The B lymphocyte–associated adaptor protein 32 kD in size (Bam32) is expressed at high levels in germinal center (GC) B cells. It has an NH2-terminal src homology 2 (SH2) domain which binds phospholipase C (PLC)γ2, and a COOH-terminal pleckstrin homology (PH) domain. Thus, Bam32 may function to integrate protein tyrosine kinase (PTK) and phosphatidylinositol 3-kinase (PI3K) signaling pathways in B cells. To further define the role Bam32 plays in B cells, we generated Bam32-deficient DT40 cells. These Bam32−/− cells exhibited lower levels of B cell antigen receptor (BCR)-induced calcium mobilization with modest decreases in tyrosine phosphorylation of phospholipase C (PLC)γ2. Moreover, BCR-induced activation of extracellular signal-regulated kinase (ERK), c-jun NH2-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) pathways was impaired in Bam32−/− cells but not the activation of Akt-related pathways. Activation of downstream transcription factors such as nuclear factor of activated T cells (NF-AT) and nuclear factor of κ binding (NF-κB) was also impaired in Bam32−/− cells. Furthermore, Bam32−/− cells were more susceptible to BCR-induced death. Taken together, these findings suggest that Bam32 functions to regulate BCR-induced signaling and cell survival most likely in germinal centers.
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7 January 2002
Brief Definitive Report|
January 07 2002
The B Lymphocyte Adaptor Molecule of 32 kD (Bam32) Regulates B Cell Antigen Receptor Signaling and Cell Survival
Hiroaki Niiro,
Hiroaki Niiro
1Department of Microbiology, University of Washington, Seattle, WA 98195
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Akito Maeda,
Akito Maeda
3Department of Molecular Genetics, Institute for Liver Research, Kansai Medical University, Moriguchi 570-8506, Japan
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Tomohiro Kurosaki,
Tomohiro Kurosaki
3Department of Molecular Genetics, Institute for Liver Research, Kansai Medical University, Moriguchi 570-8506, Japan
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Edward A. Clark
Edward A. Clark
1Department of Microbiology, University of Washington, Seattle, WA 98195
2Department of Immunology, University of Washington, Seattle, WA 98195
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Hiroaki Niiro
1Department of Microbiology, University of Washington, Seattle, WA 98195
Akito Maeda
3Department of Molecular Genetics, Institute for Liver Research, Kansai Medical University, Moriguchi 570-8506, Japan
Tomohiro Kurosaki
3Department of Molecular Genetics, Institute for Liver Research, Kansai Medical University, Moriguchi 570-8506, Japan
Edward A. Clark
1Department of Microbiology, University of Washington, Seattle, WA 98195
2Department of Immunology, University of Washington, Seattle, WA 98195
Address correspondence to Dr. Edward A. Clark, Department of Microbiology, Box 357242, University of Washington, Seattle, WA 98195. Phone: 206-543-8706; Fax: 206-685-0305; E-mail: [email protected]
A. Maeda's present address is Bayer Chair of Department of Molecular Immunology and Allergy, Kyoto University, Faculty of Medicine, Yoshida Konoe-cho, Sakyo-ku, Kyoto 606-8315, Japan.
Received:
August 31 2001
Revision Received:
October 26 2001
Accepted:
November 12 2001
Online ISSN: 1540-9538
Print ISSN: 0022-1007
The Rockefeller University Press
2002
J Exp Med (2002) 195 (1): 143–149.
Article history
Received:
August 31 2001
Revision Received:
October 26 2001
Accepted:
November 12 2001
Citation
Hiroaki Niiro, Akito Maeda, Tomohiro Kurosaki, Edward A. Clark; The B Lymphocyte Adaptor Molecule of 32 kD (Bam32) Regulates B Cell Antigen Receptor Signaling and Cell Survival . J Exp Med 7 January 2002; 195 (1): 143–149. doi: https://doi.org/10.1084/jem.20011524
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