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E J Androphy

Publications and source records attributed to E J Androphy.

67 records · Page 4Linked to original sources
PubMed1989

Mutational analysis of bovine papillomavirus E6 gene.

The bovine papillomavirus E6 gene can independently transform mouse C127 cells. To characterize E6 in greater detail, we created 16 site-directed mutations in E6, including substitution mutations in the cysteine codons of the four Cys-X-X-Cys motifs that are conserved in all papillomavirus E6 proteins. Proteins mutated in six of the seven cysteines tested, as well as those lacking the nonconserved C-terminus, were stable in transfected cells but were unable to induce morphological transformation, indicating that these amino acids play an important role in the function of E6.

Amino Acid Sequence↗
PubMed1988

The specific DNA recognition sequence of the bovine papillomavirus E2 protein is an E2-dependent enhancer.

The upstream regulatory region (URR) of the bovine papillomavirus (BPV) genome contains an enhancer that is activated by a BPV E2 gene product. We have previously found that a bacterially derived E2 fusion protein specifically interacted with several fragments of URR DNA, suggesting that E2 may activate transcription by directly binding to the enhancer. Each of the bound fragments contains at least one copy of a conserved motif (ACCN6GGT). To determine if this motif is required and sufficient for specific E2 binding, we have now constructed a bacterial expression vector that encodes a full-length E2 peptide and developed a refinement of the McKay DNA immunoprecipitation assay that allows the determination, to the nucleotide level, of the minimum sequence required for specific binding. The results show that the E2 recognition sequence is a single copy of this motif and that the variant ACCGN4CGGT is bound with greater affinity than the minimum ACCN6GGT motif. An oligonucleotide encoding the motif was able to inhibit E2-dependent trans-activation in a transient transfection assay, indicating that the virally encoded E2 also interacts with this sequence in mammalian cells. When present in two or more copies, but not in a single copy, the E2 binding element had intrinsic enhancer activity but only in cells expressing E2. The results indicate that the conserved motif alone is sufficient for E2-mediated enhancement and that the binding of E2 to the motif is probably required for efficient enhancement. Since a single motif did not have a significant enhancer activity, it is likely that bound E2 molecules act cooperatively in activating transcription.

Amino Acid Sequence↗
PubMed1988

Bovine papilloma virus-transformed cells contain multiple E2 proteins.

Genetic evidence suggests that the bovine papilloma virus type 1 (BPV) E2 open reading frame may encode at least two gene products involved in the regulation of viral gene expression. One, which is probably the full-length product, trans-activates transcription via an enhancer in the viral regulatory region. A second, containing sequences from the 3' end of the open reading frame, inhibits the trans-activating activity of the first product. We now report the identification and initial characterization of three E2-encoded proteins, with mobilities corresponding to 48, 31, and 28 kDa in cells transformed by the wild-type BPV. Pulse-chase experiments indicated that the 48-kDa protein had the longest half-life (40 min), but there was no indication that one species was the precursor of another. The 48-kDa species corresponds to the full-length trans-activating protein. The two smaller species contain only carboxyl-terminal determinants, and either or both could represent inhibitory E2 proteins. Subcellular fractionation localized all three E2 proteins to the nucleus. Consistent with the low rate of viral transcription in BPV-transformed cells, the 31-kDa presumptive repressor species was more abundant than the 48-kDa species.

Animals↗
PubMed1987

Identification of the HPV-16 E6 protein from transformed mouse cells and human cervical carcinoma cell lines.

Human cervical carcinoma cell lines that harbor human papillomavirus (HPV) have been reported to retain selectively and express HPV sequences which could encode viral E6 and E7 proteins. The potential importance of HPV E6 to tumors is suggested further by the observation that bovine papillomavirus (BPV) E6 can induce morphologic transformation of mouse cells in vitro. To identify HPV E6 protein, a polypeptide encoded by HPV-16 E6 was produced in a bacterial expression vector and used to raise antisera. The antisera specifically immunoprecipitated the predicted 18-kd protein in two human carcinoma cell lines known to express HPV-16 RNA and in mouse cells morphologically transformed by HPV-16 DNA. The 18-kd E6 protein was distinct from a previously identified HPV-16 E7 protein. The HPV-16 E6 antibodies were found to be type specific in that they did not recognize E6 protein in cells containing HPV-18 sequences and reacted weakly, if at all, to BPV E6 protein. The results demonstrate that human tumors containing HPV-16 DNA can express an E6 protein product. They are consistent with the hypothesis that E6 may contribute to the transformed phenotype in human cervical cancers that express this protein.

