Expression of the rat renal PiT-2 phosphate transporter.
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.


OBJECTIVE
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 4 kb (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.
Leung
J C
JC
Department of Pediatrics, Division of Neonatalogy, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70118, USA.
Barac-Nieto
M
M
Hering-Smith
K
K
Silverstein
D M
DM
D000375:Aging / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D004285:Dogs; D005786:Gene Expression Regulation / Q000502:physiology*; D007668:Kidney / Q000502:physiology*; D009893:Opossums; D051381:Rats; D017207:Rats, Sprague-Dawley; D050608:Sodium-Phosphate Cotransporter Proteins; D050611:Sodium-Phosphate Cotransporter Proteins, Type III; D027981:Symporters / Q000096:biosynthesis* / Q000235:genetics
C493588:Slc20a1 protein, rat; C493566:Slc20a2 protein, rat; D050608:Sodium-Phosphate Cotransporter Proteins; D050611:Sodium-Phosphate Cotransporter Proteins, Type III; D027981:Symporters