TY - JOUR
T1 - Genetic analysis reveals an intrinsic property of the germinal center B cells to generate A:T mutations
AU - Ouchida, Rika
AU - Ukai, Akiko
AU - Mori, Hiromi
AU - Kawamura, Kiyoko
AU - Dollé, Martijn E.T.
AU - Tagawa, Masatoshi
AU - Sakamoto, Akemi
AU - Tokuhisa, Takeshi
AU - Yokosuka, Tadashi
AU - Saito, Takashi
AU - Yokoi, Masayuki
AU - Hanaoka, Fumio
AU - Vijg, Jan
AU - Wang, Ji Yang
PY - 2008/8/2
Y1 - 2008/8/2
N2 - The immunoglobulin genes undergo a high frequency of point mutations at both C:G and A:T pairs in the germinal center (GC) B cells. This hypermutation process is initiated by the activation-induced cytidine deaminase (AID), which converts cytosine to uracil and generates a U:G lesion. Replication of this lesion, or its repair intermediate the abasic site, could introduce C:G mutations but the mechanisms leading to mutations at non-damaged A:T pairs remain elusive. Using a lacZ-transgenic system in which endogenous genome mutations can be detected with high sensitivity, we found that GC B cells exhibited a much higher ratio of A:T mutations as compared to naïve B, non-GC B, and cells of other tissues. This property does not require AID or active transcription of the target gene, and is dependent on DNA polymerase η. These in vivo results demonstrate that GC B cells are unique in having an intrinsic propensity to generate A:T mutations during repair of endogenous DNA damage. These findings have important implications in understanding how AID, which can only target C:G base pairs, is able to induce the entire spectrum of mutations observed in immunoglobulin variable region genes in GC B cells.
AB - The immunoglobulin genes undergo a high frequency of point mutations at both C:G and A:T pairs in the germinal center (GC) B cells. This hypermutation process is initiated by the activation-induced cytidine deaminase (AID), which converts cytosine to uracil and generates a U:G lesion. Replication of this lesion, or its repair intermediate the abasic site, could introduce C:G mutations but the mechanisms leading to mutations at non-damaged A:T pairs remain elusive. Using a lacZ-transgenic system in which endogenous genome mutations can be detected with high sensitivity, we found that GC B cells exhibited a much higher ratio of A:T mutations as compared to naïve B, non-GC B, and cells of other tissues. This property does not require AID or active transcription of the target gene, and is dependent on DNA polymerase η. These in vivo results demonstrate that GC B cells are unique in having an intrinsic propensity to generate A:T mutations during repair of endogenous DNA damage. These findings have important implications in understanding how AID, which can only target C:G base pairs, is able to induce the entire spectrum of mutations observed in immunoglobulin variable region genes in GC B cells.
KW - Activation-induced cytidine deaminase
KW - DNA polymerase η
KW - Genome mutation
KW - Germinal center B cells
KW - Mismatch repair
UR - http://www.scopus.com/inward/record.url?scp=46649119260&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=46649119260&partnerID=8YFLogxK
U2 - 10.1016/j.dnarep.2008.04.014
DO - 10.1016/j.dnarep.2008.04.014
M3 - Article
C2 - 18562254
AN - SCOPUS:46649119260
SN - 1568-7864
VL - 7
SP - 1392
EP - 1398
JO - DNA Repair
JF - DNA Repair
IS - 8
ER -