| effect of dibutyryl cyclic amp on intracellular levels of avian sarcoma virus specific rna. | | 1989 | 210389 |
| mapping unintegrated avian sarcoma virus dna: termini of linear dna bear 300 nucleotides present once or twice in two species of circular dna. | three major species of viral dna have been observed in cells infected by retroviruses: a linear, double-stranded copy of a subunit of viral rna; closed circular dna; and proviral dna inserted covalently into the genome of the host cell. we have studied the structures of the unintegrated forms of avian sarcoma virus (asa) dna using agarose gel electrophoresis in conjunction with restriction endonucleases and molecular hybridization techniques. the linear duplex dna is approximately the same lengt ... | 1984 | 215324 |
| cell-free translation of avian sarcoma virus rna: suppression of the gag termination codon does not augment synthesis of the joint gag/pol product. | | 1985 | 214247 |
| at least 104 nucleotides are transposed from the 5' terminus of the avian sarcoma virus genome to the 5' termini of smaller viral mrnas. | cells producing avian sarcoma virus (asv) contain at least three virus-specific mrnas, two of which are encoded within the 3' half of the viral genome. each of these viral rnas can hybridize with single-stranded dna(cdna5') that is complementary to a sequence of 101 nucleotides found at the 5' terminus of the asv genome, but not within the 3' half of the genome. we proposed previously (weiss, varmus and bishop, 1977) that this nucleotide sequence may be transposed to the 5' termini of viral mrna ... | 1987 | 212200 |
| synthesis and processing of avian sarcoma virus glycoproteins. | | 1991 | 208237 |
| two avian sarcoma virus mutants with defects in the dna polymerase-rnase h complex. | two mutants of avian sarcoma virus which exhibit different phenotypes have been analyzed for the properties of their rna-dependent dna polymerase and rnase h activities. la 338 is a complex multiple mutant with at least one lesioneach in transformation and replication functions. the purified rna-dependent dna polymerase-rnase h complex from the mutant is twofold more thermolabile than that from the wild-type parent. a peculiarity of this mutant is that the ability of the enzyme to respond to syn ... | 1999 | 91685 |
| inhibition of avian sarcoma virus replication by glucosamine: a specific effect on the synthesis and processing of viral proteins. | | 2003 | 180659 |
| the defective maturation of viral progeny with a temperature-sensitive mutant of avian sarcoma virus. | | 1990 | 183356 |
| complement-fixing antigens in tissue cultures of avian leucosis viruses. | avian sarcoma and leucosis virus preparations grown in chick embryo tissue cultures contained complement-fixing antigens, which were demonstrated with the use of antiserums from hamsters carrying sarcomas induced by the schmidt-ruppin strain of avian sarcoma virus. the complement-fixing antigens shared by three different strains of avian leucosis and one strain of avian sarcoma viruses were largely "soluble" (having failed to sediment when centrifuged at 59,364g for 70 minutes). sedimented parti ... | 1964 | 14169348 |
| quantification of shape and cell polarity reveals a novel mechanism underlying malformations resulting from related fgf mutations during facial morphogenesis. | fibroblast growth factor (fgf) signaling mutations are a frequent contributor to craniofacial malformations including midfacial anomalies and craniosynostosis. fgf signaling has been shown to control cellular mechanisms that contribute to facial morphogenesis and growth such as proliferation, survival, migration and differentiation. we hypothesized that fgf signaling not only controls the magnitude of growth during facial morphogenesis but also regulates the direction of growth via cell polarity ... | 2013 | 23906837 |
| deposition of fibronectin in the course of reverse transformation of chinese hamster ovary cells by cyclic amp. | the chinese hamster ovary (cho) cell, like other transformed cells, has lost the fibronectin deposit around its membrane. treatment with cyclic amp derivatives restores the typical fibroblastic deposit of fibronectin. thus, the reverse transformation process induced by cyclic amp (camp) in the cho cell restores this important property as well as other morphological, biochemical, and growth behavioral characteristics of the normal fibroblastic state. the fibronectin deposit occurs significantly l ... | 1980 | 6244595 |
| the conformational feasibility for the formation of reaching dimer in asv and hiv integrase: a molecular dynamics study. | retroviral integrases are reported to form alternate dimer assemblies like the core-core dimer and reaching dimer. the core-core dimer is stabilized predominantly by an extensive interface between two catalytic core domains. the reaching dimer is stabilized by n-terminal domains that reach to form intermolecular interfaces with the other subunit's core and c-terminal domains (ctd), as well as ctd-ctd interactions. in this study, molecular dynamics (md), brownian dynamics (bd) simulations, and fr ... | 2016 | 27835934 |
| a simple method for rapid purification of avian sarcoma virus supercoiled dna by selective precipitation of infected cell chromatin. | | 1983 | 215052 |
| microrna-379 suppresses cervical cancer cell proliferation and invasion by directly targeting v-crk avian sarcoma virus ct10 oncogene homolog-like. | cervical cancer is the fourth most common malignancy among females worldwide. microrna-379 (mir-379) is aberrantly expressed in multiple human cancer types. however, the expression pattern, roles and detailed regulatory mechanisms of mir-379 in cervical cancer remain unknown. in this study, we found that mir-379 expression was downregulated in cervical cancer tissues and cell lines. low mir-379 expression was correlated with international federation of gynecology and obstetrics (figo) stage, lym ... | 2018 | 29295725 |
| crkl overexpression promotes cell proliferation and inhibits apoptosis in endometrial carcinoma. | the v-crk avian sarcoma virus ct10 oncogene homolog-like (crkl) protein is important in cancer progression. however, its expression pattern and biological roles in human endometrial carcinoma remain unexplored. the potential mechanism of crkl-induced cancer progression is still unclear. the present study aimed to explore the expression pattern and biological roles of crkl in human endometrial carcinoma. using immunohistochemistry, it was observed that the crkl protein was overexpressed in 50.5% ... | 2017 | 28123521 |
