Localization of the active type I DNA topoisomerase gene on human chromosome 20q11.2-13.1, and two pseudogenes on chromosomes 1q23-24 and 22q11.2-13.1

Summary Different subfragments of a cDNA coding for DNA topoisomerase I were used as probes to determine the chromosomal localization of topoisomerase I sequences in human cells. Southern blotting of restricted DNA from a panel of rodent-human somatic cell hybrids revealed the localization of the complete gene on chromosome 20 and the presence of two truncated topoisomerase I pseudogene sequences on chromosomes 1 and 22. In situ chromosome hybridzation experiments confirmed these results showing the location of the complete gene on band q11.2–13.1 of chromosome 20, and the location of the pseudogene sequences on band q23–24 of chromosome 1 and q11.2–13.1 of chromosome 22.     

Ribonuclease H1 maps to chromosome 2 and has at least three pseudogene loci in the human genome

We have analyzed the genomic structure of ribonuclease H1 (RNase H1) loci in the human genome. Human PAC library screening combined with database searches indicated that several loci are present. The transcribed gene is localized on chromosome 2p25. This was confirmed by RNA analysis of a monochromosomal hybrid cell line that expressed human chromosome 2. These data contradict a previous report, as well as the current Human Genome Project (HGP) annotation, which had placed the gene on chromosome 17p11.2. This location represents a pseudogene. Another highly similar pseudogene is present at a separate locus located more distal on chromosome 17p, while a third pseudogene is localized on chromosome 1q.     

An expressed beta-tubulin gene, TUBB, is located on the short arm of human chromosome 6 and two related sequences are dispersed on chromosomes 8 and 13

The chromosomal assignments of an expressed beta-tubulin gene and two related sequences have been determined by Southern blot analysis of DNA from a panel of human x Chinese hamster somatic cell hybrids cleaved with Hind III or EcoRI. Probes containing the 3' untranslated regions of the expressed gene M40 and of pseudogene 21 beta were used to localize the M40 sequence (gene symbol TUBB) to chromosome 6 region 6p21----6pter, the 21 beta pseudogene (TUBBP1) to chromosome 8 region 8q21----8pter and a third related sequence (TUBBP2) to chromosome 13. Asynteny of expressed genes and related processed pseudogenes has now been demonstrated for several gene families.     

The human thyroglobulin gene: A polymorphic marker localized distal to C-MYC on chromosome 8 band q24

Summary We have used a cDNA clone for human phosphoglycerate kinase (PGK) to examine the chromosomal localization of three members of the human PGK gene family. Using somatic cell hybrids segregating portions of several X-autosome translocations as well as a clone panel of hybrids segregating radiation-induced fragments of the human X chromosome, we assign a PGK pseudogene to the region Xq11–Xq13, proximal to the functional X-linked PGK gene located in Xq13. In addition, using a panel of 24 somatic cell hybrids, we assign an autosomal PGK-related DNA sequence to human chromosome 19.     

An expressed β-tubulin gene, TUBB, is located on the short arm of human chromosome 6 and two related sequences are dispersed on chromosomes 8 and 13

The chromosomal assignments of an expressed β-tubulin gene and two related sequences have been determined by Southern blot analysis of DNA from a panel of human X Chinese hamster somatic cell hybrids cleaved with Hind III or EcoR I. Probes containing the 3′ untranslated regions of the expressed gene M40 and of pseudogene 21β were used to localize the M40 sequence (gene symbol TUBB) to chromosome 6 region 6p21 → 6pter, the 21β pseudogene (TUBBP1) to chromosome 8 region 8q21 → 8pter and a third related sequence (TUBBP2) to chromosome 13. Asynteny of expressed genes and related processed pseudogenes has now been demonstrated for several gene families.     

