Role of Kv channel activity in TNF– induced NFB activation and corneal epithelial cell survival

Abstract

Abstract: : Purpose: Previous studies demonstrate that Kv channels play important roles in regulating corneal epithelial cell proliferation, differentiation and apoptosis. The purpose of this study is to investigate the involvement of Kv channels in TNF–α –induced signaling pathways in the survival of corneal epithelial cells. Methods: Human corneal epithelial (HCE) cells were cultured in DMEM/F–12 medium containing 10% FBS. Kv channel activity in HCE cells was measured by using patch clamp techniques. Cell cycle progression was measured by cell cycle mapping using flow cytometer analysis. Intracellular signaling pathways and DNA binding activity were detected by Western blot and EMSA. Results: 1) Kv channel activities in HCE cells were regulated by TNF–α. Patch clamping studies indicated that TNF–α induced a modulate activation of Kv channel under the patch clamping condition. 2) TNF–α induced NFΚB nuclear translocation and increases in DNA binding activity of NFΚB. 3) Suppression of Kv channel activity by 4–AP, a specific K channel blocker, effectively prevented NFΚB nuclear translocation and DNA binding ability in response to stimulation of TNF–α. 4) TNF–α stimulation did not elicit activation of JNK signaling pathway suggesting a variation of this pathway in HCE cells. 5) TNF–α induced NFΚB activation increased DNA synthesis and prevented cell apoptosis in HCE cells. Conclusions: In HCE cells, TNF–α induces NFΚB activation without involving JNK signaling pathway. Activation of TNF–α signaling pathways promotes cell survival through regulation of a Kv channel activity.

Keywords: cornea: epithelium • cytokines/chemokines • ion channels