In this application, we will compare the responses of B cells from MRL/lpr lupus prone mice and non-autoimmune mice to receptor editing signals, testing the hypothesis that lupus-prone strains of mice have misregulated receptor editing responses. Using a short term in vitro culture system in which receptor editing can be induced by anti-idiotype antibodies, we have shown that MRL/lpr mice show much less upregulation of RAG mRNA following these receptor editing signals. We will use this culture system to determine if MRL/lpr mice show lower levels of receptor editing to low and moderate affinity soluble ligands. We will also determine if the immature B cells from MRL/lpr mice are less responsive to all BCR signals, or if the RAG upregulation response following BCR engagement is uniquely dampened. Editing at the H chain locus is controversial. We will determine if VH replacement and H chain editing is observed in MRL/lpr mice and/or normal mice, and if so, we will use the receptor editing cultures to determine if VH replacement is stimulated by receptor editing signals. Using these cultures, we will assess the accessibility at the V, D and J regions of both the H and L chain loci by chromatin immunoprecipitation with antibodies reactive with acetylated or methylated histones. We will compare the chromatin modifications at all of these loci in B cells from MRL/lpr and control mice before and after induction of receptor editing and in control cultures. Anti-DNA and other autoantibodies are often characterized by long H chain CDR3, sometimes containing two D regions. We have shown that V-D-D-J rearrangements with long CDR3 are made in adult MRL/lpr mice, but not in neonates, and we will test the hypothesis that TdT may be required for the production of these unusual V-D-D-J rearrangements. Alternatively, V(D)J assembly may be differentially regulated in newborns and adults. The information gained in these aims should give insights into the response of the various Ig loci to receptor editing signals, and how these processes may potentially be misregulated in B cells of autoimmune mice.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI061167-05
Application #
7560008
Study Section
Hypersensitivity, Autoimmune, and Immune-mediated Diseases Study Section (HAI)
Program Officer
Johnson, David R
Project Start
2005-02-01
Project End
2011-01-31
Budget Start
2009-02-01
Budget End
2011-01-31
Support Year
5
Fiscal Year
2009
Total Cost
$389,066
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
781613492
City
La Jolla
State
CA
Country
United States
Zip Code
92037
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Carey, John B; Moffatt-Blue, Chantelle S; Watson, Lisa C et al. (2008) Repertoire-based selection into the marginal zone compartment during B cell development. J Exp Med 205:2043-52
Lamoureux, Jennifer L; Watson, Lisa C; Cherrier, Marie et al. (2007) Reduced receptor editing in lupus-prone MRL/lpr mice. J Exp Med 204:2853-64
Watson, Lisa C; Moffatt-Blue, Chantelle S; McDonald, R Zachary et al. (2006) Paucity of V-D-D-J rearrangements and VH replacement events in lupus prone and nonautoimmune TdT-/- and TdT+/+ mice. J Immunol 177:1120-8