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Proc Natl Acad Sci U S A January 30, 2001; 98 (3): 1006-11.
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The midblastula transition in Xenopus embryos activates multiple pathways to prevent apoptosis in response to DNA damage.

Finkielstein CV , Lewellyn AL , Maller JL .

Apoptosis is controlled by a complex interplay between regulatory proteins. Previous work has shown that Xenopus embryos remove damaged cells by apoptosis when irradiated before, but not after, the midblastula transition (MBT). Here we demonstrate that Akt/protein kinase B is activated and mediates an antiapoptotic signal only in embryos irradiated after the MBT. In addition, an increase in xBcl-2/xBax oligomerization and a decrease in xBax homodimerization promote a protective effect against apoptosis only after the MBT. The post-MBT survival mechanism arrests cells in G(1) phase by increasing expression of the cyclin-dependent kinase inhibitor p27(Xic1). p27(Xic1) associates with cyclin D/Cdk4 and cyclin A/Cdk2 complexes to cause G(1)/S arrest, perhaps allowing more time for DNA repair. Taken together, the results define the DNA damage response as an element of the MBT and indicate that multiple mechanisms prevent apoptosis after the MBT.

PubMed ID: 11158585
PMC ID: PMC14699
Article link: Proc Natl Acad Sci U S A
Grant support: [+]

Species referenced: Xenopus
Genes referenced: agfg1 akt1 bax bcl2 cdk2 cdk4 cdknx myc znrd2

Article Images: [+] show captions
References [+] :
Adams, The Bcl-2 protein family: arbiters of cell survival. 1998, Pubmed