Heparin-binding epidermal-growth-factor-like growth factor gene expression is induced by scrape-wounding epithelial cell monolayers: involvement of mitogen-activated protein kinase cascades

2001 ◽  
Vol 354 (1) ◽  
pp. 99-106 ◽  
Author(s):  
Peter D. ELLIS ◽  
Kathryn M. HADFIELD ◽  
John C. PASCALL ◽  
Kenneth D. BROWN
Keyword(s):  
Growth Factor ◽  
Protein Kinase ◽  
Kinase Activity ◽  
Mitogen Activated Protein Kinase ◽  
Heparin Binding ◽  
Mapk Activation ◽  
Cell Monolayers ◽  
Mitogen Activated Protein ◽  
Epidermal Growth ◽  
Epithelial Cell Monolayers

Peptide growth factors can promote the cell migration and proliferation that is needed to repair epithelia after mechanical or chemical injury. We report here that scrape-wounding rat intestinal epithelial (RIE-1) cell monolayers caused a rapid increase in levels of heparin-binding epidermal-growth-factor-like growth factor (HB-EGF) mRNA, with a maximal response at approx. 1h. Hybridization in situ showed that transcript induction occurred primarily in cells at or near wound borders. The increase in HB-EGF mRNA was preceded by activation of the p42 mitogen-activated protein kinase (MAPK) in the wounded cell cultures. Moreover, the induction of HB-EGF mRNA was blocked by PD098059 and U0126, inhibitors that prevent the activation of p42/p44 MAPKs and extracellular signal-regulated protein kinase 5 (ERK5). Both p42 MAPK activation and HB-EGF mRNA induction were inhibited by genistein, indicating a requirement for an upstream tyrosine kinase activity. In contrast, neither response was affected by inhibition of phosphoinositide 3-kinase activity, down-regulation of protein kinase C, or disruption of the actin cytoskeleton with cytochalasin B. We conclude that scrape-wounding epithelial cell monolayers induces HB-EGF mRNA expression by a mechanism that most probably requires p42/p44 MAPK activation, although we cannot exclude a role for ERK5. Our results suggest a physiological role for locally synthesized HB-EGF in promoting epithelial repair after injury.

scholarly journals Dok-R Mediates Attenuation of Epidermal Growth Factor-Dependent Mitogen-Activated Protein Kinase and Akt Activation through Processive Recruitment of c-Src and Csk

2005 ◽  
Vol 25 (9) ◽  
pp. 3831-3841 ◽  
Author(s):  
Paul Van Slyke ◽  
Mariano Loza Coll ◽  
Zubin Master ◽  
Harold Kim ◽  
Jorge Filmus ◽  
...  
Keyword(s):  
Growth Factor ◽  
Protein Kinase ◽  
Epidermal Growth Factor ◽  
Growth Factor Receptor ◽  
Cancer Cell Line ◽  
Mitogen Activated Protein Kinase ◽  
Structural Determinants ◽  
Mapk Activation ◽  
Mitogen Activated Protein ◽  
Epidermal Growth

ABSTRACT Dok-R has previously been shown to associate with the epidermal growth factor receptor (EGFR) and become tyrosine phosphorylated in response to EGF stimulation. The recruitment of Dok-R to the EGFR, which is mediated through its phosphotyrosine binding (PTB) domain, results in attenuation of mitogen-activated protein kinase (MAPK) activation. Dok-R's ability to attenuate EGF-driven MAPK activation is independent of its ability to recruit rasGAP, a known attenuator of MAPK activity, suggesting an alternate Dok-R-mediated pathway. Herein, we have determined the structural determinants within Dok-R that are required for its ability to attenuate EGF signaling and to associate with c-Src and with the Src family kinase (SFK)-inhibitory kinase, Csk. We demonstrate that Dok-R associates constitutively with c-Src through an SH3-dependent interaction and that this association is essential to Dok-R's ability to attenuate c-Src activity and diminish MAPK and Akt/PKB activity. We further illustrate that EGF-dependent phosphorylation of Dok-R requires SFK activity and, more specifically, that SFK-dependent phosphorylation of tyrosine 402 on Dok-R facilitates the inducible recruitment of Csk. We propose that recruitment of Csk to Dok-R serves to bring Csk to c-Src and down-regulate its activity, resulting in a concomitant attenuation of MAPK and Akt/PKB activity. Furthermore, we demonstrate that Dok-R can abrogate c-Src's ability to protect the breast cancer cell line SKBR3 from anoikis and that an association with c-Src and Csk is required for this activity. Collectively these results demonstrate that Dok-R acts as an EGFR-recruited scaffolding molecule that processively assembles c-Src and Csk to attenuate signaling from the EGFR.

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