Expression of TASK-2 and its upregulation by B cell receptor stimulation in WEHI-231 mouse immature B cells

Stimulation of B cell receptors (BCR ligation) induces apoptosis of immature B cells, which is critical to the elimination of self-reactive clones. In the mouse immature B cell line WEHI-231, the authors previously reported two types of background K+ channels with large (∼300 pS, LKbg) and medium (∼100 pS, MKbg) conductance in divalent cation-free conditions. While the authors have recently identified LKbg as TREK-2, the molecular nature of MKbg is unknown yet. In the present study, the authors found that BCR ligation markedly increased the background K+ conductance of WEHI-231. A single-channel study revealed that MKbg activity is increased by BCR ligation and that the biophysical properties (unitary conductance and pH sensitivity) of MKbg are consistent with those of TWIK-related acid-sensitive K+ channel 2 (TASK-2). The expression of TASK-2 and its upregulation by BCR ligation were confirmed by RT-PCR and immunoblot assays in WEHI-231. The BCR ligation-induced increase of K+ current was prevented by ca...