Mater Medical Research Institute, Aubigny Place, Raymond Terrace, South Brisbane, Queensland 4101; Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland 4059.
Mater Medical Research Institute, Aubigny Place, Raymond Terrace, South Brisbane, Queensland 4101.
J Biol Chem. 2011 Dec 9;286(49):42303-42315. doi: 10.1074/jbc.M111.227462. Epub 2011 Oct 12.
Reciprocal interactions between Src family kinases (SFKs) and focal adhesion kinase (FAK) are critical during changes in cell attachment. Recently it has been recognized that another SFK substrate, CUB-domain-containing protein 1 (CDCP1), is differentially phosphorylated during these events. However, the molecular processes underlying SFK-mediated phosphorylation of CDCP1 are poorly understood. Here we identify a novel mechanism in which FAK tyrosine 861 and CDCP1-Tyr-734 compete as SFK substrates and demonstrate cellular settings in which SFKs switch between these sites. Our results show that stable CDCP1 expression induces robust SFK-mediated phosphorylation of CDCP1-Tyr-734 with concomitant loss of p-FAK-Tyr-861 in adherent HeLa cells. SFK substrate switching in these cells is dependent on the level of expression of CDCP1 and is also dependent on CDCP1-Tyr-734 but is independent of CDCP1-Tyr-743 and -Tyr-762. In HeLa CDCP1 cells, engagement of SFKs with CDCP1 is accompanied by an increase in phosphorylation of Src-Tyr-416 and a change in cell morphology to a fibroblastic appearance dependent on CDCP1-Tyr-734. SFK switching between FAK-Tyr-861 and CDCP1-Tyr-734 also occurs during changes in adhesion of colorectal cancer cell lines endogenously expressing these two proteins. Consistently, increased p-FAK-Tyr-861 levels and a more epithelial morphology are seen in colon cancer SW480 cells silenced for CDCP1. Unlike protein kinase Cδ, FAK does not appear to form a trimeric complex with Src and CDCP1. These data demonstrate novel aspects of the dynamics of SFK-mediated cell signaling that may be relevant during cancer progression.
Src 家族激酶 (SFKs) 和粘着斑激酶 (FAK) 之间的相互作用在细胞附着的变化过程中是至关重要的。最近人们认识到，另一个 SFK 底物，CUB 结构域蛋白 1 (CDCP1)，在这些事件中也有差异磷酸化。然而，SFK 介导的 CDCP1 磷酸化的分子过程还知之甚少。在这里，我们确定了一种新的机制，其中 FAK 酪氨酸 861 和 CDCP1-Tyr-734 作为 SFK 底物竞争，并证明了 SFKs 在这些位点之间切换的细胞环境。我们的结果表明，稳定表达的 CDCP1 诱导 SFK 介导的 CDCP1-Tyr-734 强烈磷酸化，同时伴随着粘着的 HeLa 细胞中 p-FAK-Tyr-861 的丢失。这些细胞中 SFK 底物的切换依赖于 CDCP1 的表达水平，并且还依赖于 CDCP1-Tyr-734，但不依赖于 CDCP1-Tyr-743 和 -Tyr-762。在 HeLa CDCP1 细胞中，SFK 与 CDCP1 的结合伴随着 Src-Tyr-416 的磷酸化增加和细胞形态向依赖于 CDCP1-Tyr-734 的成纤维样外观的改变。在这些两种蛋白内源性表达的结直肠癌细胞粘附变化过程中，SFK 也在 FAK-Tyr-861 和 CDCP1-Tyr-734 之间切换。一致地，在沉默 CDCP1 的结肠癌 SW480 细胞中，p-FAK-Tyr-861 水平增加，上皮形态更多。与蛋白激酶 Cδ 不同，FAK 似乎不会与 Src 和 CDCP1 形成三聚体复合物。这些数据显示了 SFK 介导的细胞信号转导的动态的新方面，这在癌症进展过程中可能是相关的。