| a novel homolog of protein tyrosine kinase fyn identified in lampetra japonica with roles in the immune response. | the non-receptor protein tyrosine kinase (nrptk) fyn, a member of the avian sarcoma virus transforming gene (src) kinase family, plays a very significant role in cell growth, survival, apoptosis, tumor formation and immune response. in this study, a homolog of nrptk fyn was identified for the first time in the lamprey, lampetra japonica and was named "lja-fyn". the cdna fragment of lamprey lja-fyn contains a 1611-bp open reading frame, which encodes a protein of 537 amino acids. multiple sequenc ... | 2016 | 26743129 |
| knockdown of ckrl by shrna deteriorates hypoxia/reoxygenation-induced h9c2 cardiomyocyte apoptosis and survival inhibition via bax and downregulation of p-erk1/2. | integrin β1 subunit and its downstream molecule integrin-linked kinase and focal adhesion kinase have been confirmed to be essential to cell survival and inhibition of apoptosis and hypoxia/reoxygenation (h/r)-induced injuries in cardiomyocytes. however, it is still unclear whether crkl [v-crk avian sarcoma virus ct-10 oncogene homolog (crk)-like], which acts also as a component of the integrin pathway, could also affect h/r-induced injuries in the cardiomyocytes. the rat-derived h9c2 cardiomyoc ... | 2015 | 25703803 |
| the role of ct10 regulation of kinase-like in cancer. | v-crk avian sarcoma virus ct10 oncogene homolog-like (crkl) is a member of crk family. it acts as an adaptor protein in intracellular signal transduction. crkl has been reported overexpressed in a variety of cancers affecting the aggressive and malignant behaviors of cancer cells. crkl seems to show a tumor-promotion role in gastric cancer, glioblastoma multiforme, hepatocellular carcinoma, bladder cancer, lung cancer, colon cancer, ovarian cancer, leukemia, breast cancer, head and neck cancer, ... | 2014 | 25531052 |
| the interferon-inducible antiviral protein daxx is not essential for interferon-mediated protection against avian sarcoma virus. | the antiviral protein daxx acts as a restriction factor of avian sarcoma virus (asv; retroviridae) in mammalian cells by promoting epigenetic silencing of integrated proviral dna. although daxx is encoded by a type i (α/β) interferon-stimulated gene, the requirement for daxx in the interferon anti-retroviral response has not been elucidated. in this report, we describe the results of experiments designed to investigate the role of daxx in the type i interferon-induced anti-asv response. | 2014 | 24884573 |
| peroxisome proliferator-activated receptor γ agonist efatutazone impairs transforming growth factor β2-induced motility of epidermal growth factor receptor tyrosine kinase inhibitor-resistant lung cancer cells. | epidermal growth factor receptor-tyrosine kinase inhibitors (egfr-tki) are effective for non-small cell lung cancers (nsclc) with egfr-activating mutations. however, most responders develop resistance. efatutazone, a novel peroxisome proliferator-activated receptor gamma (pparγ) agonist, is currently under clinical evaluation; it has antiproliferative effects and induces cellular morphological changes and differentiation. the present study investigated the effects of efatutazone in egfr-tki-resi ... | 2014 | 24698130 |
| genomic aberrations associated with erlotinib resistance in non-small cell lung cancer cells. | mechanisms of resistance to epidermal growth factor receptor (egfr)-tyrosine kinase inhibitors (tkis) in non-small cell lung cancer (nsclc) are not fully-understood. in this study we aimed to elucidate remaining unknown mechanisms using erlotinib-resistant nsclc cells. | 2013 | 24324054 |
| crkl promotes cell proliferation in gastric cancer and is negatively regulated by mir-126. | v-crk avian sarcoma virus ct10 oncogene homolog-like (crkl) is a member of crk family and act as an adaptor protein participating in intra-cellular signal transduction. the role of crkl in gastric cancer (gc) remains unclear. in this study, we show that crkl was aberrantly highly expressed in both gc tumor specimens and cell lines (sgc-7901, mkn-45, mkn-28 and sun-16). the expression of crkl was significantly correlated with gc clinicopathologic features including tumor size, local invasion, lym ... | 2013 | 24055140 |
| pleiotropic effects of methionine adenosyltransferases deregulation as determinants of liver cancer progression and prognosis. | downregulation of liver-specific mat1a gene, encoding s-adenosylmethionine (sam) synthesizing isozymes mati/iii, and upregulation of widely expressed mat2a, encoding matii isozyme, known as mat1a:mat2a switch, occurs in hepatocellular carcinoma (hcc). being inhibited by its reaction product, matii isoform upregulation cannot compensate for mati/iii decrease. therefore, mat1a:mat2a switch contributes to decrease in sam level in rodent and human hepatocarcinogenesis. sam administration to carcinog ... | 2013 | 23665184 |
| retroviral dna methylation and epigenetic repression are mediated by the antiviral host protein daxx. | integrated retroviral dna is subject to epigenetic transcriptional silencing at different frequencies. this process is mediated by repressive dna methylation and histone modifications on viral chromatin. however, the detailed mechanisms by which retroviral silencing is initiated and maintained are not well understood. using a model system in which avian sarcoma virus (asv) dna is epigenetically repressed in mammalian cells, we previously found that a cellular scaffolding protein, daxx, acts as a ... | 2013 | 23221555 |
| expression and function of fra2/jund in cutaneous t-cell lymphomas. | adult t-cell leukemia/lymphoma (atll) and cutaneous t-cell lymphomas (ctcls) are known to frequently express cc chemokine receptor 4 (ccr4). previously, we investigated the transcriptional control of ccr4 expression in atll and have found that an activating protein 1 (ap1) family member, fbj murine osteosarcoma viral oncogene homolog (fos)-related antigen 2 (fra2), is consistently expressed at high levels in atll and, together with v-jun avian sarcoma virus 17 oncogene homolog d (jund), up-regul ... | 2012 | 22493372 |
| nuclear import of avian sarcoma virus integrase is facilitated by host cell factors. | integration of retroviral dna into the host cell genome is an obligatory step in the virus life cycle. in previous reports we identified a sequence (amino acids 201-236) in the linker region between the catalytic core and c-terminal domains of the avian sarcoma virus (asv) integrase protein that functions as a transferable nuclear localization signal (nls) in mammalian cells. the sequence is distinct from all known nlss but, like many, contains basic residues that are essential for activity. | 2008 | 18687138 |
