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Cell surface restriction of EGFR by a tenascin cytotactin‐encoded EGF‐like repeat is preferential for motility‐related signaling
Author(s) -
Iyer Anand Krishnan V.,
Tran Kien T.,
Griffith Linda,
Wells Alan
Publication year - 2008
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.21232
Subject(s) - internalization , microbiology and biotechnology , signal transduction , epidermal growth factor , mapk/erk pathway , epidermal growth factor receptor , receptor , extracellular , cell signaling , autocrine signalling , cell surface receptor , biology , chemistry , biochemistry
The 14th EGFL‐repeat (Ten14) of human tenascin cytotactin activates the epidermal growth factor receptor (EGFR) with micromolar affinity; however, unlike EGF, Ten14‐mediated activation of EGFR does not lead to receptor internalization. As the divergent signaling pathways downstream of EGFR have been shown to be triggered from plasma membrane and cytosolic locales, we investigated whether Ten14‐mediated surface restriction of EGFR resulted in altered biochemical and cellular responses as compared to EGF. Molecules associated with migratory cascades were activated to a relatively greater extent in response to Ten14, with very weak activation of proliferation‐associated cascades. Activation of phospholipase C γ (PLCγ) and m‐calpain, associated with lamellipod protrusion and tail retraction, respectively, were noted at even at sub‐saturating doses of Ten14. However, activation of ERK/MAPK, p90RSK, and Elk1, factors affecting proliferation, remained low even at high Ten14 concentrations. Similar activation profiles were observed for EGF‐treated cells at 4°C, a maneuver that limits receptor internalization. We demonstrate a concurrent effect of such altered signaling on biophysical responses—sustained migration was observed at levels of Ten14 that activated PLCγ, but did not stimulate proliferation significantly. Here, we present a novel class of EGFR ligands that can potentially signal as a part of the extracellular matrix, triggering specific intracellular signaling cascades leading to a directed cellular response from an otherwise pleiotropic receptor. This work extends the signaling paradigm of EGFL repeat being presented in a restricted fashion as part of the extracellular matrix. J. Cell. Physiol. 214: 504–512, 2008. © 2007 Wiley‐Liss, Inc.