| characterization of the protease of a fish retrovirus, walleye dermal sarcoma virus. | three fish retroviruses infecting walleyes constitute the recently recognized genus called epsilonretrovirus. the founding member of this group, walleye dermal sarcoma virus (wdsv), induces benign skin tumors in the infected fish and replicates near 4 degrees c. while the viral genomic sequence is known, biochemical characterization of the virus has been limited to the identification of the mature structural and envelope proteins present in virions. we undertook this study to determine the cleav ... | 2002 | 11932400 |
| walleye dermal sarcoma virus reverse transcriptase is temperature sensitive. | walleye dermal sarcoma virus (wdsv) is a piscine retrovirus that replicates naturally in fish at temperatures near 4 degrees c. the reverse transcriptase (rt) protein from virus particles isolated from walleye tumours was purified and biochemically characterized. like the rt of the distantly related murine leukaemia virus, wdsv rt sediments as a monomer in the absence of template. it exhibits a k(m) of 22 microm for ttp in an assay with poly(ra) as a template and oligo(dt) as a primer. the enzym ... | 2002 | 12029151 |
| walleye dermal sarcoma virus cyclin interacts with components of the mediator complex and the rna polymerase ii holoenzyme. | walleye dermal sarcoma virus (wdsv) encodes an accessory protein, orfa, with sequence homology to cyclins (retrovirus cyclin). in cells transfected with an expression construct, orfa was localized to the nucleus and was concentrated in interchromatin granule clusters (igcs), sites where splicing factors are concentrated. other proteins identified in igcs include transcription factors, the large subunit of rna polymerase ii (pol ii), and cyclin-dependent kinase 8 (cdk8). cdk8 is the kinase partne ... | 2002 | 12134008 |
| walleye dermal sarcoma virus orf c is targeted to the mitochondria. | walleye dermal sarcomas are associated with the presence of a complex retrovirus, walleye dermal sarcoma virus (wdsv). these sarcomas develop and regress seasonally in naturally infected fish. in addition to gag, pol and env, wdsv contains three open reading frames (orfs), designated orf a, orf b and orf c. orf c is located between the 5' long terminal repeat and gag. developing tumours contain low levels of orf a and orf b transcripts, whereas regressing tumours contain high levels of genomic t ... | 2003 | 12560570 |
| comparative pathogenesis of epsilonretroviruses. | | 2003 | 14610162 |
| identification and characterization of cis-acting elements residing in the walleye dermal sarcoma virus promoter. | walleye dermal sarcoma virus (wdsv) is a complex retrovirus found associated with tumors that appear and regress on a seasonal basis. there are quantitative and qualitative differences in the amount of virus expression between developing and regressing tumors. to understand the role of host cell factors in wdsv expression, dnase i footprint analysis, electrophoretic mobility shift assays (emsa), and reporter gene assays were employed. dnase i footprint analysis of the u3 region of the wdsv long ... | 2004 | 15220434 |
| amino acid preferences for a critical substrate binding subsite of retroviral proteases in type 1 cleavage sites. | the specificities of the proteases of 11 retroviruses representing each of the seven genera of the family retroviridae were studied using a series of oligopeptides with amino acid substitutions in the p2 position of a naturally occurring type 1 cleavage site (val-ser-gln-asn-tyr pro-ile-val-gln; the arrow indicates the site of cleavage) in human immunodeficiency virus type 1 (hiv-1). this position was previously found to be one of the most critical in determining the substrate specificity differ ... | 2005 | 15767422 |
| fibrosarcoma in yellow perch, perca flavescens (mitchill). | | 2005 | 15892756 |
| an activation domain within the walleye dermal sarcoma virus retroviral cyclin protein is essential for inhibition of the viral promoter. | walleye dermal sarcoma virus (wdsv) is a complex retrovirus associated with seasonal dermal sarcomas. developing tumors have low levels of accessory gene transcripts, a1 and b, and regressing tumors have high levels of full-length and spliced transcripts. transcript a1 encodes a retroviral cyclin (rv-cyclin) with limited homology to host cyclins. the rv-cyclin is physically linked to components of the transcriptional co-activator complex, mediator, and regulates transcription. in walleye fibrobl ... | 2005 | 16150476 |
| identification and characterization of an exogenous retrovirus from atlantic salmon swim bladder sarcomas. | a novel piscine retrovirus has been identified in association with an outbreak of leiomyosarcoma in the swim bladders of atlantic salmon. the complete nucleotide sequence of the atlantic salmon swim bladder sarcoma virus (sssv) provirus is 10.9 kb in length and shares a structure and transcriptional profile similar to those of murine leukemia virus-like simple retroviruses. sssv appears unique to simple retroviruses by not harboring sequences in the atlantic salmon genome. additionally, sssv dif ... | 2006 | 16501103 |
| walleye dermal sarcoma virus retroviral cyclin directly contacts taf9. | walleye dermal sarcoma virus (wdsv) is a complex retrovirus associated with dermal sarcomas in walleye fish. a wdsv accessory gene encodes a cyclin homolog or retroviral cyclin (rv-cyclin). wdsv rv-cyclin was found to be associated with transcription complexes and to affect transcription in a cell-type and promoter-dependent manner. it inhibited the wdsv promoter in walleye fibroblasts and activated transcription from gal4 promoters when fused to the gal4 dna binding domain, and an activation do ... | 2006 | 17035330 |
