Signals discharged from the B-cell antigen receptor (BCR) control B-cell physiological responses by regulating specific transcription factors and their downstream target genes. Our long-term goal is to understand the intracellular signal transduction pathways that regulate genes under BCR control. Transcription factor NF-kappaB is coupled to the BCR and essential for B cell survival and proliferation. However, the mechanisms that regulate the BCR/NF-KB axis remain poorly understood. The applicant's laboratory has recently discovered that Bruton's tyrosine kinase (BTK), phospholipase C-gamma2 (PLC-gamma2), and IkappaB kinase (IKK) are all integral components of this pathway. Importantly, interference with NF-kappaB signaling at the level of BTK leads to B cell immunodeficiencies in mice (X-linked immunodeficiency; xid) and humans (X-linked agammaglobulinemia; XLA). This grant application is predicated on the central hypothesis that BTK stimulates PLC-gamma2 phosphorylation and activation, which leads to calcium mobilization and protein kinase C (PKC) induction. In turn, these second messengers act in concert to stimulate the effectors that activate BCRresponsive IRK complexes. To test the central hypothesis, we propose an integrated series of biochemical studies with mutant B cells that lack either BTK, PLC-gamma2, or IKK. Studies described in Specific Aim 1 will elucidate the biochemical interplay between BTK and PLC-gamma2 as well as the PKC isoforms that affect IKK function in response to BCR engagement.
Specific Aim 2 experiments will define the molecular size, phosphorylation status, and subunit composition of IKK complexes under BCR control.
In Specific Aim 3, studies are proposed to identify the precise BCR-inducible modifications to IKK that lead to NF-kappaB activation. Results from the proposed studies will uncover novel regulatory steps in the BCR/NF-kappaB axis that are crucial for the development of an adaptive immune response. Identification of these important missing links may reveal new immunotherapeutic targets for intervention in B-cell deficiency diseases such as XLA.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI050213-04
Application #
6749504
Study Section
Allergy and Immunology Study Section (ALY)
Program Officer
Miller, Lara R
Project Start
2001-09-30
Project End
2007-05-31
Budget Start
2004-06-01
Budget End
2007-05-31
Support Year
4
Fiscal Year
2004
Total Cost
$226,500
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
Shinners, Nicholas P; Carlesso, Gianluca; Castro, Iris et al. (2007) Bruton's tyrosine kinase mediates NF-kappa B activation and B cell survival by B cell-activating factor receptor of the TNF-R family. J Immunol 179:3872-80
Treml, Laura S; Carlesso, Gianluca; Hoek, Kristen L et al. (2007) TLR stimulation modifies BLyS receptor expression in follicular and marginal zone B cells. J Immunol 178:7531-9
Hoek, Kristen L; Antony, Pierre; Lowe, John et al. (2006) Transitional B cell fate is associated with developmental stage-specific regulation of diacylglycerol and calcium signaling upon B cell receptor engagement. J Immunol 177:5405-13
Bussiere, Francoise I; Chaturvedi, Rupesh; Asim, Mohammad et al. (2006) Low multiplicity of infection of Helicobacter pylori suppresses apoptosis of B lymphocytes. Cancer Res 66:6834-42
Kray, Arlene E; Carter, Robert S; Pennington, Kevin N et al. (2005) Positive regulation of IkappaB kinase signaling by protein serine/threonine phosphatase 2A. J Biol Chem 280:35974-82
Antony, P; Petro, J B; Carlesso, G et al. (2004) B-cell antigen receptor activates transcription factors NFAT (nuclear factor of activated T-cells) and NF-kappaB (nuclear factor kappaB) via a mechanism that involves diacylglycerol. Biochem Soc Trans 32:113-5
Antony, Pierre; Petro, James B; Carlesso, Gianluca et al. (2003) B cell receptor directs the activation of NFAT and NF-kappaB via distinct molecular mechanisms. Exp Cell Res 291:11-24
Petro, James B; Castro, Iris; Lowe, John et al. (2002) Bruton's tyrosine kinase targets NF-kappaB to the bcl-x promoter via a mechanism involving phospholipase C-gamma2 following B cell antigen receptor engagement. FEBS Lett 532:57-60
Petro, James B; Gerstein, Rachel M; Lowe, John et al. (2002) Transitional type 1 and 2 B lymphocyte subsets are differentially responsive to antigen receptor signaling. J Biol Chem 277:48009-19