Somatic cell genetic assignment of peptidase C and the Rh linkage group to chromosome A-1 in man

Evolution of the RH gene family in vertebrates revealed by brown hagfish (Eptatretus atami) genome sequences

In vertebrates, there are four major genes in the RH (Rhesus) gene family, RH, RHAG, RHBG, and RHCG. These genes are thought to have been formed by the two rounds of whole-genome duplication (2R-WGD) in the common ancestor of all vertebrates. In our previous work, where we analyzed details of the gene duplications process of this gene family, three nucleotide sequences belonging to this family were identified in Far Eastern brook lamprey (Lethenteron reissneri), and the phylogenetic positions of the genes were determined. Lampreys, along with hagfishes, are cyclostomata (jawless fishes), which is a sister group of gnathostomata (jawed vertebrates). Although those results suggested that one gene was orthologous to the gnathostome RHCG genes, we did not identify clear orthologues for other genes. In this study, therefore, we identified three novel cDNA sequences that belong to the RH gene family using de novo transcriptome analysis of another cyclostome: the brown hagfish (Eptatretus atami). We also determined the nucleotide sequences for the RHBG and RHCG genes in a red stingray (Dasyatis akajei), which belongs to the cartilaginous fishes. The phylogenetic tree showed that two brown hagfish genes, which were probably duplicated in the cyclostome lineage, formed a cluster with the gnathostome RHAG genes, whereas another brown hagfish gene formed a cluster with the gnathostome RHCG genes. We estimated that the RH genes had a higher evolutionary rate than the RHAG, RHBG, and RHCG genes. Interestingly, in the RHBG genes, only the bird lineage showed a higher rate of nonsynonymous substitutions. It is likely that this higher rate was caused by a state of relaxed functional constraints rather than positive selection nor by pseudogenization.

No Distinction of Orthology/Paralogy between Human and Chimpanzee Rh Blood Group Genes

On human (Homo sapiens) chromosome 1, there is a tandem duplication encompassing Rh blood group genes (Hosa_RHD and Hosa_RHCE). This duplication occurred in the common ancestor of humans, chimpanzees (Pan troglodytes), and gorillas, after splitting from their common ancestor with orangutans. Although several studies have been conducted on ape Rh blood group genes, the clear genome structures of the gene clusters remain unknown. Here, we determined the genome structure of the gene cluster of chimpanzee Rh genes by sequencing five BAC (Bacterial Artificial Chromosome) clones derived from chimpanzees. We characterized three complete loci (Patr_RHα, Patr_RHβ, and Patr_RHγ). In the Patr_RHβ locus, a short version of the gene, which lacked the middle part containing exons 4-8, was observed. The Patr_RHα and Patr_RHβ genes were located on the locations corresponding to Hosa_RHD and Hosa_RHCE, respectively, and Patr_RHγ was in the immediate vicinity of Patr_RHβ. Sequence comparisons revealed high sequence similarity between Patr_RHβ and Hosa_RHCE, while the chimpanzee Rh gene closest to Hosa_RHD was not Patr_RHα but rather Patr_RHγ. The results suggest that rearrangements and gene conversions frequently occurred between these genes and that the classic orthology/paralogy dichotomy no longer holds between human and chimpanzee Rh blood group genes.

Tempo and mode of evolution of the Rh blood group genes before and after gene duplication

The Rh blood group genes became duplicated in a common ancestor of human-chimpanzee-gorilla. We compared the evolutionary rates of the Rh blood group genes for each exon for branches connecting to humans, having duplicated Rh loci, and to orangutan, gibbon, and Old World monkeys, species having a single Rh locus. Our results show that evolutionary rates of nonsynonymous substitutions at exon 7 became accelerated in the human lineage. Furthermore, we surveyed the sequence variation in the region surrounding exon 7 of gibbons to clarify whether the diversity of the human exon 7 was introduced after the duplication or had been maintained before it. Two amino acid polymorphisms in white-handed gibbons were observed in the immediate vicinity of the D-specific motif in the human exon 7. Although the evolutionary rate of exon 7 was accelerated after the gene duplication, our results suggest that exon 7 had the potential for change even before the gene duplication.

