The CCAAT/enhancer binding protein (C/EBP alpha) gene (CEBPA) maps to human chromosome 19q13.1 and the related nuclear factor NF-IL6 (C/EBP beta) gene (CEBPB) maps to human chromosome 20q13.1.

The CEBPA gene encoding CCAAT/enhancer binding protein (C/EBP alpha) has been mapped to human chromosome 19 and the CEBPB (formerly TCF5) gene encoding NF-IL6 (C/EBP beta) to human chromosome 20 by Southern blot analysis of Chinese hamster x human and mouse x human somatic cell hybrids. CEBPA has been further mapped to 19q13.1 between the loci GPI and TGFB using human x hamster somatic cell hybrids containing restricted fragments of human chromosome 19. This position was confirmed by fluorescence in situ hybridization. Furthermore, CEBPB has been mapped to 20q13.1 by fluorescence in situ hybridization.     

Assignment of the rat parathyroid hormone-like peptide gene (PTHLH) to chromosome 4: evidence for conserved synteny between human chromosome 12, mouse chromosome 6, and rat chromosome 4

The gene coding for rat parathyroid hormone-like peptide (PTHLH) was previously assigned to rat chromosome 2 (Hendy et al., 1988). We reexamined this assignment. According to our results, the gene is on rat chromosome 4. Taking into account the known localizations of the KRAS2 (Kras-2) oncogene and the PTHLH gene, this assignment strongly suggests that a synteny group is conserved on rat chromosome 4, mouse chromosome 6, and human chromosome 12.     

Regional assignment of two genes of the human branched-chain alpha-keto acid dehydrogenase complex: the E1 beta gene (BCKDHB) to chromosome 6p21-22 and the E2 gene (DBT) to chromosome 1p31

Maple syrup urine disease (MSUD) is caused by the deficiency of the mitochondrial branched-chain alpha-keto acid dehydrogenase complex. The multienzyme complex is a macromolecule (Mr 4 X 10(6] consisting of at least six distinct subunits. In this study, the human E1 beta gene (BCKDHB) has been localized to human chromosome 6 by hybrid somatic cell analysis, and regionally assigned to chromosome bands 6p21-22 by in situ hybridization. The E2 gene (DBT), which was previously localized to chromosome 1, is regionally assigned to the chromosome band 1p31 also by in situ hybridization. Localization of the E1 beta gene to chromosome 6p21-22 assigns another major human disease locus to a region that contains several important genes, including the major histocompatability complex, tumor necrosis factor, and heat-shock protein HSP70. Mapping of the E1 beta and the E2 genes may provide information for the linkage analysis of MSUD families with mutations in these two loci.     

The interleukin-4 receptor gene (IL4R) maps to 16p11.2-16p12.1 in human and to the distal region of mouse chromosome 7.

The chromosomal location of both the human and the mouse interleukin-4 receptor (IL4R) genes have been determined. The human gene was localized to 16p11.2-16p12.1 by in situ hybridization and confirmed by Southern blot analysis of DNA from a panel of mouse-human hybrid somatic cell lines. The mouse homolog was positioned in the distal region of chromosome 7 by interspecific backcross analysis. The results suggest that the IL4R locus is unlinked to other members of the hematopoietin receptor family. Interestingly, the position on human chromosome 16 suggests that the IL4R may be a candidate for rearrangements, as 12;16 translocations are often associated with myxoid liposarcomas.     

Pro-melanin-concentrating hormone gene (PMCH) is localized on human chromosome 12q and rat chromosome 7

Melanin-concentrating hormone (MCH) is a cyclic neuropeptide that may be involved in regulation of the stress response and food intake behavior in mammals. MCH and two other putative neuropeptides, NEI and NGE, are encoded by the same precursor, designated pro-melanin-concentrating hormone (PMCH). A panel of somatic cell hybrids segregating either human or rat chromosomes was used to determine the chromosomal localization of the PMCH locus. It was assigned to human chromosome 12q and to rat chromosome 7. This is the first neuropeptide-encoding gene found in this new synteny group conserved in rat and human.     

