Phosphorylation in the C-terminal domain of Aquaporin-4 is required for Golgi transition in primary cultured astrocytes

Ikuko Kadohira, Yoichiro Abe, Mutsuo Nuriya, Kazumi Sano, Shoji Tsuji, Takeshi Arimitsu, Yasunori Yoshimura, Masato Yasui

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

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 [32P]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.

Original languageEnglish
Pages (from-to)463-468
Number of pages6
JournalBiochemical and Biophysical Research Communications
Volume377
Issue number2
DOIs
Publication statusPublished - 2008 Dec 12

Keywords

  • Aquaporin-4 (AQP4)
  • Astrocytes
  • Phosphorylation
  • Protein kinase CK2

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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