TY - JOUR
T1 - Species-specific inhibitor sensitivity of angiotensin-converting enzyme 2 (ACE2) and its implication for ACE2 activity assays
AU - Pedersen, Kim Brint
AU - Sriramula, Srinivas
AU - Chhabra, Kavaljit H.
AU - Xia, Huijing
AU - Lazartigues, Eric
PY - 2011/11
Y1 - 2011/11
N2 - Angiotensin-converting enzyme 2 (ACE2) is a component of the reninangiotensin system, and its expression and activity have been shown to be reduced in cardiovascular diseases. Enzymatic activity of ACE2 is commonly measured by hydrolysis of quenched fluorescent substrates in the absence or presence of an ACE2-specific inhibitor, such as the commercially available inhibitor DX600. Whereas recombinant human ACE2 is readily detected in mouse tissues using 1 μM DX600 at pH 7.5, the endogenous ACE2 activity in mouse tissues is barely detectable. We compared human, mouse, and rat ACE2 overexpressed in cell lines for their sensitivity to inhibition by DX600. ACE2 from all three species could be inhibited by DX600, but the half maximal inhibitory concentration (IC50) for human ACE2 was much lower (78-fold) than for rodent ACE2. Following optimization of pH, substrate concentration, and antagonist concentration, rat and mouse ACE2 expressed in a cell line could be accurately quantified with 10 μM DX600 (>95% inhibition) but not with 1 μM DX600 (<75% inhibition). Validation that the optimized method robustly quantifies ACE2 in mouse tissues (kidney, brain, heart, and plasma) was performed using wild-type and ACE2 knockout mice. This study provides a reliable method for measuring human, as well as endogenous ACE2 activity in rodents. Our data underscore the importance of validating the effect of DX600 on ACE2 from each particular species at the experimental conditions employed.
AB - Angiotensin-converting enzyme 2 (ACE2) is a component of the reninangiotensin system, and its expression and activity have been shown to be reduced in cardiovascular diseases. Enzymatic activity of ACE2 is commonly measured by hydrolysis of quenched fluorescent substrates in the absence or presence of an ACE2-specific inhibitor, such as the commercially available inhibitor DX600. Whereas recombinant human ACE2 is readily detected in mouse tissues using 1 μM DX600 at pH 7.5, the endogenous ACE2 activity in mouse tissues is barely detectable. We compared human, mouse, and rat ACE2 overexpressed in cell lines for their sensitivity to inhibition by DX600. ACE2 from all three species could be inhibited by DX600, but the half maximal inhibitory concentration (IC50) for human ACE2 was much lower (78-fold) than for rodent ACE2. Following optimization of pH, substrate concentration, and antagonist concentration, rat and mouse ACE2 expressed in a cell line could be accurately quantified with 10 μM DX600 (>95% inhibition) but not with 1 μM DX600 (<75% inhibition). Validation that the optimized method robustly quantifies ACE2 in mouse tissues (kidney, brain, heart, and plasma) was performed using wild-type and ACE2 knockout mice. This study provides a reliable method for measuring human, as well as endogenous ACE2 activity in rodents. Our data underscore the importance of validating the effect of DX600 on ACE2 from each particular species at the experimental conditions employed.
KW - (7-methoxycoumarin-4-yl) acetyl-Ala-Pro-Lys(2,4-dinitrophenyl)-OH
KW - DX600
KW - Enzyme inhibition
KW - Quenched fluorescent substrate
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U2 - 10.1152/ajpregu.00339.2011
DO - 10.1152/ajpregu.00339.2011
M3 - Article
C2 - 21880865
AN - SCOPUS:84867698215
SN - 0363-6119
VL - 301
SP - R1293-R1299
JO - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
JF - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
IS - 5
ER -