Assignment of the genes encoding human interleukin-8 receptor types 1 and 2 and an interleukin-8 receptor pseudogene to chromosome 2q35.

Two human cDNA clones that encode different interleukin-8 (IL8) receptors have recently been isolated. The interleukin-8 receptor type 1 (IL8R1) binds IL8 only, whereas the interleukin-8 receptor type 2 (IL8R2) (previously designated IL8RA) also binds growth regulated gene (GRO), and neutrophil activating protein-2 (NAP-2) with high affinity. In the process of screening a genomic library with these cDNAs to obtain large clones for use in chromosomal localization studies, we isolated an interleukin-8 receptor pseudogene (IL8RP) that bears greatest similarity to IL8R2. Using Southern hybridization analysis of human x rodent somatic cell hybrid DNAs with cDNA probes for IL8R1 and IL8R2 and probes from the IL8RP locus, we assigned the three loci to chromosome 2; fluorescence in situ hybridization (FISH) to metaphase chromosome preparations using genomic clones from each locus refined this localization to chromosome 2, band q35, for all three. By virtue of their chromosomal location, IL8R1 and IL8R2 may be considered candidate genes for several human disorders in which the involved locus has been mapped to distal 2q or that are associated with structural abnormalities of this segment, including van der Woude syndrome and the neoplastic diseases rhabdomyosarcoma and uterine leiomyomata. In addition, because this region of chromosome 2q is homologous to proximal mouse chromosome 1 in the segment containing the Lsh-Ity-Bcg locus involved in mediating host resistance to infection with intracellular pathogens, examination for abnormalities of the murine homologues of the IL8R genes should be considered in mice affected by mutations of this locus.     

Assignment of 12 loci to rat chromosome 5: evidence that this chromosome is homologous to mouse chromosome 4 and to human chromosomes 9 and 1 (1p arm)

Twelve loci have been assigned to rat chromosome 5: aldolase B (ALDOB), atrial natriuretic factor (ANF = pronatriodilatin, PND), D4RP1, DSI1, galactosyltransferase (GGTB2), glucose transporter (GLUT1), interferon alpha 1 and related interferon alpha (INFA), interferon beta (INFB), lymphocyte-specific protein-tyrosine kinase (LCK), oncogene MOS, alpha 2U-globulin (major urinary protein, MUP), and orosomucoid (ORM, also called alpha 1-acid glycoprotein, AGP). Among these, the interferon alpha and beta genes map in the q22-23 region, which also contains a transformation suppressor gene (SAI1). The other loci reside outside this region. This study also indicated that the rat genome contains 2 LCK genes, unlike the human and murine genomes. These new assignments on rat chromosome 5 demonstrate that this chromosome is highly homologous to mouse chromosome 4 and carries synteny groups conserved on human chromosome 9 (interferon alpha and beta, galactosyltransferase, orosomucoid, and aldolase B genes) and on the short arm of human chromosome 1 (MYCL, glucose transporter, protein kinase LCK, and atrial natriuretic factor genes).     

Assignment of the gene coding for the alpha 2-macroglobulin receptor to mouse chromosome 15 and to human chromosome 12q13-q14 by isotopic and nonisotopic in situ hybridization.

The assignment of the gene encoding the alpha 2-macroglobulin receptor (A2MR), which was first described as the low-density lipoprotein receptor-related protein, was confirmed by nonisotopic and isotopic in situ hybridizations on normal human metaphases to the region 12q13-q14. The same human cDNA, which has 95% sequence identity with the mouse A2mr, was hybridized to metaphases containing the Robertsonian translocation Rb(6;15)1Ald. The mouse A2mr gene was assigned to chromosome 15 in the region B2-D1. This locus and other loci on mouse chromosome 15 have been shown to be homologous with loci on human chromosome 12q.     

