Regional localization of mouse Abl and Mos proto-oncogenes by in situ hybridization

Evidence for an uncommon microsatellite instability on mouse chromosomes 2 and 4 and its possible role in radiation leukemogenesis

Although microsatellite instability (MSI), usually detected by DNA length polymorphisms, has been implicated in the induction of solid tumors in both humans and animals, its role in leukemogenesis is unclear. The goal of this study was to investigate whether there is an association between MSI and radiation leukemogenesis in CBA/Ca mice. Microsatellite lengths at 55 loci, mapped to eight different mouse chromosomes, were examined in two groups of DNA samples: 1) 10 normal DNA samples collected from the bone marrow cells of control male CBA/Ca mice, and 2) 17 DNA samples isolated from the spleens of mice that developed myeloid leukemia (ML) after exposure to neutrons, or X rays, or gamma rays. Microsatellite markers were amplified using the non-radioisotopic multiplex-touchdown PCR protocols developed in our laboratory, and the sizes of amplicons were examined on 6% non-denaturing polyacrylamide gels. Although no correlation between microsatellite length polymorphisms and radiation leukemogenesis was observed at the 55 CBA/Ca mouse loci tested in this study, an uncommon MSI, manifested as the absence of DNA bands after PCR amplification at 2 loci (D2MIT140 and D4MIT104), was observed in both control and ML samples. However, the frequency of ML samples showing this type of MSI is statistically significant (p<0.05). Although there is no direct evidence that this type of MSI predisposes mice to the development of leukemia, the results suggests that genes flanking the D2MIT140 and D4MIT104 are susceptible to spontaneous mutation and perhaps to damage caused by ionizing radiation.

Localization of the gene for branchiootorenal syndrome to chromosome 8q

Branchiootorenal syndrome is an autosomal dominant disorder that affects an estimated 2% of profoundly deaf children. In addition to hearing impairment, it is characterized by a lop-ear deformity, preauricular pits, branchial cleft sinus tracts, and renal anomalies. The pathogenesis of the disease remains unknown; however, the defective gene has been localized to chromosome 8q by family linkage studies.

Mouse microsatellites from a flow-sorted 4:6 Robertsonian chromosome

Twenty microsatellites were generated from a previously characterized lambda gt10 library containing C57BL/6J mouse DNA from a flow-sorted 4:6 Robertsonian chromosome. These sequences were analyzed for size variation between different strains of mice with the polymerase chain reaction (PCR) and mapped by use of either strain distribution patterns (SDPs) in recombinant inbred (RI) strains, or intra- and interspecific backcrosses. Eighty-five percent of the sequences showed allelic variations between different inbred strains of mice and the wild mouse, Mus spretus, and 70% were variant between inbred strains. Eight (62%) of the 13 repeats that have been mapped lie on Chromosomes (Chr) 4 and 6. This approach is an effective way of generating informative markers on specific chromosomes.

Pax: a murine multigene family of paired box-containing genes

A murine multigene family has been identified that shares a conserved sequence motif, the paired box, with developmental control and tissue-specific genes of Drosophila. To date five murine paired box-containing genes (Pax genes) have been described and one, Pax-1, has been associated with the developmental mutant phenotype undulated. Here we describe the paired boxes of three novel Pax genes, Pax-4, Pax-5, and Pax-6. Comparison of the eight murine paired domains of the mouse, the five Drosophila paired domains, and the three human paired domains shows that they fall into six distinct classes: class I comprises Pox meso, Pax-1, and HuP48; class II paired, gooseberry-proximal, gooseberry-distal, Pax-3, Pax-7, HuP1, and HuP2; class III Pax-2, Pax-5, and Pax-8; class IV Pax-4; class V Pox neuro; and class VI Pax-6. Pax-1 and the human gene HuP48 have identical paired domains, as do Pax-3 and HuP2 as well as Pax-7 and HuP1, and are likely to represent homologous genes in mouse and man. Identical intron-exon structure and extensive sequence homology of their paired boxes suggest that several Pax genes represent paralogs. The chromosomal location of all novel Pax genes and of Pax-3 and Pax-7 has been determined and reveals that they are not clustered.

The HOX-5 and surfeit gene clusters are linked in the proximal portion of mouse chromosome 2

Using an interspecies backcross, we have mapped the HOX-5 and surfeit (surf) gene clusters within the proximal portion of mouse chromosome 2. While the HOX-5 cluster of homeobox-containing genes has been localized to chromosome 2, bands C3-E1, by in situ hybridization, its more precise position relative to the genes and cloned markers of chromosome 2 was not known. Surfeit, a tight cluster of at least six highly conserved "housekeeping" genes, has not been previously mapped in mouse, but has been localized to human chromosome 9q, a region of the human genome with strong homology to proximal mouse chromosome 2. The data presented here place HOX-5 in the vicinity of the closely linked set of developmental mutations rachiterata, lethargic, and fidget and place surf close to the proto-oncogene Abl, near the centromere of chromosome 2.

