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ACE and ACE2 activity in diabetic mice.
Jan Wysocki1, Minghao Ye, Maria José Soler
1Division of Nephrology/Hypertension, The Feinberg School of Medicine, Northwestern University, Searle 10-475, 320 E. Superior, Chicago, IL 60611, USA.
Diabetes
|June 29, 2006
Summary
In diabetic mice, kidney ACE2 activity increases at the posttranscriptional level, suggesting altered regulation of angiotensin II. This study introduces a new assay for measuring ACE and ACE2 activity in tissues.
Area of Science:
- Biochemistry
- Physiology
- Nephrology
Background:
- The renin-angiotensin system (RAS) plays a crucial role in regulating blood pressure and fluid balance.
- Angiotensin-converting enzyme (ACE) and ACE-related carboxypeptidase (ACE2) are key components of the RAS, with ACE2 potentially counterbalancing ACE's effects.
- Previous studies noted changes in renal ACE and ACE2 expression in diabetes but did not assess ACE2 activity.
Purpose of the Study:
- To develop and validate a microplate-based fluorometric method for simultaneous determination of ACE and ACE2 activity in tissue samples.
- To investigate alterations in renal and cardiac ACE2 activity in rodent models of diabetes.
- To correlate ACE2 activity with ACE2 protein and mRNA expression in diabetic kidneys.
Main Methods:
- Development of a novel microplate-based fluorometric assay for concurrent ACE and ACE2 activity measurement.
- Enzymatic activity assessment in ACE and ACE2 knockout mice, db/db diabetic mice, and streptozotocin (STZ)-induced diabetic mice.
- Correlation analysis of enzymatic activity with protein and mRNA expression levels in renal and cardiac tissues.
Main Results:
- A strong positive correlation was observed between ACE2 activity and ACE2 protein expression in the renal cortex (r = 0.94).
- Renal ACE2 activity was significantly increased in both db/db and STZ-induced diabetic mice compared to controls.
- Renal ACE2 mRNA levels did not differ significantly between diabetic and control mice, indicating posttranscriptional regulation.
- Cardiac ACE2 activity was lower than in the kidney and showed no significant difference between diabetic and control groups.
Conclusions:
- Renal ACE2 expression is upregulated at the posttranscriptional level in diabetic mice.
- The developed assay facilitates the evaluation of kidney-specific alterations in ACE and ACE2 balance, crucial for understanding local angiotensin II regulation.
- Findings highlight the importance of assessing enzyme activity alongside expression levels in disease states.