Related Experiment Videos
Widespread tissue distribution of human chymase
1Max Delbrück Centre for Molecular Medicine, Department of Hypertension Research, Berlin, Germany.
Insights
Human chymase, an enzyme forming angiotensin II, is widely distributed across various human tissues. This widespread presence suggests chymase plays a significant role beyond the heart in multiple organs.
Area of Science:
- Biochemistry
- Physiology
- Enzymology
Background:
- Human chymase is a key enzyme in angiotensin II formation.
- While heart chymase's role in local angiotensin II generation is known, its systemic distribution is unclear.
- Understanding chymase distribution is crucial for elucidating the human tissue angiotensin II system.
Purpose of the Study:
- To determine the systemic distribution and expression levels of human chymase in various human tissues.
- To investigate the correlation between chymase immunoreactivity and enzymatic activity across different organs.
Main Methods:
- Western blot analysis was used to assess chymase-like immunoreactivity.
- Enzymatic assays measured the Angiotensin II-forming activity from Angiotensin I.
Main Results:
- High chymase immunoreactivity was observed in the alimentary tract, uterus, and tonsil.
- Significant enzymatic activity was detected in skin, esophagus, stomach, and uterus.
- Chymase expression varied significantly across tissues, with detectable levels in most organs studied.
Conclusions:
- Human chymase exhibits heterogeneous and widespread tissue distribution.
- Chymase likely exerts significant physiological influence in multiple human tissues, not solely in the heart.
- These findings highlight the broader role of chymase in human physiology.
Objective:
Human chymase is a potent and specific angiotensin (Ang) II-forming serine proteinase. Although the histological localization of heart chymase indicated that this enzyme contributes to extracellular Ang II formation, the systemic distribution and the level of expression of chymase in various human tissues have not been clarified. This information is needed to elucidate the human tissue Ang II system.
Methods:
Levels of immunoreactivity and enzymatic activity in various human tissues were evaluated respectively by Western blot analysis and by an enzymatic assay for Ang II-forming activity from Ang I.
Results:
High levels of chymase-like immunoreactivity were found in alimentary tract tissue, uterus and tonsil; moderate levels were found in both cardiac ventricles, lung, adenoid and liver; low levels were found in the cardiac atria, coronary artery, aorta and skin; and almost undetectable levels were found in the spleen and kidney. High levels of chymase-like enzymatic activity were detected in skin, oesophagus, stomach and uterus; moderate levels were found in both cardiac ventricles, lung, colon, tonsil, adenoid and renal cortex; and low levels were found in the cardiac atria, coronary artery, aorta, spleen, renal medulla and liver.
Conclusions:
Our studies have revealed heterogeneous and widespread tissue distribution of human chymase throughout the human body and indicate that chymase probably has a significant influence not only in the heart but also in other tissues.