Intracellular chloride channel protein CLIC1 regulates macrophage function through modulation of phagosomal acidification
Intracellular chloride channel protein CLIC1 regulates macrophage function through modulation of phagosomal acidification
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DOI：
10.1242/jcs.110072
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发表时间：
2012-11-15
影响因子：
4
通讯作者：
Breit, Samuel N.
中科院分区：
文献类型：
--
作者：
Jiang, Lele;Salao, Kanin;Breit, Samuel N.
细胞内氯离子通道蛋白1 （CLIC1）是谷胱甘肽S转移酶家族的241个氨基酸蛋白，具有氧化还原和ph依赖性膜结合和氯离子通道活性。虽然CLIC蛋白在后生动物中进化保守，表明其重要作用，但对其生物学知之甚少。在活化的巨噬细胞中表达增加的基础上首次克隆了CLIC1。因此，我们通过免疫荧光共聚焦显微镜检查了其在小鼠腹腔巨噬细胞中的亚细胞定位。在静息细胞中，CLIC1在点状细胞质结构中被观察到，这些点状细胞质结构不与内体或分泌囊泡标记物共定位。然而，当这些巨噬细胞吞噬血清调理酶蛋白时，CLIC1易位到吞噬体膜上。来自CLIC1（-/-）小鼠的巨噬细胞显示吞噬小体酸化缺陷，这是通过成像活细胞吞噬酶san来确定的，酶san标记有ph敏感的荧光团俄勒冈绿。吞噬体酸化的改变并不伴随着吞噬体-溶酶体融合的可检测损伤。然而，与酸化缺陷一致，CLIC1（-/-）巨噬细胞也表现出吞噬体蛋白水解能力受损和活性氧产生减少。此外，CLIC1（-/-）小鼠被保护免受血清转移诱导的K/BxN关节炎的发展。这些数据都表明CLIC1通过其离子通道活性在调节巨噬细胞功能中发挥重要作用，提示其是开发抗炎药物的合适靶点。
Intracellular chloride channel protein 1 (CLIC1) is a 241 amino acid protein of the glutathione S transferase fold family with redox- and pH-dependent membrane association and chloride ion channel activity. Whilst CLIC proteins are evolutionarily conserved in Metazoa, indicating an important role, little is known about their biology. CLIC1 was first cloned on the basis of increased expression in activated macrophages. We therefore examined its subcellular localisation in murine peritoneal macrophages by immunofluorescence confocal microscopy. In resting cells, CLIC1 is observed in punctate cytoplasmic structures that do not colocalise with markers for endosomes or secretory vesicles. However, when these macrophages phagocytose serum-opsonised zymosan, CLIC1 translocates onto the phagosomal membrane. Macrophages from CLIC1(-/-) mice display a defect in phagosome acidification as determined by imaging live cells phagocytosing zymosan tagged with the pH-sensitive fluorophore Oregon Green. This altered phagosomal acidification was not accompanied by a detectable impairment in phagosomal-lysosomal fusion. However, consistent with a defect in acidification, CLIC1(-/-) macrophages also displayed impaired phagosomal proteolytic capacity and reduced reactive oxygen species production. Further, CLIC1(-/-) mice were protected from development of serum transfer induced K/BxN arthritis. These data all point to an important role for CLIC1 in regulating macrophage function through its ion channel activity and suggest it is a suitable target for the development of anti-inflammatory drugs.