Physical localization of chromosome 20 markers using somatic cell hybrid cell lines and fluorescence in situ hybridization.

A panel of somatic cell hybrid cell lines containing different parts of human chromosome 20 and fluorescence in situ hybridization have been used to physically localize markers to human chromosome 20. Through these complementary approaches and genetic linkage analysis, D20S16, which is closely linked to the maturity onset diabetes of the young (MODY) locus, was mapped to band 20q12 --> q13.1. The gene for growth hormone-releasing factor (GHRF) was physically mapped and reassigned to 20q11, suggesting that GHRF plays no direct role in MODY. In addition, the genes for the chromosome 20-linked glycogen phosphorylase (GYPB) and the bone morphogenetic protein (BMP2A) have been assigned to chromosome 20p, and the interleukin-6-dependent DNA-binding protein (TCF5) has been assigned to 20q12 --> q13 by hybridization to genomic DNA from the panel of somatic cell hybrid cell lines. These approaches are useful for rapid localization of candidate genes for MODY and other DNA markers mapped to chromosome 20.     

The gene encoding TBC1D1 with homology to the tre-2/USP6 oncogene, BUB2, and cdc16 maps to mouse chromosome 5 and human chromosome 4

TBC1D1 is the founding member of a family of related proteins with homology to tre-2/UPS6, BUB2, and cdc16 and containing the tbc box motif of 180-220 amino acids. This protein family is thought to have a role in differentiation and in regulating cell growth. We set out to map the TBC1D1 gene in mouse and human. Segregation analysis of a TBC1D1 RFLP in two independent mouse RI (recombinant inbred) lines reveals that mouse Tbc1d1 is closely linked to Pgm1 on chromosome 5. The human TBC1D1 gene was assigned to human chromosome 4p15.1-->4q21 using Southern blot analyses of genomic DNAs from rodent-human somatic cell lines. A human-specific genomic fragment was observed in the somatic cell lines containing human chromosome 4 or the 4p15.1-->4q21 region of the chromosome. TBC1D1 maps to the region containing the ortholog of mouse Pgm1 adding another locus to this long region of conserved synteny between mouse and man.     

Isolation of cDNA clones coding for rat isovaleryl-CoA dehydrogenase and assignment of the gene to human chromosome 15

Rat liver mRNA encoding the cytoplasmic precursor of mitochondrial isovaleryl-CoA dehydrogenase was highly enriched by polysome immunopurification using a polyclonal monospecific antibody. The purified mRNA was used to prepare a plasmid cDNA library which was screened with two oligonucleotide mixtures encoding two peptides in the amino-terminal portion of mature rat isovaleryl-CoA dehydrogenase. Thirty-one overlapping cDNA clones, spanning a region of 2.1 kbp, were isolated and characterized. The cDNA sequence of a 5'-end clone, rIVD-13 (155 bp), predicts a mitochondrial leader peptide of 30 amino acid residues and the first 18 amino acids of the mature protein. These consecutive 18 residues completely matched the amino-terminal peptide determined by automated Edman degradation of the rat enzyme. The leader peptide contains six arginines, has no acidic residues, and is particularly rich in leucine, alanine, and proline residues. Southern blot analysis of DNAs from human-rodent somatic cell hybrids with an isolated rat cDNA (2 kbp) assigned the isovaleryl-CoA dehydrogenase gene to the long arm of chromosome 15, region q14----qter. The chromosomal assignment was confirmed and further refined to bands q14----q15 by in situ hybridization of the probe to human metaphase cells. This location differs from that of the gene for medium-chain acyl-CoA dehydrogenase, a closely related enzyme, which has been previously assigned to chromosome 1.     

