Ubiquitylated PCNA plays a role in somatic hypermutation and class-switch recombination and is required for meiotic progression.
Somatic hypermutation (SHM) and class-switch recombination (CSR) of Ig genes are dependent upon activation-induced cytidine deaminase (AID)-induced mutations. The scaffolding properties of proliferating cell nuclear antigen (PCNA) and ubiquitylation of its residue K164 have been suggested to play an important role organizing the error-prone repair events that contribute to the AID-induced diversification of the Ig locus. We generated knockout mice for PCNA (Pcna(-/-)), which were embryonic lethal. Expression of PCNA with the K164R mutation rescued the lethal phenotype, but the mice (Pcna(-/-)tg(K164R)) displayed a meiotic defect in early pachynema and were sterile. B cells proliferated normally in Pcna(-/-)tg(K164R) mice, but a PCNA-K164R mutation resulted in impaired ex vivo CSR to IgG1 and IgG3, which was associated with reduced mutation frequency at the switch regions and a bias toward blunt junctions. Analysis of the heavy chain V186.2 region after NP-immunization showed in Pcna(-/-)tg(K164R) mice a significant reduction in the mutation frequency of A:T residues in WA motifs preferred by polymerase-eta (Poleta), and a strand-biased increase in the mutation frequency of G residues, preferentially in the context of AID-targeted GYW motifs. The phenotype of Pcna(-/-)tg(K164R) mice supports the idea that ubiquitylation of PCNA participates directly in the meiotic process and the diversification of the Ig locus through class-switch recombination (CSR) and somatic hypermutation (SHM).
Roa
Sergio
S
Departments of Cell Biology and Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Avdievich
Elena
E
Peled
Jonathan U
JU
Maccarthy
Thomas
T
Werling
Uwe
U
Kuang
Fei Li
FL
Kan
Rui
R
Zhao
Chunfang
C
Bergman
Aviv
A
Cohen
Paula E
PE
Edelmann
Winfried
W
Scharff
Matthew D
MD
D000818:Animals; D002875:Chromosomes / Q000378:metabolism; D017578:Immunoglobulin Class Switching / Q000235:genetics* / Q000276:immunology*; D008540:Meiosis; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation / Q000235:genetics; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism*; D027041:Somatic Hypermutation, Immunoglobulin / Q000235:genetics* / Q000276:immunology*; D054875:Ubiquitination
D018809:Proliferating Cell Nuclear Antigen