The B subgroup bovine papillomaviruses lack an identifiable E6 open reading frame

Me, Jackson; Wd, Pennie; Re, McCaffery; Kt, Smith; Gj, Grindlay; Ms, Campo

doi:10.1002/mc.2940040510

Cited by 44 publications

(27 citation statements)

References 30 publications

(21 reference statements)

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“…E7 has been localized in BPV-4, a BPV that is quite different from BPV-1, BPV-2, and HPV viruses. While BPV-4 contains an E7 protein with an LXCXE retinoblastoma protein binding motif, it does not encode an E6 protein (14). In BPV-4 alimentary epitheliomas, E7 was detected within the nucleus of basal and parabasal cells and within the cytoplasm of differentiated spinous and granular cells (1).…”

Section: Fig 1 Specificity Of Antibodies To E7mentioning

confidence: 99%

Cooperative Transformation and Coexpression of Bovine Papillomavirus Type 1 E5 and E7 Proteins

Bohl

Hull

Pol

2001

J Virol

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Productively infected bovine fibropapillomas were examined for bovine papillomavirus type 1 (BPV-1) E7 localization. BPV-1 E7 was observed in the cytoplasm of basal and lower spinous epithelial cells, coexpressed in the cytoplasm of basal cells with the E5 oncoprotein. E7 was also observed in nucleoli throughout the basal and spinous layers but not in the granular cell layer. Ectopic expression of E7 in cultured epithelial cells gave rise to localization similar to that seen in productive fibropapillomas, with cytoplasmic and nucleolar expression observed. Consistent with the coexpression of E7 and E5 in basal keratinocytes, BPV-1 E7 cooperated with E5 as well as E6 in an anchorage independence transformation assay. While E5 is expressed in both basal and superficial differentiating keratinocytes, BPV-1 E7 is only observed in basal and lower spinous epithelial cells. Therefore, BPV-1 E7 may serve to modulate the cellular response of basal epithelial cells to E5 expression.Papillomaviruses are causative agents for a variety of epithelial neoplasms in vertebrates. Typically, virus-induced epitheliomas are benign lesions containing episomal viral DNA in proliferative basal epithelial cells, producing virus within superficial differentiated epithelial cells. The role of virus-encoded oncogenes (E5, E6, and E7) in the maintenance of viral DNA within proliferative basal epithelial cells and/or the role of these oncogenes in the transition to vegetative viral DNA amplification and virus production has yet to be fully defined. The separation of papillomavirus oncogenes into at least three separate polypeptides (E5, E6, and E7) may reflect a requirement for separate regulation of expression and activity of each product in the virus life cycle. One area of uncertainty in papillomavirus biology has been the location of each oncoprotein within the stratified epithelium of a virus-induced epithelioma.While bovine papillomavirus type 1 (BPV-1) encodes E5, E6, and E7 oncoproteins, only mutation of BPV-1 E5 decreases transformed cell focus formation by BPV-1 viral DNA. Mutations in the BPV-1 E6 or E7 genes have little effect upon focus formation or viral DNA replication, although there is a decrease in anchorage-independent growth and tumorigenicity (12,15,20). The modest oncogenic potency of BPV-1 E6 and BPV-1 E7 expressed from the wild-type BPV-1 genome is due to repression by two separate repressor mechanisms that, when mutated, reveal cooperative transformation by BPV-1 E6 and BPV-1 E7 (35). Since both BPV-1 E6 and BPV-1 E7 are thought to be translated from the same mRNA transcript, it was unproven if BPV-1 E7 had a direct role in transformation together with BPV-1 E6. Correlating with this observation, BPV-1 E6 strongly transforms murine C127 cells when expressed from retroviral long terminal repeats, whereas E7 did not (27).The E6 proteins of human papillomavirus type 16 (HPV-16) (16E6) and BPV-1 E6 bind to the cellular targets E6AP, ERC-55, and paxillin through interaction with homologous peptide sequences found on the t...

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Section: Fig 1 Specificity Of Antibodies To E7mentioning

confidence: 99%

Cooperative Transformation and Coexpression of Bovine Papillomavirus Type 1 E5 and E7 Proteins

Bohl

Hull

Pol

2001

J Virol

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“…As a rule, papillomaviruses have two oncogenes which can cooperate in transformation (Table 4). Thus the oncogenes of BPV-1 are E5 and E6 (Schiller et al, 1984(Schiller et al, , 1986Yang et al, 1985;Schlegel et al, 1986); of HPV-16, E6 and E7 (Munger et al, 1989 a;Watanabe et al, 1989); and of BPV-4, E7 and possibly E8 (Jaggar et al, 1990;Jackson et al, 1991). E6 is the major transforming gene of CRPV in in vitro assays in which E7 contributes less (Meyers & Wettstein, 1991), but E7 is essential for tumour formation in vivo (Brandsma et al, 1991), thus providing functions that E6 lacks.…”

mentioning

confidence: 99%

“…The CKII sites, although less critical (Watanabe et al, 1990;Storey et al, 1990), nevertheless contribute to the transforming activity of HPV-16 E7 (Barbosa et al, 1990;Firzlaff et al, 1991). BPV-4 E7 does not have serine residues at positions 31 and 32, which are phosphorylated in HPV-16 E7, but has the necessary p l05Rb-binding domains (Jaggar et al, 1990;Jackson et al, 1991). Given that continued expression of BPV-4 is not necessary for the maintenance of the transformed state (Campo et al, 1985;Jaggar et al, 1990), it is reasonable to postulate that either binding of pl05Rb by BPV-4 ET, albeit transient, is crucial or the protein has yet another function.…”

