Institut National de la Santé et de la Recherche Médicale, UMR1085, Institut de Recherche en Santé, Environnement et Travail, Université de Rennes 1, 35043 Rennes, France.
Mol Biol Cell. 2012 Sep;23(17):3461-72. doi: 10.1091/mbc.E11-11-0918. Epub 2012 Jul 5.
Based on its shedding and binding activities, the disintegrin and metalloprotease 12 (ADAM12) has been implicated in cell signaling. Here we investigate the intracellular protein interaction network of the transmembrane ADAM12L variant using an integrative approach. We identify the integrin-linked kinase (ILK) as a new partner for ADAM12L cellular functions. We demonstrate that ADAM12L coimmunoprecipitates with ILK in cells and that its cytoplasmic tail is required for this interaction. In human cultured hepatic stellate cells (HSCs), which express high levels of endogenous ADAM12L and ILK, the two proteins are redistributed to focal adhesions upon stimulation of a β1 integrin-dependent pathway. We show that down-regulation of ADAM12L in HSCs leads to cytoskeletal disorganization and loss of adhesion. Conversely, up-regulation of ADAM12L induces the Akt Ser-473 phosphorylation-dependent survival pathway via stimulation of β1 integrins and activation of phosphoinositide 3-kinase (PI3K). Depletion of ILK inhibits this effect, which is independent of ADAM12L proteolytic activity and involves its cytoplasmic domain. We further demonstrate that overexpression of ADAM12L promotes kinase activity from ILK immunoprecipitates. Our data suggest a new role for ADAM12L in mediating the functional association of ILK with β1 integrin to regulate cell adhesion/survival through a PI3K/Akt signaling pathway.
基于其脱落和结合活性，解整合素金属蛋白酶 12（ADAM12）已被牵涉到细胞信号转导中。在这里，我们使用综合方法研究跨膜 ADAM12L 变体的细胞内蛋白质相互作用网络。我们确定整合素连接激酶（ILK）为 ADAM12L 细胞功能的新伴侣。我们证明 ADAM12L 在细胞中与 ILK 共免疫沉淀，并且其细胞质尾巴是这种相互作用所必需的。在表达高水平内源性 ADAM12L 和 ILK 的人培养的肝星状细胞（HSCs）中，当刺激 β1 整合素依赖性途径时，两种蛋白质被重新分布到焦点粘连。我们表明，在 HSCs 中下调 ADAM12L 会导致细胞骨架紊乱和粘附丧失。相反，通过刺激β1 整合素和激活磷酸肌醇 3-激酶（PI3K），上调 ADAM12L 诱导 Akt Ser-473 磷酸化依赖性存活途径。ILK 的耗竭抑制了这种效应，该效应不依赖于 ADAM12L 的蛋白水解活性，并且涉及其细胞质结构域。我们进一步表明，ADAM12L 的过表达促进了从 ILK 免疫沉淀物中获得的激酶活性。我们的数据表明 ADAM12L 在介导 ILK 与β1 整合素的功能关联中具有新的作用，通过 PI3K/Akt 信号通路调节细胞粘附/存活。
