Submitted on May 22, 2008
Revised on August 21, 2008
Accepted on September 16, 2008
Regulation of cell proliferation by intermediate-conductance Ca2+-activated potassium and volume-sensitive chloride channels in mouse mesenchymal stem cells
Rong Tao1, Chu-Pak Lau1, Hung-Fat Tse1, and Gui-Rong Li1*
1 The University of Hong Kong
* To whom correspondence should be addressed. E-mail: grli{at}hkucc.hku.hk.
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 (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 IKCa or ICl.vol channel by specific siRNAs 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%) with application of clotrimazole (2 µM: 64.45±2.20%, P<0.05) or NPPB (200 µM: 82.89±2.49%, P<0.05), as well as with downregulation of the corresponding channel currents and proteins by 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 demonstrated that IKCa and ICl.vol channels regulate cell cycle progression and proliferation of mouse MSCs by modulating cyclin D1 and cyclin E.