| replication of avian sarcoma virus in vivo requires an interaction between the viral rna and the tpsic loop of the trna(trp) primer. | reverse transcription in avian sarcoma virus (asv) initiates from the 3' end of a trna(trp) primer, which anneals near the 5' end of the rna genome. the region around the primer-binding site (pbs) forms an elaborate stem structure composed of the u5-inverted repeat (u5-ir) stem, the u5-leader stem, and the association of the trna primer with the pbs. there is evidence for an additional interaction between the viral u5 rna and the t psi c loop of the trna(trp) (u5-t psi c). we now demonstrate tha ... | 2002 | 12097570 |
| presteady-state analysis of avian sarcoma virus integrase. ii. reverse-polarity substrates identify preferential processing of the u3-u5 pair. | the integrase-catalyzed insertion of the retroviral genome into the host chromosome involves two reactions in vivo: 1) the binding and endonucleolytic removal of the terminal dinucleotides of the viral dna termini and 2) the recombination of the ends with the host dna. kukolj and skalka (kukolj, g., and skalka, a. m. (1995) genes dev. 9, 2556-2567) have previously shown that tethering of the termini enhances the endonucleolytic activities of integrase. we have used 5'-5' phosphoramidites to desi ... | 2002 | 11821408 |
| computer aided study of ligand binding with catalytic domain of avian sarcoma virus integrase and its ligand binding loops. | we have carried out 1 nanosecond (ns) molecular dynamics (md) simulations of the drug y3 (4-acetylamino-5-hydroxynaphthalene- 2, 7-disulfonic acid) complexed with catalytic domain of avian sarcoma virus integrase (asv-in), both in vacuum and in the presence of explicit solvent. starting models were obtained on the basis of pdb co- ordinates (1a5x) of asv-in-y3 complex. mn(2+) cation was present in the active site. to neutralize the positive charge in the presence of explicit solvent, eight cl(-) ... | 2001 | 11790143 |
| characterization of retrovirus-host dna junctions in cells deficient in nonhomologous-end joining. | formation of stably integrated proviruses is inefficient in cells that are defective in the cellular nonhomologous end-joining (nhej) dna repair pathway (r. daniel, r. a. katz, and a. m. skalka, science 284:644-647, 1999; r. daniel, r. a. katz, and a. m. skalka, mol. cell. biol. 21:1164-1172, 2001). however, the requirement for nhej function is not absolute, as 10 to 20% of infected nhej-deficient cells can express retrovirus- transduced reporter genes in a stable fashion. to learn more about th ... | 2001 | 11533219 |
| selective inhibition of splicing at the avian sarcoma virus src 3' splice site by direct-repeat posttranscriptional cis elements. | the direct-repeat elements (dr1) of avian sarcoma virus (asv) and leukosis virus have the properties of constitutive transport elements (ctes), which facilitate cytoplasmic accumulation of unspliced rna. it is thought that these elements represent binding sites for cellular factors. previous studies have indicated that in the context of the avian sarcoma virus genome, precise deletion of both asv dr1 elements results in a very low level of virus replication. this is characterized by a decreased ... | 2000 | 10954552 |
| conditional cell transformation by doxycycline-controlled expression of the asv17 v-jun allele. | to investigate the molecular basis of oncogenesis induced by the v-jun oncogene of avian sarcoma virus 17 (asv17), we developed a conditional cell transformation system in which transcription of the asv17 v-jun allele is controlled by a doxycycline-sensitive transactivator (tta) or a reverse (doxycycline-dependent) transactivator (rtta), respectively. permanent cell lines of quail embryo fibroblasts conditionally transformed by a doxycycline-controlled v-jun allele revert to the normal phenotype ... | 2000 | 10772983 |
| the catalytic subunit of phosphoinositide 3-kinase: requirements for oncogenicity. | the retroviral oncogene p3k (v-p3k) of avian sarcoma virus 16 (asv16) codes for the catalytic subunit of phosphoinositide (pi) 3-kinase, p110alpha. the v-p3k protein is oncogenic in vivo and in vitro; its cellular counterpart, c-p3k, lacks oncogenicity. fusion of viral gag sequences to the amino terminus of c-p3k activates the transforming potential. activation can also be achieved by the addition of a myristylation signal to the amino terminus or of a farnesylation signal to the carboxyl termin ... | 2000 | 10692423 |
| atomic resolution structures of the core domain of avian sarcoma virus integrase and its d64n mutant. | | 1999 | 10555989 |
| characterization of the self association of avian sarcoma virus integrase by analytical ultracentrifugation. | retroviral integration protein (in) has been shown to be both necessary and sufficient for the integration of reverse-transcribed retroviral dna into the host cell dna. it has been demonstrated that self-assembly of in is essential for proper function. analytical ultracentrifugation was used to determine the stoichiometry and free energy of self-association of a full-length in in various solvents at 23.3 degrees c. below 8% glycerol, an association stoichiometry of monomer-dimer-tetramer is obse ... | 1999 | 10551846 |
| atomic resolution structures of the core domain of avian sarcoma virus integrase and its d64n mutant. | six crystal structures of the core domain of integrase (in) from avian sarcoma virus (asv) and its active-site derivative containing an asp64 --> asn substitution have been solved at atomic resolution ranging 1.02-1.42 a. the high-quality data provide new structural information about the active site of the enzyme and clarify previous inconsistencies in the description of this fragment. the very high resolution of the data and excellent quality of the refined models explain the dynamic properties ... | 1999 | 10521258 |
| structural basis for inactivating mutations and ph-dependent activity of avian sarcoma virus integrase. | crystallographic studies of the catalytic core domain of avian sarcoma virus integrase (asv in) have provided the most detailed picture so far of the active site of this enzyme, which belongs to an important class of targets for designing drugs against aids. recently, crystals of an inactive d64n mutant were obtained under conditions identical to those used for the native enzyme. data were collected at different ph values and in the presence of divalent cations. data were also collected at low p ... | 1998 | 9830010 |
