The antigen-binding regions of immunoglobulins and T-cell receptors are somatically assembled from separate V (variable)-, D (diversity)- and J (joining)-gene segments through a process called """"""""V(D)J recombination"""""""". V(D)J recombination involves site-specific cleavages to generate double-strand breaks and imprecise end joinings of these breaks. Defects in this recombination can lead to a disease syndrome known as severe combined immune deficiency (SCID). Affected individuals lack functional T- and B-cells. The scid mouse mutation results in a defect in double-strand break repair. Cells with such a defect manifest both a hypersensitivity to DNA damaging agents (such as, gamma-irradiation) and an inability to join V, D and J elements. Similar to DNA damaging agents, initiation of V(D)J recombination could be deleterious to scid lymphocytes due to accumulation of unresolved DNA breaks. These breaks could also be targets for secondary recombination which lead to chromosomal deletions and translocations. Thus, aberrant resolution of recombination-associated breaks is likely to contribute to the pathogenesis of lymphoid malignancies. To directly investigate the effect of recombination-associated breaks on survival, growth and differentiation of both normal and scid lymphocytes, we will employ two culture systems in which activation of VDJ recombination or B-cell differentiation can be induced by in vitro manipulation. One system involves the use of temperature sensitive transformed pre-B-cell lines. The other makes use of progenitors/stromal cell culture in the presence of interleukin-7 (IL-7). Specifically, we propose: 1) to examine how scid lymphocytes resolve double strand breaks made in situ as a result of V(D)J recombination; 2) to determine how unresolved breaks may affect scid cells in vitro; and 3) to investigate how a bcl-2 transgene influences survival and differentiation of break-bearing scid B lymphocytes. The long term goal of this research is to discern the role of V(D)J recombination in the pathogenesis of immunodeficiency and lymphoid malignancies. The results should provide new insights for earlier detection and intervention of these immunological diseases.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29CA073857-02
Application #
2895888
Study Section
Immunobiology Study Section (IMB)
Program Officer
Finerty, John F
Project Start
1998-09-01
Project End
2002-08-31
Budget Start
1999-09-01
Budget End
2000-08-31
Support Year
2
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Arizona State University-Tempe Campus
Department
Microbiology/Immun/Virology
Type
Schools of Arts and Sciences
DUNS #
188435911
City
Tempe
State
AZ
Country
United States
Zip Code
85287