Hydrogen-deuterium exchange effects on beta-endorphin release from AtT20 murine pituitary tumor cells.
Hydrogen-deuterium exchange effects on beta-endorphin release from AtT20 murine pituitary tumor cells.
复制标题
氢-氘交换对 AtT20 鼠垂体肿瘤细胞释放 β-内啡肽的影响。
DOI：
10.1016/s0006-3495(04)74135-1
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发表时间：
2004
影响因子：
3.4
通讯作者：
Yoshioka,Tohru
中科院分区：
文献类型：
--
作者：
Ikeda,Masayuki;Suzuki,Shigeru;Kishio,Masahiro;Hirono,Moritoshi;Sugiyama,Takashi;Matsuura,Junko;Suzuki,Teppei;Sota,Takayuki;Allen,CharlesN;Konishi,Shiro;Yoshioka,Tohru
大量证据表明氧化氘（D2 O）调节多种分泌活动，但具体机制尚不清楚。使用AtT 20细胞，我们研究了D2 O对β-内啡肽释放的生理过程的影响。免疫荧光共聚焦显微镜显示90%D2O缓冲液增加细胞胞体中肌动蛋白丝的数量，减少细胞突起中的肌动蛋白丝，而β-微管蛋白不受影响。Ca 2+成像表明，高K+诱导的Ca 2+内流在D2 O处理期间不受影响，但在D2 O洗脱后被完全抑制。在贴片电极的内部溶液中的H2O/D2 O替换减少了由去极化电压阶跃引起的Ca 2+电流，而额外的细胞外H2O/D2 O替换恢复了电流，这表明跨质膜的D2 O梯度对Ca 2+通道动力学是至关重要的。高钾诱导的β-内啡肽释放的放射免疫分析表明，在D2 O处理期间增加，在D2 O洗脱后减少。这些结果表明，H2O对D2 O诱导的β-内啡肽释放增加与肌动蛋白的重新分布相对应，而D2 O对H2O诱导的β-内啡肽释放减少与电压敏感性Ca 2+通道的抑制相对应。计算机模拟表明，质子化和氘代氨基酸之间的零点振动能的差异产生了这些氨基酸的不对称分布后D2 O洗脱，这导致钙离子通道功能障碍。
Abundant evidences demonstrate that deuterium oxide (D2O) modulates various secretory activities, but specific mechanisms remain unclear. Using AtT20 cells, we examined effects of D2O on physiological processes underlyingβ-endorphin release. Immunofluorescent confocal microscopy demonstrated that 90% D2O buffer increased the amount of actin filament in cell somas and decreased it in cell processes, whereasβ-tubulin was not affected. Ca2+imaging demonstrated that high-K+-induced Ca2+influx was not affected during D2O treatment, but was completely inhibited upon D2O washout. The H2O/D2O replacement in internal solutions of patch electrodes reduced Ca2+currents evoked by depolarizing voltage steps, whereas additional extracellular H2O/D2O replacement recovered the currents, suggesting that D2O gradient across plasma membrane is critical for Ca2+channel kinetics. Radioimmunoassay of high-K+-inducedβ-endorphin release demonstrated an increase during D2O treatment and a decrease upon D2O washout. These results demonstrate that the H2O-to-D2O-induced increase inβ-endorphin release corresponded with the redistribution of actin, and the D2O-to-H2O-induced decrease inβ-endorphin release corresponded with the inhibition of voltage-sensitive Ca2+channels. The computer modeling suggests that the differences in the zero-point vibrational energy between protonated and deuterated amino acids produce an asymmetric distribution of these amino acids upon D2O washout and this causes the dysfunction of Ca2+channels.