title: Rabbit DQ52 and DH gene expression in early B-cell development.
abstract: Rabbits predominantly rearrange the most 3'VH gene (VH1); thus combinatorial diversity is very limited. In man and mouse, the most 3'DH gene, DQ52, is preferentially rearranged early in B-cell development. To test whether this preference for rearranging a DH gene segment based on 3' end proximity exists in rabbit, we cloned and sequenced the rabbit DQ52 gene. The 11 base pair coding region sequence is identical to a published mouse DQ52, and 81.8% similar to the human sequence. It is localized approximately 805 bp upstream of the JH1 gene. However, the 3' recombination signal sequence has an atypical nonamer. We prepared mRNA from 15- to 28-day fetal rabbits and amplified expressed VDJ sequences of mu mRNA by RT-PCR. The PCR products with VDJ rearrangements were cloned and sequenced. As expected, 44 of 45 VDJ sequences reflected use of the 3' VH1a2 gene, but the DQ52 gene was utilized very infrequently, if at all. We found only one VDJ sequence from 28-day fetal liver B-cells with 8 bp that matched the germline DQ52 sequence. Instead of expressing DQ52, another DH gene, Df was frequently expressed. We cloned the genomic Df gene and localized it about 32 kb upstream of the JH region. Thus, in contrast to man and mouse, rabbits preferentially express a DH gene located in the middle of the DH region early in B cell ontogeny. This may correlate with more frequent initial rearrangement of VH to DH in rabbit B cells.
authors.affiliation: Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1892, USA.
authors.forename: H T
authors.initials: HT
authors.lastname: Chen
authors.forename: C B
authors.initials: CB
authors.lastname: Alexander
authors.forename: F F
authors.initials: FF
authors.lastname: Chen
authors.forename: R G
authors.initials: RG
authors.lastname: Mage
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D001483:Base Sequence; D002454:Cell Differentiation / Q000276:immunology; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D005333:Fetus; D005786:Gene Expression Regulation / Q000276:immunology*; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain / Q000276:immunology*; D005803:Genes, Immunoglobulin; D005854:Germ Cells / Q000378:metabolism; D006239:Haplotypes; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics* / Q000302:isolation & purification; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000276:immunology; D011817:Rabbits; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D012788:Shrews
chemical_list: D018076:DNA, Complementary; D007135:Immunoglobulin Variable Region