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Localization of mRNAs coding for isozymes of plasma membrane Ca(2+)-ATPase pump in rat kidney
M Magosci1, M Yamaki, J T Penniston
1Department of Biochemistry and Molecular Biology, Mayo Clinic, Mayo Medical School, Rochester, Minnesota 55905.
Abstract:
We have studied localization of mRNAs coding isozymes of rat plasma membrane Ca(2+)-adenosinetriphosphatase pump (rPMCA) in the rat kidney, with use of reverse transcription (RT) with subsequent amplification by polymerase chain reaction (PCR). When zones of the kidney were separated by macrodissection, a large amount of mRNA coding isozyme rPMCA1 was found in all zones; mRNA for isozyme rPMCA2 was abundant in cortex and in outer medulla, and mRNA for isozyme rPMCA3 was prominent in outer medulla. The mRNAs were analyzed in microdissected cortical nephron segments by use of RT-PCR approach described previously [T. Moriyama, H. R. Murphy, B. M. Martin, and A. Garcia-Perez. Am. J. Physiol. 258 (Renal Fluid Electrolyte Physiol. 27): F1470-F1474, 1990]. We detected mRNA for isozyme rPMCA2 in microdissected distal convoluted tubules (DCT) and in cortical thick ascending limbs (CTAL) and, less consistently, also in proximal convoluted tubule and in glomeruli. The mRNA for isozyme rPMCA1 was abundant in glomeruli but was absent in all examined cortical tubular segments. Our results document that mRNAs for all three major isozymes of rPMCA are present and show a unique distribution in the three major zones of rat renal parenchyma. Specific mRNA coding for rPMCA2 was detected in cortical tubules, namely in CTAL and DCT, whereas mRNA coding isozyme rPMCA1 was found in glomeruli. We suggest that isozyme rPMCA2 might be specifically related to epithelial cells and their function, whereas rPMCA1 is probably a component of nonepithelial cells including these in glomeruli.
Insights
Researchers mapped rat plasma membrane Ca(2+)-adenosinetriphosphatase pump (rPMCA) mRNA in the kidney. Isozyme rPMCA2 mRNA is in cortical tubules, while rPMCA1 mRNA is found in glomeruli, suggesting distinct cellular roles.
Area of Science:
- Physiology
- Molecular Biology
- Renal Science
Background:
- The plasma membrane Ca(2+)-adenosinetriphosphatase pump (PMCA) is crucial for calcium homeostasis.
- Multiple PMCA isoforms (isozymes) exist, with varying tissue distribution and functions.
- Understanding the localization of PMCA isozyme mRNAs in the kidney is key to elucidating their specific roles in renal calcium handling.
Purpose of the Study:
- To investigate the precise localization of messenger RNAs (mRNAs) encoding the three major rat plasma membrane Ca(2+)-adenosinetriphosphatase pump (rPMCA) isozymes within the rat kidney.
- To determine the distribution patterns of rPMCA1, rPMCA2, and rPMCA3 mRNAs across different renal zones and specific nephron segments.
Main Methods:
- Utilized reverse transcription coupled with polymerase chain reaction (RT-PCR) to detect and quantify rPMCA isozyme mRNAs.
- Employed macrodissection to separate kidney zones (cortex, outer medulla, inner medulla).
- Applied microdissection to isolate specific cortical nephron segments for detailed mRNA analysis.
Main Results:
- All three rPMCA isozyme mRNAs (rPMCA1, rPMCA2, rPMCA3) were detected in the rat kidney.
- rPMCA1 mRNA was abundant in all kidney zones and predominantly found in glomeruli, but absent in cortical tubules.
- rPMCA2 mRNA was abundant in the cortex and outer medulla, specifically detected in distal convoluted tubules (DCT) and cortical thick ascending limbs (CTAL), and less consistently in proximal convoluted tubules and glomeruli.
- rPMCA3 mRNA was prominent in the outer medulla.
Conclusions:
- The study reveals a unique and distinct distribution of rPMCA isozyme mRNAs across rat renal parenchyma.
- rPMCA2 mRNA's presence in cortical tubules (CTAL, DCT) suggests a role in epithelial cell function.
- rPMCA1 mRNA's localization in glomeruli indicates a potential role in nonepithelial cells within the kidney.