Identification of two paralogous regions mapping to the short and long arms of human chromosome 2 comprising LIS1 pseudogenes

Reiner et al. (1995b) reported on the existence of a gene with a coding region virtually identical to LIS1, the gene responsible for Miller-Dieker lissencephaly. This gene, LIS2, was mapped to chromosome 2p11.2, and a related pseudogene, LIS2P, was mapped to 2q13-->q14. By sequencing genomic clones that were mapped by means of 2p and 2q-only hybrids, we now demonstrate the existence of two LIS1 processed pseudogenes mapping to 2p11.2 and 2q13 (PAFAH1P1 and PAFAH1P2, respectively). The two sequences appear to lie within larger paralogous regions and share a 98.6% degree of identity. Comparative mapping data by cytogenetic analysis on great apes indicate that the duplication of the genomic region comprising the LIS1 pseudogenes occurred in humans. We also demonstrate that the cDNA sequence shown as part of the LIS2 gene and marking its chromosome 2 specificity belongs to the 3' untranslated region of a different gene (C1orf6) that we mapped to 1q21 by FISH analysis.     

Assignment of human prochymosin pseudogene to chromosome 1

Chymosin is an extremely specific aspartatic protease responsible for milk coagulation. Chymosin is expressed in a number of mammalian offspring, yet its presence in the gastric tissue of human infants remains a matter of controversy. In any event, the human genome contains chymosin-related sequences that probably represent a pseudogene. Using DNA obtained from human x hamster somatic cell hybrids as the template and polymerase chain reaction, we have mapped the human prochymosin pseudogene to chromosome 1.     

Localization of the photoreceptor gene ROM1 to human chromosome 11 and mouse chromosome 19: sublocalization to human 11q13 between PGA and PYGM.

Rom-1 is a retinal integral membrane protein that, together with the product of the human retinal degeneration slow gene (RDS), defines a photoreceptor-specific protein family. The gene for rom-1 (HGM symbol: ROM1) has been assigned to human chromosome 11 and mouse chromosome 19 by Southern blot analysis of somatic cell hybrid DNAs. ROM1 was regionally sublocalized to human 11p13-11q13 by using three mouse-human somatic cell hybrids; in situ hybridization refined the sublocalization to human 11q13. Analysis of somatic cell hybrids suggested that the most likely localization of ROM1 is in the approximately 2-cM interval between human PGA (human pepsinogen A) and PYGM (muscle glycogen phosphorylase). ROM1 appears to be a new member of a conserved syntenic group whose members include such genes as CD5, CD20, and OSBP (oxysterol-binding protein), on human chromosome 11 and mouse chromosome 19. Localization of the ROM1 gene will permit the examination of its linkage to hereditary retinopathies in man and mouse.     

Regional chromosome mapping of the human skin type I procollagen gene using adenovirus 12-fragmentation of human-mouse somatic cell hybrids

Prevous work, using human-mouse somatic cell hybrids, has localized the structural gene for human skin type I procollagen (COL 1) to chromosome 17. One of these hybrids contained only the long arm of human chromosome 17, translocated onto a mouse chromosome, as human chromosomal material. This hybrid was treated with adenovirus 12, and various clones were picked which contained different-sized fragments of human chromosome 17 that were still translocated onto a mouse chromosome. Measurements of these fragments, combined with assays for human COL 1 production and galactose kinase (GAK) activity (also localized on the long arm of human chromosome 17), has allowed us to regionally map the structural gene for human COL 1 to an area just distal to the thymidine kinase (TK) and GAK genes within bands q21 and q22 on human chromosome 17.     

Localization of the cellular retinoic acid binding protein (CRABP) gene relative to the acute promyelocytic leukemia-associated breakpoint on human chromosome 15

Summary A human genomic fragment comprising the cellular retinoic acid binding protein (CRABP) gene was isolated. By using a panel of somatic cell hybrids, this gene could be assigned to human chromosome 15. Subsequently, a possible involvement of the CRABP gene in translocation (15;17) (q22;q11) positive acute promyelocytic leukemia (APL) was investigated. Although transposition of the CRABP gene could be demonstrated, we did not observe any gross CRABP rearrangement in a series of primary APL patients, nor in the acute myeloblastic leukemia cell line HL-60. Thus, the observed lack of CRABP expression in these leukemic cells may not be caused by disruption of its gene. CRABP maps to the region 15q22-qter.     

