Regulatory mechanisms of activity and expression of voltage-gated proton channels

在大鼠小胶质细胞和小鼠破骨细胞中研究了负责控制电压门控质子（H^+）通道活性和表达的机制。在小胶质细胞中，细胞酸中毒，无论是细胞外乳酸酸中毒还是用酸性移液管溶液透析细胞，都会诱导细胞肿胀。H^+电流随着细胞肿胀而增加，这是由于半激活电压向更负的电位移动以及激活动力学的加速。酸中毒诱导的细胞肿胀和伴随的H^+电流增强需要细胞内ATP的非水解结合，并被影响肌动蛋白丝的物质（鬼笔环肽和细胞松弛素D）抑制。H^+通道的这种增强作用可能作为一种负反馈机制发挥作用，以保护小胶质细胞免受病理性CNS中细胞毒性酸中毒诱导的肿胀。在某些细胞中，H^+电流的振幅以10-30 min的间隔波动。小鼠破骨细胞基因 ...更多信息 在存在sRANK配体的情况下，从骨髓细胞中提取的H2 O2也表现出类似的H^+电流，其特征是依赖于细胞内和细胞外的pH值、外向整流、缓慢的激活动力学和被Zn^2+阻断。细胞核[大于或等于]6个的电流密度显著小于细胞核[小于或等于]5个的电流密度，但激活率不变。此外，在骨髓细胞与基质细胞系（ST 2）共培养产生的破骨细胞中，H^+电流很小或可以忽略不计。因此，在破骨细胞生成过程中，H^+通道的表达或活性通道的数量可能发生改变。在大多数[大于或等于]6个细胞核的细胞中，NADPH氧化酶的活性较低，这表明H^+通道和NADPH氧化酶的活性可能与破骨细胞的功能状态相关。本研究为小胶质细胞和破骨细胞中H^+通道的表达和活性受其细胞条件和分化过程的强烈控制提供了证据。少

Mechanisms responsible for controlling the activity and expression of the voltage-gated proton (H^+) channels were studied in rat microglia and murine osteoclasts. In microglia, cell acidosis, either by extracellular lactoacidosis or by dialyzing cells with an acidic pipette solution induced cell swelling The H^+ current was increased in association with the cell swelling by a shift of the half-activation voltage to more negative potentials and by acceleration of the activation kinetics. The acidosis-induced cell swelling and the accompanying potentiation of the H^+ current required non-hydrolytic binding of intracellular ATP and were inhibited by agents affecting actin filaments (phalloidin and cytochalasin D). This potentiation of the H^+ channel might operate as a negative feedback mechanism to protect microglia from cytotoxic acidosis-induced swelling in the pathological CNS. Amplitudes of the H^+ current fluctuate at an interval of 10-30 min in some cells. Murine osteoclasts gener … More ated from bone-marrow cells in the presence of sRANK ligand exhibited a similar H^+ current, characterized by dependencies on both intracellular and extracellular pH, outward rectification, slow activation kinetics and blockade by Zn^<2+>. The current density in cells with 【greater than or equal】6 nuclei was significantly smaller than that in cells with 【less than or equal】5 nuclei, although the activation rate unaltered. Moreover, the H^+ current was small or negligible in osteoclasts generated in the co-culture of bone marrow cells with a stromal cell line (ST2). Therefore, expression of the H^+ channel or number of active channels could alter during osteoclastogenesis. In most cells with【greater than or equal】6 nuclei activity of NADPH oxidase was low, suggesting a possibility that the activities of the H^+ channel and NADPH oxidase is correlated to the functional states of osteoclasts. This study has provided evidences that expression and activity of the H^+ channels in both microglia and osteoclasts are strongly controlled by their cellular conditions and differentiation process. Less