Nonenzymatic domains of Kalirin7 contribute to spine morphogenesis through interactions with phosphoinositides and Abl.
Nonenzymatic domains of Kalirin7 contribute to spine morphogenesis through interactions with phosphoinositides and Abl.
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DOI：
10.1091/mbc.e13-04-0215
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发表时间：
2014-05
影响因子：
3.3
通讯作者：
Eipper BA
中科院分区：
文献类型：
--
作者：
Ma XM;Miller MB;Vishwanatha KS;Gross MJ;Wang Y;Abbott T;Lam TT;Mains RE;Eipper BA
一些Rho GDP/GTP交换因子包括Sec 14结构域和血影蛋白重复序列。Kalirin 7的Sec 14结构域是棘长度的决定因素。卡林7的非催化Sec 14结构域和血影蛋白重复序列一起支持棘形成，定位于突触后密度，并吸引突触前末梢。与几种Rho GDP/GTP交换因子（GEF）一样，Kalirin 7（Kal 7）含有N-末端Sec 14结构域和多个血影蛋白重复序列。缺乏Sec 14结构域和四个血影蛋白重复序列的Kalrn的天然剪接变体无法增加脊柱形成;我们的目标是了解Sec 14和血影蛋白重复序列结构域的功能。缺乏Sec 14域的Kal 7仍然增加了棘的形成，但棘很短。引人注目的是，Kal 7截断突变体只含有Sec 14域和几个血影蛋白重复增加脊柱形成。Sec 14结构域结合磷酸肌醇，一个次要的，但至关重要的组成部分的细胞膜，并结合增加了磷酸化突变。KalSec 14-GFP在非神经元细胞中的表达损害了受体介导的内吞作用，将Kal 7与膜运输联系起来。与将Abl（一种非受体酪氨酸激酶）和Kalrn的果蝇直向同源物置于相同信号传导途径的遗传研究一致，KAL 1磷酸化Kalirin第四血影蛋白重复序列中的两个位点，增加了其对钙蛋白酶介导的降解的敏感性。用Abl抑制剂处理野生型小鼠而不是Kal 7 KO小鼠的皮质神经元引起线性棘密度的增加。Kal 7的N-末端Sec 14/血影蛋白区域中多个位点的磷酸化可能允许促进棘形态发生的许多信号通路的协调。
Several Rho GDP/GTP exchange factors include a Sec14 domain and spectrin repeats. The Sec14 domain of Kalirin 7 is a determinant of spine length. Together the noncatalytic Sec14 domain and spectrin repeats of Kalirin 7 support spine formation, localize to the postsynaptic density, and attract presynaptic endings. Like several Rho GDP/GTP exchange factors (GEFs), Kalirin7 (Kal7) contains an N-terminal Sec14 domain and multiple spectrin repeats. A natural splice variant of Kalrn lacking the Sec14 domain and four spectrin repeats is unable to increase spine formation; our goal was to understand the function of the Sec14 and spectrin repeat domains. Kal7 lacking its Sec14 domain still increased spine formation, but the spines were short. Strikingly, Kal7 truncation mutants containing only the Sec14 domain and several spectrin repeats increased spine formation. The Sec14 domain bound phosphoinositides, a minor but crucial component of cellular membranes, and binding was increased by a phosphomimetic mutation. Expression of KalSec14-GFP in nonneuronal cells impaired receptor-mediated endocytosis, linking Kal7 to membrane trafficking. Consistent with genetic studies placing Abl, a non–receptor tyrosine kinase, and the Drosophila orthologue of Kalrn into the same signaling pathway, Abl1 phosphorylated two sites in the fourth spectrin repeat of Kalirin, increasing its sensitivity to calpain-mediated degradation. Treating cortical neurons of the wild-type mouse, but not the Kal7KO mouse, with an Abl inhibitor caused an increase in linear spine density. Phosphorylation of multiple sites in the N-terminal Sec14/spectrin region of Kal7 may allow coordination of the many signaling pathways contributing to spine morphogenesis.