| in vivo selection for intronic splicing signals from a randomized pool. | retroviruses utilize balanced splicing to express multiple proteins from a single primary transcript. a number of cis -acting signals help maintain this balance, including the branch point sequence (bps), polypyrimidine tract (ppyt) and sequences within the downstream exon. in general, regulated splicing requires weak splicing signals and we have previously shown the same requirement for the simple retrovirus, avian sarcoma virus (asv). here we take advantage of the requirement for balanced spli ... | 1998 | 9742257 |
| binding of different divalent cations to the active site of avian sarcoma virus integrase and their effects on enzymatic activity. | retroviral integrases (ins) contain two known metal binding domains. the n-terminal domain includes a zinc finger motif and has been shown to bind zn2+, whereas the central catalytic core domain includes a triad of acidic amino acids that bind mn2+ or mg2+, the metal cofactors required for enzymatic activity. the integration reaction occurs in two distinct steps; the first is a specific endonucleolytic cleavage step called "processing," and the second is a polynucleotide transfer or "joining" st ... | 1997 | 9218451 |
| effect of dimerization on signal transduction and biological function of oncogenic ros, insulin, and insulin-like growth factor i receptors. | the avian sarcoma virus ur2 codes for an oncogenic gag-ros fusion protein-tyrosine kinase (ptk). we have previously derived two retroviruses, t6 and nm1, coding for oncogenic gag-insulin receptor and gag-insulin-like growth factor i receptor (igfr) fusion proteins, respectively. the gag-igfr fusion protein dimerizes, whereas gag-ros does not. to identify sequences affecting dimerization and the effect of dimerization on signaling and biological functions, we generated recombinants exchanging the ... | 1997 | 8995240 |
| differential display of rna from tumorigenic and nontumorigenic variants of hamster cells transformed with avian sarcoma virus. | differential display technique was applied to study expression of rna in tumorigenic and nontumorigenic cell variants of avian sarcoma virus transformed hamster cells. methodical conditions were worked out, which allowed identifying a cdna fragment of an unknown gene expressed in nontumorigenic cell variant only. its role in tumor suppression remains to be determined. | 1997 | 9605004 |
| a minimalist's approach to the phase problem - phasing selenomethionyl protein structures using cu kalpha data. | the feasibility of phasing protein structures through the use of the isomorphous and anomalous signal of selenomethionyl (se-met) derivative and diffraction data collected with a standard laboratory cu kalpha x-ray source has been investigated. interpretable electron-density maps were obtained for the core domain of avian sarcoma virus integrase, a typical medium-sized protein having four met residues in a sequence of 156 amino acids. the r.m.s. difference between 3.1 a experimental phases obtai ... | 1996 | 15299566 |
| multimerization determinants reside in both the catalytic core and c terminus of avian sarcoma virus integrase. | we have shown previously that the active form of avian sarcoma virus integrase (asv in) is a multimer. in this report we investigate in multimerization properties by a variety of methods that include size exclusion chromatography, chemical cross-linking, and protein overlay assays. we show that removal of the nonconserved c-terminal region of in results in a reduced capacity for multimerization, whereas deletion of the first 38 amino acids has little effect on the oligomeric state. binding of a ... | 1995 | 7493962 |
| genetic selection for balanced retroviral splicing: novel regulation involving the second step can be mediated by transitions in the polypyrimidine tract. | incomplete splicing is essential for retroviral replication; and in simple retroviruses, splicing regulation appears to occur entirely in cis. our previous studies, using avian sarcoma virus, indicated that weak splicing signals allow transcripts to escape the splicing pathway. we also isolated a series of avian sarcoma virus mutants in which env mrna splicing was regulated by mechanisms distinct from those of the wild-type virus. in vitro splicing experiments with one such mutant (insertion sup ... | 1995 | 7739546 |
| modulatory effect of the transmembrane domain of the protein-tyrosine kinase encoded by oncogene ros: biological function and substrate interaction. | there is a 3-aa insertion in the transmembrane (tm) domain of the p68gag-ros protein-tyrosine kinase encoded by avian sarcoma virus ur2 v-ros as compared with that of the protooncogene c-ros. the effect of this insertion on biological function and biochemical properties of v-ros protein was investigated by deleting these 3 aa to generate the mutant tm1. this mutant has greatly reduced transforming, mitogenic, and tumorigenic activities despite the fact that the protein-tyrosine kinase activity a ... | 1994 | 7526386 |
| origin and evolution of the c-src-transducing avian sarcoma virus pr2257. | avian sarcoma virus pr2257 transduced de novo the c-src gene and about 900 bp of 3' non-coding sequences belonging to the src locus. this virus contains only one mutation in the c-src coding sequence causing a reading frame shift after pro-525. the molecular clone studied was derived from a cell line of transformed quail fibroblasts, c7. it contains endogenous virus (ev) derived sequences in the u5 and 3' non-coding regions, indicating that multiple recombination occurred with endogenous virus. ... | 1994 | 7931166 |
| interactions between hematopoietic progenitor kinase 1 and its adaptor proteins (review). | hematopoietic progenitor kinase 1 (hpk1), also known as mitogen‑activated protein kinase kinase kinase kinase 1 is a serine/threonine protein kinase. it is involved in various cellular events, including mitogen‑activated protein kinase signaling, nuclear factor‑κb signaling, cytokine signaling, cellular proliferation and apoptosis, t cell receptor/b cell receptor signaling and t/b/dendritic cell‑mediated immune responses. therefore, hpk1 has variety of roles in immunity, and is associated with t ... | 2017 | 28901492 |
