Referenced in: none

Automatically associated channels: Kv1.1 , Kv1.2 , Kv1.3 , Kv1.4 , Kv3.1 , Kv3.4

Title: IGF-1 up-regulates K+ channels via PI3-kinase, PDK1 and SGK1.

Authors: N Gamper, S Fillon, S M Huber, Y Feng, T Kobayashi, P Cohen, F Lang

Journal, date & volume: Pflugers Arch., 2002 Feb , 443, 625-34

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/11907830

Abstract
Involvement of voltage-gated (Kv) potassium channels in IGF-1-induced proliferation of HEK293 cells was studied by patch-clamp, RT-PCR and FACS analysis. IGF-1 up-regulated outwardly rectifying whole-cell K+ current starting after 1 h of incubation and reaching a maximum after 4-6 h. The IGF-1-stimulated current was voltage-gated with an activation threshold of -30 mV to -40 mV, a half-maximal activation at +5.3+/-1.8 mV, and time constants for activation and inactivation of 4.5+/-0.4 ms and 43.5+/-5.6 ms ( n=10), respectively. The current was inhibited by TEA, margatoxin, agitoxin-2 and stichodactyla toxin. PCR amplification of different Kv subunits from HEK293 cDNA demonstrated the expression of Kv1.1, Kv1.2, Kv1.3, Kv1.4, Kv3.1 and Kv3.4 mRNA. Quantitative RT-PCR showed up-regulation of Kv1.1, 1.2 and 1.3 mRNA by IGF-1. The effect of IGF-1 on K+ current was blocked by inhibitors of phosphatidylinositol 3-kinase (PI3-kinase), wortmannin and LY294002, and mimicked by overexpression of human 3-phosphoinositide-dependent protein kinase-1 (hPDK1) or serum- and glucocorticoid-dependent kinase-1 (hSGK1), both sequential downstream targets of PI3-kinase. IGF-1-induced proliferation of HEK293 cells was inhibited by both K+ channel blockers and inhibitors of PI3-kinase. In conclusion, IGF-1 through PI3-kinase, PDK1 and SGK1 up-regulates Kv channels, an effect required for the proliferative action of the growth factor.