Localization of the rhodopsin gene to the distal half of mouse chromosome 6

We have assigned the mouse rhodopsin gene, Rho, to chromosome 6 using DNA from a set of mouse-hamster somatic hybrid cell lines and a partial cDNA clone for mouse opsin. This assignment rules out the direct involvement of the rhodopsin gene in the known mouse mutations that produce retinal degeneration, including retinal degeneration slow (rds, chromosome 17), retinal degeneration (rd, chromosome 5), Purkinje cell degeneration (pcd, chromosome 13), and nervous (nr, chromosome 8). Segregation of Rho-specific DNA fragment differences among 50 animals from an interspecific backcross (C57BL/6J X Mus spretus) X C57BL/6J indicates that the Rho locus is 4.0 +/- 2.8 map units distal to the locus for the proto-oncogene Raf-1 and 18.0 +/- 5.4 map units proximal to the locus for the proto-oncogene Kras-2. Linkage to Raf-1 was confirmed using four sets of recombinant inbred strains. The two loci RAF1 and RHO are also syntenic on human chromosome 3, but on opposite arms.     

Sublocalization of the human PDGF A-chain gene to chromosome 7, band q11.23, by in situ hybridization

The human platelet-derived growth factor A-chain (PDGFA) locus was mapped by in situ hybridization. By use of human cDNA probes encoding the PDGF A-chain precursor polypeptide the gene was assigned to the proximal long arm of chromosome 7, band q11.23. Of 76 cells with silver grains on chromosome 7, 28% had label over this band. Our assignment represents a confirmation and further sublocalization of the PDGFA locus. The location correlates with specific chromosomal abnormalities associated with certain human developmental malformations and neoplasms.     

Mapping of the human gene for the human immunodeficiency virus type 1 enhancer binding protein HIV-EP2 to chromosome 6q23-q24.

The human gene encoding the human immunodeficiency virus type 1 enhancer binding protein HIV-EP2 has been isolated. Using Southern analysis of human-rodent somatic cell hybrid DNA with a human HIV-EP2-specific cDNA probe, the HIV-EP2 gene was assigned to chromosome 6. The gene was further localized to the region 6q23-24 by fluorescence in situ hybridization.     

Assignment of the NAD-dependent deacetylase sirtuin 5 gene (SIRT5) to human chromosome band 6p23 by in situ hybridization

Sirtuin 5 (SIRT5) is a nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase and belongs to the Silent information regulator 2 (Sir2) family of sirtuin histone deacetylases (HDACs), which play a central role in epigenetic gene silencing, DNA repair and recombination, cell-cycle, microtubule organization, and in the regulation of aging. We have isolated and characterized the human SIRT5 genomic sequence, which spans a region of 28,182 bp and which has one single genomic locus. Human SIRT5 consists of eight exons and is found in two isoforms, which encode a 310 aa and a 299 aa protein, respectively. Human SIRT5 is most predominantly expressed in heart muscle cells and in lymphoblasts. Fluorescence in situ hybridization analysis localized the human SIRT5 gene to chromosome 6p23.     

Interleukin-1 receptor cluster: gene organization of IL1R2, IL1R1, IL1RL2 (IL-1Rrp2), IL1RL1 (T1/ST2), and IL18R1 (IL-1Rrp) on human chromosome 2q

The family of interleukin-1 receptor-like genes currently has six known members. We have constructed a contig of 10 overlapping human PAC clones that covers 530 kb and includes five of the six family members. The termini of the contig were mapped to the interval between D2S373 and D2S176 (chromosome 2q12) by radiation hybrid mapping. The contig contains the genes (cen --> tel), in the order given, for the type II interleukin-1 (IL-1) receptor (IL1R2), the type I IL-1 receptor (IL1R1), the IL-1 receptor-related protein 2 (IL1RL2), T1/ST2/fit-1 (IL1RL1), and the IL-1 receptor-related protein 1, which has recently been shown to be a component of the IL-18 receptor (IL18R1). We show that all the genes are transcribed in the same direction, with IL1R2 being transcribed toward the cluster. The only known family member that is absent from the human contig is the IL-1 receptor accessory protein gene (IL1RAP), which maps to 3q28.