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J Am Soc Nephrol. 2017 Apr;28(4):1073-1078. doi: 10.1681/ASN.2016070726. Epub 2016 Oct 31.

Renal Fanconi Syndrome and Hypophosphatemic Rickets in the Absence of Xenotropic and Polytropic Retroviral Receptor in the Nephron.

Author information

1
Department of Pharmacology and Toxicology and.
2
Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts.
3
Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia.
4
School of Biomedicine, Far Eastern Federal University, Vladivostok, Russia.
5
Services of Pathology and.
6
Université Pierre et Marie Curie, Paris, France.
7
Genomic Technologies Facility, University of Lausanne, Lausanne, Switzerland.
8
Department of Pharmacology and Toxicology and dmitri.firsov@unil.ch olivier.bonny@unil.ch.
9
Nephrology, Department of Medicine, University Hospital of Lausanne, Lausanne, Switzerland; and.

Abstract

Tight control of extracellular and intracellular inorganic phosphate (Pi) levels is critical to most biochemical and physiologic processes. Urinary Pi is freely filtered at the kidney glomerulus and is reabsorbed in the renal tubule by the action of the apical sodium-dependent phosphate transporters, NaPi-IIa/NaPi-IIc/Pit2. However, the molecular identity of the protein(s) participating in the basolateral Pi efflux remains unknown. Evidence has suggested that xenotropic and polytropic retroviral receptor 1 (XPR1) might be involved in this process. Here, we show that conditional inactivation of Xpr1 in the renal tubule in mice resulted in impaired renal Pi reabsorption. Analysis of Pi transport in primary cultures of proximal tubular cells or in freshly isolated renal tubules revealed that this Xpr1 deficiency significantly affected Pi efflux. Further, mice with conditional inactivation of Xpr1 in the renal tubule exhibited generalized proximal tubular dysfunction indicative of Fanconi syndrome, characterized by glycosuria, aminoaciduria, calciuria, and albuminuria. Dramatic alterations in the renal transcriptome, including a significant reduction in NaPi-IIa/NaPi-IIc expression, accompanied these functional changes. Additionally, Xpr1-deficient mice developed hypophosphatemic rickets secondary to renal dysfunction. These results identify XPR1 as a major regulator of Pi homeostasis and as a potential therapeutic target in bone and kidney disorders.

KEYWORDS:

Fanconi syndrome; hypophosphatemic rickets; kidney; phosphate homeostasis; retroviral receptor XPR1

PMID:
27799484
PMCID:
PMC5373462
DOI:
10.1681/ASN.2016070726
[Indexed for MEDLINE]
Free PMC Article

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