title: Paucity of V-D-D-J rearrangements and VH replacement events in lupus prone and nonautoimmune TdT-/- and TdT+/+ mice.
abstract: CDR3 regions containing two D segments, or containing the footprints of V(H) replacement events, have been reported in both mice and humans. However, the 12-23 bp rule for V(D)J recombination predicts that D-D rearrangements, which would occur between 2 recombination signal sequences (RSSs) with 12-bp spacers, should be extremely disfavored, and the cryptic RSS used for V(H) replacement is very inefficient. We have previously shown that newborn mice, which lack TdT due to the late onset of its expression, do not contain any CDR3 with D-D rearrangements. In the present study, we test our hypothesis that most D-D rearrangements are due to fortuitous matching of the second apparent D segment by TdT-introduced N nucleotides. We analyzed 518 sequences from adult MRL/lpr- and C57BL/6 TdT-deficient B cell precursors and found only two examples of CDR3 with D-D rearrangements and one example of a potential V(H) replacement event. We examined rearrangements from pre-B cells, marginal zone B cells, and follicular B cells from mice congenic for the Lbw5 (Sle3/5) lupus susceptibility loci and from other strains of mice and found very few examples of CDR3 with D-D rearrangements. We assayed B progenitor cells, and cells enriched for receptor editing, for DNA breaks at the "cryptic heptamer" but such breaks were rare. We conclude that many examples of apparent D-D rearrangements in the mouse are likely due to N additions that fortuitously match short stretches of D genes and that D-D rearrangements and V(H) replacement are rare occurrences in the mouse.
authors.affiliation: The Scripps Research Institute, Department of Immunology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Watson
authors.forename: Chantelle S
authors.initials: CS
authors.lastname: Moffatt-Blue
authors.forename: R Zachary
authors.initials: RZ
authors.lastname: McDonald
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Kompfner
authors.forename: Djemel
authors.initials: D
authors.lastname: Ait-Azzouzene
authors.forename: David
authors.initials: D
authors.lastname: Nemazee
authors.forename: Argyrios N
authors.initials: AN
authors.lastname: Theofilopoulos
authors.forename: Dwight H
authors.initials: DH
authors.lastname: Kono
authors.forename: Ann J
authors.initials: AJ
authors.lastname: Feeney
mesh_terms: D000818:Animals; D000916:Antibody Diversity / Q000235:genetics*; D022801:Complementarity Determining Regions / Q000235:genetics; D004249:DNA Damage; D018983:DNA Footprinting; D004253:DNA Nucleotidylexotransferase / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D020022:Genetic Predisposition to Disease; D018095:Germ-Line Mutation; D006412:Hematopoietic Stem Cells / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007133:Immunoglobulin Joining Region / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D008181:Lupus Nephritis / Q000201:enzymology / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D019463:Mice, Inbred MRL lpr; D008814:Mice, Inbred NZB; D018345:Mice, Knockout; D008822:Mice, Transgenic; D016133:Polymerase Chain Reaction; D017393:RNA Editing / Q000235:genetics / Q000276:immunology
chemical_list: D022801:Complementarity Determining Regions; D007143:Immunoglobulin Heavy Chains; D007133:Immunoglobulin Joining Region; D007135:Immunoglobulin Variable Region; D004253:DNA Nucleotidylexotransferase