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Biomedical subjects

F S Collins

Publications and source records attributed to F S Collins.

At least 127 records · Page 7Linked to original sources
PubMed1996

Repression of the NF1 gene by Tax may expain the development of neurofibromas in human T-lymphotropic virus type 1 transgenic mice.

In familial neurofibromatosis type 1 (NF1), individuals with a germ line-transmitted NF1 mutation develop multiple neurofibromas. To explain the observation that transgenic mice expressing the human T-lymphotropic virus type 1 (HTLV-1) tax gene under the control of the viral regulatory element also develop multiple neurofibromas, we demonstrate that the Tax trans-regulator can functionally repress NF1 gene expression through a cis-acting element located immediately upstream of its transcriptional start site, thereby allowing the development of benign neurofibromas without the need for direct mutations in NF1. We propose that such a mechanism would suffice to epigenetically alter NF1 gene expression. The fact that transgenic animals have localized rather than diffuse neurofibroma formation, however, suggests that additional genetic or epigenetic events may be required for neurofibroma formation.

3T3 Cells↗
PubMed1996

The geneticist's approach to complex disease.

Many studies are in progress worldwide to elucidate the genetics of complex diseases. Nevertheless, few articles are available that provide the scientific rationale and give guidelines for such ambitious endeavours. We describe the methodology and background necessary to study the genetics of complex disease and discuss how to analyze the data. We also provide a table of some ongoing studies. In particular, we wish to emphasize the analysis of intermediate, heritable, quantitative traits as a means of dissecting the genetic basis of a complex trait.

Animals↗
PubMed1996

Substrate nucleotide-determined non-templated addition of adenine by Taq DNA polymerase: implications for PCR-based genotyping and cloning.

The Applied Biosystems PRISM fluorescence-based genotyping system as well as the Invitrogen TA Cloning vector system are influenced by the tendency of Taq DNA polymerase to add an adenine nucleotide to the 3' end of PCR products after extension. Incomplete addition of adenine to a majority of PCR product strands creates problems in allele-calling during genotyping and potentially diminishes the cloning efficiency of such products. Experiments reported here show that certain terminal nucleotides can either inhibit or enhance adenine addition by Taq and that PCR primer design can be used to modulate this activity. The methods we propose can substantially improve allele-calling for problematic microsatellite markers when using GENOTYPER software.

Adenine↗
PubMed1995

How is the Human Genome Project doing, and what have we learned so far?

In this paper, we describe the accomplishments of the initial phase of the Human Genome Project, with particular attention to the progress made toward achieving the defined goals for constructing genetic and physical maps of the human genome and determining the sequence of human DNA, identifying the complete set of human genes, and analyzing the need for adequate policies for using the information about human genetics in ways that maximize the benefits for individuals and society.

Base Sequence↗
PubMed1995

TEL1, an S. cerevisiae homolog of the human gene mutated in ataxia telangiectasia, is functionally related to the yeast checkpoint gene MEC1.

Patients with the genetic disorder ataxia telangiectasia (AT) have mutations in the AT mutated (ATM) gene, which is homologous to TEL1 and the checkpoint gene MEC1. A tel1 deletion mutant, unlike a mec1 deletion, is viable and does not exhibit increased sensitivity to DNA-damaging agents. However, increased dosage of TEL1 rescues sensitivity of a mec1 mutant, mec1-1, to DNA-damaging agents and rescues viability of a mec1 disruption. mec1-1 tel1 delta 1 double mutants are synergistically sensitive to DNA-damaging agents, including radiomimetic drugs. These data indicate that TEL1 and MEC1 are functionally related and that functions of the ATM gene are apparently divided between at least two S. cerevisiae homologs.

Ataxia Telangiectasia↗
PubMed1995

17q inversion involving the neurofibromatosis type one locus in a family with neurofibromatosis type one.

We report a family with a paracentric inversion of the long arm of chromosome 17 [inv(17)(q11.2q25.1)] and neurofibromatosis type one (NF1). The family was ascertained because of NF1 and multiple miscarriages. Fluorescence in situ hybridization using cosmid probes from opposite ends of the NF1 gene confirmed that the inversion disrupts the gene. Using field inversion gel electrophoresis we have found that the inversion separates cDNA probes FB5D and AE25, which are normally adjacent to one another in the NF1 gene. This is the third published report of a gross chromosomal rearrangement responsible for NF1. The features in this family are typical for NF1, and are not unusually severe.

