Myocardin is differentially required for the development of smooth muscle cells and cardiomyocytes

Mark H. Hoofnagle, Ronald L. Neppl, Erica L. Berzin, G. C. Teg Pipes, Eric N. Olson, Brian W. Wamhoff, Avril V. Somlyo, Gary K. Owens

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Myocardin is a serum response factor (SRF) coactivator exclusively expressed in cardiomyocytes and smooth muscle cells (SMCs). However, there is highly controversial evidence as to whether myocardin is essential for normal differentiation of these cell types, and there are no data showing whether cardiac or SMC subtypes exhibit differential myocardin requirements during development. Results of the present studies showed the virtual absence of myocardin-/- visceral SMCs or ventricular myocytes in chimeric myocardin knockout (KO) mice generated by injection of myocardin-/- embryonic stem cells (ESCs) into wild-type (WT; i.e., myocardin+/+ ESC) blastocysts. In contrast, myocardin-/- ESCs readily formed vascular SMC, albeit at a reduced frequency compared with WT ESCs. In addition, myocardin-/- ESCs competed equally with WT ESCs in forming atrial myocytes. The ultrastructural features of myocardin-/- vascular SMCs and cardiomyocytes were unchanged from their WT counterparts as determined using a unique X-ray microprobe transmission electron microscopic method developed by our laboratory. Myocardin-/- ESC-derived SMCs also showed normal contractile properties in an in vitro embryoid body SMC differentiation model, other than impaired thromboxane A2 responsiveness. Together, these results provide novel evidence that myocardin is essential for development of visceral SMCs and ventricular myocytes but is dispensable for development of atrial myocytes and vascular SMCs in the setting of chimeric KO mice. In addition, results suggest that as yet undefined defects in development and/or maturation of ventricular cardiomyocytes may have contributed to early embryonic lethality observed in conventional myocardin KO mice and that observed deficiencies in development of vascular SMC may have been secondary to these defects.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume300
Issue number5
DOIs
StatePublished - May 2011

Fingerprint

Cardiac Myocytes
Smooth Muscle Myocytes
Embryonic Stem Cells
Vascular Smooth Muscle
Muscle Cells
Knockout Mice
myocardin
Cell Differentiation
Serum Response Factor
Embryoid Bodies
Thromboxane A2
Blastocyst
X-Rays
Electrons

Keywords

  • Cardiac development
  • Chimeric analysis
  • Embryonic stem cells
  • Heart
  • Mouse
  • Smooth muscle

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine

Cite this

Myocardin is differentially required for the development of smooth muscle cells and cardiomyocytes. / Hoofnagle, Mark H.; Neppl, Ronald L.; Berzin, Erica L.; Teg Pipes, G. C.; Olson, Eric N.; Wamhoff, Brian W.; Somlyo, Avril V.; Owens, Gary K.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 300, No. 5, 05.2011.

Research output: Contribution to journalArticle

Hoofnagle, Mark H. ; Neppl, Ronald L. ; Berzin, Erica L. ; Teg Pipes, G. C. ; Olson, Eric N. ; Wamhoff, Brian W. ; Somlyo, Avril V. ; Owens, Gary K. / Myocardin is differentially required for the development of smooth muscle cells and cardiomyocytes. In: American Journal of Physiology - Heart and Circulatory Physiology. 2011 ; Vol. 300, No. 5.
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