[Functional analysis of the alpha1G subunit of the T-type calcium channel in cellular proliferation].
Increases of functional T-type calcium channel (T-channel) expression have been associated with cellular proliferation although evidence for this remains controversial. In the present study, we have used a variety of cellular, molecular and electrophysiological techniques to test the hypothesis that T-type channels play a causal role in the signaling pathway leading to proliferation. The results showed that stable over-expression of alpha1G T-channel subunit in HEK-293 cells conferred a significant growth advantage. Thus, cell population doubling time was reduced to 13.7 +/- 0.3 h in alpha1G transfectants, compared to control cultures (22.1 +/- 1.1 h) and flow cytometry analysis showed that this was due to a reduction in the number of alpha1G transfectants residing in the G0/G1 phases of the cell cycle compared to controls. The selective T-type calcium channel blocker, mibefradil, induced a dose-dependent inhibition of proliferation in alpha1G tansfectants. Furthermore, the Western blotting results proved that the level of protein expression of CDK2, cyclin A and cyclin E was high in alpha1G transfectants compared to control cultures. Our results demonstrate that the T-type calcium channel provides a significant growth advantage to HEK-293 cells that might occur via effects on the G1/S cell cycle mechanism.
Wang
Yue Qun
YQ
College of Life Science, Hunan Normal University, Changsha 410081.
Brooks
Gavin
G
Yuan
Wu Zhou
WZ
Zhu
Chuan Bin
CB
Li
Yong Qing
YQ
Wu
Xiu Shan
XS
D015153:Blotting, Western; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020747:Calcium Channels, T-Type / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D019925:Cyclin A / Q000378:metabolism; D019927:Cyclin E / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D020748:Mibefradil / Q000494:pharmacology; D021122:Protein Subunits / Q000235:genetics / Q000502:physiology*
D002121:Calcium Channel Blockers; D020747:Calcium Channels, T-Type; D019925:Cyclin A; D019927:Cyclin E; D021122:Protein Subunits; D020748:Mibefradil; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2