Age-Dependent Targeting of Protein Phosphatase 1 to Ca2+/Calmodulin-Dependent Protein Kinase II by Spinophilin in Mouse Striatum
Age-Dependent Targeting of Protein Phosphatase 1 to Ca2+/Calmodulin-Dependent Protein Kinase II by Spinophilin in Mouse Striatum
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DOI：
10.1371/journal.pone.0031554
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发表时间：
2012-02-13
期刊：
影响因子：
3.7
通讯作者：
Colbran, Roger J.
中科院分区：
文献类型：
--
作者：
Baucum, Anthony J., II;Strack, Stefan;Colbran, Roger J.
纹状体中棘神经元上树突棘的年龄依赖性变化的机制知之甚少。嗜刺素是一种F-肌动蛋白和蛋白磷酸酶1（PP 1）结合蛋白，其靶向PP 1到多个下游效应子以调节树突棘的形态和功能。我们发现，钙/钙调素依赖性蛋白激酶II（CaMK II）直接和间接地与N-和C-端结构域的spinophilin，但F-肌动蛋白可以取代CaMK II的N-端结构域。在异源细胞中，亲棘蛋白将PP 1与CaMKII共定位在F-肌动蛋白细胞骨架上，而在神经元培养物中，亲棘蛋白与突触CaMKII共定位。Thr 286自身磷酸化增强CaMK II与亲棘素的体外和体内结合。虽然Thr 286自磷酸化的总水平没有变化，但从出生后第21天到成年期的成熟强烈增强了CaMKII的水平，CaMKII与小鼠纹状体提取物中的亲棘素共免疫沉淀。此外，N-和C-末端结构域片段的spinophilin结合更多的CaMKII从成人与出生后第21天纹状体裂解物。在成熟过程中，与亲棘素的C-末端结构域相互作用的其他蛋白质的总水平降低，可能降低了CaMKII与C-末端结构域结合的竞争。相反，总水平的α-internexin和结合的α-internexin的亲棘素N-末端结构域的增加与成熟，可能桥接与CaMK II的间接相互作用。此外，与出生后第21天相比，从成年和老年小鼠分离的纹状体CaMKII免疫复合物中肌球蛋白Va，α-internexin，spinophilin和PP 1的水平增加。这些变化的spinophilin/CaMKII相互作用可能有助于纹状体树突棘密度，形态和功能的变化，在正常的出生后成熟和衰老。
Mechanisms underlying age-dependent changes of dendritic spines on striatal medium spiny neurons are poorly understood. Spinophilin is an F-actin- and protein phosphatase 1 (PP1)-binding protein that targets PP1 to multiple downstream effectors to modulate dendritic spine morphology and function. We found that calcium/calmodulin-dependent protein kinase II (CaMKII) directly and indirectly associates with N- and C-terminal domains of spinophilin, but F-actin can displace CaMKII from the N-terminal domain. Spinophilin co-localizes PP1 with CaMKII on the F-actin cytoskeleton in heterologous cells, and spinophilin co-localizes with synaptic CaMKII in neuronal cultures. Thr286 autophosphorylation enhances the binding of CaMKII to spinophilin in vitro and in vivo. Although there is no change in total levels of Thr286 autophosphorylation, maturation from postnatal day 21 into adulthood robustly enhances the levels of CaMKII that co-immunoprecipitate with spinophilin from mouse striatal extracts. Moreover, N- and C-terminal domain fragments of spinophilin bind more CaMKII from adult vs. postnatal day 21 striatal lysates. Total levels of other proteins that interact with C-terminal domains of spinophilin decrease during maturation, perhaps reducing competition for CaMKII binding to the C-terminal domain. In contrast, total levels of alpha-internexin and binding of alpha-internexin to the spinophilin N-terminal domain increases with maturation, perhaps bridging an indirect interaction with CaMKII. Moreover, there is an increase in the levels of myosin Va, alpha-internexin, spinophilin, and PP1 in striatal CaMKII immune complexes isolated from adult and aged mice compared to those from postnatal day 21. These changes in spinophilin/CaMKII interactomes may contribute to changes in striatal dendritic spine density, morphology, and function during normal postnatal maturation and aging.