Conserved evolution of the Rh50 gene compared to its homologous Rh blood group gene

We have sequenced the complete coding region of the Rh blood group gene for mouse and rat and that of Rh-related 50 kD glycoprotein (Rh50) for mouse, rat, and crab-eating macaque. Phylogenetic analyses of Rh and Rh50 amino acid sequences indicate that the Rh50 gene has been evolving about two times more slowly than the Rh blood group gene in both primates and rodents. This conservative nature of the Rh50 gene suggests its relative importance to the Rh blood group gene. The time of gene duplication that produced the Rh and Rh50 genes was estimated to be about 240-310 million years ago. We also conducted window analyses of synonymous and nonsynonymous nucleotide substitutions for those two genes. Some peaks where nonsynonymous substitutions are higher than synonymous ones were located on outer membrane regions. This suggests the existence of positive Darwinian selection on Rh and Rh50 genes through host-parasite interactions.

Prevalence of the Rhesus-negative phenotype in Caucasian patients with small-cell lung cancer (SCLC)

We report that the Rhesus (Rh)-negative phenotype is more prevalent in patients with small-cell lung cancer (SCLC) than in the normal Caucasian population (SCLC: 25% Rh-negative vs. 15% expected, p less than 0.0001). This finding has been validated for a Central and a Northern European population (Switzerland and UK). In contrast, the Rh-negative phenotype is no more frequent in non-small-cell lung cancer patients or in heavy smokers with coronary heart disease than in the general population. There was a normal distribution of the ABO blood group phenotype in all patients studied. Whilst the significance of this observation is unclear, we hypothesize that a genetic predisposition to the development of SCLC may be linked to a hitherto unidentified gene on chromosome 1p near the Rh locus. Our observation may perhaps allow further progress to be made in understanding genetic mechanisms of SCLC carcinogenesis.

Genetic polymorphism of human peptidase C, PEPC (E.C.3.4.1.1): formal genetic and population data

Human peptidase C, PEPC (E.C.3.4.1.1), exhibits a previously undescribed genetic polymorphism, detectable in red cells or leukocytes by starch gel electrophoresis. Segregation analyses on 161 families with 469 offspring support the formal genetic hypothesis of two codominant alleles at an autosomal locus. Since four rare variants have previously been described, we named the polymorphic allele PEPC*6. Gene frequencies from southwestern Germany were PEPC*1 = 0.721 +/- 0.018; PEPC*6 = 0.276 +/- 0.018, and PEPC*R = 0.003 +/- 0.002.

Linkage analyses of human peptidase C (PEPC), human factor H (HF), and coagulation factor XIIIB (F13B)

Linkage data on human peptidase C (PEPC), human factor H (HF), and coagulation factor XIIIB (F13B) are presented. The results confirm linkage between HF and F13B (lod = 5.32 at theta = 0.10 in males), and give strong evidence for linkage between PEPC and HF (lod = 5.14 at theta = 0.10 in males) and between PEPC and F13B (lod = 3.55 at theta = 0.10 in males). The claim that PEPA is linked with HF must be withdrawn.

Establishment of a galactocerebrosidase-deficient twitcher mouse cell line that expresses galactocerebrosidase activity in hybrids with control human fibroblasts

Primary cell cultures from twitcher (galactocerebrosidase deficient) mice were made by enzymatic dispersion and explantation of skin obtained from 3-d-old littermates of a twi+/twi X twi+/twi mating. Galactocerebrosidase activity remained deficient for two twitcher cell lines, TM-1 and TM-2, and both lines demonstrated an initial period of growth decline, followed by accelerated growth. The TM-2 line has been subcultured for more than 3.5 yr, has a modal chromosome number of 63, a doubling time of approximately 16 h, and has remained galactocerebrosidase deficient throughout its life span. These data indicate this to be an established twitcher cell line that can be continuously maintained in culture as a transformed galactocerebrosidase-deficient mouse cell line. This established line was rendered 6-thioguanine resistant so that the cells could be fused with control human fibroblasts and selected for hybrid lines in hypoxanthine-aminopterin-thymidine medium. Also, the established twitcher cells were crossed with neomycin-resistant control human fibroblasts and selected in G418 medium. Several of the hybrid lines from both crosses had higher than deficient levels of galactocerebrosidase activity initially, followed by a decrease to twitcher levels during subculture, whereas other lines retained high levels of activity. These results indicate that twitcher-human somatic cell hybrids will express galactocerebrosidase activity and thus may be useful for determining the human chromosome or chromosomes associated with this expression.

