Act1, a negative regulator in CD40- and BAFF-mediated B cell survival.
TNF receptor (TNFR) superfamily members, CD40, and BAFFR play critical roles in B cell survival and differentiation. Genetic deficiency in a novel adaptor molecule, Act1, for CD40 and BAFF results in a dramatic increase in peripheral B cells, which culminates in lymphadenopathy and splenomegaly, hypergammaglobulinemia, and autoantibodies. While the B cell-specific Act1 knockout mice displayed a similar phenotype with less severity, the pathology of the Act1-deficient mice was mostly blocked in CD40-Act1 and BAFF-Act1 double knockout mice. CD40- and BAFF-mediated survival is significantly increased in Act1-deficent B cells, with stronger IkappaB phosphorylation, processing of NF-kappaB2 (p100/p52), and activation of JNK, ERK, and p38 pathways, indicating that Act1 negatively regulates CD40- and BAFF-mediated signaling events. These findings demonstrate that Act1 plays an important role in the homeostasis of B cells by attenuating CD40 and BAFFR signaling.
Department of Immunology, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
Youcun
Y
Qian
Jinzhong
J
Qin
Grace
G
Cui
Mayumi
M
Naramura
E Charles
EC
Snow
Carl F
CF
Ware
Robert L
RL
Fairchild
Sidne A
SA
Omori
Robert C
RC
Rickert
Martin
M
Scott
Brian L
BL
Kotzin
Xiaoxia
X
Li
D000818:Animals; D001323:Autoantibodies / Q000097:blood; D053264:B-Cell Activating Factor; D053265:B-Cell Activation Factor Receptor; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D015139:Blotting, Southern; D015153:Blotting, Western; D019013:CD40 Antigens / Q000276:immunology* / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002470:Cell Survival / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006942:Hypergammaglobulinemia / Q000209:etiology; D020672:I-kappa B Proteins / Q000276:immunology / Q000378:metabolism; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D048031:JNK Mitogen-Activated Protein Kinases / Q000276:immunology / Q000378:metabolism; D008221:Lymphoid Tissue / Q000166:cytology / Q000276:immunology / Q000473:pathology; D048670:MAP Kinase Kinase 4; D008565:Membrane Proteins / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D020929:Mitogen-Activated Protein Kinase Kinases / Q000276:immunology / Q000378:metabolism; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology* / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000276:immunology / Q000378:metabolism
D001323:Autoantibodies; D053264:B-Cell Activating Factor; D053265:B-Cell Activation Factor Receptor; D019013:CD40 Antigens; D002352:Carrier Proteins; D020672:I-kappa B Proteins; D008565:Membrane Proteins; D016328:NF-kappa B; D018124:Receptors, Tumor Necrosis Factor; C435926:TNFRSF13C protein, human; C505719:TNFSF13B protein, human; C505720:Tnfsf13b protein, mouse; D014409:Tumor Necrosis Factor-alpha; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases