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A M Buchberg

Publications and source records attributed to A M Buchberg.

14 recordsLinked to original sources
PubMed1992

A leucine-to-proline mutation in the putative first transmembrane domain of the 22-kDa peripheral myelin protein in the trembler-J mouse.

Peripheral myelin protein PMP-22 is a potential growth-regulating myelin protein that is expressed by Schwann cells and predominantly localized in compact peripheral myelin. A point mutation in the Pmp-22 gene of inbred trembler (Tr) mice was identified and proposed to be responsible for the Tr phenotype, which is characterized by paralysis of the limbs as well as tremors and transient seizures. In support of this hypothesis, we now report the fine mapping of the Pmp-22 gene to the immediate vicinity of the Tr locus on mouse chromosome 11. Furthermore, we have found a second point mutation in the Pmp-22 gene of trembler-J (TrJ) mice, which results in the substitution of a leucine residue by a proline residue in the putative first transmembrane region of the PMP-22 polypeptide. Tr and TrJ were previously mapped genetically as possible allelic mutations giving rise to similar, but not identical, phenotypes. This finding is consistent with the discovery of two different mutations in physicochemically similar domains of the PMP-22 protein. Our results strengthen the hypothesis that mutations in the Pmp-22 gene can lead to heterogeneous forms of peripheral neuropathies and offer clues toward possible explanations for the dominant inheritance of these disorders.

3T3 Cells↗
PubMed1992

A molecular genetic linkage map of mouse chromosome 18 reveals extensive linkage conservation with human chromosomes 5 and 18.

An interspecific backcross between C57BL/6J and Mus spretus was used to generate a molecular genetic linkage map of mouse chromosome 18 that includes 23 molecular markers and spans approximately 86% of the estimated length of the chromosome. The Apc, Camk2a, D18Fcr1, D18Fcr2, D18Leh1, D18Leh2, Dcc, Emb-rs3, Fgfa, Fim-2/Csfmr, Gnal, Grl-1, Grp, Hk-1rs1, Ii, Kns, Lmnb, Mbp, Mcc, Mtv-38, Palb, Pdgfrb, and Tpl-2 genes were mapped relative to each other in one interspecific backcross. A second interspecific backcross and a centromere-specific DNA satellite probe were used to determine the distance of the most proximal chromosome 18 marker to the centromere. The interspecific map extends the known regions of linkage homology between mouse chromosome 18 and human chromosomes 5 and 18 and identifies a new homology segment with human chromosome 10p. It also provides molecular access to many regions of mouse chromosome 18 for the first time.

Animals↗
PubMed1991

cDNA sequence and genomic structure of EV12B, a gene lying within an intron of the neurofibromatosis type 1 gene.

The gene responsible for neurofibromatosis type 1 (NF1), one of the more common inherited human disorders, was identified recently, and segments of it were cloned. Two translocation breakpoints that interrupt the NF1 gene in NF1 patients flank a 60-kb segment of DNA that contains the EV12A locus (previously reported as the EV12 locus), the human homolog of a mouse gene, Evi-2A, implicated in retrovirus-induced murine myeloid tumors. EVI2A lies within an intron of the NF1 gene and is transcribed from telomere toward centromere, opposite to the direction of transcription of the NF1 gene. Here we describe a second locus, EVI2B, also located between the two NF1 translocation breakpoints. Full-length cDNAs from the EV12B locus detect a 2.1-kb transcript in bone marrow, peripheral blood mononuclear cells, and fibroblasts. Sequencing studies predict an EV12B protein of 448 amino acids that is proline-rich and contains an N-terminal signal peptide, an extracellular domain with four potential glycosylation sites, a single hydrophobic transmembrane domain, and a cytoplasmic hydrophilic domain. At the level of genomic DNA the EV12B locus lies within the same intron of the NF1 gene as EV12A and contains a 57-bp 5' exon that is noncoding, an 8-kb intron, and a 2078-bp 3' exon that includes the entire open reading frame. EV12B is transcribed in the same direction as EV12A; its 5' exon lies only 4 kb downstream from the 3' exon of the EV12A locus. In the mouse the 5' exon of the homologous gene, Evi-2B, lies approximately 2.8 kb from the 3' end of Evi-2A, in the midst of a cluster of viral integration sites identified in retrovirus-induced myeloid tumors; thus, Evi-2B may function as an oncogene in these tumors.

Amino Acid Sequence↗
PubMed1991

The NF1 translocation breakpoint region.

