鉴定出几种与AMPA受体相互作用且可能调节其突触靶向的蛋白质，但关于AMPA受体与细胞骨架的相互作用却知之甚少。在研究AMPA受体GluR1亚基与神经元蛋白的相互作用时，我们确定GluR1与红细胞膜细胞骨架蛋白4.1的同源物4.1G和4.1N蛋白相互作用。利用酵母双杂交系统和异源细胞系统，我们证明4.1G和4.1N都与GluR1 C末端的膜近端区域结合，并且4.1G或4.1N C末端结构域内的一个区域足以介导这种相互作用。我们还发现4.1N在体内可与GluR1结合，并在兴奋性突触处与AMPA受体共定位。GluR1与4.1N相互作用的破坏或肌动蛋白丝的破坏会降低异源细胞中GluR1的表面表达。此外，培养的皮质神经元中肌动蛋白丝的破坏显著降低了表面AMPA受体的水平。这些结果表明，4.1N蛋白可能将AMPA受体与肌动蛋白细胞骨架联系起来。
