Sex-Specific Changes in Renal Angiotensin-Converting Enzyme and Angiotensin-Converting Enzyme 2 Gene Expression and Enzyme Activity at Birth and Over the First Year of Life

Abstract

Objective: Angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2) are key enzymes of the renin-angiotensin system. We investigated developmental changes in renal ACE and ACE2 gene expression and activity in both male and female sheep.

Methods: Three groups of sheep (fetus, newborn, and adult) were used. Renal ACE and ACE2 activities, messenger RNA (mRNA), and protein expression were studied.

Results: Renal ACE and ACE2 activities increased at 1 year in males, while there were no changes throughout development in females. Renal ACE and ACE2 mRNA and protein showed no sex differences but increased by 1 year of age.

Conclusion: There are sex-related differences in the development of renal-converting enzyme activities that may have functional implications in terms of the regulation of blood pressure and renal function in men and women. The difference in the patterns of gene expression and enzyme activity indicates that changes in gene expression may not accurately reflect changes in activity.

Keywords: angiotensin-converting enzyme; angiotensin-converting enzyme 2; kidney; renin–angiotensin system; sex.

Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

© The Author(s) 2015.

Figures

Figure 1.

Representative chromatograms of ACE activity. A, The figure shows the quantity of angiotensin I (Ang I) after a control membrane sample incubated with Ang I with ACE activity blocked with lisinopril. B, The figure shows the quantity of Ang I and angiotensin II (Ang II) after a control membrane sample incubated with Ang I without blockade of ACE. ACE indicates angiotensin-converting enzyme.

Figure 2.

Representative chromatograms of ACE2 activity. A, The figure shows the quantity of angiotensin II (Ang II) after a control membrane sample incubated with Ang II with ACE2 activity blocked with C16. B, The figure shows the quantity of Ang II and angiotensin 1-7 (Ang-1-7) after a control membrane sample incubated with Ang I without blockade of ACE2. ACE2 indicates angiotensin-converting enzyme 2.

Figure 3.

Fluorescent stain of ACE and ACE2 in the renal cortex. A, The figure shows the fluorescent ACE staining in the renal cortex was primarily localized to the brush border of proximal tubules (left: bright green shows ACE. Right, negative control. Magnification: 1:20). B, The figure shows the fluorescent ACE2 staining in the renal cortex was primarily localized to the brush border of proximal tubules (left, bright red shows ACE2. Right, negative control. Magnification: 1:20). ACE indicates angiotensin-converting enzyme.

Figure 4.

The developmental changes in renal ACE activity, ACE2 activity, and their ratio. A. Renal ACE activity during development. Renal ACE activity increased at 1 year of age (1 year; *P < .01 vs 135 days of gestation [135 GA], P < .001 vs newborns [NBs]) in males. Males had higher renal ACE activity compared to that in females at 1 year of age (+P < .001). B, Renal ACE2 activity during development. Renal ACE2 activity increased at 1 year of age (*P < .001 vs 135 GA and NBs) in males. Males had higher renal ACE2 activity compared to that in females at 1 year of age (+P < .001). C, ACE/ACE2 activity ratio during development. The ACE/ACE2 ratio decreased at 1 year (*P < .05 vs NB) in males. ACE indicates angiotensin-converting enzyme.

Figure 5.

The developmental changes in renal cortical ACE mRNA, ACE2 mRNA, and their ratio. A, Renal cortical ACE mRNA expression. Renal ACE mRNA increased at 1 year of age in female (*P < .05 vs newborns [NBs] and 135 GA) but not in males. B, Renal cortical ACE2 mRNA expression during development. Renal ACE2 mRNA expression was significantly increased at 1 year of age in both males (P < .05 vs NBs) and females (P < .05 vs NBs and 135 GA). C, The ACE/ACE2 mRNA expression ratio during development. There were no effects of age or sex and no interactions. ACE indicates angiotensin-converting enzyme; mRNA, messenger RNA; 135 GA, 135 days of gestation.

Figure 6.

The developmental change in renal cortical ACE protein. Panel A: renal cortical ACE protein expression. Renal ACE protein expression increased at 1 year old in both males (*P < .01 vs newborns [NBs]) and females (*P < .01 vs NB). Panel B: Western blot of renal cortical ACE. ACE indicates angiotensin-converting enzyme.

Figure 7.

The developmental change in renal cortical ACE2 protein. Panel A: renal cortical ACE2 protein expression. Renal ACE2 protein expression increased at 1 year old in both males (*P < .01 vs NB) and females (*P < .05 vs NB and 135 days of gestation [135 GA]). Panel B: Western blot of renal cortical ACE2. ACE2 indicates angiotensin-converting enzyme 2