title: High phosphorus diet-induced changes in NaPi-IIb phosphate transporter expression in the rat kidney: DNA microarray analysis.
abstract: The mechanism by which phosphorus levels are maintained in the body was investigated by analyzing changes in gene expression in the rat kidney following administration of a high phosphorus (HP) diet. Male Wistar rats were divided into two groups and fed a diet containing 0.3% (control) or 1.2% (HP) phosphorous for 24 days. Phosphorous retention was not significantly increased in HP rats, but fractional excretion of phosphorus was significantly increased in the HP group compared to controls, with an excessive amount of the ingested phosphorus being passed through the body. DNA microarray analysis of kidney tissue from both groups revealed changes in gene expression profile induced by a HP diet. Among the genes that were upregulated, Gene Ontology (GO) terms related to ossification, collagen fibril organization, and inflammation and immune response were significantly enriched. In particular, there was significant upregulation of type IIb sodium-dependent phosphate transporter (NaPi-IIb) in the HP rat kidney compared to control rats. This upregulation was confirmed by in situ hybridization. Distinct signals for NaPi-IIb in both the cortex and medulla of the kidney were apparent in the HP group, while the corresponding signals were much weaker in the control group. Immunohistochemical analysis showed that NaPi-IIb localized to the basolateral side of kidney epithelial cells surrounding the urinary duct in HP rats but not in control animals. These data suggest that NaPi-IIb is upregulated in the kidney in response to the active excretion of phosphate in HP diet-fed rats.
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Suyama
authors.forename: Shinji
authors.initials: S
authors.lastname: Okada
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ishijima
authors.forename: Kota
authors.initials: K
authors.lastname: Iida
authors.forename: Keiko
authors.initials: K
authors.lastname: Abe
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nakai
mesh_terms: D000818:Animals; D001692:Biological Transport; D001835:Body Weight; D002118:Calcium / Q000097:blood; D004032:Diet; D004435:Eating; D005786:Gene Expression Regulation; D007668:Kidney / Q000033:anatomy & histology / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008903:Minerals / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D009929:Organ Size; D010758:Phosphorus / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D050614:Sodium-Phosphate Cotransporter Proteins, Type IIb / Q000235:genetics* / Q000378:metabolism; D014508:Urea / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D008903:Minerals; C493559:Slc34a2 protein, rat; D050614:Sodium-Phosphate Cotransporter Proteins, Type IIb; D014867:Water; D010758:Phosphorus; D014508:Urea; D009584:Nitrogen; D002118:Calcium