Search PubMed⌕ Search

Biomedical subjects

T Hanafusa

Publications and source records attributed to T Hanafusa.

At least 217 records · Page 12Linked to original sources
PubMed1981

Mutants of Fujinami sarcoma virus which are temperature sensitive for cellular transformation and protein kinase activity.

Two temperature-sensitive mutants of Fujinami sarcoma virus were isolated and characterized. Cells infected with the mutants were temperature sensitive in focus formation, colony formation, increased sugar uptake, and synthesis of plasminogen activator. The changes between transformed and nontransformed states of cultures were completely reversible by shifting the temperature. A Fujinami sarcoma virus-specific protein of 130,000 daltons, p130, was synthesized in mutant-infected cells regardless of the temperature, but the immunoprecipitates of p130 from extracts of infected cells were active in protein kinase only when cells had been incubated at the permissive temperature. These results appear to indicate that p130 is the transforming protein of Fujinami sarcoma virus, and that its protein kinase activity plays a crucial role in cell transformation by this virus.

Alpharetrovirus↗
PubMed1980

Characterization of protein kinase activity associated with the transforming gene product of Fujinami sarcoma virus.

Fujinami sarcoma virus (FSV), a newly characterized avian sarcoma virus, produces a protein of 140,000 daltons (p140) in infected cells. p140 is the product of a fused gene consisting of a part of the gag gene of avian retrovirus and FSV-unique sequences which are not related to the src sequences of Rous sarcoma virus. In vivo, p140 was found to be phosphorylated at both serine and tyrosine residues. Immunoprecipitates of p140 with antiserum against gag gene-coded proteins had a cyclic nucleotide-independent protein kinase activity which phosphorylated p140 itself, rabbit IgG of the immune complex and alpha-casein, an externally added soluble protein substrate. The phosphorylation was specific to tyrosine of the substrate proteins. p140 was phosphorylated in vitro at the same two tyrosine residues that were phosphorylated in vivo. The phosphate transferred to tyrosine residues of p140 forms a stable bond: it does not turn over during the kinase reaction, and the 32P-phosphate of p140 labeled in vitro or in vivo is not transferred to alpha-casein. FSV-p140 differs from p60src, the transforming protein of Rous sarcoma virus, in its marked preference of Mn2+ to Mg2+ ions, and in its inability to use GTP instead of ATP as the donor of gamma-phosphate.

Alpharetrovirus↗
PubMed1980

Homology exists among the transforming sequences of avian and feline sarcoma viruses.

Fujinami sarcoma virus (FSV) of chickens does not contain nucleotide sequences related to the src gene of Rous sarcoma virus, but it carries unique sequences of at least 3000 bases, which are likely to code for the transforming protein of this virus. Using radioactive DNA complementary to FSV-unique sequences, we investigated the relatedness of FSV to other sarcoma-leukemia retroviruses in vertebrates. Under conditions of moderate stringency, no cross-hybridization was detected between FSV cDNA and RNAs of Rous sarcoma virus, Y73 avian sarcoma virus, several representative avian acute leukemia viruses, or Abelson murine leukemia virus. This cDNA, however, did hybridize with RNA of PRCII sarcoma virus of chickens to the extent of 56%. In addition, FSV cDNA was found to hybridize with RNAs of Gardner-Arnstein and Snyder-Theilen strains of feline sarcoma virus to the extent of 27% and 19%, respectively, but not with RNA of McDonough feline sarcoma virus. Studies on thermal denaturation of hybrids showed that the melting temperatures of the heteroduplexes of the FSV cDNA with RNAs of PRCII and Gardner-Arnstein feline sarcoma virus were 7 degrees C and 12 degrees C lower, respectively, compared with the melting temperature of the homologous hybrid of FSV, and suggested less than 10% mismatching in both heteroduplexes. These results indicate that nucleotide sequences closely related to at least a part of FSV-unique sequences are present in the genomes of other sarcoma viruses obtained in chickens and in cats.

Alpharetrovirus↗
PubMed1980

Characterization of the transforming gene of Fujinami sarcoma virus.

