Transforming potentials of epidermal growth factor and nerve growth factor receptors inversely correlate with their phospholipase C gamma affinity and signal activation.

Abstract

The exchange of nerve growth factor receptor/Trk and epidermal growth factor receptor (EGFR) phospholipase C gamma (PLC gamma) binding sites resulted in the transfer of their distinct affinities for this Src homology 2 domain‐containing protein. Relative to wild‐type EGFR, the PLC gamma affinity increase of the EGFR switch mutant EGFR.X enhanced its inositol trisphosphate (IP3) and calcium signals and resulted in a more sustained mitogen‐activated protein (MAP) kinase activation and accelerated receptor dephosphorylation. In parallel, EGFR.X exhibited a significantly decreased mitogenic and transforming potential in NIH 3T3 cells. Conversely, the transfer of the EGFR PLC gamma binding site into the Trk cytoplasmic domain context impaired the IP3/calcium signal and attenuated the MAP kinase activation and receptor dephosphorylation, but resulted in an enhancement of the ETR.X exchange mutant mitogenic and oncogenic capacity. Our findings establish the significance of PLC gamma affinity for signal definition, the role of this receptor tyrosine kinase substrate as a negative feedback regulator and the importance of this regulatory function for mitogenesis and its disturbance in oncogenic aberrations.

Differential Ca2+ Signaling Induced by Activation of the Epidermal Growth Factor and Nerve Growth Factor Receptors

“…In order to address this question, Ca 2ϩ transients induced by activation of epidermal growth factor receptor (EGFR) 1 and nerve growth factor receptor (NGFR/Trk) were investigated.…”

“…Both receptors are known to activate Ras and to cause an elevation of cytosolic free Ca 2ϩ (1,(12)(13)(14). The studies presented here were performed with NIH3T3 cells overexpressing either EGFR or an EGFR/Trk chimeric receptor consisting of an extracellular EGFR domain and the cytosolic domain of Trk as described previously (1).…”

“…The studies presented here were performed with NIH3T3 cells overexpressing either EGFR or an EGFR/Trk chimeric receptor consisting of an extracellular EGFR domain and the cytosolic domain of Trk as described previously (1). This system permits the study of both receptors in the same cellular environment employing the same agonist.…”

“…When expressed in fibroblasts, however, activation of NGFR causes a proliferative response (20). Both receptors have been shown to activate a phosphatidylinositol-specific phospholipase C, resulting in the generation of inositol 1,4,5-trisphosphate (IP 3 ) and a release of Ca 2ϩ from intracellular stores (1). In fibroblasts, Ca 2ϩ -release is followed or accompanied by an enhanced influx of Ca 2ϩ through voltageindependent Ca 2ϩ channels of the plasma membrane (21,22).…”

Mutation of Threonine 766 in the Epidermal Growth Factor Receptor Reveals a Hotspot for Resistance Formation against Selective Tyrosine Kinase Inhibitors

“…Human EGFR cDNA was either cloned in the expression vector pRK5 or in the retroviral expression vector pLXSN, which allows moderate protein expression upon transient plasmid transfection (11,12). pcDNA3-HA-ERK2 has been described previously (10).…”