Potassium channel expression level is dependent on the proliferation state in the GH3 pituitary cell line.
Previously, we showed that the peak density of the transient outward K(+) current (I(to)) expressed in GH3 cells was different in the S phase than in other phases of the cell cycle. Using cell synchronization, we show here that I(to) drops precisely at the quiescent (G(0) phase)/proliferating transition. This change is not due to a modification in the voltage dependence of I(to), but rather to a modification in its inactivation kinetics. Molecular determination of K(+) channel subunits showed that I(to) required the expression of Kv1.4, Kv4.1, and Kv4.3. We found that the increase in I(to) density during the quiescent state was accompanied by an increase in Kv1.4 protein expression, whereas Kv4.3 expression remained unchanged. We further demonstrate that the link between I(to) expression and cell proliferation is not mediated by variations in cell excitability. These results provide new evidence for the cell cycle dependence of I(to) expression, which could be relevant in understanding the mechanisms leading to pituitary adenomas.
Czarnecki
Antonny
A
Laboratoire de Physiologie et Physiopathologie de la Signalisation Cellulaire, CNRS UMR 5543, Université de Bordeaux 2, 33076 Cedex Bordeaux, France.
Dufy-Barbe
Luce
L
Huet
Sylvie
S
Odessa
Marie-Francoise
MF
Bresson-Bepoldin
Laurence
L
D000818:Animals; D002453:Cell Cycle; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D004594:Electrophysiology; D016193:G1 Phase / Q000502:physiology; D051665:Kv1.4 Potassium Channel; D010902:Pituitary Gland / Q000166:cytology* / Q000378:metabolism* / Q000502:physiology; D015221:Potassium Channels / Q000378:metabolism* / Q000502:physiology; D024642:Potassium Channels, Voltage-Gated; D016192:Resting Phase, Cell Cycle / Q000502:physiology; D051672:Shal Potassium Channels; D013997:Time Factors
D051665:Kv1.4 Potassium Channel; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D051672:Shal Potassium Channels