Chromosomal localization of a cytochrome b5 gene to human chromosome 18 and a cytochrome b5 pseudogene to the X chromosome.

We have isolated cDNA clones that code for human cytochrome b5. Owing to the high degree of evolutionary conservation of cytochrome b5 sequences and the existence of human and rodent cytochrome b5 processed pseudogenes, we were unable to map unambiguously the chromosomal localization of the human gene(s) by Southern blot hybridization of DNA from human-rodent somatic cell hybrids. An alternative approach, based on restriction enzyme digestion of PCR-amplified DNA, enabled us to map the human cytochrome b5 gene(s) to chromosome 18 and one of its processed pseudogenes to the X chromosome. We propose the designations CYB5 and CYB5P1 for the gene and pseudogene loci, respectively.     

Localization of a beta-crystallin gene, Hu beta A3/A1 (gene symbol: CRYB1), to the long arm of human chromosome 17

We have assigned a human beta-crystallin gene, Hu beta A3/A1 (gene symbol: CRYB1), to chromosome 17 using a panel of 19 human-hamster somatic cell hybrids and blot-hybridization analysis of cell hybrid DNA. Positive probe-hybridization signal was detected in a hybrid that had lost the short arm of human chromosome 17 but retained the long arm, translocated to a hamster chromosome. In addition, in situ hybridization analysis of metaphase chromosome spreads of this cell line suggested that the most probable location for CRYB1 is on the long arm of chromosome 17, in the region q21.     

Assignment of the gene coding for the alpha-subunit of prolyl 4-hydroxylase to human chromosome region 10q21.3-23.1.

Prolyl 4-hydroxylase, an alpha 2 beta 2 tetramer, catalyzes the formation of 4-hydroxyproline in collagens by the hydroxylation of proline residues in peptide linkages and plays a crucial role in the synthesis of these proteins. The gene for the beta-subunit of prolyl 4-hydroxylase has recently been mapped to the long arm of human chromosome 17, at band 17q25. We report here chromosomal localization of the gene for the catalytically and regulatorily important alpha-subunit of human prolyl 4-hydroxylase. Analysis of 24 rodent x human cell hybrids by Southern blotting with cDNA probes for the human alpha-subunit indicated complete cosegregation of the gene for the alpha-subunit with human chromosome 10. A cell hybrid containing only part of chromosome 10 mapped the gene to 10q11----qter. In situ hybridization mapped the gene to 10q21.3-23.1. The gene for the alpha-subunit is thus not physically linked to that for the beta-subunit of the enzyme.     

Localization of HeLa cell tumor-suppressor gene to the long arm of chromosome II.

Cytogenetic and molecular genetic analyses of human intraspecific HeLa x fibroblast hybrids have provided evidence for the presence of a tumor-suppressor gene(s) on chromosome 11 of normal cells. In the present study, we have carried out extensive RFLP analysis of various nontumorigenic and tumorigenic hybrids with at least 50 different chromosome 11-specific probes to determine the precise location of this tumor-suppressor gene(s). Two different hybrid systems, (1) microcell hybrids derived by the transfer of a normal chromosome 11 into a tumorigenic HeLa-derived hybrid cell and (2) somatic cell hybrids derived by the fusion of the HeLa (D98OR) cells to a retinoblastoma (Y79) cell line, were particularly informative. The analysis showed that all but one of the nontumorigenic hybrid cell lines contained a complete copy of the normal chromosome 11. This variant hybrid contained a segment of the long arm but had lost the entire short arm of the chromosome. The tumorigenic microcell and somatic cell hybrids had retained the short arm of the chromosome but had lost at least the q13-23 region of the chromosome. Thus, these results showed a perfect correlation between the presence of the long arm of chromosome 11 and the suppression of the tumorigenic phenotype. We conclude therefore that the gene(s) involved in the suppression of the HeLa cell tumors is localized to the long arm (q arm) of chromosome 11.     

