Mohammadi M, Dikic I, Sorokin A, Burgess WH, Jaye M, Schlessinger JIdentification of six novel autophosphorylation sites on fibroblast growth factor receptor 1 and elucidation of their importance in receptor activation and signal transduction. Mol Cell Biol 16:977-989

Department of Pharmacology, New York University Medical Center, 10016, USA.
Molecular and Cellular Biology (Impact Factor: 4.78). 04/1996; 16(3):977-89.
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Fibroblast growth factor receptor (FGFR) activation leads to receptor autophosphorylation and increased tyrosine phosphorylation of several intra cellular proteins. We have previously shown that autophosphorylated tyrosine 766 in FGFR1 serves as a binding site for one of the SH2 domains of phospholipase Cy and couples FGFR1 to phosphatidylinositol hydrolysis in several cell types. In this report, we describe the identification of six additional autophosphorylation sites (Y-463, Y-583, Y-585, Y-653, Y-654 and Y-730) on FGFR1. We demonstrate that autophosphorylation on tyrosines 653 and 654 is important for activation of tyrosine kinase activity of FGFR1 and is therefore essential for FGFR1-mediated biological responses. In contrast, autophosphorylation of the remaining four tyrosines is dispensable for FGFR1-mediated mitogen-activated protein kinase activation and mitogenic signaling in L-6 cells as well as neuronal differentiation of PC12 cells. Interestingly, both the wild-type and a mutant FGFR1 (FGFR1-4F) are able to phosphorylate Shc and an unidentified Grb2-associated phosphoprotein of 90 kDa (pp90). Binding of the Grb2/Sos complex to phosphorylated Shc and pp90 may therefore be the key link between FGFR1 and the Ras signaling pathway, mito-genesis, and neuronal differentiation.

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Available from: Moosa Mohammadi, Feb 01, 2014
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    • "The FRS2 is an adaptor protein linking MAPK and PI3K/Akt pathways to the activated FGFR [44]. As expected, analysis of signalling pathways triggered by FGF2 in three, FGFR2 expressing cell lines: HB2, SKBR3 and MDA-MB-361, has confirmed the importance of autophosphorylation of the receptor at tyrosines 653 and 654 for stimulation of receptor kinase's activity and FGFR-mediated biological responses [45]. The activation of FGFR specific effectors, FRS2 and PLCγ, as well as other downstream targets such as AKT, p38 and ERK, but not Src, has also been observed (Fig. 2A and Supplementary Fig. 1). "
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    ABSTRACT: The members of p90 ribosomal S6 kinase (RSK) family of Ser/Thr kinases are downstream effectors of MAPK/ERK pathway that regulate diverse cellular processes including cell growth, proliferation and survival. In carcinogenesis, RSKs are thought to modulate cell motility, invasion and metastasis. Herein, we have studied an involvement of RSKs in FGF2/FGFR2-driven behaviours of mammary epithelial and breast cancer cells. We found that both silencing and inhibiting of FGFR2 attenuated phosphorylation of RSKs, whereas FGFR2 overexpression and/or its stimulation with FGF2 enhanced RSKs activity. Moreover, treatment with ERK, Src and p38 inhibitors revealed that p38 kinase acts as an upstream RSK2 regulator. We demonstrate for the first time that in FGF2/FGFR2 signalling, p38 but not MEK/ERK, indirectly activated RSK2 at Tyr529, which facilitated phosphorylation of its other residues (Thr359/Ser363, Thr573 and Ser380). In contrast to FGF2-triggered signalling, inhibition of p38 in the EGF pathway affected only RSK2-Tyr529, without any impact on the remaining RSK phosphorylation sites. p38-mediated phosphorylation of RSK2-Tyr529 was crucial for transactivation of residues located at kinase C-terminal domain and linker-region, specifically, in the FGF2/FGFR2 signalling pathway. Furthermore, we show that FGF2 promoted anchorage-independent cell proliferation, formation of focal adhesions and cell migration, which was effectively abolished by treatment with RSKs inhibitor (FMK). These indicate that RSK2 activity is indispensable for FGF2/FGFR2-mediated cellular effects. Our findings identified a new FGF2/FGFR2-p38-RSK2 pathway which may play a significant role in the pathogenesis and progression of breast cancer, and hence, may present a novel therapeutic target in the treatment of FGFR2-expressing tumours.
    Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 07/2014; 1843(11). DOI:10.1016/j.bbamcr.2014.06.022 · 5.02 Impact Factor
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    • "We also note that major sites previously implicated in receptor internalization and downregulation (Sorokin et al, 1994; Persaud et al, 2011) are preserved in Opto-mFGFR1. Collectively, these results agree well with published data on mFGFR1 signalling (Sorokin et al, 1994; Mohammadi et al, 1996; Ong et al, 2000; Wang et al, 2001) and indicate that activation and coupling to downstream signalling of Opto-mFGFR1 resembles that of mFGFR1. "
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    ABSTRACT: Receptor tyrosine kinases (RTKs) are a large family of cell surface receptors that sense growth factors and hormones and regulate a variety of cell behaviours in health and disease. Contactless activation of RTKs with spatial and temporal precision is currently not feasible. Here, we generated RTKs that are insensitive to endogenous ligands but can be selectively activated by low-intensity blue light. We screened light-oxygen-voltage (LOV)-sensing domains for their ability to activate RTKs by light-activated dimerization. Incorporation of LOV domains found in aureochrome photoreceptors of stramenopiles resulted in robust activation of the fibroblast growth factor receptor 1 (FGFR1), epidermal growth factor receptor (EGFR) and rearranged during transfection (RET). In human cancer and endothelial cells, light induced cellular signalling with spatial and temporal precision. Furthermore, light faithfully mimicked complex mitogenic and morphogenic cell behaviour induced by growth factors. RTKs under optical control (Opto-RTKs) provide a powerful optogenetic approach to actuate cellular signals and manipulate cell behaviour.
    The EMBO Journal 07/2014; 33(15). DOI:10.15252/embj.201387695 · 10.43 Impact Factor
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    • "This gene is involved in intracellular signaling. If FGF binds to its receptor, the receptor autophosphorylates and there is an increase in tyrosine phosphorylation of several intracellular proteins [Mohammadi et al., 1996]. "
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    ABSTRACT: The purposes of this study were to find a novel mutation of FGFR2 in Korean Crouzon syndrome patients and to identify the functional consequences of this mutation. The samples consisted of 16 Crouzon patients. Peripheral venous blood was collected from the patients. FGFR2 mutation screening was performed by direct PCR sequencing of all exons and part of the introns. Restriction fragment length polymorphism (RFLP) analysis was performed to confirm the novel mutation. For functional studies, we performed luciferase assay for Runx2 transcriptional activity, real-time PCR for the bone markers (osteocalcin and alkaline phosphatase), and Western blot for phosphorylated FGFR2 and ERK1/2-MAPK protein. Among 16 patients, ten showed FGFR2 mutations that had already been reported elsewhere. A novel FGFR2 mutation associated with tyrosine kinase II (TK-II) domain, L617F, was found in one Crouzon syndrome patient by direct PCR sequencing. Presence of this mutation was confirmed using RFLP analysis. Runx2 transcriptional activity and expression of osteocalcin and alkaline phosphatase significantly increased in L617F-transfected cells compared to wild-type cells. FGFR2 autophosphorylation in L617F-transfected cells increased in 1% serum, but ERK1/2-MAPK protein was not activated. The FGFR2-L617F mutation associated with the TK domain is potentially related to premature suture closure in Crouzon syndrome patient. J. Cell. Biochem. © 2013 Wiley Periodicals, Inc.
    Journal of Cellular Biochemistry 01/2014; 115(1). DOI:10.1002/jcb.24637 · 3.26 Impact Factor
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