grp (chk1) replication-checkpoint mutations and DNA damage trigger a Chk2-dependent block at the Drosophila midblastula transition
Graduate School of Biomedical Sciences; Program in Molecular Medicine; Department of Molecular Genetics and Microbiology
Life Sciences | Medicine and Health Sciences
The 13 syncytial cleavage divisions that initiate Drosophila embryogenesis are under maternal genetic control. The switch to zygotic regulation of development at the midblastula transition (MBT) follows mitosis 13, when the cleavage divisions terminate, transcription increases and the blastoderm cellularizes. Embryos mutant for grp, which encodes Checkpoint kinase 1 (Chk1), are DNA-replication-checkpoint defective and fail to cellularize, gastrulate or to initiate high-level zygotic transcription at the MBT. The mnk (also known as loki) gene encodes Checkpoint kinase 2 (Chk2), which functions in DNA-damage signal transduction. We show that mnk grp double-mutant embryos are replication-checkpoint defective but cellularize, gastrulate and activate high levels of zygotic gene expression. We also show that grp mutant embryos accumulate DNA double-strand breaks and that DNA-damaging agents induce a mnk-dependent block to cellularization and zygotic gene expression. We conclude that the DNA-replication checkpoint maintains genome integrity during the cleavage divisions, and that checkpoint mutations lead to DNA damage that induces a novel Chk2-dependent block at the MBT.
DOI of Published Version
Development. 2007 May;134(9):1737-44. Epub 2007 Apr 4. Link to article on publisher's site
Development (Cambridge, England)
Takada S, Kwak S, Koppetsch BS, Theurkauf WE. (2007). grp (chk1) replication-checkpoint mutations and DNA damage trigger a Chk2-dependent block at the Drosophila midblastula transition. Morningside Graduate School of Biomedical Sciences Student Publications. https://doi.org/10.1242/dev.02831. Retrieved from https://escholarship.umassmed.edu/gsbs_sp/504