title: FGF23, klotho and vitamin D interactions: What have we learned from in vivo mouse genetics studies?
abstract: The molecular interactions of fibroblast growth factor 23 (FGF23), klotho and vitamin D coordinate to regulate the delicate phosphate levels of the body. Vitamin D can induce both FGF23 and klotho synthesis to influence renal phosphate balance. In the presence of klotho, FGF23 protein gains bioactivity to influence systemic phosphate homeostasis. Experimental studies have convincingly shown that in the absence of klotho, FGF23 is unable to regulate in vivo phosphate homeostasis. Furthermore, genetic inactivation of FGF23, klotho or both of the genes have resulted in markedly increased renal expression of 1-alpha hydroxylase [1α(OH)ase] and concomitant elevated serum levels of 1,25, dihydroxyvitamin D [1,25(OH)(2)D] in the mutant mice. Vitamin D can induce the expression of both FGF23 and klotho while, FGF23 can suppress renal expression of 1α(OH)ase to reduce 1,25(OH)(2)D activity. In this brief chapter, I will summarize the possible in vivo interactions of FGF23, klotho and vitamin D, in the light of recent mouse genetics studies.
authors.affiliation: Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA. mrazzaque@hms.harvard.edu
authors.forename: M Shawkat
authors.initials: MS
authors.lastname: Razzaque
mesh_terms: D000818:Animals; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000235:genetics* / Q000378:metabolism*; D005966:Glucuronidase / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D007674:Kidney Diseases / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D000090265:Klotho Proteins; D051379:Mice; D011485:Protein Binding; D015398:Signal Transduction; D014807:Vitamin D / Q000378:metabolism*
chemical_list: C000717427:FGF23 protein, human; C000717428:Fgf23 protein, mouse; D014807:Vitamin D; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D005966:Glucuronidase; D000090265:Klotho Proteins