Stirnweiss Jörg, Valkova Christina, Ziesché Elisabeth, Drube Sebastian, Liebmann Claus
Institute of Biochemistry and Biophysics, Biological and Pharmaceutical Faculty, Friedrich-Schiller-University, Philosophenweg 12, D-07743 Jena, Germany.
Cell Signal. 2006 Aug;18(8):1338-49. doi: 10.1016/j.cellsig.2005.10.018. Epub 2005 Dec 7.
Transactivation of epidermal growth factor receptor (EGFR) by G protein-coupled receptors (GPCRs) has been attributed to the activation of matrix metalloproteases (MMPs) and the release of EGF family ligands such as HB-EGF. This mode of transactivation leads to signalling downstream of EGFR which is indistinguishable from that induced by the ligand. Here we provide evidence that in the COS-7 cell model EGFR transactivation via the muscarinic M2 receptor (M2R) is independent of MMPs and results in an incomplete EGFR signalling including ERK and Akt but not PLCgamma1. Using dominant-negative mutants of c-Src and Fyn and Src-deficient SYF cells as well as by co-immunoprecipitation studies, we can demonstrate that the M2R-mediated transactivation of EGFR specifically involves Fyn but not c-Src or Yes. This specific role of Fyn can be verified in SH-SY5Y human neuroblastoma cells with endogenously expressed M2 receptors.
G蛋白偶联受体（GPCRs）对表皮生长因子受体（EGFR）的反式激活作用被认为归因于基质金属蛋白酶（MMPs）的激活以及诸如肝素结合表皮生长因子（HB-EGF）等EGF家族配体的释放。这种反式激活模式导致EGFR下游信号传导，与配体诱导的信号传导难以区分。在此，我们提供证据表明，在COS-7细胞模型中，通过毒蕈碱M2受体（M2R）介导的EGFR反式激活独立于MMPs，并且导致包括ERK和Akt但不包括PLCγ1的不完全EGFR信号传导。使用c-Src和Fyn的显性负性突变体以及Src缺陷型SYF细胞，以及通过免疫共沉淀研究，我们可以证明M2R介导的EGFR反式激活特别涉及Fyn，而不涉及c-Src或Yes。Fyn的这种特定作用可以在内源表达M2受体的SH-SY5Y人神经母细胞瘤细胞中得到验证。