Establishment of a molecular genetic map of distal mouse chromosome 1: further definition of a conserved linkage group syntenic with human chromosome 1q

A linkage map of distal mouse chromosome 1 was constructed by restriction fragment length polymorphism analysis of DNAs from seven sets of recombinant inbred (RI) strains. The data obtained with seven probes on Southern hybridization combined with data from previous studies suggest the gene order Cfh, Pep-3/Ren-1,2, Ly-5, Lamb-2, At-3, Apoa-2/Ly-17,Spna-1. These results confirm and extend analyses of a large linkage group which includes genes present on a 20-30 cM span of mouse chromosome 1 and those localized to human chromosome 1q21-32. Moreover, the data indicate similar relative positions of human and mouse complement receptor-related genes REN, CD45, LAMB2, AT3, APOA2, and SPTA. These results suggest that mouse gene analyses may help in detailed mapping of human genes within such a syntenic group.

Assignment of mouse beta-spectrin gene to chromosome 12

The structural gene for the beta-subunit of the mouse erythrocyte spectrin, hereinafter designated as Sp-b, was assigned to the mouse chromosome 12. This assignment was made by Southern analysis of genomic DNA from mouse X Chinese hamster hybrid cells using cloned mouse erythrocyte beta-spectrin cDNA as a probe. In the PstI-digested genomic hamster cell DNA a single band of 2.0 kb was detected, whereas PstI-digested mouse DNA gave a band of 4.2 kb, when probed with the mouse erythroid beta-spectrin cDNA clone. This allowed us to analyze a panel of mouse X Chinese hamster somatic cell hybrids to map this gene to chromosome 12. Interestingly, this assignment is different from that observed for the alpha-subunit of spectrin, which has been mapped to chromosome 1 in mouse. These results serve as a basis for further genetic characterization of the mouse hemolytic anemias.

Peptidases A, B, C, D and S in the American mink: polymorphism and chromosome localization

An electrophoretic analysis of peptidases was carried out in a population of American mink. Based on substrate and tissue specificities, as well as subunit composition, homologies were established between mink peptidases A, B, C, D and S and human peptidases. Polymorphism for peptidases B and D was demonstrated for minks of three coat colour types. Breeding data indicated that the peptidase variations are under the control of allele pairs at distinct autosomal loci designated as PEPB and PEPD, respectively. Using a panel of American mink-Chinese hamster hybrid clones, the gene for PEPB was assigned to mink chromosome 9.

Chromosome 1 in relation to human disease

Chromosome 1 is thought to represent about 6% of the total human genome and the 85 loci so far identified may constitute about 1% of the genes present on this chromosome. The existence of at least 22 loci sufficiently polymorphic in Europeans to be useful as genetic markers has allowed the construction of an elementary genetic map. This permits comparisons with physical and chiasma maps and has demonstrated striking homologies between different regions of chromosome 1 and mouse chromosomes 1, 3, and 4. The existence of a map should be of great help in developing a more systematic approach to further mapping studies. A wide range of disease can be attributed to allelic variation on chromosome 1 and the homologies with the mouse may be useful in predicting the position of other genes involved in human disease. Rearrangements of this chromosome are a common finding in many different types of malignancy. Loss of material from the short arm and activation of one or more of the four oncogenes in this region may play an important role in the later stages of tumour development. Polymorphic markers of all kinds will be useful in the future for investigating the somatic events which have occurred during the malignant process.

The alpha-spectrin gene is on chromosome 1 in mouse and man

By using alpha-spectrin cDNA clones of murine and human origin and somatic cell hybrids segregating either mouse or human chromosomes, the gene for alpha-spectrin has been mapped to chromosome 1 in both species. This assignment of the mouse alpha-spectrin gene to mouse chromosome 1 by DNA hybridization strengthens the previous identification of the alpha-spectrin locus in mouse with the sph locus, which previously was mapped by linkage analysis to mouse chromosome 1, distal to the Pep-3 locus. By in situ hybridization to human metaphase chromosomes, the human alpha-spectrin gene has been localized to 1q22-1q25; interestingly, the locus for a non-Rh-linked form of elliptocytosis has been provisionally mapped to band 1q2 by family linkage studies.

