Novel Variants of Angiotensin Converting Enzyme-2 of Shorter Molecular Size to Target the Kidney Renin Angiotensin System

Wysocki, Jan; Schulze, Arndt; Batlle, Daniel

To examine whether kidneys from ACE2-deficient mice infused with ACE2 1-619 gain substantial ACE2 activity, the ACE2 619 truncate was injected and kidneys harvested after infusion ( Figure 10 ). In isolated kidney cortices from ACE2-deficient mice, ACE2 activity was not detectable in either in PBS-or rACE2 1-740-infused mice. In contrast, kidney cortex ACE2 activity after rACE2 1-619 was clearly detectable (2.7 ± 0.7 RFU/µg prot./h) and significantly higher than in PBS (0.2 ± 0.1 RFU/µg prot./h, p < 0.05) and rACE2 1-740 groups (−0.2 ± 0.8 RFU/µg prot./h, p < 0.01) ( Figure 10A ). In ex vivo experiments, kidneys from 1-619-infused mice, when spiked with Ang II, also exhibited significantly higher Ang 1-7 formation than kidneys from PBS-mice (p < 0.001) or native rACE2-1-740-infused mice (p < 0.01) by 2-way Anova ( Figure 10B ). This shows that kidney uptake translates into increased kidney ACE2 activity and capability of Ang II to Ang 1-7 conversion. Figure 9 . Glomerular filtration and tubular uptake of 1-605-(blue, n = 8) and 1-619-mACE2 (green, n = 6) as compared to native 1-740 rACE2 (red, n = 4) in ACE2-deficient mice. Immediately after voiding (baseline urine collection), ACE2-deficient mice were injected i.v. with 1 µg/g BW rACE2. Urine was collected again within the first 2 h after ACE2-injection ("rACE2"). L-Lysine was injected i.p. two hours after rACE2-injection and urine was collected within the next 2 h. ("rACE2/L-Lysine"). Recovery of ACE2-activity in the urine normalized to creatinine excretion is depicted. Repeated measures one-way ANOVA was used for comparisons within the experimental groups, followed by post-hoc analysis; * denotes p < 0.05 or p < 0.01.