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 structural gene for argininosuccinate synthetase to proximal mouse chromosome 2

In order to develop linkage markers for the murine argininosuccinate synthetase locus (Ass-1), we have searched for restriction fragment length polymorphisms in the mouse genome using cloned sequences from the mouse arginosuccinate synthetase structural gene. Five restriction fragment length polymorphisms were found among the recombinant inbred progenitor strains AKR/J, BALB/cByJ, C3H/HeJ, C57BL/6J, C57L/J, DBA/2J, and SWR/J. Of these, four polymorphisms were found to distinguish the SWR/J strain from the other six strains, which all had the same fragment. The fifth polymorphism revealed differences among the progenitor strains for recombinant inbred strain sets AKXL, BXD, and SWXL. The strain distribution pattern for this polymorphism indicated close linkage of Ass-1 to Hc (the fifth component of complement) on proximal mouse chromosome 2 with a recombination fraction of 0.016 and a 95% confidence interval of 0.003 to 0.054. These data place Ass-1 in a syntenic group with the genes Hc, Abl, Fpgs, and Ak-1 whose linkage has been conserved between human chromosome 9q and mouse chromosome 2.

Cytogenetic and molecular observations in human and experimental salivary gland tumors

The chromosomal banding patterns in 189 benign and malignant salivary gland tumors are reviewed. For comparison, karyotypic data from a recent series of polyoma virus-induced salivary gland tumors in the mouse are discussed. Special interest is focused on the relationships between the highly specific patterns of translocations and deletions in these tumors and different genes involved in neoplasia, in particular oncogenes, and tumor suppressor genes.

Localization of the muscle, liver, and brain glycogen phosphorylase genes on linkage maps of mouse chromosomes 19, 12, and 2, respectively

Mammalian glycogen phosphorylases comprise a family of three isozymes, muscle, liver, and brain, which are expressed selectively and to varying extents in a wide variety of cell types. To better understand the regulation of phosphorylase gene expression, we isolated partial cDNAs for all three isozymes from the rat and used these to map the corresponding genes in the mouse. Chromosome mapping was accomplished by comparing the segregation of phosphorylase restriction fragment length polymorphisms (RFLPs) with 16 reference loci in a multipoint interspecies backcross between Mus musculus domesticus and Mus spretus. The genes encoding muscle, liver, and brain phosphorylases (Pygm, Pygl, and Pygb) are assigned to mouse chromosomes 19, 12, and 2, respectively. Their location on separate chromosomes indicates that distinct cis-acting elements govern the differential expression of phosphorylase isozymes in various tissues. Our findings significantly extend the genetic maps of mouse chromosomes 2, 12, and 19 and can be used to define the location of phosphorylase genes in man more precisely. Finally, this analysis suggests that the previously mapped "muscle-deficient" mutation in mouse, mdf, is closely linked to the muscle phosphorylase gene. However, muscle phosphorylase gene structure and expression appear to be unaltered in mdf/mdf mice, indicating that this mutation is not an animal model for the human genetic disorder McArdle's disease.

The Mos proto-oncogene maps near the centromere on mouse chromosome 4

The Mos proto-oncogene, the cellular homolog of the transforming gene of Moloney murine sarcoma virus, was originally assigned to mouse chromosome 4 using independent panels of mouse/hamster somatic cell hybrids. By in situ hybridization to metaphase chromosomes and standard genetic backcrosses, we have confirmed this assignment and determined that Mos maps near the centromere in a region devoid of other markers. We have also identified a restriction fragment length polymorphism (RFLP) that defines two alleles of the Mos locus in selected inbred strains of laboratory mice. Using the RFLP, we determined the strain distribution pattern for the Mos gene in three sets of recombinant inbred strains and in five strains congenic for histocompatibility antigen genes localized on chromosome 4. These results establish Mos as a useful marker in a poorly characterized region of the mouse genome. In addition, these results will facilitate the genetic analysis of the Mos locus.

Linkage analysis of the murine mos proto-oncogene on chromosome 4

A linkage analysis of the murine Mos gene, which codes for the c-mos proto-oncogene, was performed in 88 backcross progeny of an interspecies cross of laboratory mice and Mus spretus. Linkage was tested for four different genes on mouse chromosome 4: Aco-1, Mup-1, b, and Ifb. The gene order (from centromere) with intervening percentage recombination is Mos-15.9 (+/- 3.9)-Aco-1-5.6 (+/- 2.4)-Mup-1-3.4 (+/- 1.9)-b-5.6 (+/- 2.4)-Ifb. These results confirm the previous assignment of Mos to chromosome 4 on the basis of segregation in somatic cell hybrids (D. Swan et al., 1982, J. Virol. 44: 752-754) and show furthermore that Mos and the Ifa/Ifb clusters are not tightly linked as a group of intronless genes, but are separated by a map distance of 30.6 +/- 4.9 recombination units. The linkage data obtained in the present study place Mos in a region compatible with the physical map (D. W. Threadgill and J. E. Womack, 1988, Genomics 3: 82-86).

Chromosome maps of man and mouse. IV

Current knowledge of man-mouse genetic homology is presented in the form of chromosomal displays, tables and a grid, which show locations of the 322 loci now assigned to chromosomes in both species, as well as 12 DNA segments not yet associated with gene loci. At least 50 conserved autosomal segments with two or more loci have been identified, twelve of which are over 20 cM long in the mouse, as well as five conserved segments on the X chromosome. All human and mouse chromosomes now have conserved regions; human 17 still shows the least evidence of rearrangement, with a single long conserved segment which apparently spans the centromere. The loci include 102 which are known to be associated with human hereditary disease; these are listed separately. Human parental effects which may well be the result of genomic imprinting are reviewed and the location of the factors concerned displayed in relation to mouse chromosomal regions which have been implicated in imprinting phenomena.