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Published on: June 27, 2015
OSR1-sensitive renal tubular phosphate reabsorption
Ganesh Pathare1, Michael Föller, Arezoo Daryadel
1Department of Physiology, University of Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
Kidney & Blood Pressure Research
|October 26, 2012
Summary
Oxidative stress-responsive kinase 1 (OSR1) regulates renal phosphate transport and FGF23 release. This study found OSR1 up-regulates phosphate transport and impacts phosphate excretion and FGF23 levels in vivo.
Area of Science:
- Nephrology
- Molecular Biology
- Physiology
Background:
- Oxidative stress-responsive kinase 1 (OSR1) is known to regulate renal salt excretion and blood pressure.
- The role of OSR1 in other renal transport systems, particularly phosphate transport, is largely unknown.
- This study investigates the effect of OSR1 on NaPiIIa, a key renal phosphate transporter.
Purpose of the Study:
- To determine the localization of OSR1 and NaPiIIa in the kidney.
- To analyze the impact of OSR1 on NaPiIIa-mediated phosphate transport.
- To investigate the in vivo role of OSR1 in phosphate homeostasis and hormone regulation.
Main Methods:
- Immunohistochemistry and confocal microscopy for protein localization.
- Xenopus oocyte expression system to study NaPiIIa activity with and without OSR1.
- In vivo studies in genetically modified mice (osr1tg/(+)) and wild-type littermates (osr1(+/+)) to assess serum phosphate, hormone levels, and urinary phosphate excretion.
Main Results:
- OSR1 and NaPiIIa are co-expressed in proximal renal tubule cells.
- Coexpression of OSR1 significantly enhanced NaPiIIa-dependent phosphate transport in Xenopus oocytes.
- In vivo, OSR1 overexpression led to increased urinary phosphate excretion, decreased brush border NaPiIIa abundance, and elevated serum FGF23 levels, despite similar PTH and calcitriol levels.
Conclusions:
- OSR1 is present in proximal renal tubules.
- OSR1 plays a role in regulating renal tubular phosphate transport.
- OSR1 influences FGF23 release, impacting phosphate homeostasis.
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