Expression and Modulation of the Intermediate- Conductance Ca2+-Activated K+ Channel in Glioblastoma GL-15 Cells
- 1 January 2006
- journal article
- Published by S. Karger AG in Cellular Physiology and Biochemistry
- Vol. 18 (1-3), 47-56
- https://doi.org/10.1159/000095135
Abstract
We report here the expression and properties of the intermediate-conductance Ca(2+)-activated K(+) (IK(Ca)) channel in the GL-15 human glioblastoma cell line. Macroscopic IK(Ca) currents on GL-15 cells displayed a mean amplitude of 7.2+/-0.8 pA/pF at 0 mV, at day 1 after plating. The current was inhibited by clotrimazole (CTL, IC(50)=257 nM), TRAM-34 (IC(50)=55 nM), and charybdotoxin (CTX, IC(50)=10.3 nM). RT-PCR analysis demonstrated the expression of mRNA encoding the IK(Ca) channel in GL-15 cells. Unitary currents recorded using the inside-out configuration had a conductance of 25 pS, a K(D) for Ca(2+) of 188 nM at -100 mV, and no voltage dependence. We tested whether the IKCa channel expression in GL-15 cells could be the result of an increased ERK activity. Inhibition of the ERK pathway with the MEK antagonist PD98059 (25 muM, for 5 days) virtually suppressed the IK(Ca) current in GL-15 cells. PD98059 treatment also increased the length of cellular processes and up-regulated the astrocytic differentiative marker GFAP. A significant reduction of the IKCa current amplitude was also observed with time in culture, with mean currents of 7.17+/-0.75 pA/pF at 1-2 days, and 3.11+/-1.35 pA/pF at 5-6 days after plating. This time-dependent downregulation of the IK(Ca) current was not accompanied by changes in the ERK activity, as assessed by immunoblot analysis. Semiquantitative RT-PCR analysis demonstrated a ~35% reduction of the IK(Ca) channel mRNA resulting from ERK inhibition and a approximately 50% reduction with time in culture.Keywords
This publication has 51 references indexed in Scilit:
- Selective intermediate‐/small‐conductance calcium‐activated potassium channel (KCNN4) blockers are potent and effective therapeutics in experimental brain oedema and traumatic brain injury caused by acute subdural haematomaEuropean Journal of Neuroscience, 2004
- K+ channels as targets for specific immunomodulationTrends in Pharmacological Sciences, 2004
- Inhibition of the antigen-induced activation of RBL-2H3 cells by cetiedil and some of its analoguesEuropean Journal of Pharmacology, 2003
- Design of a potent and selective inhibitor of the intermediate-conductance Ca2+-activated K+channel,IKCa1: A potential immunosuppressantProceedings of the National Academy of Sciences of the United States of America, 2000
- Characterization of the cloned human intermediate-conductance Ca2+-activated K+channelAmerican Journal of Physiology-Cell Physiology, 1998
- Calcium-activated potassium channelsCurrent Opinion in Neurobiology, 1998
- The antifungal antibiotic, clotrimazole, inhibits chloride secretion by human intestinal T84 cells via blockade of distinct basolateral K+ conductances. Demonstration of efficacy in intact rabbit colon and in an in vivo mouse model of cholera.JCI Insight, 1997
- A Novel Gene, hKCa4, Encodes the Calcium-activated Potassium Channel in Human T LymphocytesPublished by Elsevier BV ,1997
- A human intermediate conductance calcium-activated potassium channelProceedings of the National Academy of Sciences of the United States of America, 1997
- hSK4, a member of a novel subfamily of calcium-activated potassium channelsProceedings of the National Academy of Sciences of the United States of America, 1997