Abstract
The Mre11-Rad50-NBS1 (MRN) complex has many roles in response to DNA double-strand breaks, but its functions in repair by nonhomologous end joining (NHEJ) pathways are poorly understood. We have investigated requirements for MRN in class switch recombination (CSR), a programmed DNA rearrangement in B lymphocytes that requires NHEJ. To this end, we have engineered mice that lack the entire MRN complex in B lymphocytes or that possess an intact complex that harbors mutant Mre11 lacking DNA nuclease activities. MRN deficiency confers a strong defect in CSR, affecting both the classic and the alternative NHEJ pathways. In contrast, absence of Mre11 nuclease activities causes a milder phenotype, revealing a separation of function within the complex. We propose a model in which MRN stabilizes distant breaks and processes DNA termini to facilitate repair by both the classical and alternative NHEJ pathways.
Publication types
-
Research Support, N.I.H., Extramural
-
Research Support, Non-U.S. Gov't
MeSH terms
-
ATP-Binding Cassette Transporters / genetics
-
ATP-Binding Cassette Transporters / metabolism
-
Acid Anhydride Hydrolases
-
Adaptor Proteins, Signal Transducing
-
Animals
-
Ataxia Telangiectasia Mutated Proteins
-
B-Lymphocytes / cytology
-
B-Lymphocytes / metabolism*
-
Base Sequence
-
Blotting, Western
-
Cell Cycle Proteins / genetics
-
Cell Cycle Proteins / metabolism
-
Cell Proliferation
-
Cells, Cultured
-
DNA Repair Enzymes / genetics
-
DNA Repair Enzymes / metabolism
-
DNA Repair*
-
DNA-Binding Proteins / genetics
-
DNA-Binding Proteins / metabolism
-
Female
-
Flow Cytometry
-
Histones / genetics
-
Histones / metabolism
-
Immunoglobulin Class Switching*
-
Immunoglobulin Heavy Chains / genetics
-
In Situ Hybridization, Fluorescence
-
Intracellular Signaling Peptides and Proteins / genetics
-
Intracellular Signaling Peptides and Proteins / metabolism
-
MRE11 Homologue Protein
-
Male
-
Mice
-
Mice, Knockout
-
Molecular Sequence Data
-
Mutation
-
Nuclear Proteins / genetics
-
Nuclear Proteins / metabolism
-
Protein Serine-Threonine Kinases / genetics
-
Protein Serine-Threonine Kinases / metabolism
-
Recombination, Genetic
-
Signal Transduction / genetics
-
Signal Transduction / physiology*
-
Tumor Suppressor Proteins / genetics
-
Tumor Suppressor Proteins / metabolism
Substances
-
ATP-Binding Cassette Transporters
-
Adaptor Proteins, Signal Transducing
-
Cell Cycle Proteins
-
DNA-Binding Proteins
-
H2AX protein, mouse
-
Histones
-
Immunoglobulin Heavy Chains
-
Intracellular Signaling Peptides and Proteins
-
MDC1 protein, mouse
-
Mre11a protein, mouse
-
Nijmegen breakage syndrome 1 protein, mouse
-
Nuclear Proteins
-
Tumor Suppressor Proteins
-
Ataxia Telangiectasia Mutated Proteins
-
Atm protein, mouse
-
Protein Serine-Threonine Kinases
-
MRE11 Homologue Protein
-
Acid Anhydride Hydrolases
-
Rad50 protein, mouse
-
DNA Repair Enzymes