Regulation of cell proliferation by intermediate-conductance [Ca.sup.2+]-activated potassium and volume-sensitive chloride channels in mouse mesenchymal stem cells

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.sup.2+]-activated potassium ([IK.sub.Ca]) and volume-sensitive chloride ([I.sub.Cl.vol]) channels, in regulating proliferation of mouse MSCs. We found that inhibition of [IK.sub.Ca] with clotrimazole and [I.sub.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 [IK.sub.Ca] or [I.sub.cl.vol] density and channel protein and produced a remarkable suppression of cell proliferation (by 24.4 [+ or -] 9.6% and 29.5 [+ or -] 7.2%, respectively, P < 0.05 vs. controls). Flow cytometry analysis showed that mouse MSCs retained at [G.sub.0]/[G.sub.1] phase (control: 51.65 [+ or -] 3.43%) by inhibiting [[K.sub.Ca] or [I.sub.Cl.vol] using clotrimazole (2 [micro]M: 64.45 [+ or -] 2.20%, P < 0.05) or NPPB (200 [micro]M: 82.89 [+ or -] 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 [IK.sub.Ca] and [I.sub.Cl.vol] channels regulate cell cycle progression and proliferation of mouse MSCs by modulating cyclin D1 and cyclin E expression. intermediate conductance [Ca.sub.2+]-activated [K.sup.+] current; volume sensitive [Cl.sup.-] current; cell cycle progression; short interference RNA