The genetic locus that harbors mutation(s) responsible for neurofibromatosis type 1 (NF1) is on chromosome 17, within band q11.2. We have mapped the human homologue of a murine gene (Evi-2) that is implicated in myeloid tumors, to a location between two NF1 translocation breakpoints on chromosome 17. Sequencing studies predict that EVI2 is a membrane protein that may complex with itself and/or other proteins within the membrane, perhaps to function as part of a cell-surface receptor. In the course of these studies we have also identified three other transcripts (classes of cDNAs) from the NF1 region. Two of them map between the NF1 translocation breakpoints; the remaining transcript maps just outside this region. The map location implicates these four genes as possible candidates for harboring NF1 mutations.

Chromosome Aberrations↗
PubMed1991

His-1 and His-2: identification and chromosomal mapping of two commonly rearranged sites of viral integration in a myeloid leukemia.

To identify genes that contribute to myeloid leukemogenesis we have cloned viral integration sites from a CasBrM-MuLV-induced interleukin 3-independent myeloid leukemia cell line. Genomic probes derived from cellular sequences flanking two integrated proviruses were used to screen restriction digests of DNAs from a panel of 52 hematopoietic cell lines, 30 of which were established from CasBrM-MuLV- or MoMuLV-induced mouse leukemias. Probes from one integration site (His-1) defined a region that was rearranged in 3/52 cell lines, and probes from a second integration site (His-2) identified a rearrangement in 2/52 cell lines. Both cases of His-2 rearrangements occurred in concert with viral insertions in the His-1 locus. Genetic mapping of these loci using interspecific backcross analysis assigned the His-1 locus to mouse chromosome 2 and the His-2 locus to mouse chromosome 19. In situ hybridization with a probe from the human homologous region mapped the His-1 locus to human chromosome 2q14-q21. No recombinants were observed between His-2 and Gin-1, a common site of provirus integration in Gross passage A MuLV-induced T-cell leukemias, in 131 backcross animals, suggesting that these loci are tightly linked. The His-1 locus maps to mouse chromosome 2 distinct from any known oncogene or common site of integration but near the proximal breakpoint for a deletion that is observed in over 90% of radiation-induced leukemias.

Animals↗
PubMed1990

Sequence homology shared by neurofibromatosis type-1 gene and IRA-1 and IRA-2 negative regulators of the RAS cyclic AMP pathway.

Neurofibromatosis type-1 (NF-1) is one of the most frequently inherited genetic disorders affecting humans. NF-1 primarily affects cells of neural crest origin and is characterized by patches of skin pigmentation (café-au-lait spots) and neurofibromas. Cloning of the human NF-1 gene shows that it encodes an 11-13 kilobase transcript that is frequently disrupted in NF-1 patients. The frequent disruption of the NF-1 gene in NF-1 patients combined with the autosomal dominant mode of inheritance of NF-1 strongly suggest that the NF-1 gene is a tumour-suppressor gene. We have now sequenced a portion of the murine NF-1 gene and show that the predicted amino-acid sequence is nearly the same as the corresponding region of the human NF-1 gene product. Northern blotting identified mouse NF-1 transcripts that are equivalent in size and complexity to those in human tissues, and Southern blotting shows that this region of the NF-1 gene is evolutionarily well conserved. Finally, computer searches identified homology between the mouse NF-1 gene and IRA-1 and IRA-2, two genes identified in Saccharomyces cerevisiae that negatively regulate the RAS-cyclic AMP pathway. These findings provide important new insights into the possible function of the NF-1 gene.

Adenylyl Cyclases↗
PubMed1990

Deletions and a translocation interrupt a cloned gene at the neurofibromatosis type 1 locus.

Three new neurofibromatosis type 1 (NF1) mutations have been detected and characterized. Pulsed-field gel and Southern blot analyses reveal the mutations to be deletions of 190, 40, and 11 kb of DNA. The 11 kb deletion does not contain any of the previously characterized genes that lie between two NF1 translocation breakpoints, but it does include a portion of a rodent/human conserved DNA sequence previously shown to span one of the translocation breakpoints. By screening cDNA libraries with the conserved sequence, we identified a number of cDNA clones from the translocation breakpoint region (TBR), one of which hybridizes to an approximately 11 kb mRNA. The TBR gene crosses at least one of the chromosome 17 translocation breakpoints found in NF1 patients. Furthermore, the newly characterized NF1 deletions remove internal exons of the TBR gene. Although these mutations might act by compromising regulatory elements affecting some other gene, these findings strongly suggest that the TBR gene is the NF1 gene.

Adult↗
PubMed1990

The human homolog of murine Evi-2 lies between two von Recklinghausen neurofibromatosis translocations.