The gene cluster for human U2 RNA is located on chromosome 17q21

The gene cluster for human U2 RNA has been mapped to chromosome 17q21 by in situ hybridization and hybridization analysis of DNA from mouse/human somatic cell hybrids.     

Intrachromosomal gene mapping in man: the gene for tryptophyl-tRNA synthetase maps in region q21 leads to qter of chromosome 14

A gene for tryptophanyl-tRNA synthetase (EC 6.1.1.2), the enzyme which attaches tryptophan to its tRNA, has previously been assigned to human chromosome 14 by analysis of man-mouse somatic cell hybrids. We report here a method for the electrophoretic separation of Chinese hamster and human tryptophanyl-tRNA synthetases and its application to a series of independently derived Chinese hamster-human hybrids in which part of the human chromosome 14 has been translocated to the human X chromosome. When this derivative der (X),t(X;14) (Xqter leads to Xp22::14q21 leads to 14qter) chromosome carrying the human gene for hypoxanthine-guanine phosphoribosyltransferase was selected for and against in cell hybrid lines by the appropriate selective conditions, the human tryptophanyl-tRNA synthetase activity was found to segregate concordantly. These results provide additional confirmation for the assignment of the tryptophanyl-tRNA synthetase gene to human chromosome 14 and define its intrachromosomal location in the region 14q21 leads to 14qter. Our findings indicate that the genes for tryptophanyl-tRNA synthetase and for ribosomal RNA are not closely linked on chromosome 14.     

Assignment of human pepsinogen A locus to the q12-pter region of chromosome 11

Summary A 0.9 kb cDNA fragment, corresponding to a large part of Rhesus monkey pepsinogen A mRNA, was used as probe for the chromosomal localization of the human pepsinogen A gene(s) using human-rodent somatic cell hybrids. Southern blot analysis of 14 human-Chinese hamster and three human-mouse cell hybrids, strongly indicates that the human PGA locus is on chromosome 11. The human-mouse hybrids, containing a translocation involving chromosome 11, allow sublocalization to the region q12-pter.     

Localization of the gene for the erythroid anion exchange protein, band 3 (EMPB3), to human chromosome 17

We have isolated genomic DNA clones which code for the human erythroid membrane protein band 3 (EMPB3). The identification of the gene has been confirmed by comparison of the amino acid sequence derived from the nucleotide sequence for two restriction fragments from the 5' end of the gene. Two exons have been identified. One exon encodes 20 amino acids which are identical to residues 36 to 56 of the band 3 protein, and the other encodes 44 amino acids homologous to residues 118 to 162. Southern analysis of genomic DNA derived from a panel of rodent-human somatic cell hybrids, which retain different complements of human chromosomes, with band 3 probes has allowed us to localize EMPB3 to human chromosome 17. The gene has been further localized between 17q21 and qter by analysis of DNA from somatic cell hybrids which carry derivative chromosomes from translocations involving chromosome 17 and either chromosome 15 or 21.     

Localization of monocyte chemotactic protein-1 gene (SCYA2) to human chromosome 17q11.2-q21.1

Monocyte chemotactic protein-1 (MCP-1) is a member of the small inducible gene (SIG) family. It has been shown to play a role in the recruitment of monocytes to sites of injury and infection. By analysis of a panel of somatic cell hybrids, we have localized the MCP-1 gene, designated SCYA2, to human chromosome 17. In situ hybridization confirmed this assignment and further localized the gene to 17q11.2-q21.1.     

The gene for tissue inhibitor of metalloproteinases-2 is localized on human chromosome arm 17q25.

Tissue inhibitor of metalloproteinases-2 (TIMP2) is a natural inhibitor of several proteinases that are involved in the degradation of the extracellular matrix. By means of somatic cell hybrids segregating human chromosomes, the gene encoding this inhibitor was assigned to human chromosome 17. Fluorescence in situ hybridization confirmed this assignment and allowed mapping of the gene to the terminal region (17q25) of the chromosome.