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Endothelial apoptosis in Braf-deficient mice
L Wojnowski1, A M Zimmer, T W Beck
1Section on Genetics, National Institute of Mental Health/National Human Genome Research Institute, Bethesda, Maryland 20892, USA.
Nature Genetics
|July 1, 1997
Summary
The Braf gene is crucial for vascular system development and regulating programmed cell death. Braf-deficient mice exhibit severe vascular defects and increased endothelial cell apoptosis, highlighting Braf
Area of Science:
- Molecular Biology
- Developmental Biology
- Genetics
Background:
- Tyrosine kinase receptors and Ras/Raf/MEK/MAPK signaling pathways influence programmed cell death.
- Raf proteins, including Craf1, may suppress cell death independently of Ras, potentially through interactions with Bcl-2 family proteins at mitochondria.
- Previous genetic studies in model organisms and mice lacking Araf or Craf1 have not definitively established a role for Raf in cell death suppression.
Purpose of the Study:
- To investigate the role of the Braf gene in embryonic development and programmed cell death.
- To determine if Braf plays a critical role in vascular system formation.
- To provide genetic evidence for the function of Raf genes in regulating apoptosis.
Main Methods:
- Targeted gene disruption in mice to create Braf knockout (Braf-/-) embryos.
- Comparative analysis of Braf-/- embryos with Araf-/- and Craf1-/- embryos.
- Histological examination of embryonic vasculature and assessment of cell death.
Main Results:
- Mice with a targeted disruption in the Braf gene (Braf-/-) exhibit embryonic lethality due to vascular defects during mid-gestation.
- Braf-/- embryos display an increased number of endothelial precursor cells and significantly enlarged blood vessels.
- Apoptotic death of differentiated endothelial cells is observed in Braf-/- embryos.
Conclusions:
- Braf is an essential signaling factor for the proper formation of the vascular system.
- These findings provide the first genetic evidence for a critical role of a Raf gene (Braf) in the regulation of programmed cell death.
- The study underscores the importance of Braf in endothelial cell survival and vascular development.