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Temporal and spatial expression pattern of the angiotensinogen gene in mice and rats
1Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
Abstract:
In situ hybridization for mouse angiotensinogen (Ao) mRNA was performed using a Stu I-Pst I 0.43-kb fragment of exon 2 as a template to synthesize RNA probes. The mouse Ao mRNA expression patterns were different from those reported for rats. Ao mRNA was expressed in the fetal liver as early as 12.5 days postcoitus, and the liver remained the predominant organ of its expression in utero. Within the developing kidney, Ao mRNA was demonstrated at 17.5 days postcoitus in the proximal straight tubules undergoing loop formation in the medulla. In the matured mouse kidney, the expression site is within the outer stripe of outer medulla, hence identified as the pars recta, not proximal convoluted tubules. Additional studies revealed that, in rats also, Ao mRNA was localized in the pars recta. This was in contrast to previously published results that showed that Ao mRNA was localized primarily in the proximal convoluted tubules in rats. Thus the pars recta appears to be an important intrarenal source of Ao for both rats and mice throughout pre- and postnatal periods, whereas the liver can be the major extrarenal source in utero in mice, but not in rats.
Insights
Angiotensinogen (Ao) mRNA is found in the developing mouse kidney
Area of Science:
- Renal physiology
- Molecular biology
- Developmental biology
Background:
- Angiotensinogen (Ao) is a key component of the renin-angiotensin system.
- Previous studies suggested Ao mRNA is primarily in rat proximal convoluted tubules.
- Understanding Ao expression is crucial for renal and cardiovascular research.
Purpose of the Study:
- To investigate the expression patterns of angiotensinogen (Ao) mRNA in developing and mature mouse kidneys.
- To compare Ao mRNA localization in mice with existing data in rats.
- To identify intrarenal and extrarenal sources of Ao.
Main Methods:
- In situ hybridization using RNA probes synthesized from a mouse Ao exon 2 fragment.
- Analysis of Ao mRNA expression in fetal and mature mouse kidneys.
- Comparative analysis with rat kidney Ao mRNA localization.
Main Results:
- Mouse Ao mRNA is expressed in fetal liver and developing kidney (proximal straight tubules).
- In mature mouse kidneys, Ao mRNA is localized to the pars recta (outer stripe of outer medulla).
- Rat Ao mRNA was also found in the pars recta, contradicting prior studies.
Conclusions:
- The pars recta is a significant intrarenal source of Ao in both mice and rats.
- The fetal liver is a major extrarenal source of Ao in utero for mice, but not rats.
- Ao expression sites in the kidney differ from previous reports, highlighting species-specific differences.