This Article Full Text Full Text (PDF) Data Supplement All Versions of this Article: 102/5/554    most recent CIRCRESAHA.105.162628v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kolodziejska, K. M. Articles by Husain, M. Search for Related Content PubMed PubMed Citation Articles by Kolodziejska, K. M. Articles by Husain, M. Pubmed/NCBI databases Gene GEO Profiles HomoloGene Nucleotide Protein UniGene Related Collections Developmental biology Gene expression Smooth muscle proliferation and differentiation

(Circulation Research. 2008;102:554.)
© 2008 American Heart Association, Inc.

Molecular Medicine

c-Myb–Dependent Smooth Muscle Cell Differentiation

Karolina M. Kolodziejska, M.H. Noyan-Ashraf, Andras Nagy, Andrea Bacon, Jon Frampton, Hong-Bo Xin, Michael I. Kotlikoff, Mansoor Husain

From the Heart & Stroke Richard Lewar Center of Excellence in Cardiovascular Research (K.M.K., M.H.N.-A., M.H.), Department of Medicine, University of Toronto, and the McEwen Centre for Regenerative Medicine, Toronto General Hospital Research Institute, Canada; Samuel Lunenfeld Research Institute (A.N.), Department of Molecular and Medical Genetics, University of Toronto, and Mount Sinai Hospital, Toronto, Canada; Division of Immunity and Infection (A.B., J.F.), Birmingham University Medical School, UK; and Department of Biomedical Sciences (H.-B.X., M.I.K.), College of Veterinary Medicine, Cornell University, Ithaca, NY.

Correspondence to Dr Mansoor Husain, University of Toronto, 200 Elizabeth St, TMDT 3-909, Toronto, Canada M5G 2C4. E-mail mansoor. husain{at}utoronto.ca

Both in vitro and in vivo studies have implicated the c-Myb transcription factor in vascular smooth muscle cell (SMC) proliferation and hematopoiesis. However, its role in differentiation and maturation of contractile, as opposed to proliferating, SMCs has not been investigated. Here we demonstrate that c-myb^–/– embryonic stem cells (ESCs) are incapable of producing embryoid bodies (EBs) with spontaneously contracting SMCs but can differentiate into contracting cardiomyocytes unimpaired. Quantitative real-time RT-PCR revealed that whereas mesodermal differentiation was unaffected, myocardin, a critical determinant of SMC differentiation, became upregulated at day 7 in wild-type, but not in c-myb^–/– EBs. SMC-specific genes, smooth muscle -actin, SM22 and smooth muscle myosin heavy chain reached peak expression levels by day 15 of differentiation and were 2- to 3-fold higher in wild-type as compared with c-myb^–/– derived EBs. Similarly, fluorescence-activated cell-sorting analysis confirmed significantly different proportions of smooth muscle -actin–positive cells in wild-type (26.8±0.7%) versus c-myb^–/– (12.3±0.4%) EBs. Temporal induction of these SMC-specific markers preceded and paralleled contractile SMC appearance and predicted the relative (in)ability of c-myb^–/– and wild-type ESC lines to generate EBs with contracting SMCs. Importantly, data from EBs faithfully predicted a significant reduction in c-myb^–/– cell contribution to SMC lineage in vivo, in chimeric E11.5 embryo and adult aortas relative to brain and skin chimerism, respectively. Moreover, the visceral SMC population in chimeric embryos was nearly devoid of c-myb^–/– cells. Our data are the first to implicate c-Myb in SMC differentiation from precursor stem cell–derived populations, reinforcing its potential role in phenotypic modulation of SMCs and vascular disease.

Key Words: smooth muscle cell • differentiation • c-Myb • ES cell

This article has been cited by other articles:

				C. L. Bauwens, R. Peerani, S. Niebruegge, K. A. Woodhouse, E. Kumacheva, M. Husain, and P. W. Zandstra Control of Human Embryonic Stem Cell Colony and Aggregate Size Heterogeneity Influences Differentiation Trajectories Stem Cells, September 1, 2008; 26(9): 2300 - 2310. [Abstract] [Full Text] [PDF]

				X. Long, R. D. Bell, W. T. Gerthoffer, B. V. Zlokovic, and J. M. Miano Myocardin Is Sufficient for a Smooth Muscle-Like Contractile Phenotype Arterioscler. Thromb. Vasc. Biol., August 1, 2008; 28(8): 1505 - 1510. [Abstract] [Full Text] [PDF]