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Nkx2-5 activity is essential for cardiomyogenesis.
M Jamali1, P J Rogerson, S Wilton
1Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada.
The Journal of Biological Chemistry
|August 30, 2001
Summary
Nkx2-5 is crucial for cardiac muscle development. Researchers used a dominant-negative mutant to show that Nkx2-5’s N-terminal region and homeodomain are sufficient for cardiomyogenesis.
Area of Science:
- Developmental Biology
- Molecular Biology
- Cardiovascular Research
Background:
- The homeobox transcription factor tinman is vital for heart vessel formation in Drosophila.
- Murine homologue Nkx2-5 is essential for cardiac looping but not myocyte development in mice, possibly due to genetic redundancy.
Purpose of the Study:
- To investigate the role of Nkx2-5 in cardiomyogenesis in mammalian systems.
- To identify the minimal functional domain of Nkx2-5 required for inducing cardiac muscle cell development.
Main Methods:
- Created a dominant-negative mutant of Nkx2-5 (Nkx/EnR) by fusing the engrailed 2 repressor domain to the Nkx2-5 homeodomain.
- Assessed the effect of Nkx/EnR on DMSO-induced cardiomyogenesis and skeletal myogenesis in P19 cells.
- Analyzed the expression of cardiac and skeletal lineage markers.
- Examined the cardiomyogenic activity of various Nkx2-5 deletion mutants.
Main Results:
- Nkx/EnR expression inhibited cardiomyogenesis but not skeletal myogenesis in P19 cells.
- Nkx/EnR suppressed cardiomyoblast markers (GATA-4, MEF2C) but not mesoderm or skeletal lineage markers.
- The C-terminal domain of Nkx2-5 is not essential for inducing cardiomyogenesis.
Conclusions:
- Nkx2-5 plays an essential role in the commitment of mesoderm to the cardiac muscle lineage.
- The N-terminal region and homeodomain of Nkx2-5 are sufficient for inducing cardiomyogenesis in P19 cells.