TY - JOUR
T1 - Activation-induced deaminase-mediated class switch recombination is blocked by anti-IgM signaling in a phosphatidylinositol 3-kinase-dependent fashion
AU - Heltemes-Harris, Lynn M.
AU - Gearhart, Patricia J.
AU - Ghosh, Paritosh
AU - Longo, Dan L.
N1 - Funding Information:
This work was supported by the NIH Intramural Research Program. LH-H was supported by a National Research Council Research Associateship Award.
PY - 2008/3
Y1 - 2008/3
N2 - Activation-induced deaminase (AID) is expressed in activated B lymphocytes and initiates somatic hypermutation and class switch recombination. To determine if different stimuli affect the expression and function of AID, we monitored AID activity in murine B cells stimulated ex vivo with various ligands. AID was rapidly expressed at both the RNA and protein levels following stimulation with LPS, LPS plus IL-4, and anti-CD40 plus IL-4, but was delayed after stimulation with anti-IgM plus IL-4. By day 4, AID was expressed in all groups; however, cells stimulated with anti-IgM plus IL-4 did not undergo switch recombination. These cells expressed normal levels of γ1 germline transcripts, implying that the γ1 switch region was accessible. Furthermore, switching was suppressed by the addition of anti-IgM to cells stimulated with LPS plus IL-4 or anti-CD40 plus IL-4, even though AID was expressed. The lack of class switch recombination could be reversed by inhibition of phosphatidylinositol 3-kinase (PI3K). This suggests that activation through the B cell receptor induces PI3K, which interferes with the function of AID.
AB - Activation-induced deaminase (AID) is expressed in activated B lymphocytes and initiates somatic hypermutation and class switch recombination. To determine if different stimuli affect the expression and function of AID, we monitored AID activity in murine B cells stimulated ex vivo with various ligands. AID was rapidly expressed at both the RNA and protein levels following stimulation with LPS, LPS plus IL-4, and anti-CD40 plus IL-4, but was delayed after stimulation with anti-IgM plus IL-4. By day 4, AID was expressed in all groups; however, cells stimulated with anti-IgM plus IL-4 did not undergo switch recombination. These cells expressed normal levels of γ1 germline transcripts, implying that the γ1 switch region was accessible. Furthermore, switching was suppressed by the addition of anti-IgM to cells stimulated with LPS plus IL-4 or anti-CD40 plus IL-4, even though AID was expressed. The lack of class switch recombination could be reversed by inhibition of phosphatidylinositol 3-kinase (PI3K). This suggests that activation through the B cell receptor induces PI3K, which interferes with the function of AID.
KW - Activation-induced deaminase
KW - Antibodies
KW - B cells
KW - Cell activation
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U2 - 10.1016/j.molimm.2007.09.020
DO - 10.1016/j.molimm.2007.09.020
M3 - Article
C2 - 17983655
AN - SCOPUS:38949145383
SN - 0161-5890
VL - 45
SP - 1799
EP - 1806
JO - Molecular Immunology
JF - Molecular Immunology
IS - 6
ER -
