Epidermal Growth Factor Stimulates Cell Proliferation by Activating Voltage-Gated Potassium Channels in Rat Bone Marrow-Derived Mesenchymal Stem Cells

Poster PresentationBackground and objective: We have previously found that voltage-gated delayed rectifier potassium current (IKDR, encoded by Kv1.2 and Kv2.1) participated in regulation of cell cycling progression in rat mesenchymal stem cells (MSCs) from bone marrow. The present study was designed to investigate whether epidermal growth factor (EGF) regulates cell growth is mediated by activating IKDR. Methods: Whole-cell patch voltage-clamp, RT-PCR, Western blots, siRNA, cell proliferation assay were employed in the present study Results: EGF increased cell proliferation in a concentration-dependent manner, and the effect was countered by the broad spectrum protein tyrosine (PTK) inhibitor genistein and the EGFR kinase inhibitor AG556. We found that genistein and AG556 inhibited IKDR in a concentration-dependent manner, The protein tyrosine phosphatase (PTP) inhibitor orthovanadate enhanced IKDR, and counted the inhibitory effect of IKDR by genistein or AG556, suggesting the PTK-mediating modulation of IKDR. Interestingly EGF also increased IKDR, Downregulation of IKDR with siRNA targeting to Kv1.2 or Kv2.1 channels inhibited basal proliferation, and prevented EGF-stimulated proliferation in rat MSCs. Conclusion: These results demonstrate for the first time that EGF stimulates cell proliferation activating IKDR, and silencing Kv1.2 or Kv2.1 channels prevents the augmentation of proliferation by EFG, indicating that Kv1.2 and Kv2.1 channels mediate EGF effect in regulating cell growth in rat MSCs.published_or_final_versio