Higher expression of KCNK10 (TREK-2) K+ channels and their functional upregulation by lipopolysaccharide treatment in mouse peritoneal B1a cells.

Si Won Choi, Joohan Woo, Kyung Sun Park, Juyeon Ko, Young Keul Jeon, Seong Woo Choi, Hae Young Yoo, Inseong Kho, Tae Jin Kim, Sung Joon Kim

Pflugers Archiv : European journal of physiology 2021 Apr

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Innate-like CD5+ B1a cells localized in serous cavities are activated by innate stimuli, such as lipopolysaccharide (LPS), leading to T cell-independent antibody responses. Although ion channels play crucial roles in the homeostasis and activation of immune cells, the electrophysiological properties of B1a cells have not been investigated to date. Previously, in the mouse B cell lymphoma cells, we found that the voltage-independent two-pore-domain potassium (K2P) channels generate a negative membrane potential and drive Ca2+ influx. Here, we newly compared the expression and activities of K2P channels in mouse splenic follicular B (FoB), marginal zone B (MZB), and peritoneal B1a cells. Next-generation sequencing analysis showed higher levels of transcripts for TREK-2 and TWIK-2 in B1a cells than those in FoB or MZB cells. Electrophysiological analysis, using patch clamp technique, revealed higher activity of TREK-2 with the characteristic large unitary conductance (~ 250 pS) in B1a than that in FoB or MZB cells. TREK-2 activity was further increased by LPS treatment (>2 h), which was more prominent in B1a than that in MZB or FoB cells. The cytosolic Ca2+ concentration of B cells was decreased by high-K+-induced depolarization (ΔRKCl (%)), suggesting the basal Ca2+ influx to be driven by negative membrane potential. The LPS treatment significantly increased the ΔRKCl (%) in B1a, though not in FoB and MZB cells. Our study was the first to compare the K2P channels in mouse primary B cell subsets, elucidating the functional upregulation of TREK-2 and augmentation of Ca2+ influx by the stimulation of Toll-like receptor 4 in B1a cells.

Citation

Si Won Choi, Joohan Woo, Kyung Sun Park, Juyeon Ko, Young Keul Jeon, Seong Woo Choi, Hae Young Yoo, Inseong Kho, Tae Jin Kim, Sung Joon Kim. Higher expression of KCNK10 (TREK-2) K+ channels and their functional upregulation by lipopolysaccharide treatment in mouse peritoneal B1a cells. Pflugers Archiv : European journal of physiology. 2021 Apr;473(4):659-671