| identification of potential biomarkers and therapeutic targets for human iga nephropathy and hypertensive nephropathy by bioinformatics analysis. | in order to further elucidate the potential correlations and treatments of iga nephropathy (igan) and hypertensive nephropathy (ht), bioinformatics analysis of igan and ht was performed. the mrna expression profiles of human renal biopsy samples from patients with igan, patients with ht and pre‑transplant healthy living controls (ld) were downloaded from the gene expression omnibus database. then, the differentially expressed genes (degs) were identified and functions of degs were analyzed. fina ... | 2017 | 28713898 |
| up-regulation of crkl by microrna-335 methylation is associated with poor prognosis in gastric cancer. | micrornas have been suggested to play a vital role in regulating carcinogenesis, tumor progression and invasion. mir-335 is involved in suppressing metastasis and invasion in various human cancers. however, the mechanisms responsible for the aberrant expression of mir-335 in gastric cancer (gc) remain unknown. | 2017 | 28239297 |
| v-jun oncogene prevents terminal differentiation and suppresses muscle-specific gene expression in asv-17-infected muscle cells. | infection of replicating quail myoblasts with avian sarcoma virus 17 (asv-17) results in the inhibition of terminal differentiation into multinucleated myotubes and in the acquisition of anchorage-independent proliferation. expression of v-jun, the asv-17 oncogene, concomitantly leads to the accumulation of the gag-jun polyprotein p65 in the nucleus and to the lack of expression of typical differentiation-specific genes such as myosin heavy chain (mhc) and alpha-actinin. surprisingly, expression ... | 1991 | 1923502 |
| control of retroviral rna splicing through maintenance of suboptimal processing signals. | the full-length retroviral transcript serves as genomic rna for progeny virions, as an mrna for structural proteins and enzymes, and as a pre-mrna substrate for splicing that yields subgenomic mrnas that encode other essential proteins. thus, rna splicing to form subgenomic mrnas must be incomplete or regulated in order to preserve some of the full-length transcripts. we have used the avian sarcoma virus system to delineate the viral functions that are required in the regulation of the splicing ... | 1990 | 2153921 |
| mutations in 3'-untranslated region of avian sarcoma virus mutant la46 genome confer the cis-acting temperature-sensitive replication defect. | avian sarcoma virus (asv) prcii mutant la46 carried a unique cis-acting temperature sensitive (ts) defect affecting virus replication. the 3'-untranslated region of the la46 genome contained multiple base substitutions in the direct repeat region and a long insertion. although these sequences were not present in prcii, most of these changes were found in various other asvs and the long insertion shared extensive homology with the so called e region in certain asv strains. by constructing chimeri ... | 1989 | 2552664 |
| suppression of tumorigenicity in clones of hamster cells transformed with avian sarcoma virus. | hamster cells transformed with avian sarcoma virus, which had been selected for resistance to 8-azaguanine, were cloned. several single cell clones were isolated which differed significantly in their tumorigenicity in comparison to the parental highly tumorigenic cells. the nontumorigenic cell clones contained rescuable avian virus. both parental and resistant cells possessed transformed phenotype. comparative studies with parental highly tumorigenic cells and nontumorigenic cell clones failed t ... | 1988 | 2836743 |
| methylation of the enhancer region of avian sarcoma virus long terminal repeat suppresses transcription. | the effect of methylation of an enhancer on transcription was studied. a 245 bp enhancer-containing a fragment of the ltr of the avian sarcoma virus was methylated in vitro and ligated back into a vector which lacked the upstream enhancer sequence. the transient expression in qt6 cells indicated that methylation of the enhancer-containing sequence severely reduced the extent of transcription. | 1987 | 3040472 |
| immunization with envelope glycoprotein of an avian rna tumor virus protects against sarcoma virus tumor induction: role of subgroup. | avian rna tumor virus envelope glycoprotein protects against sarcoma development by an avian sarcoma virus of the same subgroup. avian rna tumor viruses, members of the retrovirus family, induce various malignancies in fowl (weiss et al. (eds.), 1982, rna tumor viruses, cold spring harbor, n.y.). these viruses consist of a genomic rna core surrounded by an envelope with embedded glycoproteins, of 85 and 37 kda. the 85 kda glycoprotein is antigenically specific for each subgroup as determined by ... | 1987 | 2821707 |
| avian sarcoma virus 17 carries the jun oncogene. | biologically active molecular clones of avian sarcoma virus 17 (asv 17) contain a replication-defective proviral genome of 3.5 kilobases (kb). the genome retains partial gag and env sequences, which flank a cell-derived putative oncogene of 0.93 kb, termed jun. the jun gene lacks preserved coding domains of tyrosine-specific protein kinases. it also shows no significant nucleic acid homology with other known oncogenes. the probable transformation-specific protein in asv 17-transformed cells is a ... | 1987 | 3033666 |
| transfection and recombination with molecularly cloned derivatives of avian sarcoma virus ur2. | a cloned version of avian sarcoma virus ur2, plasmid pkd6, which includes the full, nonpermuted proviral sequence between two ltr regions, has been prepared. the plasmid is biologically active in transfection experiments, even when intact. two transformation-defective mutants with nonoverlapping deletions within the transforming gene ros were constructed from pkd6. these mutants recombine to produce transforming virus when mixed dna from both is used to transfect chick embryo fibroblasts along w ... | 1986 | 3020788 |
| activation of the cellular src gene by transducing retrovirus. | newly isolated strains of avian sarcoma virus, s1 and s2, were shown to have the transduced cellular src gene as their viral transforming gene (yamagishi et al., virology 137:266-275, 1984). in this work, the s1 and s2 genomes were molecularly cloned, and the junction sequences between the viral genomes and the c-src genes and the complete nucleotide sequences of the v-src genes transduced in these viruses were determined. data on the junction sequences suggested that 5' recombination had occurr ... | 1986 | 3097513 |
