The nuclear chloride ion channel NCC27 is involved in regulation of the cell cycle

1. NCC27 is a nuclear chloride ion channel, identified in the PMA-activated U937 human monocyte cell line. NCC27 mRNA is expressed in virtually all ce lls and tissues and the gene encoding NCC27 is also highly conserved. Becau se of these factors, we have examined the hypothesis that NCC27 is involved in cell cycle regulation. 2. Electrophysiological studies in Chinese hamster ovary (CHO-K1) cells ind icated that NCC27 chloride conductance varied according to the stage of the cell cycle, being expressed only on the plasma membrane of cells in G2/M p hase. 3. We also demonstrate that Cl- ion channel blockers known to block NCC27 l ed to arrest of CHO-K1 cells in the Q2/M stage of the cell cycle, the same stage at which this ion channel is selectively expressed on the plasma memb rane. 4. These data strongly support the hypothesis that NCC27 is involved, in so me as vet undetermined manner, in regulation of the cell cycle.