title: Genetic ablation of sfrp4 in mice does not affect serum phosphate homeostasis.
abstract: Serum phosphate levels are regulated by PTH and the fibroblast growth factor 23 (Fgf23)/Klotho endocrine system, which both affect expression of Npt2a and thus the apical reabsorption of phosphate in the proximal renal tubules. In addition to Fgf23, secreted frizzled-related protein 4 (Sfrp4) has recently been implicated as an additional phosphate regulator in vivo and in vitro. Here we demonstrate that ablation of the Sfrp4 gene in mice does not lead to altered serum or urine phosphate levels. Furthermore, Sfrp4 is unable to compensate for the absence of Fgf23 or Klotho because double knockouts have a similar biochemical profile and phenotype as animals with ablation of Fgf23 or Klotho alone. Taken together, our data suggest that Sfrp4 does not contribute to the long-term regulation of serum phosphate levels in mice.
authors.affiliation: Department of Medicine, Harvard School of Dental Medicine, Boston, Massachusetts 02115, USA. mchrist3@bidmc.harvard.edu
authors.forename: Marta
authors.initials: M
authors.lastname: Christov
authors.forename: Shany
authors.initials: S
authors.lastname: Koren
authors.forename: Quan
authors.initials: Q
authors.lastname: Yuan
authors.forename: Roland
authors.initials: R
authors.lastname: Baron
authors.forename: Beate
authors.initials: B
authors.lastname: Lanske
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000097:blood; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000378:metabolism; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D006706:Homeostasis; D000090265:Klotho Proteins; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010641:Phenotype; D010710:Phosphates / Q000097:blood* / Q000652:urine; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa / Q000378:metabolism; D013997:Time Factors; D000094742:Secreted Frizzled-Related Proteins
chemical_list: D002118:Calcium; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors; D005966:Glucuronidase; D000090265:Klotho Proteins; D010710:Phosphates; D011518:Proto-Oncogene Proteins; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa; C000717428:Fgf23 protein, mouse; C498454:Sfrp4 protein, mouse; D000094742:Secreted Frizzled-Related Proteins; C493555:Slc34a1 protein, mouse