| altered stem cell (cfu-s) function following infection of hematopoietic cells with a virus carrying v-src. | long-term murine bone marrow cultures were used to support the growth and development of hematopoietic cells. after hematopoiesis was established, the cultures were infected with a recombinant murine amphotropic virus carrying the avian sarcoma virus src gene and the cfu-s kinetics were examined. the cfu-s from the src-infected cultures displayed a reduced seeding efficiency in the standard spleen colony assay. the self-renewal capacity of these cfu-s was tested by their ability to reestablish h ... | 1986 | 3510679 |
| membrane association of the transforming protein of avian sarcoma virus ur2 and mutants temperature sensitive for cellular transformation and protein kinase activity. | the localization of the transforming protein p68gag-ros of avian sarcoma virus ur2, which has a hydrophobic region at the n terminus of its ros-specific tyrosine kinase-encoding sequence, was examined by subcellular fractionation. p68 behaved as an integral membrane protein associated with the plasma membrane of transformed cells. p68 became membrane associated very rapidly in its biogenesis. three temperature-sensitive mutants of ur2 were isolated and characterized. cells infected with the muta ... | 1985 | 2999433 |
| v-src inhibits differentiation via an extracellular intermediate(s). | murine 3t3l1 preadipocytes transformed by avian sarcoma virus were unable to differentiate in response to insulin or dexamethasone plus 1-methyl-3-isobutylxanthine, both potent inducers of differentiation of the nontransformed 3t3l1 parental line. conditioned medium from transformed cells contained a relatively heat-stable factor(s) which inhibited the differentiation of untransformed parental 3t3l1 cells but did not induce any changes in their morphology. a protease-sensitive mitogen was also d ... | 1985 | 3939255 |
| cloned dna of defective avian sarcoma virus mutant la46 encodes the cis-acting temperature-sensitive defect in replication. | avian defective sarcoma virus mutant la46 carries a temperature-sensitive defect in replication and transformation. to elucidate this defect, we cloned the integrated provirus of la46. by dna-mediated transfection, the cloned dna induced fusiform-transformed foci in chick embryo fibroblasts without helper virus. la46-encoded transformation-specific protein p105 was expressed in these transformants in the absence of helper virus-encoded proteins. superinfection of the transformed cells with diffe ... | 1985 | 2998036 |
| nucleotide sequence of avian sarcoma virus ur2 and comparison of its transforming gene with other members of the tyrosine protein kinase oncogene family. | the genome of avian sarcoma virus ur2 was completely sequenced and found to have a size of 3,165 nucleotides. the ur2-specific transforming sequence, ros, with a length of 1,273 nucleotides, is inserted between the truncated gag gene coding for p19 and the env gene coding for gp37 of the ur2av helper virus. the deduced amino acid sequence for the ur2 transforming protein p68 gives a molecular weight of 61,113 and shows that it is closely related to the oncogene family coding for tyrosine protein ... | 1985 | 2983097 |
| promoter sequences of murine alpha a crystallin, murine alpha 2(i) collagen or of avian sarcoma virus genes linked to the bacterial chloramphenicol acetyl transferase gene direct tissue-specific patterns of chloramphenicol acetyl transferase expression in transgenic mice. | | 1985 | 3006999 |
| transforming protein of avian sarcoma virus ur2 is associated with phosphatidylinositol kinase activity: possible role in tumorigenesis. | the transforming protein of avian sarcoma virus ur2, p68v-ros, has an associated tyrosine-specific protein kinase activity similar to that of p60v-src and several other oncogene products. however, this activity has not been linked unequivocally to transformation, and the physiological action of these proteins remains in doubt. we now have found that immunoprecipitated p68v-ros also is associated with phosphatidylinositol (ptdins) kinase (atp:ptdins 4-phosphotransferase, ec 2.7.1.67) activity. pt ... | 1984 | 6326140 |
| evidence for involvement of an rna primer in initiation of strong-stop plus dna synthesis during reverse transcription in vitro. | employing enzymatic reactions in vitro, we have identified the presence of oligoribonucleotides at the 5' end of strong-stop plus [(+)] dna. similar results were obtained whether the strong-stop (+) dna was synthesized by preparations of detergent-disrupted avian sarcoma virus or reconstructed reactions containing purified reverse transcriptase and a template that mimics the purported natural template for strong-stop (+) dna synthesis. the latter reactions provide a system to delineate more prec ... | 1984 | 6200608 |
| [isolation of nonintegrated forms of proviral dna of oncogenic viruses using preparative electrophoresis]. | nonintegrated forms of avian sarcoma virus (asv) d6 proviral dna have been analyzed in transformed chick embryo fibroblasts (cef) 72 h after the initial infection. it is shown that nonintegrated proviral dna in cef cultures are represented by circular (form i) and linear (form iii) forms. the molecular mass of the linear form of asv d6 proviral dna is 5.4-5.6 md. the new method of preparative electrophoresis is proposed for isolation and separation of the nonintegrated forms of asv d6 proviral d ... | 1984 | 6096113 |
| selective cleavage in the avian retroviral long terminal repeat sequence by the endonuclease associated with the alpha beta form of avian reverse transcriptase. | m13 recombinant dna clones containing a 350-base sequence derived from the ecori fragment of two tandemly linked rous-associated virus 2 (rav-2) long terminal repeat (ltr) sequences have been used to map reverse transcriptase-associated endonuclease (rt-endonuclease) cleavage sites by primer extension studies. under appropriate conditions, the alpha beta form of rt-endonuclease (composed of both the alpha and beta subunits) purified from avian sarcoma virus (pr-c and b-77 strains) introduces a s ... | 1983 | 6196775 |
| involvement of directly repeated sequences in the generation of deletions of the avian sarcoma virus src gene. | nucleotide sequence analysis of two molecular clones of transformation-defective avian sarcoma virus indicate that direct repeated sequences of 6 and 20 nucleotides are involved in the formation of the src deletions in these clones. | 1983 | 6312073 |
