Myocardin regulates expression of contractile genes in smooth muscle cells and is required for closure of the ductus arteriosus in mice
Jianhe Huang, … , Jonathan A. Epstein, Michael S. Parmacek
Jianhe Huang, … , Jonathan A. Epstein, Michael S. Parmacek
Published January 10, 2008
Citation Information: J Clin Invest. 2008;118(2):515-525. https://doi.org/10.1172/JCI33304.
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Myocardin regulates expression of contractile genes in smooth muscle cells and is required for closure of the ductus arteriosus in mice

Abstract

Myocardin (Myocd) is a potent transcriptional coactivator that has been implicated in cardiovascular development and adaptation of the cardiovascular system to hemodynamic stress. To determine the function of myocardin in the developing cardiovascular system, MyocdF/F/Wnt1-Cre+ and MyocdF/F/Pax3-Cre+ mice were generated in which the myocardin gene was selectively ablated in neural crest–derived SMCs populating the cardiac outflow tract and great arteries. Both MyocdF/F/Wnt1-Cre+ and MyocdF/F/Pax3-Cre+ mutant mice survived to birth, but died prior to postnatal day 3 from patent ductus arteriosus (PDA). Neural crest–derived SMCs populating the ductus arteriosus (DA) and great arteries exhibited a cell autonomous block in expression of myocardin-regulated genes encoding SMC-restricted contractile proteins. Moreover, Myocd-deficient vascular SMCs populating the DA exhibited ultrastructural features generally associated with the SMC synthetic, rather than contractile, phenotype. Consistent with these findings, ablation of the Myocd gene in primary aortic SMCs harvested from Myocd conditional mutant mice caused a dramatic decrease in SMC contractile protein expression. Taken together, these data demonstrate that myocardin regulates expression of genes required for the contractile phenotype in neural crest–derived SMCs and provide new insights into the molecular and genetic programs that may underlie PDA.

Authors

Jianhe Huang, Lan Cheng, Jian Li, Mary Chen, Deying Zhou, Min Min Lu, Aaron Proweller, Jonathan A. Epstein, Michael S. Parmacek

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Figure 5

MyocdF/F/Wnt1-Cre+ mutant mice exhibit a generalized defect in vascular SMC differentiation.

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MyocdF/F/Wnt1-Cre+ mutant mice exhibit a generalized defect in vascular...
(A, D, G, and J) Serial histological sections of the AAo of an E16.5 MyocdF/F control mouse. (A) H&E-stained AAo. (D, G, and J) Robust expression of SMA (D), SM-MyHC (G), and SM22α (J) is observed. (B, E, H, and K) Serial histological sections showing the AAo of an E16.5 MyocdF/F/Wnt1-Cre+ mutant mouse. (B) H&E-stained AAo. (E, H, and K) Expression of SMA (E), SM-MyHC (H), and SM22α (K) is markedly diminished in the AAo of MyocdF/F/Wnt1-Cre+ mutant mouse. (C, F, I, and L) Serial histological sections showing the DAo of an E16.5 MyocdF/F/Wnt1-Cre+ mutant mouse. (C) H&E-stained section of the DAo. (F, I, and L) Robust expression of SMA (F), SM-MyHC (I), and SM22α (L) is observed in the DAo of a MyocdF/F/Wnt1-Cre+ mutant mouse. Original magnification, ×200. (M) RT-PCR analysis of SMC contractile gene expression in MyocdF/F/Wnt1-Cre+ mutant and control mice. mRNA harvested from the proximal aorta, carotid arteries, and DA of 4 P2 MyocdF/F/Wnt1-Cre+ mice and 4 control mice was analyzed for expression of GAPDH, SMA, calponin-h1 (calponin), SM-MyHC, and SM22α by real-time RT-PCR as described (28). Data are expressed as mean gene expression (arbitrary units) ± SEM. Gray bars represent gene expression in MyocdF/F/Wnt1-Cre+ mutant mice and black bars represent gene expression in control mice.