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 8

Myocardin-regulated maintenance of the contractile SMC phenotype.

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Myocardin-regulated maintenance of the contractile SMC phenotype. Primar...
Primary SMCs isolated from MyocdF/F aortae were infected with Ad-GFP (GFP) (A–C, G–I, and M–O) or Ad-Cre recombinase (Cre) (D–F, J–L, and P–R). Six days after infection, SMCs were immunostained with antibodies that recognize GFP, Cre, SM-MyHC (B, C, E, and F), calponin-h1 (H, I, K, and L), and SM22α (N, O, Q, and R), respectively. SMCs transduced with GFP and Cre stain green, while SMC contractile proteins stains red. (A–C) Colocalization of GFP and MyHC is observed. (D–F) By contrast, SMCs transduced with Ad-Cre (green) do not stain red indicating decreased SM-MyHC expression. (G–I) Colocalization of GFP and calponin is observed. (J–L) SMCs transduced with Ad-Cre do not stain red indicating decreased calponin expression. (M–O) Colocalization of GFP and SM22 is observed. SMCs transduced with Ad-Cre do not stain red indicating decreased SM22α expression. Original magnification, ×200. (S) Western blot analysis of cell lysates harvested from MyocdF/F SMCs transduced with Ad-Cre and Ad-GFP. Abundant GFP and Cre are observed in cells transduced with Ad-GFP and Ad-Cre, respectively (rows 1 and 2). Expression of SMA and SM22α was dramatically decreased in MyocdF/F SMCs transduced with Ad-Cre relative to levels observed in cells transduced with Ad-GFP (lanes 3 and 4). Expression of GAPDH was comparable in SMCs transduced with Ad-Cre and Ad-GFP (lane 5).