Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California, Davis, Davis, CA 95616, USA.
J Cell Biol. 2011 Mar 7;192(5):813-24. doi: 10.1083/jcb.201007113. Epub 2011 Feb 28.
Kv1 channels are concentrated at specific sites in the axonal membrane, where they regulate neuronal excitability. Establishing these distributions requires regulated dissociation of Kv1 channels from the neuronal trafficking machinery and their subsequent insertion into the axonal membrane. We find that the auxiliary Kvβ2 subunit of Kv1 channels purified from brain is phosphorylated on serine residues 9 and 31, and that cyclin-dependent kinase (Cdk)-mediated phosphorylation at these sites negatively regulates the interaction of Kvβ2 with the microtubule plus end-tracking protein EB1. Endogenous Cdks, EB1, and Kvβ2 phosphorylated at serine 31 are colocalized in the axons of cultured hippocampal neurons, with enrichment at the axon initial segment (AIS). Acute inhibition of Cdk activity leads to intracellular accumulation of EB1, Kvβ2, and Kv1 channel subunits within the AIS. These studies reveal a new regulatory mechanism for the targeting of Kv1 complexes to the axonal membrane through the reversible Cdk phosphorylation-dependent binding of Kvβ2 to EB1.
Kv1 通道集中在轴突膜的特定部位，调节神经元的兴奋性。建立这些分布需要 Kv1 通道与神经元运输机制的调节解离，然后将其插入轴突膜。我们发现，从大脑中纯化的 Kv1 通道的辅助 Kvβ2 亚基在丝氨酸残基 9 和 31 上磷酸化，Cdk 介导的这些位点的磷酸化负调节 Kvβ2 与微管正端追踪蛋白 EB1 的相互作用。内源性 Cdk、EB1 和磷酸化丝氨酸 31 的 Kvβ2 在培养的海马神经元的轴突中共定位，在轴突起始段（AIS）处富集。Cdk 活性的急性抑制导致 AIS 内 EB1、Kvβ2 和 Kv1 通道亚基的细胞内积累。这些研究揭示了一种新的调节机制，通过 Cdk 磷酸化依赖性的 Kvβ2 与 EB1 的可逆结合，将 Kv1 复合物靶向到轴突膜。
