Characterization of the metastasis-associated protein, S100A4 - Roles of calcium binding and dimerization in cellular localization and interaction with myosin
Characterization of the metastasis-associated protein, S100A4 - Roles of calcium binding and dimerization in cellular localization and interaction with myosin
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DOI：
10.1074/jbc.m304909200
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发表时间：
2003-08-08
影响因子：
4.8
通讯作者：
Helfman, DM
中科院分区：
文献类型：
--
作者：
Kim, EJ;Helfman, DM
S100A4 蛋白表达升高与转移性肿瘤进展相关，似乎是临床预后的强有力的分子标志物。 S100A4 是一种钙结合蛋白，已知可形成同二聚体并以钙依赖性方式与多种蛋白质相互作用。在这里，我们表明，S100A4 定位于迁移性乳腺癌衍生细胞系中的板状伪足结构，并与已知的 S100A4 相互作用蛋白肌球蛋白重链 IIA 共定位于前沿。我们证明，二聚化能力或钙结合能力有缺陷的 S100A4 突变体无法与肌球蛋白重链 IIA 相互作用。缺乏钙结合的 S100A4 突变体保留了形成同二聚体的能力，这表明 S100A4 在体内可以以无钙或钙结合二聚体的形式存在。然而，钙结合的S100A4单体仅与另一个钙结合的单体相互作用，而不与不结合钙的S100A4突变体相互作用。有趣的是，尽管与已知蛋白质伴侣的相互作用依赖于钙，但钙结合对于定位到板状伪足来说并不是必需的。野生型和缺乏钙结合的突变体都与活跃形成板状伪足前缘的已知标记物、Arp3 和神经元 Wiskott-Aldrich 综合征蛋白共定位。这些数据表明，S100A4 以不依赖于钙的方式定位于前沿，并且鉴定参与将 S100A4 定位于板状足结构的蛋白质可能为 S100A4 调节转移的机制提供新的见解。
Elevated S100A4 protein expression is associated with metastatic tumor progression and appears to be a strong molecular marker for clinical prognosis. S100A4 is a calcium-binding protein that is known to form homodimers and interacts with several proteins in a calcium-dependent manner. Here we show that S100A4 localizes to lamellipodia structures in a migrating breast cancer-derived cell line and colocalizes with a known S100A4-interacting protein, myosin heavy chain IIA, at the leading edge. We demonstrate that S100A4 mutants that are defective in either their ability to dimerize or in calcium binding are unable to interact with myosin heavy chain IIA. An S100A4 mutant that is deficient for calcium binding retains the ability to form homodimers, suggesting that S100A4 can exist as calcium-free or calcium-bound dimers in vivo. However, a calcium-bound S100A4 monomer only interacts with another calcium-bound monomer and not with an S100A4 mutant that does not bind calcium. Interestingly, despite the calcium dependence for interaction with known protein partners, calcium binding is not necessary for localization to lamellipodia. Both wild type and a mutant that is deficient for calcium binding colocalize with known markers of actively forming leading edges of lamellipodia, Arp3 and neuronal Wiskott-Aldrich syndrome protein. These data suggest that S100A4 localizes to the leading edge in a calcium-independent manner, and identification of the proteins that are involved in localizing S100A4 to the lamellipodial structures may provide novel insight into the mechanism by which S100A4 regulates metastasis.