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confidence: 99%

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Cell transformation by animal papillomaviruses

1992

Journal of General Virology

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“…Based on the lack of significant similarity of the putative E7-X-ORF to the E6/E7, we suggest that the putative E7-X-ORF and E6-E7 ORFs have evolved adaptive functions for specialization within specific species from a common ancestral precursor (5). Interestingly, BPV3, BPV4, and BPV6 have E7 but not E6 ORFs which might have evolved, at least in part, through genomic rearrangements (9,11). Phocoena spinipinnis PV (PsPV) causes genital warts in small cetaceans and has an E6 ORF containing four copies of the C-X-X-C motif spaced at regular and invariant intervals but lacks an identifiable E7 (23).…”

Section: Vol 76 2002 Notes 10021mentioning

confidence: 99%

Lack of Canonical E6 and E7 Open Reading Frames in Bird Papillomaviruses: Fringilla coelebs Papillomavirus and Psittacus erithacus timneh Papillomavirus

Terai¹,

DeSalle

Burk

2002

J Virol

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Determination and analyses of the complete sequence of Fringilla coelebs papillomavirus and Psittacus erithacus timneh papillomavirus indicate that they represent a distinct and distant lineage of papillomaviruses. The lack of canonical E6-E7 open reading frames suggests that they serve adaptive functions during papillomavirus evolution.Papillomaviruses (PVs) are a heterogeneous group of DNA viruses with closed-circular double-stranded DNA genomes about 8 kb in size. They are highly species-specific pathogens and cause benign and malignant lesions of squamous and mucosal epithelium in a wide range of animal species (22). The reported incidence of external neoplasms in wild birds is low, except for squamous papillomas found on the foot and lower leg of chaffinches (Fringilla coelebs) (13). The causative agent of these lesions was characterized as a PV based on the size and density of virus particles, physical properties of viral DNA, and analysis of capsid proteins by electrophoresis (20). The other known PV infection among avian species was in an African gray parrot (Psittacus erithacus timneh) (12). The PV genomes isolated from a chaffinch and an African gray parrot were cloned and partially sequenced (16, 18). We have determined and characterized the complete sequences of F. coelebs PV (FPV) and P. erithacus timneh PV (PePV).The FPV genome was cloned into the EcoRI site of pBR328, and the PePV genome was cloned into the SalI site of pBR322 (16,18). To determine the nucleotide sequence, each cloned DNA was sequenced with the first primers selected from the vector sequence, and thereafter, additional primers were designed by sequence walking (7). Sequencing was performed in the Albert Einstein College of Medicine DNA sequencing core facility. The overlapping sequences were assembled manually. Several additional primers were designed and used to clarify sequence ambiguities. Once assembled, the sequence was analyzed for similarity to other PVs by using the basic local alignment sequence tool (BLAST) software (1). The same software was used to determine protein sequence similarities.The assembled sequences revealed a total size of 7,729 bp for FPV and 7,304 bp for PePV. The complete sequences of the genomes are available from the GenBank database under accession no. AY057109 (FPV) and AF420235 (PePV). Examination of the FPV and PePV sequences for potential genes showed the typical complement of E1, E2, L2, and L1 open reading frames (ORFs) comparable in size with, and at positions similar to, those of other PVs, including overlaps between the E1 and E2 and the L2 and L1 ORFs. None of the small ORFs in FPV and PePV showed significant similarity with sequences for known E4 and E5 proteins. The PePV long control region contains one exact 12-bp E2-binding motif, whereas the FPV long control region contains four E2-binding motifs with one base pair mismatch. The predicted ORFs of FPV and PePV are shown in Fig. 1. The similarity of the FPV and PePV L1 ORF nucleotide and amino acid sequences was higher (nucleotide, 56.8%...

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The B subgroup bovine papillomaviruses lack an identifiable E6 open reading frame

Cited by 44 publications

References 30 publications

Cooperative Transformation and Coexpression of Bovine Papillomavirus Type 1 E5 and E7 Proteins

Cooperative Transformation and Coexpression of Bovine Papillomavirus Type 1 E5 and E7 Proteins

Cell transformation by animal papillomaviruses

Lack of Canonical E6 and E7 Open Reading Frames in Bird Papillomaviruses: Fringilla coelebs Papillomavirus and Psittacus erithacus timneh Papillomavirus

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