Horm Metab Res 2005; 37(5): 265-269
DOI: 10.1055/s-2005-870096
Original Basic
© Georg Thieme Verlag KG Stuttgart · New York

Expression of the Rat Renal PiT-2 Phosphate Transporter

J.  C.  Leung1 , M.  Barac-Nieto2 , K.  Hering-Smith3 , D.  M.  Silverstein4
  • 1 Department of Pediatrics, Divisions of Neonatalogy, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
  • 2 Department of Physiology, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
  • 3 Department of Medicine, Tulane University Medical Center, New Orleans, Louisiana, USA
  • 4 Department of Pediatrics, Divisions of Nephrology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
Further Information

Publication History

Received 7 September 2004

Accepted after revision 20 December 2004

Publication Date:
22 June 2005 (online)

Abstract

Background: NaPi-2a is the main sodium-dependent Pi (Na+-Pi) transporter in the apical membrane of the renal proximal tubule. Another group of Pi transporters, Glvr-1 (PiT-1) and Ram-1 (PiT-2), was identified. The PiT-2 cRNA induces Na+-dependent Pi uptake into Xenopus laevis oocytes. Prior studies have revealed the presence of the Pit-2 transporter in the kidney. Objectives: Further characterization of the PiT-2 transporter in the kidney and assessment of its developmental regulation. Methods: Using primers specific for the PiT-2 mRNA and an antibody specific for the PiT-2 protein, we assessed the expression and developmental regulation of the renal PiT-2 mRNA and protein. Results: RT-PCR analysis revealed that a 182 bp product was evident in the total kidney (TK), cortex (C), and medulla (M). Northern blots demonstrated a PiT-2 mRNA of approximately 4kb (expected size) in the TK, C, and M. PiT-2 mRNA expression was similar in all kidney regions. RT-PCR and Northern blot analysis revealed that the PiT-2 cDNA was highly abundant in OK and MDCK culture cells. RT-PCR and Northern blot analysis revealed expected products at all ages studied. Densitometry demonstrated similar levels of expression of PiT-2 mRNA in the kidneys of older versus younger animals, and persistent expression in elderly rats. The PiT-2 protein was present in the TK, C, and M, and in OK and MDCK cells. PiT-2 protein abundance was similar at all ages studied. Conclusions: These studies further characterize the renal PiT-2 transporter and show that its expression is stable throughout development and ageing.

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M. Douglas

Silverstein, Children’s Hospital, Department of Pediatrics, Division of Nephrology ·

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