Acid-sensing ion channel 1a mediates acid-induced increases in intracellular calcium in rat articular chondrocytes
Acid-sensing ion channel 1a mediates acid-induced increases in intracellular calcium in rat articular chondrocytes
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DOI：
10.1007/s11010-010-0412-y
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发表时间：
2010-02
影响因子：
4.3
通讯作者：
Feng-Lai Yuan;Feihu Chen;Wei-guo Lu;Xia Li;Fan‐rong Wu;Jian-ping Li;Cheng-wan Li;Yu Wang
中科院分区：
文献类型：
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作者：
Feng-Lai Yuan;Feihu Chen;Wei-guo Lu;Xia Li;Fan‐rong Wu;Jian-ping Li;Cheng-wan Li;Yu Wang
酸感离子通道（asic）是由细胞外酸化激活的阳离子通道，与疼痛感知、缺血性中风、机械感觉、学习和记忆有关。研究表明ASIC1a是中枢和周围神经系统的细胞外pH传感器，但其在非神经细胞中的生理和病理作用尚不清楚。我们证明了ASIC1a在大鼠关节软骨细胞中的一种新的生理功能。采用逆转录聚合酶链反应（RT-PCR）和Western blotting检测大鼠关节软骨细胞中ASIC1a mRNA和蛋白的表达。采用免疫荧光细胞染色法测定ASIC1a蛋白在关节软骨细胞中的分布。通过记录软骨细胞内钙（[Ca2+]i）来评估关节软骨细胞pH感应的可能分子机制，我们使用激光扫描共聚焦显微镜技术进行了分析。采用乳酸脱氢酶释放试验和电镜观察酸暴露后细胞损伤情况。mRNA和蛋白表达显示ASIC1a在这些细胞中大量表达。在培养的软骨细胞中，在细胞外Ca2+存在的情况下，细胞外pH 6.0增加了细胞内钙。asic1a特异性阻滞剂PcTX毒液显著降低了[Ca2+]i的增加，并抑制酸诱导的关节软骨细胞损伤。然而，在没有细胞外Ca2+的情况下，没有观察到[Ca2+]i的增加和关节软骨细胞损伤。这些发现表明，通过ASIC1a介导的[Ca2+]i的增加可能导致酸中毒诱导的关节软骨细胞损伤。
Acid-sensing ion channels (ASICs) are cationic channels that are activated by extracellular acidification and implicated in pain perception, ischemic stroke, mechanosensation, learning, and memory. It has been shown that ASIC1a is an extracellular pH sensor in the central and peripheral nervous systems, but its physiological and pathological roles in non-neural cells are poorly understood. We demonstrated a novel physiological function of ASIC1a in rat articular chondrocytes. The expression of ASIC1a mRNA and protein in rat articular chondrocytes was evaluated by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting. The distribution of ASIC1a protein located in articular chondrocytes was determined by using immunofluorescence cell staining. The possible molecular mechanisms of articular chondrocytes pH sensing, as assessed by recording intracellular calcium ([Ca2+]i) in chondrocytes, were analyzed by using the laser scanning confocal microscopy technique. The cell injure following acid exposure was analyzed with lactate dehydrogenase release assay and electron microscopy. mRNA and protein expression showed that ASIC1a was expressed abundantly in these cells. In cultured chondrocytes, extracellular pH 6.0 increased intracellular calcium in the presence of extracellular Ca2+. The ASIC1a-specific blocker PcTX venom significantly reduced this increase in [Ca2+]i, and inhibited acid-induced articular chondrocyte injury. However, the increase in [Ca2+]i and articular chondrocyte injury were not observed in the absence of extracellular Ca2+. These findings show that increased [Ca2+]i, mediated via ASIC1a, might contribute to acidosis-induced articular chondrocyte injury.