Role of voltage-gated potassium channels in the fate determination of embryonic stem cells

Embryonic stem cells (ESCs) possess two unique characteristics: self-renewal and pluripotency. In this study, roles of voltage-gated potassium channels (K_v) in maintaining mouse (m) ESC characteristics were investigated. Tetraethylammonium (TEA⁺), a K_v blocker, attenuated cell proliferation in a concentration-dependent manner. Possible reasons for this attenuation, including cytotoxicity, cell cycle arrest and differentiation, were examined. Blocking K_v did not change the viability of mESCs. Interestingly, K_v inhibition increased the proportion of cells in G₀/G₁ phase and decreased that in S phase. This change in cell cycle distribution can be attributed to cell cycle arrest or differentiation. Loss of pluripotency as determined at both molecular and functional levels was detected in mESCs with K_v blockade, indicating that K_v inhibition in undifferentiated mESCs directs cells to differentiate instead of to self-renew and progress through the cell cycle. Membrane potential measurement revealed that Kv blockade led to depolarization, consistent with the role of K_v as the key determinant of membrane potential. The present results suggest that membrane potential changes may act as a "switch" for ESCs to decide whether to proliferate or to differentiate: hyperpolarization at G1 phase would favor ESCs to enter S phase while depolarization would favor ESCs to differentiate. Consistent with this notion, S-phase-synchronized mESCs were found to be more hyperpolarized than G₀/G₁-phase-synchronized mESCs. Moreover, when mESCs differentiated, the differentiation derivatives depolarized at the initial stage of differentiation. This investigation is the first study to provide evidence that Kv and membrane potential affect the fate determination of ESCs.