Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report the molecular analysis of an 8;14 reciprocal chromosome translocation in a case of acute lymphocytic leukemia (L3 type). DNA from primary leukemic cells was analyzed on the basis of restriction endonuclease mapping by hybridization with various human c-myc and Ig heavy chain probes. The breakpoint of the translocation is within an approximately equal to 200-base-pair region in the first intron of the c-myc gene. The first, untranslated exon thereby remains on chromosome 8q-, whereas the whole protein-coding region is rearranged in the C alpha 1 locus on chromosome 14q+. RNA transfer blot analysis showed high levels of at least two different c-myc transcripts originated from the translocated gene. Both differ in size from the normal 2.2- and 2.4-kilobase transcripts. Both c-myc structure and expression were apparently normalized in remission phase. These studies demonstrate rearrangement and abnormal expression of c-myc in primary cells from an acute leukemia patient, thus adding to the concept of a key role for c-onc in human oncogenesis.
...
PMID:Translocation and rearrangement of c-myc into immunoglobulin alpha heavy chain locus in primary cells from acute lymphocytic leukemia. 608 8

Site-specific methylation of the human c-myc oncogene was investigated in a set of cultured human tumor cell lines and normal human fibroblast strains. As previously reported, all of the tumor cell lines in contrast to normal cells were hypomethylated to various degrees in their total genomic DNA. The presence of methylation in specific regions of the c-myc gene was analyzed by use of the restriction endonuclease isoschizomers MspI and HpaII, which recognize the sequence 5'-CCGG-3' (CCGG = DNA sequence of 2 cytosine bases followed by 2 guanine bases) but differ in their abilities to cleave at the internal cytosine residue when it is methylated. The first exon, first intervening sequence, and the second exon were hypomethylated in all cell types, regardless of whether the cells were normal or oncogenically transformed and regardless of the degree of total genomic methylation of the cell. However, the solitary CCGG site in the third exon was fully methylated in normal cell strains. In contrast, in 3 of 5 tumor cell lines measured, this site was hypomethylated. This is the first demonstration of a site-specific DNA methylation defect in a cellular oncogene. Some possible implications relating disruption of DNA methylation to oncogene control and oncogenesis are discussed.
...
PMID:Hypomethylation of DNA in human cancer cells: a site-specific change in the c-myc oncogene. 609 64

We have screened different cultured cell lines established from human tumors for the ability of their DNAs to induce transformed foci in NIH/3T3 cells. Based on restriction endonuclease digestions and the presence of human sequences in mouse transformants, we conclude that five of these human tumor cell lines contain a gene or genes capable of transforming mouse cells and that at least three different transforming genes are present in these five lines. Three cell lines, two derived from lung carcinomas and one derived from a colon carcinoma, transfer the same or closely related human genes. If these transforming genes are mediating the tumorigenic state of the human cells, then our results indicate that overlapping pathways leading to tumorigenesis may arise independently.
...
PMID:Human-tumor-derived cell lines contain common and different transforming genes. 610 Dec 1

The arrangement of viral DNA sequences in a hamster cell line derived from a tumor induced by a recombinant plasmid DNA preparation containing the entire polyoma virus genome was examined. In the recombinant plasmid employed, viral DNA sequences specifying the large species of polyoma tumor antigen but not the small and middle tumor antigens were interrupted by the insertion of plasmid DNA at the EcoRI restriction endonuclease site. Blot-hybridization analyses of tumor cell DNA indicated that the "joints" linking viral and plasmid DNAs in the original recombinant plasmid used in animal inoculation had been preserved. Integration into the hamster cell genome had apparently occurred within plasmid DNA sequences. These results indicate that polyoma large tumor antigen is not required for tumorigenesis mediated by viral DNA.
...
PMID:Polyoma large tumor antigen is not required for tumorigenesis mediated by viral DNA. 624 89

