Differential Ca2+ signaling induced by activation of the epidermal growth factor and nerve growth factor receptors.
Stimulation by epidermal growth factor (EGF) of NIH3T3 cells overexpressing the EGF receptor (EGFR) results in a release of Ca2+ from internal stores. Ca2+ release is followed by an influx of extracellular calcium which can be recorded by the influx of the calcium surrogate Mn2+. Both Ca2+ release and Mn2+/Ca2+ influx are inhibited by expression of the dominant negative Asn17-Ras mutant and abrogated by microinjected neutralizing anti-Ras antibody Y13-259, whereas microinjection of the anti-Ras antibody Y13-238 which does not interact with the effector binding domain of Ras is without any effect on the EGF-induced Ca2+ transient. Neither Asn17-Ha-Ras nor the Y13-259 antibody interferes with the thapsigargin-induced Mn2+/Ca2+ influx. The nerve growth factor receptor (Trk)-mediated Ca2+ transient was found to be unaffected by the dominant negative Ras mutant or microinjected neutralizing anti-Ras antibodies. Substitution of the phospholipase Cgamma1 (PLCgamma1) binding site of the EGFR by the PLCgamma binding domain of Trk renders the EGFR-induced Ca2+ influx insensitive to the expression of Asn17-Ha-Ras, whereas the Ca2+ signal induced by Trk carrying the PLC binding site of EGFR is Ras-dependent and abrogated by the dominant negative Ras mutant. It is concluded that the Ca2+ transient induced by the activated EGFR, not, however, the Ca2+ transient elicited by the activated NGFR/Trk, is a Ras-mediated phenomenon and that the role of Ras in regulating EGFR-induced Ca2+ influx depends on the structure of the PLCgamma binding domain.
Tinhofer
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I
Department of Medical Chemistry and Biochemistry, University of Innsbruck, Fritz-Pregl-Strasse 3, 6020 Innsbruck, Austria. Karl.Maly@uibk.ac.at
Maly
K
K
Dietl
P
P
Hochholdinger
F
F
Mayr
S
S
Obermeier
A
A
Grunicke
H H
HH
D016475:3T3 Cells; D000818:Animals; D002118:Calcium / Q000502:physiology*; D003600:Cytosol / Q000502:physiology; D066246:ErbB Receptors / Q000502:physiology*; D007527:Isoenzymes / Q000502:physiology; D051379:Mice; D051966:Phospholipase C gamma; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology; D017475:Receptors, Nerve Growth Factor / Q000502:physiology*; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000502:physiology
D007527:Isoenzymes; D017475:Receptors, Nerve Growth Factor; D066246:ErbB Receptors; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D016283:Proto-Oncogene Proteins p21(ras); D002118:Calcium