The human apolipoprotein A-II gene is located on chromosome 1

Apolipoprotein (apo) A-II is a major constituent of high density lipoproteins (HDL). The gene for apoA-II has been localized to the p21----qter region of chromosome 1 in man by Southern blot hybridization analysis of DNA from human-mouse cell hybrids using a cloned human apoA-II cDNA probe. The regional assignment was established using two hybrids carrying a reciprocal translocation involving chromosomes 1 and 2. Comparison with previously established gene loci on chromosomes 1 suggests that apoA-II may reside in a conserved linkage group with renin and peptidase C. On the other hand, apoA-II is not linked to the apoA-I gene, which has been localized previously to chromosome 11.

Chromosome mapping in cattle using mouse myeloma/calf lymph node cell hybridomas

A study correlating the presence of bovine isozymes in mouse myeloma/calf hybridomas with specific banded chromosomes of their bovine complement has enabled tentative assignments to be made of the bovine isozyme locus for peptidase C (PEP C) to chromosome 5 and the syntenic group lactate dehydrogenase B/peptidase B (LDH B/PEP B) to chromosome 19. There was some evidence for the association of LDH A with one of the last seven small pairs (23-29) of the complement and of superoxide dismutase 1 (SOD 1) with chromosome 13.

Assignment of the human gene for peptidase E to the chromosomal region 17q23----17qter

Peptidase E has been studied in 16 independent human-Syrian hamster hybrids and 16 subclones. Evidence is presented indicating that the human gene for Peptidase E is on chromosome 17 in the region 17q23----17qter.

Clonal origin of the Philadelphia translocation in chronic myeloid leukemia demonstrated in somatic cell hybrids using an adenylate kinase-1 polymorphism

Hybrid cell lines were derived from fusion of rodent cells with leukocytes from a t(9q+; 22q-)-positive chronic myeloid leukemia (CML) patient carrying a chromosome No. 9-linked adenylate kinase-1 (AK1) polymorphism (AK1 1-2). The AK1*2 allele was consistently expressed when 9q+ was present, whereas the AK1*1-coded isozyme was formed when the normal chromosome No. 9 was present. These results provide additional data confirming the clonal origin of the Ph1 translocation in CML.

A new era in mammalian gene mapping: somatic cell genetics and recombinant DNA methodologies

Mammalian gene mapping techniques are now sufficiently advanced to contribute significantly to prenatal diagnosis and to human molecular genetics. Restriction fragment mapping can be used to place polymorphic genetic markers at random sites within the genome, and these sites used to assign genes responsible for disease conditions to a chromosomal region. Somatic cell genetic techniques can then be applied to saturate that region with additional restriction fragment markers, some of which will be closely linked to the disease gene. Closely linked restriction fragment markers, especially flanking pairs of markers, can act as predictors for the transmission of defective genes to offspring. A series of tightly linked flanking restriction markers might in addition contribute to the eventual isolation and cloning of the disease gene itself.

Identification of human gene products from hybrid cells: a new approach

A method is described for detection of human polypeptides from hybrid cells, following high-resolution two-dimensional polyacrylamide gel electrophoresis of total cellular protein. 3H-labeled hybrid cell proteins are mixed with 14C-labeled parental cell proteins, electroporesis is carried out, and polypeptides that occur only in the 3H-labeled preparation are detected by double-label autoradiography. The possibility of developing a standard human polypeptide two-dimensional gel map, which would allow identification of electrophoretically separable components as specific proteins, is discussed.

Assignment of peptidase S (PEPS) to chromosome 4 in man using somatic cell hybrids

A starch gel electrophoretic procedure is described that resolves peptidase S (PEPS) as well as the peptidases A, B, and C in man-rodent, rodent-rodent, and primate-rodent interspecific somatic cell hybrids. The interspecific PEPS cell hybrid phenotype can be resolved into a pattern which suggests that PEPS is composed of five or six identical subunits. Results are presented supporting assignment of the PEPS locus to chromosome 4 in man using man-mouse and man-Chinese hamster somatic cell hybrids. Human genes coding for peptidases A, B, C, and D were assigned to chromosome 18, 12, 1, and 19, respectively, confirming previous assignments. These somatic cell genetic data demonstrate the independent genetic control of the several human peptidases.

