Faculty Bibliography

We have confirmed the localization of human acid alpha-glucosidase (GAA) to 17q21----q25 and of adenosine deaminase (ADA) to 20q13----20qter by examination of hybrid clones derived from a fusion between a human cell line carrying a 17/20 balanced translocation (17pter----17q25::20q13----20qter;20pter-- --20q13::17q25----17qter) and a mouse line deficient in thymidine kinase. These hybrids were constantly maintained in HAT selective media in order to select for the presence of the human thymidine kinase gene on the intact chromosome 17 (17q21----22) or the 17/20 (17pter----17q25::20q13----20qter) translocation chromosome. We detected human GAA by rocket immunoelectrophoresis, using a heterologous antibody raised against human acid alpha-glucosidase. A clone which contained the 17/20 translocation and no intact chromosome 17 was still positive for GAA. This finding confirms the exclusion of GAA from 17q25----17qter reported by Nickel et al. (1982). Combined with earlier results (Weil et al. 1979), GAA can be assigned to 17q21----17q25. A clone which contained only the 17/20 translocation chromosome and no intact chromosome 20 contained ADA. This confirms the previous localization of ADA to 20q13.2----qter by gene dosage studies (Philip et al. 1980)

In murine plasmacytomas, the c-myc gene has frequently been found to undergo rearrangement by virtue of a T(12;15) chromosome translocation. The immunoglobulin heavy chain gene switch region (S alpha) constitutes the target for most of these recombinations particularly in IgA producing plasmacytomas. We sought to identify non-S alpha myc target sites in several IgG producing tumors. The c-myc target in MPC-11 (a BALB/c IgG2b producing plasmacytoma) has been cloned, localized to the Igh-C locus and identified as the gamma 2a heavy chain gene switch region (S gamma 2a). Furthermore, by Southern blot hybridization, we have determined that the S gamma 2b region is the c-myc target in two NZB IgG2b producing plasmacytomas. The potential relation between Ig class expressed and c-myc translocation target is discussed

In the anterior pituitary pro-opiomelanocortin (POMC) is the protein precursor to both adrenocorticotropin and beta-lipotropin but in the intermediate pituitary POMC serves as the precursor to alpha-melanocyte-stimulating hormone and beta-endorphin. In addition, POMC expression in the anterior pituitary is inhibited by glucocorticoids but stimulated by corticotropin-releasing factor while POMC expression in the intermediate lobe is not responsive to glucocorticoids but is inhibited by dopamine. In this study we have asked whether tissue-specific processing and regulation of POMC could be related to the presence of more than one POMC gene. We report here that the mouse genome contains two POMC related gene sequences, alpha- and beta-POMC, that alpha-POMC is located on mouse chromosome 12 while beta-POMC is on a different chromosome, probably chromosome 19. Sequencing of phage lambda recombinants containing alpha- and beta-POMC sequences indicated that the alpha-POMC gene in mouse is very similar to the single POMC gene found in human, bovine, and rat genomes. The sequence of the mouse beta-POMC gene is quite different from that of the alpha-POMC gene. One important difference is that the beta-POMC gene has a translation stop signal in place of the first amino acid in beta-endorphin (Tyr). The beta-POMC gene has many features in common with the pseudogene of the beta-globin family

The utility of somatic cell genetic analysis for the chromosomal localization of genes in mammals is well established. With the development of recombinant DNA probes and efficient blotting techniques that allow visualization of single-copy cellular genes, somatic cell genetics has been extended from the level of phenotypes expressed by whole cells to the level of the cellular genome itself. This extension has proved invaluable for the analysis of genes not readily expressed in somatic cell hybrids and for the study of multigene families, especially pseudogenes dispersed in different chromosomes throughout the genome

The creation of a functional antibody gene requires the precise recombination of gene segments initially separated on the chromosome. Frequently errors occur in the process, resulting in the formation of a non-functional gene. The non-functional genes can be generated by incomplete rearrangements, frameshifts, or the use of pseudo V or J joining segments. It is likely that these aberrant rearrangements arise by the same mechanism as is used in generating functional genes, a process which we have suggested may involve unequal sister chromatid exchange. Aberrant rearrangements of immunoglobulin genes occur in normal lymphocytes and play a major part in allelic exclusion. However, it has recently been suggested that aberrant rearrangements involving immunoglobulin and non-immunoglobulin genes may be involved in tumorigenesis. This suggestion has been stimulated by the frequent occurrence of translocations involving chromosomes known to carry immunoglobulin genes in B-cell malignancies. The rearrangement of non-immunoglobulin DNA to the heavy-chain locus has recently been reported. Some aberrant rearrangements of the kappa locus appear to be due to rearrangements to sites that do not include the conventional sequence for V gene segment joining. Here we describe an aberrant kappa rearrangement that has led to the joining of DNA from chromosomes 15, 6 and 12, and so appears to be the result of chromosomal translocations or transpositions. As 15/6 or 15/12 translocations have frequently been found in mouse plasmacytomas (as have analogous translocations in human lymphocyte tumours) this aberrant kappa rearrangement may be unique to the plasmacytoma from which it was isolated

The Moloney sarcoma virus-specific onc gene, referred to as v-mos, was used as probe to hybridize to restricted DNAs from various mouse-Chinese hamster hybrid cell lines. These hybrid cells contain, in addition to all of the Chinese hamster chromosomes, various numbers (less than a full complement) of mouse chromosomes. Comparison of the presence or absence of the mouse cellular mos gene with the known karyotype in each of the hybrid cell lines allows us to conclude that the mos gene is on mouse chromosome 4

A DNA sequence that generates aberrantly rearranged immunoglobulin heavy chain constant region genes in murine plasmacytomas is shown to participate in a chromosome translocation. We have previously termed this DNA sequence NIARD for non-immunoglobulin-associated rearranging DNA. NIARD rearrangements were found frequently in murine plasmacytomas but were not detected in normal lymphocytes. These rearrangements occasionally involve the switch region of the C alpha gene. In this study, DNA samples obtained from mouse-Chinese hamster somatic cell hybrid lines were digested with various restriction endonucleases and analyzed by the Southern transfer technique with a NIARD hybridization probe. These experiments show that NIARD resides on chromosome 15 in the mouse germ line. Since NIARD is found adjacent to the C alpha gene (located on chromosome 12) in some plasmacytomas, it is apparent that a translocation involving these two chromosomes has occurred. We have proposed a rcpT(12;15) model to explain our data. The implications of NIARD rearrangements for malignant transformation are discussed

The major urinary proteins (MUPs) of mouse are a family of at least three major proteins which are synthesized in the liver of all strains of mice. The relative levels of synthesis of these proteins with respect to each other in the presence of testosterone is regulated by the Mup-a locus located on chromosome 4. In an effort to determine the mechanism of this regulation in molecular terms, a cDNA clone containing most of the coding region of a MUP protein has been isolated and identified by partial DNA sequence analysis. Using a combination of hybridization analysis and somatic cell genetics, the structural gene family has been unambiguously mapped to mouse chromosome 4. These data suggest that Mup-a regulation operates in a cis fashion and that models proposing trans regulation of MUP protein synthesis are unlikely

DNA sequences closely homologous to argininosuccinate synthetase are present at ten or more distinct locations in the human genome, including sites on chromosomes 6, 9 and X. Argininosuccinate synthetase thus represents one of the most widely dispersed multigene families described to date, the first instance of a multigene family associated with an enzyme of intermediary metabolism and, perhaps most striking, the first instance of a multigene family with members on both autosomes and sex chromosomes