The src gene present in all avian sarcoma viruses is not present in the genome of Fujinami sarcoma virus, a potent sarcoma-inducing virus in chickens. Fujinami virus is defective and requires helper virus for replication. RNA from a mixture of helper and transforming viruses consists of two components, 35S and 28S. Oligonucleotide fingerprinting of each RNA component revealed that the 35S component was identical to the RNA of the helper virus. Thus, the genome of Fujinami virus must be the 28S RNA, which corresponds approximately to a molecular weight of 1.7 x 10(6) or 5300 nucleotides. Fujinami viral RNA shares several oligonucleotides with helper viral RNA at both 3' and 5' ends but contains a unique sequence of at least 3000 nucleotides in the middle of the genome. Fujinami viral RNA contains no src-specific oligonucleotides of the Rous sarcoma virus genome and did not hybridize with DNA complementary to the src sequences. The 60,000-dalton src protein of Rous sarcoma virus was undetectable in Fujinami virus-transformed cells. Instead, these transformed cells contain a protein of 140,000 daltons precipitable by antisera against virion proteins, which is likely to be the transforming protein of this virus.

Alpharetrovirus↗
PubMed1980

Evidence for the common origin of viral and cellular sequences involved in sarcomagenic transformation.

The src genes of six different strains of avian sarcoma virus (ASV) were compared with those of a series of newly isolated sarcoma viruses, termed "recovery avian sarcoma viruses" (rASV's). The rASV's were isolated recently from chicken and quail tumors induced by transformation-defective (td) deletion mutants of Schmidt-Ruppin Rous sarcoma virus. The RNase T1-resistant oligonucleotide maps were constructed for the RNA genomes of different strains of ASV and td mutants. The src-specific sequences, characterized by RNase T1-resistant oligonucleotides ranging from 9 to 19 nucleotides long, were defined as those mapping between approximately 600 and 2,800 nucleotides from the 3' polyadenylate end of individual sarcoma viral RNAs, and missing in the corresponding td viral RNAs. Our results revealed that 12 src-specific oligonucleotides were highly conserved among several strains of ASV, including the rASV's, whereas certain strains of ASV were found to contain one to three characteristic src-specific oligonucleotides. We previously presented evidence supporting the idea that most of the src-specific sequences present in rASV RNAs are derived from cellular genetic information. Our present data indicate that the src genes of rASV's are closely related to other known ASVs. We conclude that the src genes of different strains of ASV and the cellular sarc sequences are of common origin, although some divergence has occurred among different viral src genes and related cellular sequences.

Alpharetrovirus↗
PubMed1980

A case of insulin autoimmune syndrome associated with small insulinomas and rheumatoid arthritis.

Twenty five cases of insulin autoimmune syndrome including this case has been reported so far without having the pathogenesis clarified. This paper describes a case which suggests one aspect of pathogenesis. The patient, a housewife concurrently had insulinoma and severe rheumatoid arthritis, complaining of hypoglycemic syncope attacks. During the attacks her blood sugar levels ranged from 19 to 22 mg%. Her serum extractable immunoreactive insulin (IRI) and insulin binding antibody levels were 557 microunits/ml and 0.390 mU/ml, respectively. gamma-Globulin-bound insulin was also measured electrophoretically. Bio-Gel P 10 column chromatography eluted almost all IRI at the void volume at pH 7.4 and a smaller but significant IRI peak also at pH 3.0. Selective angiography revealed a tumor-like staining in the pancreas body. Pancreatectomy relieved her of hypoglycemic attacks. Histology disclosed two small insulinomas. Insulinoma, rheumatoid arthritis and insulin autoimmune syndrome coexisted in this case, suggesting some causal relationship among them.

Adenoma, Islet Cell↗
PubMed1980

Parallel dysfunctions of pancreatic A, B and PP cells in insulin dependent diabetes.

To test the possibility that insulitis might play an etiological role in the pathogenesis of insulin dependent diabetes, functions of 3 kinds of islet constituting cells (A, B and PP cells) were estimated by quantifying secretory responses of glucagon-, C-peptide-and pancreatic polypeptide-producing cells to hyperglycemia and hypoglycemia. In insulin dependent diabetes, all 3 hormonal responses were severely impaired to the same extent. On the other hand, 3 islet cell functions were uniformly but less severely impaired in insulin independent diabetics without a diabetic family history. These results suggest that A, B, and PP cells of islet of Langerhans are evenly destroyed in parallel fashion at least in insulin dependent diabetes and in some insulin independent diabetes, suggesting insulitis as a possible cause of these types of diabetes.

Blood Glucose↗
PubMed1976

Pheasant virus: new class of ribodeoxyvirus.

