E. Browaeyspoly et al., FIBROBLAST AND EPIDERMAL GROWTH-FACTOR RECEPTOR EXPRESSION IN XENOPUSOOCYTES DISPLAYS DISTINCT CALCIUM OSCILLATORY PATTERNS, Biochimica et biophysica acta. Molecular cell research, 1404(3), 1998, pp. 484-489
Electrophysiological study performed with the voltage clamp technique
was used to examine the intracellular calcium pathway activated by tyr
osine kinase receptor members. Three FGF receptors from Pleurodeles PR
1, PR3, PR4, homologs to human receptors, and the human EGF receptor w
ere expressed in Xenopus oocytes. Under FGF1, FGF2 and FGF4 stimulatio
n, PR1 and PR3 display a one phase inward chloride calcium dependent c
urrent superimposed by sustained oscillations, whereas PR4 did not sho
w any oscillations. These currents were dependent on intracellular cal
cium mobilisation, as the responses were reduced by caffeine (10 mM. S
olely PR4 responses were affected by an extracellular calcium depleted
solution suggesting the involvement of concomitant extracellular and
intracellular calcium intervention in the calcium chloride current, wh
ereas PR1 and PR3 did not. Under EGF stimulation, the EGF receptor eli
cits a two component inward current composed of an undelayed rapid tra
nsient dependent on intracellular calcium store recruitment followed b
y a second slower current dependent on calcium influx. The specific pa
ttern and amplitude of the calcium oscillations induced by the combina
torial action of growth factors on their receptors could be relevant i
n numerous calcium dependent cell functions. 0167-4889/98/$ - see fron
t matter (C) 1998 Published by Elsevier Science B.V, All rights reserv
ed.