Relative positions of chromosome 1 loci Fy, PGM1, Sc, UMPK, Rh, PGD and ENO1 in man

Ongoing linkage studies of red cell antigens and enzymes in many families along with concentration on a large Mennonite kindred segregating for Sc have resulted in lods, recombinant: nonrecombinant counts and multi-point information which support an order with approximate recombination fractions as measured in the male as follows: Fy--.25--PGM1--.20--Sc--less than .05--UMPK--.15--Rh--.20--PGD, with ENO1 close to PGD. The insertion of Sc and UMPK between PGM1 and Rh allows the recognition of double crossing-over between the latter pair; indications are that this is not a rare event in the female. In the male no evidence of double crossing-over was found in the similar distances PGM1--Rh and Sc--PGD in 13 and 19 opportunities respectively.

The status of the gene map of the human chromosomes

In man, the specific chromosome that carries each of about 210 gene loci is known. These loci include at least one assigned to each chromosome (including the Y), about 110 assigned to specific autosomes, and about 100 to the X chromosome. For many loci, information on regional chromosomal localization is also available. The information comes mainly from studies in families and somatic cell hybrids, as well as an intgratsight of results from the two methods. Knowledge of the chromosome map gives insight into evolution, chromosomal organization in relation to genetic control mechanisms, and the pathogenesis of neoplasms and malformations. Furthermore, it is useful in prenatal or premorbid diagnosis of hereditary diseases.

Expression of the human adenylate kinase isozymes, phosphopyruvate hydratase, 6-phosphogluconate dehydrogenase, and phosphoglucomutase-1 in man-rodent somatic cell hybrids

The expression of the adenylate kinase isozymes and of phosphopyruvate hydratase was studied in man-mouse and man-hamster hybrid clones. Concordant segregation of the loci coding for AK-2 and PPH was observed in 54 of 55 primary hybrid clones, and these loci were demonstrated to be synthetic with the loci specifying PGM-1 and PGD. The pattern of expression of the four enzymes in discordant clone suggests the gene order 1pter-(PGD, PPH)-AK-2-PGM-1-centromere. In addition, AK-1 was found to be expressed independently of AK-2.

Gene linkage analysis in the mouse by somatic cell hybridization: assignment of adenine phosphoribosyltransferase to chromosome 8 and alpha-galactosidase to the X chromosome

Somatic cell hybridization techniques were applied to gene linkage analysis in the laboratory mouse. Cells of an established line of Chinese hamster lung fibroblasts were fused with mouse embryo fibroblasts and with mouse peritoneal macrophages obtained from different inbred strains. From 3 hybridization experiments, 123 primary and secondary clones were isolated in HAT selective medium and 24 were back-selected in 8-azaguanine. Hybrid clones were characterized for the expression of 16 murine isozymes by starch, acrylamide, and Cellogel electrophoresis, and on the basis of segregation data, 3 syntenic associations could be made. Malate oxidoreductase decarboxylating (MOD) and mannose phosphate isomerase (MPI) segregated concordantly, confirming an established linkage relationship; adenine phosphoribosyltransferase (APRT) segregated concordantly with glutathione reductase (GR) which is known to be on chromosome 8; alpha-galactosidase was observed to be syntenic with hypoxanthine phosphoribosyltransferase (HPRT), and X-linked enzyme. All other isozymes examined segregated independently of one another.

Present status of the Duffy blood group system

In 1950 a new blood group antibody was recognized in the serum of a multi-transfused hemophiliac patient. The reactive red-cell antigen was identified in 65% of random caucasians, and the systemic name Duffy was proposed. Two common antigens, Fy-a and Fy-b, were recognized and shown to be products of autosomal allelic genes, but the great majority of negro individuals were found to lack both antigens. In 1968 genetic studies showed Duffy to be linked to Un-1, which is an inherited structural variation of chromosome number 1. Duffy thus became the first autosomal blood group gene to be allocated to a specific chromosome. Recent studies have allowed recognition of three new antibodies (anti-Fy3, anti-Fy4, and anti-Fy5) in the Duffy system. The Rh blood group locus has also been assigned to chromosome 1, and there is evidence that the antigen defined by anti-Fy5 is a product of interaction between Duffy and Rh genes. The Duffy blood group appears to be one of importance in clinical blood transfusion practice, and possibly makes the greatest distinction of any of the red cell systems between different groups of the world population.

