title: Hypoxia and expression of hypoxia-inducible factor in the aging kidney.
abstract: Renal senescence is characterized by interstitial fibrosis and loss of peritubular capillaries. In this study, we provided evidence of tubulointerstitial hypoxia and the operation of hypoxia-inducible factor (HIF) in the aging kidney. Using two distinct methods, pimonidazole immunostaining and the expression of the "hypoxia-responsive" reporter of the transgenic rats, we identified the age-related expansion of hypoxia in all areas of the kidney. Expansion was most prominent in the cortex. Clusters of hypoxic tubules were observed in the superficial cortical zones, areas adjacent to the outer nephrons and expanded in the medullary rays. The degree of hypoxia was positively correlated with the age-related tubulointerstitial injury (R(2) = 0.88, p <.01), which was associated with the upregulation of HIF-regulated genes, such as vascular endothelial growth factor (VEGF) and glucose transporter-1 (GLUT1) (real-time polymerase chain reaction). These findings point to the involvement of hypoxia and highlight the pathological relevance of HIF and its target genes in the aging kidney.
authors.affiliation: Division of Nephrology and Endocrinology, University of Tokyo School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Tanaka
authors.forename: Hideki
authors.initials: H
authors.lastname: Kato
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kojima
authors.forename: Takamoto
authors.initials: T
authors.lastname: Ohse
authors.forename: Daisuke
authors.initials: D
authors.lastname: Son
authors.forename: Takahisa
authors.initials: T
authors.lastname: Tawakami
authors.forename: Toshiya
authors.initials: T
authors.lastname: Yatagawa
authors.forename: Reiko
authors.initials: R
authors.lastname: Inagi
authors.forename: Toshiro
authors.initials: T
authors.lastname: Fujita
authors.forename: Masaomi
authors.initials: M
authors.lastname: Nangaku
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D030801:Animals, Genetically Modified; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D015687:Cell Hypoxia / Q000502:physiology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D000099162:Endothelial PAS Domain-Containing Protein 1