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Updated: Jul 5, 2026

Optogenetic Inhibition of Rho1-Mediated Actomyosin Contractility Coupled with Measurement of Epithelial Tension in Drosophila Embryos
Published on: April 14, 2023
Myocardin is sufficient for a smooth muscle-like contractile phenotype
Xiaochun Long1, Robert D Bell, William T Gerthoffer
1Aab Cardiovascular Research Institute, University of Rochester School of Medicine & Dentistry, 211 Bailey Road, Rochester, New York 14586, USA.
Background:
Myocardin (Myocd) is a strong coactivator that binds the serum response factor (SRF) transcription factor over CArG elements embedded within smooth muscle cell (SMC) and cardiac muscle cyto-contractile genes. Here, we sought to ascertain whether Myocd-mediated gene expression confers a structural and physiological cardiac or SMC phenotype.
Methods And Results:
Adenoviral-mediated expression of Myocd in the BC(3)H1 cell line induces cardiac and SMC genes while suppressing both skeletal muscle markers and cell growth. Immunofluorescence microscopy shows that SRF and a SMC-like cyto-contractile apparatus are elevated with Myocd overexpression. A short hairpin RNA to Srf impairs BC(3)H1 cyto-architecture; however, cotransduction with Myocd results in complete restoration of the cyto-architecture. Electron microscopic studies demonstrate a SMC ultrastructural phenotype with no evidence for cardiac sarcomerogenesis. Biochemical and time-lapsed videomicroscopy assays reveal clear evidence for Myocd-induced SMC-like contraction.
Conclusions:
Myocd is sufficient for the establishment of a SMC-like contractile phenotype.
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