Angiotensin-converting enzyme: characteristics in human skin fibroblasts

Area of Science:

• Biochemistry
• Cell Biology
• Enzymology

Background:

• Angiotensin-converting enzyme (ACE) is found in various tissues beyond vascular endothelium.
• Hormonal regulation of ACE activity by glucocorticoids and thyroid hormone has been suggested.
• The presence and regulation of ACE in human skin fibroblasts remain to be fully elucidated.

Purpose of the Study:

• To investigate the presence and characterize the activity of angiotensin-converting enzyme (ACE) in cultured human skin fibroblasts.
• To determine the effect of specific hormones on fibroblast ACE activity.

Main Methods:

• Cultured human skin fibroblasts were used to measure ACE activity via a radiometric assay.
• Enzyme kinetics, including optimal pH, temperature, and substrate concentration (Km), were determined.
• The effects of various inhibitors and competitive substrates were assessed.
• Fibroblasts were incubated with hormones (T3, 1,25(OH)2D3, dexamethasone, R1881) to evaluate changes in ACE activity.

Main Results:

• Angiotensin-converting enzyme (ACE) was identified in all tested human skin fibroblast strains.
• Optimal conditions for fibroblast ACE activity were determined (pH 6.9-7.6, 37°C).
• Captopril was identified as a potent inhibitor, and angiotensin-I, substance P, and bradykinin acted as competitive substrates.
• Incubation with tested hormones did not significantly alter cellular ACE activity.

Conclusions:

• Human skin fibroblasts possess measurable angiotensin-converting enzyme (ACE) activity.
• The activity of ACE in these fibroblasts is not significantly modulated by the tested hormonal agents.
• These findings contribute to understanding the tissue-specific roles and regulation of ACE.