Role of abnormal neutral endopeptidase-like activities in Hyp mouse bone cells in renal phosphate transport.
We investigated whether the absence of Phex (phosphate-regulating gene with homologies to endopeptidases on the X chromosome) in the Hyp mouse affects the expression and activity of neprilysin (NEP) and of endothelin-converting enzyme-like endopeptidase (ECEL1/DINE) in bone marrow stromal cells (BMSC) and osteoblasts (Ob). Total NEP-like activity was higher in Ob than in BMSC regardless of genotype, and Hyp cells showed higher activities than normal. Conditioned media (CM) from Hyp BMSC and Ob inhibited inorganic phosphate (P(i)) uptake by mouse proximal tubule cells, and incubating Hyp Ob with phosphoramidon prevented the production of the inhibitor of renal P(i) uptake. A linear relationship was observed between the NEP-like activity of Hyp and normal cells and the inhibition of P(i) uptake. NEP and ECEL1/DINE mRNA levels were higher in Hyp cells than in normal cells, and in situ hybridization of ECEL1/DINE confirmed higher levels of expression in the Hyp mouse than in normal cells. In conclusion, we observed a correlation between the inhibition of P(i) uptake by CM from Hyp cells and elevated NEP-like activities.
Dubois
Stéphanie G
SG
Unité de recherche en Arthrose, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Montreal H2L 4M1, Quebec, Canada H3C 3J7.
Ruchon
Andréa Frota
AF
Delalandre
Aline
A
Boileau
Guy
G
Lajeunesse
Daniel
D
D000818:Animals; D001842:Bone and Bones / Q000166:cytology / Q000201:enzymology*; D002460:Cell Line; D015870:Gene Expression; D017674:Hypophosphatemia / Q000235:genetics / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008297:Male; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D015260:Neprilysin / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology / Q000201:enzymology; D053402:PHEX Phosphate Regulating Neutral Endopeptidase; D010641:Phenotype; D010710:Phosphates / Q000378:metabolism; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis
D010710:Phosphates; D011506:Proteins; D012333:RNA, Messenger; C120591:Ecel1 protein, mouse; D008666:Metalloendopeptidases; D053402:PHEX Phosphate Regulating Neutral Endopeptidase; C506232:Phex protein, mouse; D015260:Neprilysin