Organization and evolution of immunoglobulin VH gene subgroups.

Abstract

The organization and evolution of immunoglobulin variable region genes was studied by comparing human and mouse heavy chain variable region (VH) genes. We show that a VH gene subgroup constitutes a physically linked multigene family separated from another VH subgroup. We mapped the VHIII gene subgroup to be 3' to the VHII gene subgroup based on deletion of VH genes after V-D-J rearrangement. The results indicate that the human VHIII gene subgroup underwent a significant gene expansion as compared to the mouse VHIII subgroup. Amino acid sequence data indicate that human VHIII genes correspond to only a small subset of mouse VHIII genes. Human VHIII genes contain a shorter intron and are two codons shorter than most BALB/c mouse VHIII genes. The nature of nucleotide substitutions between VH genes within a species (human) is similar to that between genes of different species (human/mouse). Both contain approximately 50% silent substitutions.Both somatic and genetic ("germ line") factors operate in generating antibody diversity (1-3). The somatic processes probably act sequentially: first, by combinatorial joining of two or three gene segments, which is accompanied by junctional variation (4-6), and second, by somatic mutations, which take place after the switching process from IgM expression to other immunoglobulin classes (2,7,8). However, it is clear that the diversity of germ line heavy chain variable region and light chain variable region (VH and VL, respectively) genes is extensive and is accumulated throughout evolution (1, 9). Amino acid sequence data indicated that the variable regions of immunoglobulins can be divided into subgroups according to their extent of homology (10-13). A similar subdivision can be made on the level of the genes on the basis of cross hybridization of different V genes with various cDNA probes in which hybridization takes place with distinct sets of V genes (1, 14-17). Subgroups of genes defined by cross hybridization do not always correspond to subgroups defined by protein sequence (17), but in many cases-depending on the conditions of hybridization-there is a good correlation between the two (15).The evolution of multigene families like the V gene subgroups may lead to gene expansion or contraction (11,18), thereby modifying the germ line repertoire of V genes. Comparison of VH gene subgroups from different species may increase our understanding of the evolutionary factors operating in generating antibody diversity. We studied some aspects of the organization and evolution of the VHIII subgroup by comparing human and mouse VH genes. We show by deletion mapping that VHIII genes are located 3' to VHII genes on the mouse chromosome and that the two subgroups are not intermingled with each other. Our sequence analysis data of human VHIII genes suggest that they correspond to a particular subset of mouse VHIII genes. However, the VHIII gene subgroup in human contains significantly more genes than does VHIII in BALB/c mice. The sequence comparison also demonstrates that the pr...

The organization of the mouse Igh-V locus. Dispersion, interspersion, and the evolution of VH gene family clusters.

“…Bothwell et al (36) and Givol et al (37) reported similar findings for members of the VJ558 family. Previous analyses of B cell lines for V gene deletions (11,12,38,39) were consistent with a clustered organization of V gene family members. V gene analysis of Igh-recombinant mouse strains constructed by Riblet (40) also indicated a generally clustered organization of VH families (10).…”

A fetally expressed immunoglobulin VH1 gene belongs to a complex set of alleles.

“…2 C). In the two exceptions, an M27 + band was not detected by probe HI 1 1, once at 4.3 kb (not shown) and once at 4.0 kb (Fig. 2, B and C, lane 2).…”

“…PCR primers were TTC TTG GTG GCA GCA GCC ACA GG (5' primer) and AG GAT GTG GTT TCT CAC ACT GTG (3' primer), corresponding to the hv1263 sequence (33) immediately 5' of the leader intron and 3' of the VH coding region, respectively. PCR product (1)(2)(3)(4) ,gl; in some cases, first separated in an agarose gel, extracted, and ethanol precipitated) was blunt-end ligated into the HincIl or SmaI site of Ml 3mp19 (Pharmacia LKB Biotechnology Inc., Uppsala, Sweden), transformed into DH5aF' competent cells, and plated in YT agarose with JM101 lawn cells, isopropyl-f3-D-thiogalactopyranoside, and 5-bromo-4-chloro-3-indoyl-j3-D-galactoside according to standard methods. Nitrocellulose filter lifts of the primary plates were screened by hybridization with appropriate sense and antisense oligonucleotide probes (Table I) to identify clones with inserts in each orientation.…”

Germline variable region gene segment derivation of human monoclonal anti-Rh(D) antibodies. Evidence for affinity maturation by somatic hypermutation and repertoire shift.

“…The VH genes from the four IgM antibodies appear to be derived from only two germline VH gene segments, hv3O19b9 (VH3) and VH4-21 (VH4) (or its polymorphic allelic form, Tou-VH4-21 [63]), with an average of only 3.3 point mutations per gene. In contrast, the VH genes from the 10 IgG antibodies appear to be derived not only from the original two germline gene segments used by the IgM antibodies (six antibodies) but from an additional four germline gene segments as well (hv3005 [64], V71-4 [65], V2-1 [66], and Hl l [67]). In addition, the VH genes of the IgG antibodies were more somatically mutated, with an average of 9.6 point mutations per gene.…”