| localization of active promoters for eucaryotic rna polymerase ii in the long terminal repeat of avian sarcoma virus dna. | the nucleotide sequences in the long terminal repeat of avian sarcoma virus that are recognized in vitro by hela cell rna polymerase ii have been identified. for this purpose, various 5' and 3' deletions were introduced into a cloned long terminal repeat fragment. the effects of these deletions on transcription initiation in hela whole-cell extracts were then studied. three specific transcripts have been identified. the major transcript is initiated at nucleotide +1 (relative to the cap site). d ... | 1983 | 6306447 |
| ts transformation mutants of avian sarcoma virus prcii: lack of strict correlation between transforming ability and properties of the p105-associated kinase. | | 1983 | 6187125 |
| effect of aphidicolin on avian sarcoma virus replication. | we studied the effect of aphidicolin, an inhibitor of eucaryotic dna polymerase alpha, on viral dna replication and integration during the first 24 h after infection of quail embryo fibroblasts with avian sarcoma virus. in drug-treated cells, the synthesis of unintegrated linear viral dna species was not impaired; however, the subsequent accumulation of circular viral dna species and integrated proviral dna was reversibly inhibited. after removal of the drug, circular viral dna species were deri ... | 1982 | 6292514 |
| morphological evidence for cyclic amp-induced reverse transformation in vole cells infected with avian sarcoma virus. | normal fibroblasts of the vole displayed moderately spread or flattened, spindle-shaped, or polygonal morphologies and attached firmly to a substrate. topographic features of these cells included sparse microvilli, ruffles, and filopodia. microfilament bundles, intermediate filaments, and long microtubules generally parallel to each other, and the long axis of the cell or its extensions were present in the cytoplasm. fibronectin was abundant, and fibronectin fibrils often formed junctions at the ... | 1982 | 6100914 |
| reverse transformation of vole cells transformed by avian sarcoma virus containing the src gene. | vole cells transformed by avian sarcoma virus carrying the src gene lose their fibroblastic morphology, the organized cytoskeletal system of the normal fibroblastic cell, the typical fibronectin deposit around the cell membrane, and the ability to shut off multiplication when suspended in liquid medium. all of these transformation characteristics are reversed by treatment with camp derivatives. moreover, the camp treatment does not cause loss of activity of the src gene product. these data imply ... | 1981 | 6265480 |
| an avian sarcoma virus mutant which produces an aberrant transformation affecting cell morphology. | | 1981 | 6263000 |
| anti-pp60src antibodies are substrates for egf-stimulated protein kinase. | epidermal growth factor (egf) stimulates phosphorylation of its own receptor at a tyrosine residue. similarly, the viral gene product pp60src, which is responsible for cellular transformation by avian sarcoma virus (asv), phosphorylates itself and immunoglobulin directed against pp60src at tyrosine residues. this unusual site of phosphorylation catalysed by two membrane-associated protein kinases involved in growth control prompted us to study the immunological relatedness of the egf-stimulated ... | 1981 | 6261145 |
| tandem duplication of the proviral dna in an avian sarcoma virus-transformed quail clone. | previous study has shown that an avian sarcoma virus-transformed quail clone, q-b77-11, apparently contains full-size proviral dna and releases virus particles which contain polymerase activity, but are unable to form foci. recently, we have found that after extended tissue culture of q-b77-11, the predominant cell type changed from one in which there was a single copy of the integrated viral dna to one with two copies in tandem. there was approximately one copy of the large terminal redundancy ... | 1981 | 6264101 |
| effect of tumor promoters on sarc gene expression in normal and transformed chick embryo fibroblasts. | the effects of 12-o-tetradecanoylphorbol-13-acetate (tpa) on the sarc protein kinase of normal chick embryo fibroblasts (cef) and of the src kinase of cells transformed by a temperature-sensitive mutant of avian sarcoma virus (cef-tsasv) were studied and compared with the known effects of tpa on cell morphology and plasminogen activator (pa) activity. one hr after the addition of tpa to normal cef, there was a 3- to 8-fold stimulation of kinase activity when compared to control cultures; during ... | 1981 | 6260344 |
| the localization of glial fibrillary acidic protein in brain tumors induced in hamsters with avian sarcoma virus. | the immunohistochemical localization of glial fibrillary acidic protein (gfap) was studied by the peroxidase-antiperoxidase (pap) method in avian sarcoma virus (asv)-induced brain tumors in hamsters. one hundred twenty-four tumors including 54 astrocytomas, 64 pleomorphic gliomas, five sarcomas, and one unclassified tumor were stained with anti-gfap serum. a positive immunostaining was seen in astrocytomas and in pleomorphic gliomas. sarcomas and an unclassified tumor were negative. these result ... | 1981 | 6277141 |
| the transformation-specific protein pp60src from an avian sarcoma virus. | | 1981 | 6274752 |
| identification of a cellular protein substrate phosphorylated by the avian sarcoma virus-transforming gene product. | the avian sarcoma virus-transforming gene product (pp60src) appears potentially able to mediate cell transformation via phosphorylation since it is tightly associated with a protein kinase activity. we have searched for and have been able to identify a normal cellular protein that appears to be a substrate of pp60src. the phosphorylation of this protein (34k) in transformation-specific in asv-transformed cells of both avian and mammalian origin. moreover, the 34k polypeptide serves as a substrat ... | 1980 | 6254669 |
| comparison of protein kinase activities in normal cells and cells transformed by a temperature-sensitive mutant of avian sarcoma virus to those of cell-free viral translational products. | | 1980 | 6253227 |
| activities of the src-gene product of avian sarcoma virus. | | 1980 | 6253226 |
| expression of the src-gene product, pp60src, in transformed and reverted mammalian cells infected with avian sarcoma virus. | | 1980 | 6253180 |
| reverse transcription of avian sarcoma virus rna into dna might involve copying of the trna primer. | some of the double-stranded dna products from the endogenous reaction of detergent-disrupted virions contain up to 18 3'-terminal nucleotides at a location consistent with their being transcribed from the trna primer. | 1980 | 6245249 |
