The immunoglobulin κ gene families of human and mouse: a cottage industry approach

Some aspects of the work of our group on the human and mouse immunoglobulin κ genes are reviewed. The human κ locus contains a large duplication: a 600 kb C κ-proximal copy with 40 V κ genes is found in the close vicinity of a 440 kb C κ-distal copy with 36 very similar, but not identical, V κ genes. The chimpanzee has only the C κ -proximal copy of the locus. The κ locus of the mouse is close to 3.2 Mb in size, of which 3.1 Mb have been cloned in four contigs, leaving three small gaps of together about 90 kb; 140 V κ genes and pseudogenes were localized and sequenced. In parallel to the elucidation of the structure of the κ loci, the mechanisms of the V-J rearrangement, somatic hypermutation and κ gene expression were studied. Various polymorphisms were detected in the human population and a number of haplotypes defined. in addition to the V κ genes within the loci numerous V κ orphons were localized on different chromosomes. Comparing the κ loci of different species allows some interesting conclusions as to the evolution of this multigene family. Finally our strategy of elucidating the structure and function of the κ loci, which has been termed a `cottage industry approach', is discussed in relation to the large-scale genome analysis as pursued today using automated methods

Localization, analysis and evolution of transposed human immunoglobulin VK genes

The localization of Vκ gene regions to chromosome 2, on which the κ locus is located, and to other chromosomes is described. The Vκ genes that have been transposed to other chromosomes are called orphons. The finding of two new Vκ genes on chromosome 22 is reported. A Vκ II gene of this region and two Vκ I genes of the Chr 1 and the cos 118 regions were sequenced. The two Vκ I orphon sequences and two others that had been determined previously were 97.5% identical, indicating that they may have evolved from a common ancestor by amplification. A model of the evolution of the human Vκ orphons is discussed. Author Keywords: Human-rodent cell hybrids; cosmids; restriction maps; ligation artifacts; orphon; recombinant DNA Abbreviations: aa, amino acid(s); bp, base pair(s); Chr1, Vκ gene-containing regions of chromosomes 1; Chr22, Vκ gene-containing regions of chromosomes 22; FR, framework regions; CDR, complementary determining regions; kb, kilo-base(s) or 1000 bp; L, L′, parts of a leader gene segment; m219-1, the first subclone of the cosmid clone cos 219; orphon, Vκ gene outside the κ locus on chromosome 2pl2; SSC, 0.15 M NaCl, 0.015 M Na3-citrate, pH 7.6; V, variable gene segments; J, joining gene segments; C, constant gene segments; Vκ I to Vκ IV, variable gene segments of immunoglobulin light chains of the κ type belonging to subgroups I to IV; for reasons of simplicity Vκ gene segments are generally called Vκ gene

Tissue specificity of the initiation of immunoglobulin k gene transcription

Falkner FG, Neumann E, Zachau HG. Tissue specificity of the initiation of immunoglobulin k gene transcription. Hoppe-Seyler's Zeitschrift für physiologische Chemie. 1984;365:1331-1343.The transient transcription of a rearranged mouse immunoglobulin k gene was studied in a monkey fibroblast cell line. The gene was inserted into an SV40 expression vector and the calcium phosphate coprecipitation method was used for transfection. The transcripts were correctly spliced; transcription, however, was initiated within the vector and not at the correct site 23-26 bp upstream of the gene, irrespective of the length of the upstream sequences (90, 160, 370, and 870 bp) in the plasmid constructs. In contrast, accurately initiated transcripts were observed when a plasmid containing the k gene with 870 bp of its upstream sequence was introduced into a lymphoid cell line; the plasmid was constructed from the pSV2-gpt vector and the electric impulse method was used fro gene transfer in most experiments. Tissue-specific expression of k light chain genes in lymphoid cells is known to depend on the presence of an enhancer element in the J-C intron. The results reported in this paper suggest that the sequence elements pd and dc which are located upstream of the leader gene segment also act in a tissue-specific manner ant that it is the initiation of transcription which is a tissue-specific event