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Abnormalities of developmental cell death in Dad1-deficient mice
1Department of Developmental Molecular Anatomy, Faculty of Medicine, Kyushu University, 3-1-1 Maidashi, Fukuoka 812-8582, Japan. kiyo@mailserver.med.kyushu-u.ac.jp
Background:
Dad1, the defender against apoptotic cell death, comprises the oligosaccharyltransferase complex and is well conserved among eukaryotes. In hamster BHK21-derived tsBN7 cells, loss of Dad1 causes apoptosis which cannot be prevented by Bcl-2.
Results:
To determine the role of Dad1 function in vivo, we prepared by gene targeting, mice harbouring a disrupted Dad1 gene. Homozygous mutants died shortly after they were implanted with the characteristic features of apoptosis. In an in vitro blastocyst culture system, Dad1-null cells displayed abnormalities which were comparable to those obtained in vivo. However, oligosaccharyltransferase activity was apparently retained even after the Dad1-null cells were destined to die. Some live-born heterozygous mutants displayed soft-tissue syndactyly. Mild thymic hypoplasia was also indicated in heterozygotes.
Conclusion:
These results suggest the involvement of the Dad1 gene in the acquisition of a common syndactyly phenotype, as well as in the control of programmed cell death during development.