Cortactin-Binding Protein 2 Modulates the Mobility of Cortactin and Regulates Dendritic Spine Formation and Maintenance
Cortactin-Binding Protein 2 Modulates the Mobility of Cortactin and Regulates Dendritic Spine Formation and Maintenance
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DOI：
10.1523/jneurosci.4405-11.2012
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发表时间：
2012-01-18
影响因子：
5.3
通讯作者：
Hsueh, Yi-Ping
中科院分区：
文献类型：
--
作者：
Chen, Yi-Kai;Hsueh, Yi-Ping
树突棘是树突上富含肌动蛋白的突起，是哺乳动物大脑中兴奋性突触的位置。许多调节肌动蛋白动力学的分子也影响树突棘的形态和/或密度。由于树突棘是神经元特异性的亚细胞结构，神经元特异性蛋白或信号被期望控制棘发生。在这份报告中，我们的特点神经元主导皮质素结合蛋白2（CTTNBP 2）在啮齿类动物的分布和功能。对表达序列标签数据库的分析揭示了小鼠CTTNBP 2的三种剪接变体：短、长和内含子。免疫印迹表明，短形式是大脑中占主导地位的CTTNBP 2变体。CTTNBP 2蛋白在培养的大鼠海马神经元以及小鼠脑中的树突棘高度集中。在神经元中敲低CTTNBP 2降低了树突棘的密度和大小。与这些形态学变化一致，CTTNBP 2敲低神经元中的微型EPSC的频率低于对照神经元中的那些。Cornea蛋白在脊髓发生中作用于CTTNBP 2的下游，因为由CTTNBP 2敲低引起的缺陷通过Cornea蛋白的过表达而不是缺乏Cornea蛋白相互作用的CTTNBP 2突变体蛋白的表达来挽救。最后，免疫荧光染色表明，与皮质粘附素不同，即使在谷氨酸刺激后，CTTNBP 2也稳定地驻留在树枝状棘上。光漂白后的荧光恢复进一步表明CTTNBP 2调节神经元中的coronin的移动性。CTTNBP 2因此可能有助于在树突棘中抑制coronin并控制树突棘的密度。
Dendritic spines, the actin-rich protrusions emerging from dendrites, are the locations of excitatory synapses in mammalian brains. Many molecules that regulate actin dynamics also influence the morphology and/or density of dendritic spines. Since dendritic spines are neuron-specific subcellular structures, neuron-specific proteins or signals are expected to control spinogenesis. In this report, we characterize the distribution and function of neuron-predominant cortactin-binding protein 2 (CTTNBP2) in rodents. An analysis of an Expressed Sequence Tag database revealed three splice variants of mouse CTTNBP2: short, long, and intron. Immunoblotting indicated that the short form is the dominant CTTNBP2 variant in the brain. CTTNBP2 proteins were highly concentrated at dendritic spines in cultured rat hippocampal neurons as well as in the mouse brain. Knockdown of CTTNBP2 in neurons reduced the density and size of dendritic spines. Consistent with these morphological changes, the frequencies of miniature EPSCs in CTTNBP2 knockdown neurons were lower than those in control neurons. Cortactin acts downstream of CTTNBP2 in spinogenesis, as the defects caused by CTTNBP2 knockdown were rescued by overexpression of cortactin but not expression of a CTTNBP2 mutant protein lacking the cortactin interaction. Finally, immunofluorescence staining demonstrated that, unlike cortactin, CTTNBP2 stably resided at dendritic spines even after glutamate stimulation. Fluorescence recovery after photobleaching further suggested that CTTNBP2 modulates the mobility of cortactin in neurons. CTTNBP2 may thus help to immobilize cortactin in dendritic spines and control the density of dendritic spines.