Disruption of ECE-1 and ECE-2 reveals a role for endothelin-converting enzyme-2 in murine cardiac development
Hiromi Yanagisawa, … , David E. Clouthier, Masashi Yanagisawa
Hiromi Yanagisawa, … , David E. Clouthier, Masashi Yanagisawa
Published May 15, 2000
Citation Information: J Clin Invest. 2000;105(10):1373-1382. https://doi.org/10.1172/JCI7447.
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Article

Disruption of ECE-1 and ECE-2 reveals a role for endothelin-converting enzyme-2 in murine cardiac development

Abstract

Endothelin-converting enzyme-1 and -2 (ECE-1 and -2) are membrane-bound metalloproteases that can cleave biologically the inactive endothelin-1 (ET-1) precursor to form active ET-1 in vitro. We previously reported developmental defects in specific subsets of neural crest–derived tissues, including branchial arch–derived craniofacial structures, aortic arch arteries, and the cardiac outflow tract in ECE-1 knockout mice. To examine the role of ECE-2 in cardiovascular development, we have now generated a null mutation in ECE-2 by homologous recombination. ECE-2 null mice develop normally, are healthy into adulthood, are fertile in both sexes, and live a normal life span. However, when they are bred into an ECE-1–null background, defects in cardiac outflow structures become more severe than those in ECE-1 single knockout embryos. In addition, ECE-1–/–; ECE-2–/– double null embryos exhibited abnormal atrioventricular valve formation, a phenotype never seen in ECE-1 single knockout embryos. In the developing mouse heart, ECE-2 mRNA is expressed in the endocardial cushion mesenchyme from embyronic day (E) 12.5, in contrast to the endocardial expression of ECE-1. Levels of mature ET-1 and ET-2 in whole ECE-1–/–; ECE-2–/– embryos at E12.5 do not differ appreciably from those of ECE-1–/– embryos. The significant residual ET-1/ET-2 in the ECE-1–/–; ECE-2–/– embryos indicates that proteases distinct from ECE-1 and ECE-2 can carry out ET-1 activation in vivo.

Authors

Hiromi Yanagisawa, Robert E. Hammer, James A. Richardson, Noriaki Emoto, S. Clay Williams, Shin-ichi Takeda, David E. Clouthier, Masashi Yanagisawa

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Transverse sections of the heart of term wild-type (a, d, and g), ECE-1–...
Transverse sections of the heart of term wild-type (a, d, and g), ECE-1–/– (b, e, and h), and ECE-1–/–; ECE-2–/– (c, f, and i) embryos stained with hematoxylin and eosin. Original magnification is ×10. (a, d, and g) At the level of the pulmonary trunk (P), the ascending aorta (As) is seen as posterior and right to the pulmonary trunk in wild-type embryos. The aortic outflow (Ao) comes from the left ventricle (LV) (d), and the left AV valve opens to the left ventricle (g). (b, e, and h) In ECE-1–/– embryos, relative distance between the ascending aorta and the pulmonary trunk shortens, and the ascending aorta is seen anteriorly (b). Owing to the malalignment of outflow tracts, aortic and pulmonary tracts are seen in the same plane, originating from the right ventricle (RV) (DORV). Two great vessels do cross over (e). A small VSD is indicated by an arrow (h). (c, f, and i) In double homozygous embryos, the ascending aorta is seen further anteriorly, with the pulmonary trunk seen posteriorly to ascending aorta (c). Aortic and pulmonary outflows both originate from the right ventricle (DORV), and the two great vessels do not cross over. Note hypoplasia of the muscular wall of the great vessels (arrow) (f). (i) In a severe case, formation of the endocardial cushion (asterisk) is markedly impaired and the AV valve is not formed. A large VSD is indicated by double arrows. AV, arterioventricular valve; pv, pulmonary vein.