Phosphorylation in the C-terminal domain of Aquaporin-4 is required for Golgi transition in primary cultured astrocytes
Phosphorylation in the C-terminal domain of Aquaporin-4 is required for Golgi transition in primary cultured astrocytes
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DOI：
10.1016/j.bbrc.2008.09.155
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发表时间：
2008-12-12
影响因子：
3.1
通讯作者：
Yasui, Masato
中科院分区：
文献类型：
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作者：
Kadohira, Ikuko;Abe, Yoichiro;Yasui, Masato
水通道蛋白4（AQP 4）表达于哺乳动物脑内血管周围和软膜下星形胶质细胞终足，是维持水钾平衡的重要组成部分。在这里，我们研究是否AQP 4磷酸化在原代培养的小鼠星形胶质细胞。用[32] P磷酸代谢标记星形胶质细胞，然后用抗AQP 4抗体免疫沉淀AQP 4。我们观察到，AQP 4是组成性磷酸化，这是减少与蛋白激酶CK 2抑制剂治疗。为了阐明AQP 4的磷酸化CK 2，myc标记的野生型或突变体AQP 4瞬时转染原代培养的星形胶质细胞。用Ala残基取代CK 2 C端的4个磷酸化位点，可抑制AQP 4的磷酸化。免疫荧光显微镜显示，四倍体突变体定位在高尔基体。这些观察结果表明，AQP 4的C-末端结构域至少部分被蛋白激酶CK 2组成性磷酸化，并且它是高尔基体转换所必需的。(C)2008年爱思唯尔公司All rights reserved.
Aquaporin-4 (AQP4) is expressed in the perivascular and subpial astrocytes end-feet in mammalian brain, and plays a critical component of an integrated water and potassium homeostasis. Here we examine whether AQP4 is phosphorylated in primary cultured mouse astrocytes. Astrocytes were metabolically labeled with [(32)p]phosphoric acid, then AQP4 was immunoprecipitated with anti-AQP4 antibody. We observed that AQP4 was constitutively phosphorylated, which is reduced by treatment with protein kinase CK2 inhibitors. To elucidate the phosphorylation of AQP4 by CK2, myc-tagged wild-type or mutant AQP4 was transiently transfected in primary cultured astrocytes. Substitution of Ala residues for four putative CK2 phosphorylation sites in the C terminus abolished the phosphorylation of AQP4. Immunofluorescent microscopy revealed that the quadruple mutant was localized in the Golgi apparatus. These observations indicate that the C-terminal domain of AQP4 is constitutively phosphorylated at least in part by protein kinase CK2 and it is required for Golgi transition. (C) 2008 Elsevier Inc. All rights reserved.