Conditional mutagenesis of the murine serum response factor gene blocks cardiogenesis and the transcription of downstream gene targets

Zhiyv Niu, Wei Yu, Shu Xing Zhang, Matthew Barron, Narasimhaswamy S. Belaguli, Michael D. Schneider, Michael Parmacek, Alfred Nordheim, Robert J. Schwartz

Research output: Contribution to journalArticlepeer-review

92 Scopus citations


Serum response factor (SRF) homozygous-null embryos from our backcross of SRFLacZ/+ "knock-in" mice failed to gastrulate and form mesoderm, similar to the findings of an earlier study (Arsenian, S., Weinhold, B., Oelgeschlager, M., Ruther, U., and Nordheim, A. (1998) EMBO J. 17, 6289-6299). Our use of embryonic stem cells provided a model system that could be used to investigate the specification of multiple embryonic lineages, including cardiac myocytes. We observed the absence of myogenic α-actins, SM22α, and myocardin expression and the failure to form beating cardiac myocytes in aggregated SRF null embryonic stem cells, whereas the appearance of transcription factors Nkx2-5 and GATA4 were unaffected. To study the role of SRF during heart organogenesis, we then performed cardiac-specific ablation of SRF by crossing the transgenic α-myosin heavy chain Cre recombinase line with SRF LoxP-engineered mice. Cardiac-specific ablation of SRF resulted in embryonic lethality due to cardiac insufficiency during chamber maturation. Conditional ablation of SRF also reduced cell survival concomitant with increased apoptosis and reduced cellularity. Significant reductions in SRF (≥95%), atrial naturetic factor (≥80%), and cardiac (≥60%), skeletal (≥90%), and smooth muscle (≥75%) α-actin transcripts were also observed in the cardiac-conditional knock-out heart. This was consistent with the idea that SRF directs de novo cardiac and smooth muscle gene activities. Finally, quantitation of the knock-in LacZ reporter gene transcripts in the hearts of cardiac-conditional knock-out embryos revealed an ∼30% reduction in gene activity, indicating SRF gene autoregulation during cardiogenesis.

Original languageEnglish (US)
Pages (from-to)32531-32538
Number of pages8
JournalJournal of Biological Chemistry
Issue number37
StatePublished - Sep 16 2005

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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