The human immunodeficiency disease X-linked a gamma globulinemia (XLA) is caused by mutations in Bruton's tyrosine kinase (Btk) but it is not clear how defective expression of this kinase leads to low serum immunoglobulin levels and blocks in B lymphocyte development. Mice with a point mutation in Btk have produce a murine model for studying x- linked immunodeficiency, but the phenotype of the disease in mice is less severe than in man. Xid mice produce circulating B lymphocytes, albeit at lower levels than in normal mice, and the block in B cell development is at the immature B cell stage instead of the pro-B to pre-B cell stage, as occurs in man. The reasons for the differences in presentation of the disease in mouse and man are unknown, but could be due to intrinsic differences in B cell development or to differential interactions of Btk with additional proteins. Our studies in mice indicate that the transcription factor Bright (B cell regulator of immunoglobulin heavy chain transcription) interacts with Btk. Bright is a 70 kDa protein that binds to promoter and enhancer sequences of the immunoglobulin heavy chain locus where it has been associate with increases in transcription. Although sequences of the immunoglobulin heavy chain locus where it has been associated with increases in transcription. Although xid cells can express Bright protein, they are deficient in Bright DNA-binding activity. Furthermore, while Bright and Btk co-precipitate from control B lymphocytes, they do not appear to interact in xid cells. Little is known about human Bright, but our preliminary data suggest that it also interacts with Btk and that it can be induced in normal peripheral blood lymphocytes. However, we have observed a number of differences between mouse and human Bright-like proteins. To learn more about human Bright and its potential role in XLA, it will be necessary to evaluate Bright expression and interactions with Btk. We propose to utilize the information produced from the other three projects to assess Bright's role in human lymphopoiesis.
The specific aims proposed are: (1) to define where Bright is expressed during human lymphocyte development by RT-PCR, Western blotting and mobility shift assay of sorted subpopulations, (2) to define the molecular interactions that occur between human Bright and Btk using co-precipitation, plasmon resonance, co-transfection and directed yeast two-hybrid assays, (3) to determine how XLA mutations affect these interactions using the same techniques, and (4) to identify human gene targets for Bright using classical methods and antibody facilitated cloning. These studies will yield important new information about human Bright and its interactions with Btk, and may also lead to insights into B cell development and XLA.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Program Projects (P01)
Project #
1P01AI045864-01
Application #
6228588
Study Section
Special Emphasis Panel (ZAI1-SCO-I (M1))
Project Start
1999-09-30
Project End
2003-08-31
Budget Start
Budget End
Support Year
1
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Oklahoma Medical Research Foundation
Department
Type
DUNS #
937727907
City
Oklahoma City
State
OK
Country
United States
Zip Code
73104
Joachims, Michelle L; Chain, Jennifer L; Hooker, Scott W et al. (2006) Human alpha beta and gamma delta thymocyte development: TCR gene rearrangements, intracellular TCR beta expression, and gamma delta developmental potential--differences between men and mice. J Immunol 176:1543-52
Yokota, Takafumi; Huang, Jiaxue; Tavian, Manuela et al. (2006) Tracing the first waves of lymphopoiesis in mice. Development 133:2041-51
Igarashi, Hideya; Medina, Kay L; Yokota, Takafumi et al. (2005) Early lymphoid progenitors in mouse and man are highly sensitive to glucocorticoids. Int Immunol 17:501-11
Rajaiya, Jaya; Hatfield, Melissa; Nixon, Jamee C et al. (2005) Bruton's tyrosine kinase regulates immunoglobulin promoter activation in association with the transcription factor Bright. Mol Cell Biol 25:2073-84
Chain, J L; Joachims, M L; Hooker, S W et al. (2005) Real-time PCR method for the quantitative analysis of human T-cell receptor gamma and beta gene rearrangements. J Immunol Methods 300:12-23
Yao, Longbiao; Yokota, Takafumi; Xia, Lijun et al. (2005) Bone marrow dysfunction in mice lacking the cytokine receptor gp130 in endothelial cells. Blood 106:4093-101
Kolar, G R; Capra, J D (2004) Immunoglobulin heavy-chain receptor editing is observed in the NOD/SCID model of human B-cell development. Scand J Immunol 60:108-11
Nixon, Jamee C; Rajaiya, Jaya; Webb, Carol F (2004) Mutations in the DNA-binding domain of the transcription factor Bright act as dominant negative proteins and interfere with immunoglobulin transactivation. J Biol Chem 279:52465-72
Nixon, Jamee C; Rajaiya, Jaya B; Ayers, Neil et al. (2004) The transcription factor, Bright, is not expressed in all human B lymphocyte subpopulations. Cell Immunol 228:42-53
Kolar, Grant R; Yokota, Takafumi; Rossi, Maria Isabel D et al. (2004) Human fetal, cord blood, and adult lymphocyte progenitors have similar potential for generating B cells with a diverse immunoglobulin repertoire. Blood 104:2981-7

Showing the most recent 10 out of 20 publications