| the src gene product of transformed and morphologically reverted asv-infected mammalian cells. | morphological revertants of avian sarcoma virus transformed vole cells contain the sarcoma gene product (pp60src) in an enzymatically active form, suggesting that the presence of pp60src protein kinase activity is infussicient to induce morphological transformation. structural analyses of pp60src from infected vole cell clones suggest that in one of the revertant clones on alteration in pp60src may be responsible for morphological reversion while in a second clone, reversion may result from an a ... | 1979 | 225672 |
| effect of viral rnase h on the avian sarcoma viral genome during early transcription in vitro. | we investigated the influence of viral rnase h on the transcription of the avian sarcoma virus rna in a virion-associated reaction. the ability of rnase h to degrade the rna moiety of the initially formed rna-dna hybrid at the 5' end of the viral genome was found to be greatly dependent on the exact concentration of nonionic detergent used to activate the reaction. at a detergent concentration optimal for extensive and faithful in vitro transcription of avian sarcoma virus rna by the virion-asso ... | 1979 | 229244 |
| avian sarcoma virus envelope glycoprotein (gp85) specifically binds chick embryo fibroblasts. | | 1979 | 224590 |
| characterization of an immune complex kinase in immunoprecipitates of avian sarcoma virus-transformed fibroblasts. | kinase activity detected in immune complexes containing the src gene product of the avian sarcoma virus has been reported. to further characterize this immune complex kinase, we developed a routine quantitative assay involving trichloroacetic acid precipitation on filters. the enzyme reaction required either mg2+ or mn2+, but was inactive with ca2+. the kinetics of the phosphorylation reaction indicated a transient enzyme activity limited by rapid substrate-dependent inactivation of the enzyme. ... | 1979 | 41953 |
| suppression of multiplication of avian sarcoma virus by rapid spread of transformation-defective virus of the same subgroup. | we have tested the hypothesis that some transformation-defective (td) viruses grow faster than the avian sarcoma viruses (asv) from which they are derived, resulting in establishment of interference by the td virus and suppression of the asv multiplication. using an asv of subgroup a (asv-a) that does not contain td virus and an independently isolated tdasv-a, we performed separate and mixed infections to test this hypothesis. at multiplicities of 1 or less, tdasv alone grew to higher titers and ... | 1979 | 225561 |
| heterogeneity of neoplastic cells derived from a hamster tumor induced by avian sarcoma virus b77. | cells derived from a hamster tumor induced by avian sarcoma virus bratislava 77 (b77) in vivo, were cultivated in vitro. after few passages two morphologically different cell lines were isolated from the parental culture (b77/h). one cell line consisted of fibroblastic cells (b77/h/fi and the other from epithelioid cells (b77/h/ep). cells of both lines were highly tumorigenic in neonatal syngeneic hamsters, b77/h/ep cells were able to form colonies in soft agar and contained complete integrated ... | 1979 | 232249 |
| characterization of a normal avian cell protein related to the avian sarcoma virus transforming gene product. | | 1978 | 83198 |
| binding of tryptophanyl-trna to the reverse transcriptase of replication-defective avian sarcoma viruses. | the ability of reverse transcriptase to bind to [3h]tryptophanyl-trna and to function as dna polymerase was compared for five temperature-sensitive mutants of avian sarcoma virus. both activities of the reverse transcriptase were found to be heat labile in la 335 and la 336 as compared with the wild-type parents. for the other mutant viruses, la 338, la 343, and la 672, grown at the permissive temperature, the reverse transcriptase was nearly as heat stable as for the wild-type parents in terms ... | 1978 | 82623 |
| in vitro synthesis of a functional avian sarcoma virus transforming-gene product. | | 1978 | 210399 |
| studies on the amino acid sequence content of proteins specified by the gag and pol genes of avian sarcoma virus b77. | | 1978 | 80058 |
| kinetics of synthesis, structure and purification of avian sarcoma virus-specific dna made in the cytoplasm of acutely infected cells. | | 1978 | 205652 |
| virus-specific dna in the cytoplasm of avian sarcoma virus-infected cells is a precursor to covalently closed circular viral dna in the nucleus. | three principal forms of viral dna have been identified in cells infected with avian sarcoma virus: (i) a linear duplex molecule synthesized in the cytoplasm, (ii) a covalently closed circular molecule found in the nucleus, and (iii) proviral dna covalently linked to high-molecular-weight cell dna. to define precursor product relationships among these forms of viral dna, we performed pulsechase experiments using 5-bromodeoxyuridine to label by density the linear species of viral dna in the cytop ... | 1978 | 202729 |
| occurrence of partial deletion and substitution of the src gene in the rna genome of avian sarcoma virus. | the genome size of 20 transformation-defective (td) viruses derived from different strains of rous sarcoma viruses [prague (subgroups a and c), schmidt-ruppin (subgroups a and d) (sr-d), bratislava 77, and carr-zilber subgroup d)] was examined by polyacrylamide gel electrophoresis. all of the td viruses except td sr-d have 35s rna of the same size-i.e., class b rna. two of five td sr-d viruses examined have a slightly larger rna, corresponding to a td deletion that is about 25% smaller than that ... | 1977 | 200931 |
| major phosphoprotein of avian sarcoma virus: peptide analysis of the variously charged species. | | 1977 | 200228 |
| the rna-dependent dna polymerase of avian sarcoma virus b77. binding of viral and nonviral ribonucleic acids to the alpha, beta2, and alphabeta forms of the enzyme. | the extent of binding of various rna species to the three forms of avian sarcoma virus b77 rna-dependent dna polymerase was determined using a sensitive nitrocellulose filter binding technique which was capable of detecting binding reactions with association constants as low as 3 x 10(6) liters x mole-1. all three enzyme forms, alphabeta, beta2, and alpha, bound to all single-stranded rna species that were tested, including nonviral rnas. 70 s viral rna exhibited the highest association constant ... | 1977 | 70428 |