Avian erythroblastosis virus (AEV) causes erythroblastosis and sarcomas in birds and transforms both erythroblasts and fibroblasts to neoplastic phenotypes in culture. The viral genetic locus required for oncogenesis by AEV is at present poorly defined; moreover, we know very little of the mechanism of tumorigenesis by the virus. To facilitate further analysis of these problems, we used molecular cloning to isolate the genome of AEV as recombinant DNA in a procaryotic vector. The identity of the isolated DNA was verified by mapping with restriction endonucleases and by tests for biological activity. The circular form of unintegrated AEV DNA was purified from synchronously infected quail cells and cloned into the EcoRI site of lambda gtWES x B. A restriction endonuclease cleavage map was established. By hybridization with complementary DNA probes representing specific parts of avian retrovirus genomes, the restriction map of the cloned AEV DNAs was correlated with a genetic map. These data show that nucleotide sequences unique to AEV comprise at least 50% of the genome and are located approximately in the middle of the AEV genome. Our data confirm and extend previous descriptions of the AEV genome obtained by other procedures. We studied in detail two recombinant clones containing AEV DNA: the topography of the viral DNA in the two clones was virtually identical, except that one clone apparently contained two copies of the terminal redundancy that occurs in linear viral DNA isolated from infected cells; the other clone probably contained only one copy of the redundant sequence. To recover infectious virus from the cloned DNA, we developed a procedure for transfection that compensated for the defectiveness of AEV in replication. We accomplished this by ligating cloned AEV DNA to the cloned DNA of a retrovirus (Rous-associated virus type 1) whose genome could complement the deficiencies of AEV. Ligation of the two viral DNAs was facilitated by using a neutral fragment of DNA as linker between otherwise noncompatible termini. Cloned AEV DNA gave rise to infectious AEV capable of transforming fibroblasts and bone marrow cells in culture and of inducing both sarcomas and erythroleukemia in chickens. We conclude that the cloned DNAs represent the authentic genome of AEV undisturbed by the cloning procedure. Molecular cloning offers a powerful approach to the identification and characterization of retrovirus genomes.
...
PMID:Molecular cloning of the avian erythroblastosis virus genome and recovery of oncogenic virus by transfection of chicken cells. 625 78

The patterns of the milk-transmitted (exogenous) mouse mammary tumor virus (MuMTV) DNA restriction endonuclease fragments in the nodule and tumor stages of BALB/cfC3H mouse mammary neoplasia were compared with the use of the Southern blot analysis. Acquired MuMTV restriction fragments were detected in DNA from hyperplastic alveolar nodules (HAN), from primary hyperplastic outgrowths (HPO), from families of transplanted HPO, from tumors from HPO, and from serially transplanted tumors. The restriction fragment patterns suggested that the HAN were composed of clonal dominant populations. Transplantation of subdivisions of individual HAN resulted in HPO with DNA restriction patterns suggesting that HAN also contained two or more subpopulations. In all cases, HAN subpopulations shared MuMTV restriction fragments suggesting a common origin. Forty-seven tumors arising from HPO shared MuMTV restriction fragments with the HPO. Most but not all tumors had additional acquired MuMTV restriction fragments not detected in the progenitor HPO, indicating that they were composed of a distinct subpopulation that originated from the HPO. The restriction fragment pattern in some tumor lines was remarkably stable through many transplant generations. Some tumors had no major additional restriction fragments, suggesting that major rearrangements of MuMTV DNA are not required for tumorigenesis.
...
PMID:Alterations of acquired mouse mammary tumor virus DNA during mammary tumorigenesis in BALB/cfC3H mice. 631 8

