Oligomerizing potential of a focal adhesion LIM protein Hic-5 organizing a nuclear-cytoplasmic shuttling complex
Oligomerizing potential of a focal adhesion LIM protein Hic-5 organizing a nuclear-cytoplasmic shuttling complex
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DOI：
10.1074/jbc.m513111200
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发表时间：
2006-08-04
影响因子：
4.8
通讯作者：
Shibanuma, Motoko
中科院分区：
文献类型：
--
作者：
Mori, Kazunori;Asakawa, Masayuki;Shibanuma, Motoko
Hic-5是一种粘着斑LIM蛋白，在整合素信号传导中充当支架。该蛋白在其N-末端一半中包含四个LD结构域，在其C-末端一半中包含四个LIM结构域，在LD 3中具有核输出信号，并且在细胞质和细胞核隔室之间穿梭。在这项研究中，免疫沉淀和体外交联实验表明，Hic-5同源寡聚化通过其最C-末端LIM结构域，LIM 4。引人注目的是，与Hic-5同源性最高的蛋白桩蛋白没有显示出这种能力。凝胶过滤分析还揭示了Hic-5与桩蛋白的不同之处在于其在细胞环境中具有多种形式，并且Hic-5而不是桩蛋白能够与仅LIM蛋白PINCH（在粘着斑处的另一种分子支架）异源寡聚化。Hic-5的第四个LIM结构域和PINCH的第五个LIM结构域区域构成了相互作用的界面。该复合物包括整合素连接激酶，PINCH的结合伴侣，其也通过包含Hic-5的pleckstrin同源样结构域和LIM结构域的区域与Hic-5相互作用。值得注意的是，Hic-5轻微影响PINCH的亚细胞分布，但在存在整联蛋白连接激酶的情况下指导其在细胞质和细胞核区室之间穿梭。Hic-5和PINCH两个信号平台通过干扰异源寡聚化而解偶联导致细胞生长受损。因此，Hic-5是一种分子支架，具有通过LIM结构域与另一种支架对接的潜力，组织移动的超分子单元并协调两个隔室中的粘附信号与细胞活性。
Hic-5 is a focal adhesion LIM protein serving as a scaffold in integrin signaling. The protein comprises four LD domains in its N-terminal half and four LIM domains in its C-terminal half with a nuclear export signal in LD3 and is shuttled between the cytoplasmic and nuclear compartments. In this study, immunoprecipitation and in vitro cross-linking experiments showed that Hic-5 homo-oligomerized through its most C-terminal LIM domain, LIM4. Strikingly, paxillin, the protein most homologous to Hic-5, did not show this capability. Gel filtration analysis also revealed that Hic-5 differs from paxillin in that it has multiple forms in the cellular environment, and Hic-5 but not paxillin was capable of hetero-oligomerization with a LIM- only protein, PINCH, another molecular scaffold at focal adhesions. The fourth LIM domain of Hic-5 and the fifth LIM domain region of PINCH constituted the interface for the interaction. The complex included integrin-linked kinase, a binding partner of PINCH, which also interacted with Hic-5 through the region encompassing the pleckstrin homology-like domain and LIM domains of Hic-5. Of note, Hic-5 marginally affected the subcellular distribution of PINCH but directed its shuttling between the cytoplasmic and nuclear compartments in the presence of integrin-linked kinase. Uncoupling of the two signaling platforms of Hic-5 and PINCH through interference with the hetero-oligomerization resulted in impairment of cellular growth. Hic-5 is, thus, a molecular scaffold with the potential to dock with another scaffold through the LIM domain, organizing a mobile supramolecular unit and coordinating the adhesion signal with cellular activities in the two compartments.