Cocultivation of cells derived from embryos of golden pheasants or Amherst pheasants with chicken embryo cells infected with Bryan strain of Rous sarcoma virus resulted in the detection of viruses which appear to be endogenous in these pheasant cells. The pheasant viruses (PV) were similar to avian leukosis-sarcoma viruses (ALSV) in their gross morphology, in the size of their RNA, in the presence of a virion-associated RNA-dependent DNA polymerase (DNA nucleotidyltransferase; deoxynucleoside triphosphate: DNA deoxynucleotidyltransferase; EC 2.7.7.7), and in their growth characteristics. PV also serves as a helper for the glycoprotein-defective Rous sarcoma virus. However, PV was shown to be different from both ALSV and reticuloendotheliosis virus in the following properties: (i) PV does not have ALSV group specific antigens; (ii) the protein composition of PV is different from those of the other two groups of viruses; (iii) PV fails to complement the defective polymerase of alpha type Rous sarcoma virus; and (iv) PV RNA shows no detectable homology with nucleic acids of the other two groups of viruses. Thus, PV appears to be a new class of RNA viruses which contain RNA-dependent DNA polymerase.

Alpharetrovirus↗
PubMed1975

Quantitation of avian RNA tumor virus reverse transcriptase by radioimmunoassay.

A radioimmunoassay was developed that can detect and quantitate 3 ng or more of the avian RNA tumor virus reverse transcriptase. The assay detected no antigenic sites in Rous sarcoma virus alpha virions or in virions of a murine RNA tumor virus. About 70 molecules of reverse transcriptase were found per virion of avian myleloblastosis virus with this assay or with an assay based on antibody inhibition of enzymatic activity. The assay detected about 270 ng of enzyme per mg of cell protein in virus-producing cells; uninfected cells had much less antigenic material but contained some determinants able to displace radioactive antigen. No additional antigenic determinants on reverse transcriptase could be detected that were not found on the separated alpha subunit of the enzyme. Although sevenfold less sensitive than enzymatic activity as a measure of reverse transcriptase, the radioimmunoassay can detect antigen using small amounts of protein and in the presence of inhibtors.

Animals↗
PubMed1972

Deoxyribonucleic acid polymerase activities in normal and leukovirus-infected chicken embryo cells.

Chicken embryo cells normally contain, in addition to deoxyribonucleic acid (DNA)-dependent DNA (D-DNA) polymerases, a novel "R-DNA-polymerase" which specifically copies polyriboadenylic acid strands. This R-DNA polymerase cannot copy natural ribonucleic acid or polyribocytidylic acid strands to a significant extent. Infection of cells with the leukovirus RAV-2 leads to the intracellular formation of large amounts of the viral RNA-dependent DNA polymerase whose properties differ from the cell R-DNA polymerase. Chicken cells transformed by a Rous sarcoma virus mutant which produce noninfectious alpha-type Rous sarcoma virus (f), a leukovirus known to be deficient in the viral RNA-dependent DNA polymerase, do not contain detectable viral RNA-dependent DNA polymerase, whereas the cellular R-DNA polymerase is found in normal amounts. There seems to be no relationship between the cellular R-DNA polymerase and the RNA-dependent DNA polymerase of the avian leukoviruses.

Animals↗
PubMed1971

DNA in uninfected and virus-infected cells complementary to avian tumor virus RNA.

The 70S RNA component of several avian tumor viruses was hybridized with DNA extracted from avian tumor virus-infected and uninfected chicken and Japanese quail cells. Tritium-labeled 70S RNAs from Rous sarcoma virus (RSV), Rous associated virus-1 (RAV-1), RAV-60, and Schmidt-Ruppin-RSV (SR-RSV) hybridize from 3 to 10 times more with DNA from uninfected chicken cells than with DNA from Escherichia coli, calfthymus, or baby hamster kidney cells. After infection of chicken cells with RSV(RAV-1), SR-RSV, or RAV-2, the amount of 70S avian tumor virus [(3)H]RNA hybridized increases by 1.6 times. The specificity of the hybridization reaction was shown by the specific competition of 70S SR-RSV [(3)H]RNA with 70S RNA from RSV(RAV-1), and not with RNA from Sendai virus or chicken cells. There was no difference in the hybridization of 70S RNA from RSV (RAV-1), RAV-1, or RAV-60 with DNA either from chicken cells that contain RAV-60 in a nonreplicating form or from chicken cells that do not appear to contain RAV-60. These results indicate that both types of uninfected chicken cells contain DNA that is complementary to RNA from several avian tumor viruses and that the amount of complementary DNA increases in such cells after infection with an avian tumor virus. The RNAs of genetically different avian tumor viruses appear to have indistinguishable base sequences by this technique.

Alpharetrovirus↗