Faculty Collaboration Database

Conditional mutagenesis of the murine serum response factor gene blocks cardiogenesis and the transcription of downstream gene targets. J Biol Chem 2005 Sep 16;280(37):32531-8

Date

06/03/2005

Pubmed ID

15929941

DOI

10.1074/jbc.M501372200

Scopus ID

2-s2.0-25444458851 (requires institutional sign-in at Scopus site)   104 Citations

Abstract

Serum response factor (SRF) homozygous-null embryos from our backcross of SRF(LacZ/)(+) "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 alpha-actins, SM22alpha, 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 alpha-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 (> or =95%), atrial naturetic factor (> or =80%), and cardiac (> or =60%), skeletal (> or =90%), and smooth muscle (> or =75%) alpha-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 approximately 30% reduction in gene activity, indicating SRF gene autoregulation during cardiogenesis.

Author List

Niu Z, Yu W, Zhang SX, Barron M, Belaguli NS, Schneider MD, Parmacek M, Nordheim A, Schwartz RJ

Author

Matthew R. Barron PhD Research Scientist I in the Surgery department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Actins
Animals
Apoptosis
Cell Lineage
DNA-Binding Proteins
Down-Regulation
Embryo, Mammalian
GATA4 Transcription Factor
Gene Expression Regulation
Genes, Reporter
Homeobox Protein Nkx-2.5
Homeodomain Proteins
Immunohistochemistry
In Situ Hybridization
In Situ Nick-End Labeling
Lac Operon
Mice
Mice, Knockout
Mice, Transgenic
Microscopy, Fluorescence
Muscle, Skeletal
Mutagenesis, Site-Directed
Myocardium
Myocytes, Cardiac
Nuclear Proteins
Protein Binding
RNA, Messenger
Reverse Transcriptase Polymerase Chain Reaction
Serum Response Factor
Stem Cells
Time Factors
Trans-Activators
Transcription Factors
Transcription, Genetic
Transgenes
beta-Galactosidase