Giemsa banding of chromosome 1gh+ and linkage analysis

A four-generation transmission of 1qh+ chromosome was ascertained by routine chromosome analysis of a mildly dysmorphic and retarded 61/2-year-old female. Concordance between synophrys and the 1qh+ marker was the only consistent phenotypic relationship. The variant chromosome did not appear uncoiled, and Giemsa centromeric staining (C-bands) revealed an increased width of the heterochromatin commensurate with the increased length of the long arm. Giemsa banding of the entire chromosome (G-bands) revealed two heterochromatin bands, identical in appearance, in the centromeric region with the remainder of the chromosome showing normal banding. The distribution of Duffy blood groups in the pedigree was consistent with the locus being on chromosome No. 1.

Mapping human autosomes: evidence supporting assignment of rhesus to the short arm of chromosome No. 1

Rh-negative erythrocytes were found in the blood of an Rh-positive man suffering from myelofibrosis. Nucleated hemopoietic precursors were also circulating in his blood, and these cells had an abnormal chromosome complement from which identifiable chromosome segments had been deleted. Correlation of the serological and cytogenetic findings, combined with previous data, indicates that the Rhesus blood group locus is on the distal portion of the short arm of chromosome No. 1.

Restoration of the conversion of desmosterol to cholesterol in L-cells after hybridization with human fibroblasts

Hybrids between different human cells (which synthesize cholesterol) and mouse cells (whose end-product of sterol synthesis is desmosterol) were analyzed for the ability to convert desmosterol to cholesterol. Conversion of [(14)C]desmosterol to cholesterol and incorporation of [(14)C]acetate into the end-product sterol were studied in the parental and hybrid cells. Concordant segregation of the conversion of desmosterol to cholesterol and the human chromosome F-20 was observed.

Regional localization of loci for human PGM and 6PGD on human chromosome one by use of hybrids of Chinese hamster-human somatic cells

The human gene loci phosphoglucomutase(1) (PGM(1), EC 2.7.5.1) and 6-phosphogluconate dehydrogenase (6PGD, EC 1.1.1.43), which are located on human chromosome one, have been assigned to a specific region of the short arm of that chromosome, by use of a hybrid cell line derived from a Chinese hamster cell line deficient in hypoxanthine phosphoribosyl transferase and a strain of human diploid fibroblasts. Cytogenetic analysis of a hybrid clone maintained for about 50 generations in vitro revealed two populations of cells, the first containing a human chromosome one with a break point at band 1p33, such that about 25% of the short arm of this chromosome was deleted. The second cell population contained a normal chromosome one. Biochemical analysis of subclones derived by cloning this mixed population revealed two phenotypic classes, one of which expressed all three chromosome-one markers, PGM(1), 6PGD, and peptidase C (Pep C), while the other expressed only Pep C. Cytogenetic analysis showed that the subclones expressing all three markers carried the normal human chromosome one, while those expressing only Pep C carried the deleted chromosome. These data indicate that the human gene loci PGM(1) and 6PGD are located on the short arm of chromosome one distal to the break point, while Pep C lies elsewhere on the chromosome.

Reexpression of the rat hypoxanthine phosphoribosyltransferase gene in rat-human hybrids

Fusion of hypoxanthine phosphoribosyltransferase (HPRT)(-) rat hepatoma cells with HPRT(+) human fibroblasts yielded hybrid clones that grew in HAT selective medium and contained all the rat chromosomes and one to nine human chromosomes. Among the retained chromosomes was the human X chromosome. In all clones backselected in medium containing 8-azaguanine, human X chromosome was absent. Electrophoretic analysis revealed that, without exception, hybrid clones growing in HAT medium had an active HPRT enzyme, either human or rat, or both. When these clones were backselected in 8-azaguanine, they did not show HPRT enzyme activity. Hybrids that contained the human X chromosome also had human glucose-6-phosphate dehydrogenase. The observed reexpression of rat HPRT in hybrid cells derived from HPRT(-) rat cells suggests that a genetic factor from the human cell determined the expression of the rat structural gene for HPRT.