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Distribution of kallikrein-binding protein mRNA in kidneys and difference between SHR and WKY rats
T Yang1, Y Terada, H Nonoguchi
1Second Department of Internal Medicine, Tokyo Medical and Dental University, Japan.
Abstract:
We investigated kallikrein-binding protein (KBP) mRNA distribution in the kidney of Sprague-Dawley (SD) rats, spontaneously hypertensive rats (SHR), and Wistar-Kyoto strain (WKY) rats. Northern blot analysis revealed that KBP mRNA was located mainly in the medulla and with lower amounts in SHR than in WKY rats. KBP mRNA in microdissected nephron segments was detected by reverse transcription and polymerase chain reaction (RT-PCR) followed by Southern blot analysis. In SD rats, the most abundant signals were consistently found in inner medullary collecting duct (IMCD), with small amounts in outer medullary collecting duct, proximal convoluted tubule, and glomerulus. No signals were found in connecting tubule and cortical collecting duct. The nephron distribution of KBP mRNA was similar in WKY and SD rats. Only a small amount of signal was found, however, in IMCD of SHR. In conclusion, 1) KBP mRNA was predominantly distributed in the medullary segments of the distal nephron, downstream from the known kallikrein activity site in the collecting duct, and 2) KBP mRNA expression was significantly decreased in the kidney of SHR.
Insights
Kallikrein-binding protein (KBP) mRNA is mainly in the kidney medulla. SHR rats show significantly decreased KBP mRNA in the kidney compared to WKY rats.
Area of Science:
- Nephrology
- Molecular Biology
- Hypertension Research
Background:
- Kallikrein-binding protein (KBP) plays a role in regulating the kallikrein-kinin system.
- Understanding KBP mRNA distribution is crucial for kidney physiology and disease.
Purpose of the Study:
- To investigate the distribution of kallikrein-binding protein (KBP) mRNA in the kidneys of different rat strains.
- To compare KBP mRNA expression levels between normotensive (WKY, SD) and spontaneously hypertensive (SHR) rats.
Main Methods:
- Northern blot analysis for overall kidney mRNA distribution.
- Reverse transcription-polymerase chain reaction (RT-PCR) coupled with Southern blot analysis for microdissected nephron segments.
Main Results:
- KBP mRNA was predominantly found in the kidney medulla.
- In Sprague-Dawley (SD) rats, KBP mRNA was most abundant in the inner medullary collecting duct (IMCD).
- Spontaneously hypertensive rats (SHR) exhibited significantly lower KBP mRNA levels in the kidney medulla, particularly in the IMCD, compared to Wistar-Kyoto (WKY) rats.
Conclusions:
- KBP mRNA is primarily located in the medullary segments of the distal nephron.
- Kidney KBP mRNA expression is significantly reduced in spontaneously hypertensive rats (SHR).