Deletion of the nucleotide excision repair gene Ercc1 reduces immunoglobulin class switching and alters mutations near switch recombination junctions.
The structure-specific endonuclease ERCC1-XPF is an essential component of the nucleotide excision DNA repair pathway. ERCC1-XPF nicks double-stranded DNA immediately adjacent to 3' single-strand regions. Substrates include DNA bubbles and flaps. Furthermore, ERCC1 interacts with Msh2, a mismatch repair (MMR) protein involved in class switch recombination (CSR). Therefore, ERCC1-XPF has abilities that might be useful for antibody CSR. We tested whether ERCC1 is involved in CSR and found that Ercc1(-)(/)(-) splenic B cells show moderately reduced CSR in vitro, demonstrating that ERCC1-XPF participates in, but is not required for, CSR. To investigate the role of ERCC1 in CSR, the nucleotide sequences of switch (S) regions were determined. The mutation frequency in germline Smicro segments and recombined Smicro-Sgamma3 segments cloned from Ercc1(-)(/)(-) splenic B cells induced to switch in culture was identical to that of wild-type (WT) littermates. However, Ercc1(-)(/)(-) cells show increased targeting of the mutations to G:C bp in RGYW/WRCY hotspots and mutations occur at sites more distant from the S-S junctions compared with WT mice. The results indicate that ERCC1 is not epistatic with MMR and suggest that ERCC1 might be involved in processing or repair of DNA lesions in S regions during CSR.
Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, 55 Lake Ave. North, Worcester, MA 01655, USA.
Carol E
CE
Schrader
Joycelyn
J
Vardo
Erin
E
Linehan
Michael Z
MZ
Twarog
Laura J
LJ
Niedernhofer
Jan H J
JH
Hoeijmakers
Janet
J
Stavnezer
D000818:Animals; D020137:Base Pair Mismatch; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004720:Endonucleases / Q000235:genetics / Q000502:physiology*; D017578:Immunoglobulin Class Switching; D051379:Mice; D008810:Mice, Inbred C57BL; D051718:MutS Homolog 2 Protein; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000502:physiology; D011995:Recombination, Genetic
D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D004720:Endonucleases; C499360:Ercc1 protein, mouse; C497173:Msh2 protein, mouse; D051718:MutS Homolog 2 Protein