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Brca2 is required for embryonic cellular proliferation in the mouse
A Suzuki1, J L de la Pompa, R Hakem
1Amgen Institute, Toronto, Ontario, Canada.
Abstract:
Mutations of the tumor suppressor gene BRCA2 are associated with predisposition to breast and other cancers. Homozygous mutant mice in which exons 10 and 11 of the Brca2 gene were deleted by gene targeting (Brca2(10-11)) die before day 9.5 of embryogenesis. Mutant phenotypes range from severely developmentally retarded embryos that do not gastrulate to embryos with reduced size that make mesoderm and survive until 8.5 days of development. Although apoptosis is normal, cellular proliferation is impaired in Brca2(10-11) mutants, both in vivo and in vitro. In addition, the expression of the cyclin-dependent kinase inhibitor p21 is increased. Thus, Brca2(10-11) mutants are similar in phenotype to Brca1(5-6) mutants but less severely affected. Expression of either of these two genes was unaffected in mutant embryos of the other. This study shows that Brca2, like Brca1, is required for cellular proliferation during embryogenesis. The similarity in phenotype between Brca1 and Brca2 mutants suggests that these genes may have cooperative roles or convergent functions during embryogenesis.
Insights
The tumor suppressor gene BRCA2 is essential for embryonic development. Brca2 mutations impair cellular proliferation, leading to embryonic lethality, similar to Brca1 mutations.
Area of Science:
- Developmental Biology
- Cancer Genetics
- Molecular Biology
Background:
- Mutations in the tumor suppressor gene BRCA2 are linked to hereditary breast and other cancers.
- BRCA2 plays a critical role in DNA repair and maintaining genomic stability.
Purpose of the Study:
- To investigate the role of the Brca2 gene during mouse embryogenesis.
- To characterize the phenotypic consequences of Brca2 gene deletion in mice.
Main Methods:
- Gene targeting was used to create homozygous mutant mice (Brca2(10-11)) with deletion of exons 10 and 11.
- Embryonic development, cellular proliferation, apoptosis, and gene expression (p21) were analyzed in mutant embryos.
Main Results:
- Brca2(10-11) homozygous mutant embryos exhibit developmental defects and die before embryonic day 9.5.
- Cellular proliferation is significantly impaired in Brca2 mutants, while apoptosis remains normal.
- Increased expression of the cyclin-dependent kinase inhibitor p21 was observed in Brca2 mutants.
Conclusions:
- Brca2 is crucial for cellular proliferation during embryogenesis, similar to Brca1.
- The phenotypic similarities between Brca1 and Brca2 mutants suggest potential cooperative or convergent functions in embryonic development.