| murine endogenous retrovirus muerv-l is the progenitor of the "orphan" epsilon viruslike particles of the early mouse embryo. | viruslike particles which displayed a peculiar wheellike appearance that distinguished them from a-, b- or c-type particles had previously been described in the early mouse embryo. the maximum expression of these so-called epsilon particles was observed in two-cell-stage embryos, followed by their rapid decline at later stages of development and no particles detected at the zygote one-cell stage. here, we show that these particles are in fact produced by a newly discovered murine endogenous retr ... | 2008 | 18045933 |
| walleye dermal sarcoma virus orf b functions through receptor for activated c kinase (rack1) and protein kinase c. | walleye dermal sarcoma virus is a complex retrovirus that is associated with walleye dermal sarcomas that are seasonal in nature. fall developing tumors contain low levels of spliced accessory gene transcripts a and b, suggesting a role for the encoded proteins, orf a and orf b, in oncogenesis. in explanted tumor cells the 35 kda orf b accessory protein is localized to the cell periphery in structures similar to focal adhesions and along actin stress fibers. similar localization was observed in ... | 2008 | 18343476 |
| enhanced propagation of fish nodaviruses in bf-2 cells persistently infected with snakehead retrovirus (snrv). | fish nodaviruses are causative agents of viral nervous necrosis causing high mortality in cultured marine fishes around the world. the first successful isolation of fish nodavirus was made with ssn-1 cells, which are persistently infected with snakehead retrovirus (snrv). in the present study, a bf-2 cell line persistently infected with snrv (pi-bf-2) was established to evaluate the influence of snrv on the production of fish nodavirus. the pi-bf-2 cells were slightly more slender than bf-2 cell ... | 2008 | 18429438 |
| walleye dermal sarcoma virus rv-cyclin inhibits nf-kappab-dependent transcription. | the retroviral cyclin protein (rv-cyclin) of walleye dermal sarcoma virus contains two known functional domains, a cyclin box motif and a carboxy terminal transcription activation domain (ad). the ad contacts tata-binding protein-associated factor 9 (taf9), and this action is necessary for both positive and negative regulation of transcription from host and viral promoters. negative regulation occurs via interference with taf9 binding by transcriptional activators. transcription factors that sha ... | 2009 | 19176230 |
| transgenic expression of walleye dermal sarcoma virus rv-cyclin gene in zebrafish and its suppressive effect on liver tumor development after carcinogen treatment. | a retrovirus homologue gene of cellular cyclin d₁, walleye dermal sarcoma virus rv-cyclin gene (orf a or rv-cyclin), was expressed in the livers of zebrafish under the control of liver fatty acid-binding protein (lfabp) promoter. to prevent possible fatality caused by overexpression of the oncogene, the gal4/upstream activation sequence (gal4/uas) system was used to maintain the transgenic lines. thus, both gal4-activator [tg(lfabp:gal4)] and uas-effector [tg(uas:rvcyclin)] lines were generated, ... | 2010 | 20052603 |
| transgenic expression of walleye dermal sarcoma virus rv-cyclin (orfa) in zebrafish does not result in tissue proliferation. | walleye dermal sarcoma (wds) is a benign tumor of walleye fish that develops and completely regresses seasonally. the retrovirus associated with this disease, walleye dermal sarcoma virus, encodes three accessory genes, two of which, rv-cyclin (orfa) and orfb, are thought to play a role in tumor development. in this study, we attempted to recapitulate wds development by expressing rv-cyclin in chimeric and stable transgenic zebrafish. six stable transgenic lines expressing rv-cyclin from the con ... | 2011 | 20349325 |
| the retroviral cyclin of walleye dermal sarcoma virus binds cyclin-dependent kinases 3 and 8. | walleye dermal sarcoma virus encodes a retroviral cyclin (rv-cyclin) with a cyclin box fold and transcription activation domain (ad). co-immune precipitation (co-ip) identified an association of rv-cyclin with cyclin-dependent kinase 8 (cdk8). cdk8 is dependent upon cyclin c and regulates transcription with the mediator complex, a co-activator of transcription. mutation of cyclin residues, required for cdk binding, disrupts rv-cyclin-cdk8 co-ip. mutation or removal of the ad has no effect on cdk ... | 2010 | 21067790 |
| characterization of a xenopus tropicalis endogenous retrovirus with developmental and stress-dependent expression. | we report on the identification and characterization of xterv1, a full-length endogenous retrovirus (erv) within the genome of the western clawed frog (xenopus tropicalis). xterv1 contains all the basic genetic elements common to ervs, including the classical 5'-long terminal repeat (ltr)-gag-pol-env-3'-ltr architecture, as well as conserved functional motifs inherent to each retroviral protein. using phylogenetic analysis, we show that xterv1 is related to the epsilonretrovirus genus. the x. tr ... | 2010 | 21159866 |
| walleye dermal sarcoma virus: molecular biology and oncogenesis. | retroviruses have been detected in most vertebrate species and are etiologic agents of a variety of neoplastic diseases. the study of retroviruses has been instrumental in uncovering the molecular mechanisms responsible for oncogenesis. retroviruses have been isolated from three neoplastic diseases in fish, two of which affect the dermis and regress naturally coincident with spawning. this feature provides a unique model to study mechanisms of tumor development and regression. three complex retr ... | 2010 | 21994717 |