Adolescent↗
PubMed1995

A single ataxia telangiectasia gene with a product similar to PI-3 kinase.

A gene, ATM, that is mutated in the autosomal recessive disorder ataxia telangiectasia (AT) was identified by positional cloning on chromosome 11q22-23. AT is characterized by cerebellar degeneration, immunodeficiency, chromosomal instability, cancer predisposition, radiation sensitivity, and cell cycle abnormalities. The disease is genetically heterogeneous, with four complementation groups that have been suspected to represent different genes. ATM, which has a transcript of 12 kilobases, was found to be mutated in AT patients from all complementation groups, indicating that it is probably the sole gene responsible for this disorder. A partial ATM complementary DNA clone of 5.9 kilobases encoded a putative protein that is similar to several yeast and mammalian phosphatidylinositol-3' kinases that are involved in mitogenic signal transduction, meiotic recombination, and cell cycle control. The discovery of ATM should enhance understanding of AT and related syndromes and may allow the identification of AT heterozygotes, who are at increased risk of cancer.

Amino Acid Sequence↗
PubMed1995

Structure of the leukemia-associated human CBFB gene.

We have determined the structure of the human CBFB gene, which encodes the beta subunit of the heterodimeric transcription factor core binding factor (CBF). This gene becomes fused to the MYH11 gene encoding smooth muscle myosin heavy chain by an inversion of chromosome 16 that occurs in the M4Eo subtype of acute myeloid leukemia. The CBFB gene contains 6 exons and spans 50 kb. The gene is highly conserved in animal species as distant as Drosophila, and the exon boundaries are in locations identical to those of the murine Cbfb homologue. The CBFB promoter region has typical features of a housekeeping gene, including high G+C content, high frequency of CpG dinucleotides, and lack of canonical TATA and CCAAT boxes. This gene has a single transcriptional start site, 345 nucleotides upstream of the beginning of the coding region. The human and mouse CBFB promoters show conservation of several transcriptional regulatory sequence motifs, including binding sites for Sp1, Ets family members, and Myc, but do not contain any CBF binding sites. The 5' end of the human CBFB gene also contains a highly polymorphic, transcribed CGG repeat that is not present in the murine homologue.

Acute Disease↗
PubMed1995

Identification of a new murine runt domain-containing gene, Cbfa3, and localization of the human homolog, CBFA3, to chromosome 1p35-pter.

Core binding factor (CBF) is a heterodimeric transcription factor composed of two distinct subunits. The monomeric beta subunit is ubiquitously expressed, whereas expression of the three alpha subunits isolated previously seems to be restricted mainly to hematopoietic tissues. To isolate additional alpha genes, degenerate oligonucleotides derived from the runt domain--a region shared by all alpha genes--were used for screening cDNA libraries. A 228-bp fragment was isolated from a mouse thymus cDNA library, which showed 82 and 76% DNA sequence identity to the previously isolated murine alpha genes, Cbfa1 and Cbfa2. This novel alpha gene was named Cbfa3. The corresponding sequence from the human homolog CBFA3 was obtained by cosmid cloning and sequencing of the appropriate restriction fragment. The corresponding regions of mouse Cbfa3 and human CBFA3 show 91% nucleotide identity and 100% protein identity. In situ hybridization and physical mapping of somatic cell hybrids localized CBFA3 to chromosome 1p35-pter.

Amino Acid Sequence↗
PubMed1995

The leukemic core binding factor beta-smooth muscle myosin heavy chain (CBF beta-SMMHC) chimeric protein requires both CBF beta and myosin heavy chain domains for transformation of NIH 3T3 cells.

An inversion of chromosome 16 associated with the M4Eo subtype of acute myeloid leukemia produces a chimeric protein fusing the beta subunit of the transcription factor core binding factor (CBF beta) to the tail region of smooth muscle myosin heavy chain (SMMHC). We investigated the oncogenic properties of this CBF beta-SMMHC chimeric protein using a 3T3 transformation assay. NIH 3T3 cells expressing CBF beta-SMMHC acquired a transformed phenotype, as indicated by their ability to form foci, grow in soft agarose, and form tumors in nude mice. Cells expressing normal CBF beta or the SMMHC tail domain did not become transformed. Electrophoretic mobility-shift assays showed that extracts from cells transformed by CBF beta-SMMHC no longer formed the normal CBF/DNA complex but instead formed a much larger complex that did not migrate into the gel. Analysis of CBF beta-SMMHC deletion mutants demonstrated that the chimeric protein was transforming only if two domains were both present: (i) CBF beta sequences necessary for association with the CBF alpha subunit, and (ii) SMMHC sequences important for the formation of multimeric filaments. These results are direct evidence that CBF beta-SMMHC can function as an oncoprotein.

