title: Adenoviral expression of NHERF-1 in NHERF-1 null mouse renal proximal tubule cells restores Npt2a regulation by low phosphate media and parathyroid hormone.
abstract: Sodium-dependent phosphate transport in NHERF-1(-/-) proximal tubule cells does not increase when grown in a low phosphate media and is resistant to the normal inhibitory effects of parathyroid hormone (PTH). The current experiments employ adenovirus-mediated gene transfer in primary cultures of mouse proximal tubule cells from NHERF-1 null mice to explore the specific role of NHERF-1 on regulated Npt2a trafficking and sodium-dependent phosphate transport. NHERF-1 null cells have decreased sodium-dependent phosphate transport compared with wild-type cells. Infection of NHERF-1 null cells with adenovirus-GFP-NHERF-1 increased phosphate transport and plasma membrane abundance of Npt2a. Adenovirus-GFP-NHERF-1 infected NHERF-1 null proximal tubule cells but not cells infected with adenovirus-GFP demonstrated increased phosphate transport and Npt2a abundance in the plasma membrane when grown in low phosphate (0.1 mM) compared with high phosphate media (1.9 mM). PTH inhibited phosphate transport and decreased Npt2a abundance in the plasma membrane of adenovirus-GFP-NHERF-1-infected NHERF-1 null proximal tubule cells but not cells infected with adenovirus-GFP. Interestingly, phosphate transport is inhibited by activation of protein kinase A and protein kinase C in wild-type proximal tubule cells but not in NHERF-1(-/-) cells. Together, these results highlight the requirement for NHERF-1 for physiological control of Npt2a trafficking and suggest that the Npt2a/NHERF-1 complex represents a unique PTH-responsive pool of Npt2a in renal microvilli.
authors.affiliation: Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
authors.forename: Rochelle
authors.initials: R
authors.lastname: Cunningham
authors.forename: Deborah
authors.initials: D
authors.lastname: Steplock
authors.forename: Xiaofei
authors.initials: X
authors.lastname: E
authors.forename: Rajat S
authors.initials: RS
authors.lastname: Biswas
authors.forename: Fengying
authors.initials: F
authors.lastname: Wang
authors.forename: Shirish
authors.initials: S
authors.lastname: Shenolikar
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Weinman
mesh_terms: D000256:Adenoviridae; D000818:Animals; D003470:Culture Media; D005822:Genetic Vectors; D051379:Mice; D018345:Mice, Knockout; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010710:Phosphates / Q000494:pharmacology; D010750:Phosphoproteins / Q000172:deficiency* / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics* / Q000378:metabolism; D050608:Sodium-Phosphate Cotransporter Proteins / Q000378:metabolism*; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa / Q000378:metabolism*
chemical_list: D003470:Culture Media; D010281:Parathyroid Hormone; D010710:Phosphates; D010750:Phosphoproteins; D011994:Recombinant Proteins; C493555:Slc34a1 protein, mouse; D017923:Sodium-Hydrogen Exchangers; D050608:Sodium-Phosphate Cotransporter Proteins; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa; C093376:sodium-hydrogen exchanger regulatory factor