Regulation of cell proliferation by intermediate-conductance Ca2+-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 Ca2+-activated potassium and volume-sensitive chloride channels in mouse mesenchymal stem cells. Am J Physiol Cell Physiol 295: C1409C1416, 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 Ca2+-activated potassium (IKCa) and volume-sensitive chloride (I-Cl.vol) channels, in regulating proliferation of mouse MSCs. We found that inhibition of IKCa with clotrimazole and I-Cl.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 G(0)/G(1) phase (control: 51.65 +/- 3.43%) by inhibiting IKCa or I-Cl.vol using clotrimazole (2 mu M: 64.45 +/- 2.20%, P < 0.05) or NPPB (200 mu 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 I-Cl.vol channels regulate cell cycle progression and proliferation of mouse MSCs by modulating cyclin D1 and cyclin E expression.