Expression of the rat renal PiT-2 phosphate transporter

• Published in: Hormone and metabolic research Vol. 37; no. 5; p. 265
• Main Authors: Leung, J C, Barac-Nieto, M, Hering-Smith, K, Silverstein, D M
• Format: Journal Article
• Language: English
• Published: Germany 01.05.2005
• Subjects: Aging - physiology; Animals; Cells, Cultured; Dogs; Gene Expression Regulation - physiology; Kidney - physiology; Opossums; Rats; Rats, Sprague-Dawley; Sodium-Phosphate Cotransporter Proteins; Sodium-Phosphate Cotransporter Proteins, Type III; Symporters - biosynthesis; Symporters - genetics
• ISSN: 0018-5043
• DOI: 10.1055/s-2005-870096

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. Further characterization of the PiT-2 transporter in the kidney and assessment of its developmental regulation. 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. 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. These studies further characterize the renal PiT-2 transporter and show that its expression is stable throughout development and ageing.