TY - JOUR
T1 - ATM increases activation-induced cytidine deaminase activity at downstream s regions during class-switch recombination
AU - Khair, Lyne
AU - Guikema, Jeroen E.J.
AU - Linehan, Erin K.
AU - Ucher, Anna J.
AU - Leus, Niek G.J.
AU - Ogilvie, Colin
AU - Lou, Zhenkun
AU - Schrader, Carol E.
AU - Stavnezer, Janet
PY - 2014/5/15
Y1 - 2014/5/15
N2 - Activation-induced cytidine deaminase (AID) initiates Ab class-switch recombination (CSR) in activated B cells resulting in exchanging the IgH C region and improved Ab effector function. During CSR, AID instigates DNA double-strand break (DSB) formation in switch (S) regions located upstream of C region genes. DSBs are necessary for CSR, but improper regulation of DSBs can lead to chromosomal translocations that can result in B cell lymphoma. The protein kinase ataxia telangiectasia mutated (ATM) is an important proximal regulator of the DNA damage response (DDR), and translocations involving S regions are increased in its absence. ATM phosphorylates H2AX, which recruits other DNA damage response (DDR) proteins, including mediator of DNA damage checkpoint 1 (Mdc1) and p53 binding protein 1 (53BP1), to sites of DNA damage. As these DDR proteins all function to promote repair and recombination of DSBs during CSR, we examined whether mouse splenic B cells deficient in these proteins would show alterations in S region DSBs when undergoing CSR.We find that in atm1/1 cells Sm DSBs are increased, whereas DSBs in downstream Sg regions are decreased. We also find that mutations in the unrearranged Sg3 segment are reduced in atm1/1 cells. Our data suggest that ATM increases AID targeting and activity at downstream acceptor S regions during CSR and that in atm1/1 cells Sm DSBs accumulate as they lack a recombination partner.
AB - Activation-induced cytidine deaminase (AID) initiates Ab class-switch recombination (CSR) in activated B cells resulting in exchanging the IgH C region and improved Ab effector function. During CSR, AID instigates DNA double-strand break (DSB) formation in switch (S) regions located upstream of C region genes. DSBs are necessary for CSR, but improper regulation of DSBs can lead to chromosomal translocations that can result in B cell lymphoma. The protein kinase ataxia telangiectasia mutated (ATM) is an important proximal regulator of the DNA damage response (DDR), and translocations involving S regions are increased in its absence. ATM phosphorylates H2AX, which recruits other DNA damage response (DDR) proteins, including mediator of DNA damage checkpoint 1 (Mdc1) and p53 binding protein 1 (53BP1), to sites of DNA damage. As these DDR proteins all function to promote repair and recombination of DSBs during CSR, we examined whether mouse splenic B cells deficient in these proteins would show alterations in S region DSBs when undergoing CSR.We find that in atm1/1 cells Sm DSBs are increased, whereas DSBs in downstream Sg regions are decreased. We also find that mutations in the unrearranged Sg3 segment are reduced in atm1/1 cells. Our data suggest that ATM increases AID targeting and activity at downstream acceptor S regions during CSR and that in atm1/1 cells Sm DSBs accumulate as they lack a recombination partner.
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U2 - 10.4049/jimmunol.1303481
DO - 10.4049/jimmunol.1303481
M3 - Article
C2 - 24729610
AN - SCOPUS:84901260711
SN - 0022-1767
VL - 192
SP - 4887
EP - 4896
JO - Journal of Immunology
JF - Journal of Immunology
IS - 10
ER -