title: Decreased abundance of urinary exosomal aquaporin-1 in renal ischemia-reperfusion injury.
abstract: Urinary exosomes, secreted into urine from renal epithelial cells, are known to contain many types of renal functional membrane proteins. Here, we studied whether renal ischemia-reperfusion (I/R) affects urinary exosomal aquaporin-1 (AQP1) excretion in rats subjected to renal I/R and patients who underwent renal transplantation. Immunoblotting studies demonstrated reduction of the urinary exosomal AQP1 level even at 6 h after renal I/R, and the level continued to be low over 96 h after I/R. Renal AQP1 mRNA and protein analyses revealed that the decreased excretion of urinary exosomal AQP1 is associated with renal AQP1 protein retention in the early phase and with a decreased expression level of renal AQP1 in the later phase of renal I/R injury. Decreased abundance of urinary exosomal AQP1 in a recipient patient was also observed at 48 h after renal allograft transplantation. No significant decrease in urinary exosomal AQP1 was observed in a rat model of nephropathy or in patients with proteinuria. Our studies suggest that the renal AQP1 expression level is possibly controlled by its urinary exosomal excretion and indicate that urinary exosomal AQP1 is a novel urinary biomarker for renal I/R injury.
authors.affiliation: Dept. of Veterinary Pharmacology, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Sonoda
authors.forename: Naoko
authors.initials: N
authors.lastname: Yokota-Ikeda
authors.forename: Sayaka
authors.initials: S
authors.lastname: Oshikawa
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Kanno
authors.forename: Kazuya
authors.initials: K
authors.lastname: Yoshinaga
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Uchida
authors.forename: Yuuji
authors.initials: Y
authors.lastname: Ueda
authors.forename: Kouichi
authors.initials: K
authors.lastname: Kimiya
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Uezono
authors.forename: Akira
authors.initials: A
authors.lastname: Ueda
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Ito
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ikeda
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic; D051398:Aquaporin 1 / Q000652:urine*; D002609:Chediak-Higashi Syndrome / Q000652:urine; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism*; D016030:Kidney Transplantation; D008297:Male; D011507:Proteinuria / Q000652:urine*; D011691:Puromycin; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000097:blood / Q000652:urine*
chemical_list: C496020:AQP1 protein, human; D000964:Antimetabolites, Antineoplastic; C496022:Aqp1 protein, rat; D012333:RNA, Messenger; D051398:Aquaporin 1; D011691:Puromycin