3T3 Cells↗
PubMed1995

Molecular characterization of 16p deletions associated with inversion 16 defines the critical fusion for leukemogenesis.

The inversion of chromosome 16 [inv(16)] in acute myeloid leukemia (AML) is associated with a p-arm deletion in a subset of patients. The inversion results in two fusion genes: 5'-CBFB/MYH11-3' on 16p and 5'-MYH11/CBFB-3' on 16q. We have studied cells from 42 patients with inv(16) (38 patients) or t(16;16) (four patients) to define the frequency and characteristics of the deletion further. Using fluorescence in situ hybridization (FISH) with probes from cosmids, cosmid contigs, and yeast artificial chromosomes (YACs), we found that six patients with inv(16) had a deletion of between 150 and 350 kb centromeric to the p-arm inversion breakpoint cluster region (p-ibc). This region was shown to contain the 5' portion of the myosin heavy chain (MYH11) gene. YACs containing the p-ibc, which had been useful as FISH probes in the diagnosis of inv(16), detected the inversion in deletion as well as nondeletion patient cells. Thus, the deleted region identified in patients is entirely contained within the human genomic content of the YACs. Southern blot experiments using probes flanking the p-ibc indicated that the deletion removes segments within 10 kb centromeric of the p-ibc. Reverse transcription-polymerase chain reaction (RT-PCR) using primers from the 5' region of CBFB and the 3' region of MYH11 (distal to the p-ibc) produced the 5'-CBFB/MYH11-3' chimeric transcript in inv(16)/del patients. These data confirm that the 5'-CBFB/MYH11-3' chimeric transcript, rather than the reciprocal 5'-MYH11/CBFB-3', is the critical product for chromosome 16-related leukemogenesis.

Acute Disease↗
PubMed1995

A high-density microsatellite map of the ataxia-telangiectasia locus.

The locus of the autosomal recessive disorder ataxia-telangiectasia (A-T) has been assigned by linkage analysis with biallelic markers to a 4-Mb interval on chromosome 11q22-23, between GRIA4 and D11S1897. We have undertaken to saturate the A-T region with highly polymorphic microsatellite markers. To this end, we have identified seven new polymorphic CA-repeats in this region, and have mapped to it five new markers generated by Genethon and the Cooperative Human Linkage Center. These markers are in addition to 12 others that we have previously mapped or generated at the A-T locus. All 24 markers have been integrated into a high-density microsatellite map spanning some 6 Mb DNA. This map, which contains the A-T locus and flanking sequences, allows the construction of extensive, highly informative haplotypes.

Ataxia Telangiectasia↗
PubMed1995

Transcript identification in the BRCA1 candidate region.

Chromosome 17q12-21 is known to contain a gene (or genes) which confers susceptibility to early-onset breast cancer and ovarian cancer (BRCA1). Identification and isolation of BRCA1 will likely provide the basis for increased understanding of the pathogenesis of breast and ovarian cancer, the development of targeted diagnostic and therapeutic approaches, and a means of screening women at risk of being BRCA1 mutation carriers. Genetic and physical maps of the BRCA1 candidate region have been largely completed and efforts are being directed at identification of candidate genes from within this region. We have begun the task of identifying transcripts from this region employing three complementary strategies. These include: 1) direct cDNA screening with cosmids derived from the BRCA1 region; 2) exon amplification; and 3) magnetic bead capture. Transcripts identified using these approaches are being characterized for: 1) tissue expression pattern; 2) the presence of genomic rearrangement in DNA derived from affected members of families believed to show linkage between breast cancer and genetic markers in the BRCA1 candidate interval; 3) altered size and/or expression pattern in RNA prepared from such individuals; and 4) homology to known genes or functional motifs. Germline mutations in affected individuals from these families will serve as presumptive evidence of BRCA1 identity.

Breast Neoplasms↗