Convergence of CpG DNA- and BCR-mediated signals at the c-Jun N-terminal kinase and NF-kappaB activation pathways: regulation by mitogen-activated protein kinases.
Depending on the experimental model, unmethylated CpG motifs in bacterial DNA or synthetic oligodeoxynucleotides (CpG DNA) either augment or antagonize BCR-induced signals in B cells. CpG DNA synergizes with BCR-induced proliferation and Ig production of mature B cells, but blocks BCR-mediated apoptosis of immature B cells. Here, we demonstrate using a murine B lymphoma cell line WEHI-231, which is a model for immature B lymphocytes, that CpG DNA augments BCR-mediated signals for the activation of mitogen-activated protein kinase (MAPK) kinase (MKK)3, MKK4 and MKK6, and their subsequent downstream effectors c-Jun N-terminal kinase (JNK) and p38, but does not enhance MEK1/2 or extracellular signal-regulated kinase (ERK) activation. CpG DNA- and BCR-mediated signals also synergize for the activation of transcription factors AP-1, NFAT and NF-kappaB, but not for cAMP-responsive elements binding factor. Synergistic activations of JNK and p38 contribute to the synergistic production of cytokines induced by CpG DNA- and BCR-mediated signals, but have little or no effect on the ability of CpG DNA to protect WEHI-231 cells from anti-IgM-induced growth arrest. In contrast, all three MAPK, JNK, ERK and p38, contribute to the synergistic induction of splenic mature B cell proliferation by CpG DNA and anti-IgM. These results indicate that CpG DNA- and BCR-mediated signals converge at the level of MKK, NF-kappaB and NFAT activation, and that MAPK have differential regulatory roles for CpG DNA-mediated cytokine production versus cell proliferation in splenic mature B cells and WEHI-231 cells.
Yi
Ae-Kyung
AK
Children's Foundation Research Center at Le Bonheur Children's Medical Center, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN 38103, USA. ayi@utmem.edu
Yoon
Jae-Geun
JG
Krieg
Arthur M
AM
D000818:Animals; D018899:CpG Islands / Q000502:physiology; D004247:DNA / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D016393:Lymphoma, B-Cell / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
D016328:NF-kappa B; D011947:Receptors, Antigen, B-Cell; D004247:DNA; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D020929:Mitogen-Activated Protein Kinase Kinases