Regulation of cell proliferation by intermediate-conductance Ca -activated potassium and volume-sensitive chloride channels in mouse mesenchymal stem cells

Tao R, Lau CP, Tse HF, Li GR. Regulation of cell proliferation by intermediate-conductance Ca -activated potassium and volumesensitive chloride channels in mouse mesenchymal stem cells. Am J Physiol Cell Physiol 295: C1409–C1416, 2008. First published September 24, 2008; doi:10.1152/ajpcell.00268.2008.—Bone marrow mesenchymal stem cells (MSCs) are a promising cell source for regenerative medicine; however, their cellular physiology is not fully understood. The present study aimed at exploring the potential roles of the two dominant functional ion channels, intermediate-conductance Ca -activated potassium (IKCa) and volume-sensitive chloride (ICl.vol) channels, in regulating proliferation of mouse MSCs. We found that inhibition of IKCa with clotrimazole and ICl.vol with 5-nitro-1-(3-phenylpropylamino) benzoic acid (NPPB) reduced cell proliferation in a concentration-dependent manner. Knockdown of KCa3.1 or Clcn3 with specific short interference (si)RNAs significantly reduced IKCa or ICl.vol density and channel protein and produced a remarkable suppression of cell proliferation (by 24.4 9.6% and 29.5 7.2%, respectively, P 0.05 vs. controls). Flow cytometry analysis showed that mouse MSCs retained at G0/G1 phase (control: 51.65 3.43%) by inhibiting IKCa or ICl.vol using clotrimazole (2 M: 64.45 2.20%, P 0.05) or NPPB (200 M: 82.89 2.49%, P 0.05) or the specific siRNAs, meanwhile distribution of cells in S phase was decreased. Western blot analysis revealed a reduced expression of the cell cycle regulatory proteins cyclin D1 and cyclin E. Collectively, our results have demonstrated that IKCa and ICl.vol channels regulate cell cycle progression and proliferation of mouse MSCs by modulating cyclin D1 and cyclin E expression.