Laboratory of Immunobiology and Ionic Transport Regulation, University Center for Biomedical Research, University of Colima, Colima, Mexico.
Department of Molecular Biomedicine, CINVESTAV-IPN, Mexico City, Mexico.
Cell Physiol Biochem. 2020 Sep 5;54(5):842-852. doi: 10.33594/000000273.
BACKGROUND/AIMS: Kv1.3 channel is the only voltage-dependent potassium channel in plasma membrane of human lymphocytes. Bearing in mind a rather steep voltage-dependence of Kv1.3 activation and inactivation, its modulation by B and T cells activation and by co-culture with stromal bone-marrow cells was addressed.
Patch-clamp technique in the whole cell mode was applied to human resting and activated human B and T cells, in monoculture and co-culture with stromal OP9 cells.
Polyclonal activation of B and T cells in monoculture caused Kv1.3 current in B cells to activate at more negative and in T cells at more positive potentials, whereas the inactivation of Kv1.3 current in resting T cells occurred at more negative voltages. Co-culture with OP9 cells abolished the shift of voltage dependence upon the polyclonal activation but fixed the substantial difference between B and T cells, resting or activated, with both activation and inactivation negatively shifted by 15 mV for T lymphocytes. However, activated B cells displayed an incomplete inactivation, which was augmented by the co-culture. Neither activation nor co-culture caused substantial changes in the Kv1.3 current density.
The combination of activation and inactivation processes yields the fraction of steady-state Kv1.3 current (window current), which was higher in activated B cells, partly due to an incomplete inactivation. A relatively smaller window current in resting B cells and resting T cells in co-culture correlated with a more depolarized resting membrane potential. Rather than insignificant changes in the Kv1.3 channels functional expression, the modulation of their voltage dependence by activation and co-culture with bone-marrow stromal cells was essential for the control of membrane potential.
背景/目的：Kv1.3 通道是人类淋巴细胞质膜上唯一的电压依赖性钾通道。鉴于 Kv1.3 的激活和失活具有相当陡峭的电压依赖性，本研究探讨了 B 和 T 细胞激活以及与基质骨髓细胞共培养对其的调制作用。
采用全细胞膜片钳技术，在单核培养和与基质 OP9 细胞共培养的情况下，研究了静止和激活的人类 B 和 T 细胞中的 Kv1.3 电流。
单核培养中 B 和 T 细胞的多克隆激活导致 B 细胞中的 Kv1.3 电流在更负的电位下激活，而 T 细胞中的 Kv1.3 电流在更负的电压下失活。与 OP9 细胞共培养消除了多克隆激活对电压依赖性的转变，但固定了静止或激活的 B 和 T 细胞之间的显著差异，T 淋巴细胞的激活和失活均负向移动 15 mV。然而，激活的 B 细胞显示出不完全失活，共培养增强了这种失活。激活或共培养均未导致 Kv1.3 电流密度的实质性变化。
激活和失活过程的结合产生了稳态 Kv1.3 电流的分数（窗口电流），激活的 B 细胞中的窗口电流更高，部分原因是不完全失活。在共培养中，静止的 B 细胞和静止的 T 细胞的窗口电流较小，与更去极化的静息膜电位相关。激活和与骨髓基质细胞的共培养对 Kv1.3 通道电压依赖性的调节对于控制膜电位至关重要，而不是 Kv1.3 通道功能表达的无意义变化。