Von Recklinghausen neurofibromatosis (NF1) is one of the most common inherited human disorders. The genetic locus that harbors the mutation(s) responsible for NF1 is near the centromere of chromosome 17, within band q11.2. Translocation breakpoints that have been found in this region in two patients with NF1 provide physical landmarks and suggest an approach to identifying the NF1 gene. As part of our exploration of this region, we have mapped the human homolog of a murine gene (Evi-2) implicated in myeloid tumors to a location between the two translocation breakpoints on chromosome 17. Cosmid-walk clones define a 60-kb region between the two NF1 translocation breakpoints. The probable role of Evi-2 in murine neoplastic disease and the map location of the human homolog suggest a potential role for EVI2 in NF1, but no physical rearrangements of this gene locus are apparent in 87 NF1 patients.

Animals↗
PubMed1990

Identification and characterization of transcripts from the neurofibromatosis 1 region: the sequence and genomic structure of EVI2 and mapping of other transcripts.

Mapping of the EVI2 gene between the translocation breakpoints of two patients with neurofibromatosis type 1 (NF1), combined with the likely role of its murine homolog in neoplastic disease, implicates EVI2 as a possible candidate for the NF1 gene. We report here the expression of a 1.6-kb EVI2 transcript in normal human brain and peripheral blood mononuclear cells. Sequencing studies predict an EVI2 protein of 232 amino acids that contains an N-terminal signal peptide, an extracellular domain with five potential glycosylation sites, a single hydrophobic transmembrane domain with a leucine zipper, and a hydrophilic cytoplasmic domain. These features are all well-conserved with respect to the mouse Evi-2 protein and are consistent with the hypothesis that EVI2 is a membrane protein that may complex with itself and/or other proteins within the membrane, perhaps to function as part of a cell-surface receptor. In the course of these studies we have also identified three other transcripts (classes of cDNAs) from the NF1 region. Two of these transcripts map between the NF1 translocation breakpoints; the remaining transcript maps just outside this region.

Amino Acid Sequence↗
PubMed1990

Chromosomal localization of seven members of the murine TGF-beta superfamily suggests close linkage to several morphogenetic mutant loci.

Chromosomal locations have been assigned to seven members of the TGF-beta superfamily using an interspecific mouse backcross. Probes for the Tgfb-1, -2, and -3, Bmp-2a and -3, and Vgr-1 genes recognized only single loci, whereas the Bmp-2b probe recognized two independently segregating loci (designated Bmp-2b1 and Bmp-2b2). The results show that the seven members of the TGF-beta superfamily map to eight different chromosomes, indicating that the TGF-beta family has become widely dispersed during evolution. Five of the eight loci (Tgfb-1, Bmp-2a, Bmp-2b1, Bmp-2b2, Vgr-1) mapped near mutant loci associated with connective tissue and skeletal disorders, raising the possibility that at least some of these mutations result from defects in TGF-beta-related genes.

Amino Acid Sequence↗
PubMed1990

A molecular genetic linkage map of mouse chromosome 13 anchored by the beige (bg) and satin (sa) loci.

A molecular genetic linkage map of mouse chromosome 13 was constructed using cloned DNA markers and interspecific backcross mice from two independent crosses. The map locations of Ctla-3, Dhfr, Fim-1, 4/12, Hexb, Hilda, Inhba, Lamb-1.13, Ral, Rrm2-ps3, and Tcrg were determined with respect to the beige (bg) and satin (sa) loci. The map locations of these genes confirm and extend regions of homology between mouse chromosome 13 and human chromosomes 5 and 7, and identify a region of homology between mouse chromosome 13 and human chromosome 6. The molecular genetic linkage map of chromosome 13 provides a framework for establishing linkage relationships between cloned DNA markers and known mouse mutations and for identifying homologous genes in mice and humans that may be involved in disease processes.

Animals↗
PubMed1990

Evi-2, a common integration site involved in murine myeloid leukemogenesis.

BXH-2 mice have the highest incidence of spontaneous retrovirally induced myeloid leukemia of any known inbred strain and, as such, represent a valuable model system for identifying cellular proto-oncogenes involved in myeloid disease. Chronic murine leukemia viruses often induce disease by insertional activation or mutation of cellular proto-oncogenes. These loci are identified as common viral integration sites in tumor DNAs. Here we report on the characterization of a novel common viral integration site in BXH-2 myeloid leukemias, designated Evi-2. Within the cluster of viral integration sites that define Evi-2, we identified a gene that has the potential for encoding a novel protein of 223 amino acids. This putative proto-oncogene possesses all of the structural features of a transmembrane protein. Within the transmembrane domain is a "leucine zipper," suggesting that Evi-2 is involved in either homopolymer or heteropolymer formation, which may play an important role in the normal functioning of Evi-2. Interestingly, the human homolog of Evi-2 has recently been shown to be tightly linked to the von Recklinghausen neurofibromatosis locus, suggesting a role for Evi-2 in human disease as well.

Amino Acid Sequence↗