• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.39-39
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• 2003

In our previous study, WEHI-231, an immature B cell line, showed intractable increase in [C $a^{2+}$]$_{c}$ after the B-cell receptor (BCR) ligation and treatment with 2-aminoethoxydiphenylborate (2-APB), which was never observed in Bal-17, a mature B cell line (Nam et al., 2003, FEBS Lett). In this study, a whole cell voltage clamp study revealed a specific expression of a novel type of $K^{+}$ current, namely voltage-independent background-type $K^{+}$ channels (IK-bg), in WEHI-231 cells. IK-bg was dramatically increase by the application of 2-APB (50 $\square$M), which induced severe hyperpolarization of WEHI-231 from -45 ㎷ to -90 ㎷, When dialyzed with $Mg^{2+}$ and ATP-free pipette solution, a spontaneous development of IK-bg and membrane hyperpolarization were observed. IK-bg was insensitive to classical $K^{+}$ channel blockers (TEA, glibenclamide, $Ba^{2+}$(1 mM)), whereas blocked by quinine and quinidine in a voltage-dependent manner ($IC_{50}$/=6~9 $\square$M at +60㎷). Phorbol myrstate, a PKC activator, decreased the amplitude of IK-bg. Extracellular acidification (pH 6.5) slightly inhibited IK-bg. Arachidonic acid, riluzole, or hyposmotic stress could not affect the IK-bg after the full development by the intracellular dialysis with Mg-ATP-free solution. In a cell-attached mode of single channel recording from WEHI231, we found two types of voltage-independent $K^{+}$ channels with unitary conductance of 300 pS and 120 pS, respectively. Both channels showed very short mean open times and their open probabilities were increase by the application of 2-APB. In Bal-17 cells, no such $K^{+}$ current was observed in 50 cells tested. In summary, WEHI-231 immature B cells express background $K^{+}$ channels. The pharmacological properties and the large unitary conductance suggest that novel types of two-pore domain $K^{+}$ channels (2-P-K channels) might be expressed in WEHI-231, which may provide an intriguing targets of signal transduction in the immature B lymphocytes.e B lymphocytes.

• 한국수정란이식학회지
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• 제29권3호
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• pp.249-255
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• 2014

Programmed cell death or apoptosis is associated with changes in $K^+$ concentration in many cell types. Recent studies have demonstrated that two-pore domain $K^+$ ($K_{2P}$) channels are involved in mouse embryonic development and apoptotic volume decrease of mammalian cells. In cerebellar granule neurons that normally undergo apoptosis during the early developmental stage, TASK-1 and TASK-3, members of $K_{2P}$ channels, were found to be critical for cell death. This study was performed to identify the role of $K^+$ channels in the $H_2O_2$-induced or cryo-induced cell death of mouse and bovine embryos. Mouse and bovine two-cell stage embryos (2-cells) exposed to $H_2O_2$ for 4 h suffered from apoptosis. The 2-cells showed positive TUNEL staining. Treatment with high concentration of KCl (25mM) inhibited $H_2O_2$-induced apoptosis of 2-cells by 19%. Cryo-induced death in bovine blastocysts showed positive TUNEL staining only in the cells near the plasma membrane. Cryoprotectant supplemented with 25 mM KCl reduced apoptosis slightly compared to cryoprotectant supplemented with 5 mM KCl. However, the combination of antioxidants (${\beta}$-mercaptoethanol) with 25 mM KCl significantly decreased the rate of $H_2O_2$-induced and cryo-induced apoptosis compared to treatments with only antioxidants or 25 mM KCl. These results show that blockage of $K^+$ channel efflux for a short-time reduces $H_2O_2$- and cryo-induced apoptosis in mouse and bovine embryos. Our findings suggest that apoptosis in mouse and bovine embryos might be controlled by modulation of $K^+$ channels which are highly expressed in a given cell type.

• Experimental and Molecular Medicine
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• 제50권11호
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• pp.4.1-4.13
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• 2018

Two-pore domain $K^+$ (K2P) channels have been shown to modulate neuronal excitability. The physiological role of TWIK-1, the first identified K2P channel, in neuronal cells is largely unknown, and we reported previously that TWIK-1 contributes to the intrinsic excitability of dentate gyrus granule cells (DGGCs) in mice. In the present study, we investigated the coexpression of TWIK-1 and TASK-3, another K2P member, in DGGCs. Immunohistochemical staining data showed that TASK-3 proteins were highly localized in the proximal dendrites and soma of DGGCs, and this localization is similar to the expression pattern of TWIK-1. TWIK-1 was shown to associate with TASK-3 in DGGCs of mouse hippocampus and when both genes were overexpressed in COS-7 cells. shRNA-mediated gene silencing demonstrated that TWIK-1/TASK-3 heterodimeric channels displayed outwardly rectifying currents and contributed to the intrinsic excitability of DGGCs. Neurotensin-neurotensin receptor 1 (NT-NTSR1) signaling triggered the depolarization of DGGCs by inhibiting TWIK-1/TASK-3 heterodimeric channels, causing facilitated excitation of DGGCs. Taken together, our study clearly showed that TWIK-1/TASK-3 heterodimeric channels contribute to the intrinsic excitability of DGGCs and that their activities are regulated by NT-NTSR1 signaling.

• BMB Reports
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• 제55권11호
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• pp.565-570
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• 2022

Pulmonary arterial hypertension (PAH) is a progressive and devastating disease whose pathogenesis is associated with a phenotypic switch of pulmonary arterial vascular smooth muscle cells (PASMCs). Bone morphogenetic protein (BMP) signaling and potassium two pore domain channel subfamily K member 3 (KCNK3) play crucial roles in PAH pathogenesis. However, the relationship between BMP signaling and KCNK3 expression in the PASMC phenotypic switching process has not been studied. In this study, we explored the effect of BMPs on KCNK3 expression and the role of KCNK3 in the BMP-mediated PASMC phenotypic switch. Expression levels of BMP receptor 2 (BMPR2) and KCNK3 were downregulated in PASMCs of rats with PAH compared to those in normal controls, implying a possible association between BMP/BMPR2 signaling and KCNK3 expression in the pulmonary vasculature. Treatment with BMP2, BMP4, and BMP7 significantly increased KCNK3 expression in primary human PASMCs (HPASMCs). BMPR2 knockdown and treatment with Smad1/5 signaling inhibitor substantially abrogated the BMP-induced increase in KCNK3 expression, suggesting that KCNK3 expression in HPASMCs is regulated by the canonical BMP-BMPR2-Smad1/5 signaling pathway. Furthermore, KCNK3 knockdown and treatment with a KCNK3 channel blocker completely blocked BMP-mediated anti-proliferation and expression of contractile marker genes in HPAMSCs, suggesting that the expression and functional activity of KCNK3 are required for BMP-mediated acquisition of the quiescent PASMC phenotype. Overall, our findings show a crosstalk between BMP signaling and KCNK3 in regulating the PASMC phenotype, wherein BMPs upregulate KCNK3 expression and KCNK3 then mediates BMP-induced phenotypic switching of PASMCs. Our results indicate that the dysfunction and/or downregulation of BMPR2 and KCNK3 observed in PAH work together to induce aberrant changes in the PASMC phenotype, providing insights into the complex molecular pathogenesis of PAH.