The complexity and structural organization of defective-interfering (DI) particle DNA of equine herpesvirus type 1 (EHV-1) have been elucidated by using restriction enzyme and Southern blot hybridization analyses. DI particles were generated by serial high-multiplicity passage of EHV-1 in L-M cells, and total viral DNA was extracted from virus purified from supernatants of these serial passages. EHV-1 DI particle DNA was quantitatively separated from standard (STD) DNA by several cycles of CsCl isopycnic banding in a vertical rotor. Restriction endonuclease digestion profiles of pure DI DNA were completely different from the mapped patterns observed for EHV-1 STD DNA. Digestion of pure defective DNA with restriction enzymes (Bg/II, EcoRI, and XbaI), for which there are few or no cleavage sites within the S (short) region of the EHV-1 STD genome, yielded high-molecular-weight supermolar DNA bands, suggesting that a large subgenomic repeat unit was present in defective DNA. DNA blot hybridization analysis with the Bg/II supermolar fragment of defective DNA, intact DI particle genomic DNA, and EHV-1 STD DNA restriction enzyme fragments as 32P-labeled probes indicated that the EHV-1 DI particle genome originates predominately from the STD DNA S region (0.77 to 1.00 map units) and to a lesser extent from the left terminus of the unique long (UL) region (0.00 to 0.05 map units). None of the EHV-1 DNA sequences associated to date with EHV-1 oncogenesis (0.32 to 0.38 map units; O'Callaghan et al. in B. Roizman [ed.], Herpesviruses, in press; Robinson et al., Cell 32:204-219, 1983, and Proc. Natl. Acad. Sci., U.S.A., 78:6684-6688, 1981) were detected in the DI particle DNA. The importance of these data with regard to DNA replication of DI particles and the role of DI particles in one model system of EHV-1 oncogenic transformation are discussed.
...
PMID:Structure and genetic complexity of the genomes of herpesvirus defective-interfering particles associated with oncogenic transformation and persistent infection. 632 84

Inheritance of a mutation at the Rb-1 locus, which has been mapped to band q14 of human chromosome 13, results in predisposition to retinoblastoma. Cloned DNA segments homologous to arbitrary loci of human chromosome 13 and which reveal polymorphic restriction endonuclease recognition sequences, have been used to look for somatic genetic events that might occur during tumorigenesis. A comparison of constitutional and tumour genotypes from several cases indicates that tumorigenesis may result from the development of homozygosity for the mutant allele at the Rb-1 locus. The homozygosity in these cases results from mitotic nondisjunction, resulting in loss of the homologous wild-type chromosome, or from a mitotic recombination event.
...
PMID:Expression of recessive alleles by chromosomal mechanisms in retinoblastoma. 663 49

Molecular investigations on 18 naturally occurring sarcoid tumors removed from donkeys identified papillomaviral DNA homologous to bovine papillomavirus (BPV)-2 DNA under stringent conditions, in all the samples. Restriction endonuclease analysis of 15 of the tumours demonstrated papillomaviral DNA similar to BPV-1 and BPV-2. The type of DNA was not specific to either the site or the type of lesion. The analysis of the nucleotide base sequence of a cloned papillomaviral element from a sarcoid showed that the isolate was 96 and 98 per cent homologous to BPV-1 in the L1 and E5 open reading frames, respectively. It was concluded that the disease in the donkey is similar to that in the horse and that the E5 open reading frame may be involved in oncogenesis in the sarcoid.
...
PMID:Detection, cloning and characterisation of papillomaviral DNA present in sarcoid tumours of Equus asinus. 784 35

During the initial stages of crown gall tumorigenesis, the T-DNA region of the Agrobacterium tumefaciens Ti-plasmid is processed, resulting in the production of T-DNA molecules that are subsequently transferred to the plant cell. Processing of the T-DNA in the bacterium involves the nicking of T-DNA border sequences by an endonuclease encoded by the virD locus, and the subsequent tight (possibly covalent) association of the VirD2 protein with the 5' end of the processed single-stranded or double-stranded T-DNA molecule. To investigate the interaction of the VirD1,D2 endonuclease with a right T-DNA border, a set of plasmids containing both the border and virD sequences on the same high-copy-number replicon has been constructed and introduced into Escherichia coli. In this model system a tight nucleoprotein complex is formed between the relaxed double-stranded substrate plasmid and the VirD2 protein. This putative T-DNA processing complex may be analogous to the covalent relaxation complex formed between the pilot protein and plasmid DNA during bacterial conjugation. VirD2 attachment to the relaxed substrate plasmid was resistant to denaturing agents but sensitive to S1 nuclease digestion, indicating a single-stranded region near the site of protein attachment. We speculate that this structure may be an intermediate formed prior to T-strand unwinding from the substrate plasmid in a host bacterium.
...
PMID:Formation of a putative relaxation intermediate during T-DNA processing directed by the Agrobacterium tumefaciens VirD1,D2 endonuclease. 835 16


<< Previous 1 2 3 4 5 6 7 Next >>

---