Animals↗
PubMed1986

Papillomaviruses and interferon.

Papillomaviruses are infectious agents which cause benign tumours, or warts, of cutaneous, uterine cervical and laryngeal epithelia. These infections are very common, yet no uniformly effective therapy exists. Current treatments do not selectively inhibit viral processes but destroy the infected epithelial cells. Since interferons have antiviral effects in vivo and in vitro, it was hypothesized that they might be useful for treating papillomavirus-induced conditions. Interferons have now been demonstrated to be effective in several forms of papillomavirus infection. In vitro, chronic treatment of bovine papillomavirus-transformed cells led to the loss of the papillomavirus genomes and return of the cells to a normal morphology. In humans, interferons have been used for treating laryngeal papillomatosis, cutaneous and anogenital warts and epidermodysplasia verruciformis. Partial and total remissions have been achieved with both intralesional and systemic administration. Ongoing studies aim to identify which conditions are most responsive, the optimal dosage and regimen and the most effective class of interferon. The mechanisms by which these responses occur are unknown, but are thought to depend on interferon inducing specific cellular proteins.

Animals↗
PubMed1985

Identification of the protein encoded by the E6 transforming gene of bovine papillomavirus.

Papillomaviruses (PV) contain several conserved genes that may encode nonstructural proteins; however, none of these predicted gene products have been identified. Papillomavirus E6 genes are retained and expressed as RNA in PV-associated human and animal carcinomas and cell lines. This suggests that the E6 gene product may be important in the maintenance of the malignant phenotype. The E6 open reading frame of the bovine papillomavirus (BPV) genome has been identified as one of two BPV genes that can independently transform mouse cells in vitro. A polypeptide encoded by this region of BPV was produced in a bacterial expression vector and used to raise antisera. The antisera specifically immunoprecipitated the predicted 15.5-kilodalton BPV E6 protein from cells transformed by the E6 gene. The E6 protein was identified in both the nuclear and membrane fractions of these transformed cells.

Animals↗
PubMed1985

X-linked inheritance of epidermodysplasia verruciformis. Genetic and virologic studies of a kindred.

We describe a family with typical epidermodysplasia verruciformis (EV) in which only male members are affected. Whereas none of the index patient's ten children have EV, four of eight grandsons born to his daughters have inherited the disorder. All are infected with human papillomavirus (HPV) 3 and HPV 8. The inheritance in this kindred most likely results from an X-linked recessive genetic defect. Since other kindreds have been described with autosomal inheritance, this novel inheritance pattern suggests that the persistent high clinical susceptibility to HPV infection characteristic of EV may result from defects in either of at least two different genetic loci, one of which may be located on the X chromosome.

Animals↗
PubMed1984

Response of warts in epidermodysplasia verruciformis to treatment with systemic and intralesional alpha interferon.

The susceptibility of human papillomavirus infection to polyclonal human leukocyte interferon (IFN-alpha) has been evaluated in patients with epidermodysplasia verruciformis (EV), a disease with extensive chronic papillomavirus-induced warts. In a double-blind, placebo-controlled study with intralesional IFN-alpha, four of five IFN-alpha-treated warts regressed; none of the placebo-treated warts responded (p = 0.024). Three patients with EV were treated with systemic IFN-alpha for 4 weeks in an open study, achieving partial regression of warts in all three. In a double-blind, placebo-controlled study, warts in two children with EV regressed with systemic IFN-alpha while two who received placebo showed no improvement. The lesions recurred following cessation of therapy. At the completion of therapy with IFN-alpha, histologic normalization was accompanied by a 95% decrease in the number of viral antigen-containing cells in the warts (p less than 0.001). We conclude that warts in EV respond to systemic and intralesional IFN-alpha.

Adult↗
PubMed1984

Tumor viruses, oncogenes, and human cancer.

We review the biology of transforming retroviruses and their relationship to cellular transforming genes (tumor oncogenes). Evidence is discussed for the involvement of a retrovirus in a newly described syndrome, "adult T cell leukemia/lymphoma," which has a high incidence of skin involvement. This virus is related to the animal retroviruses which induce tumors in susceptible hosts after a long latent period. Cellular transforming genes encode proteins which directly change the oncogenic potential of a cell. These genes, which are altered forms of normal cellular genes, have been isolated from a wide variety of human tumors. Viral and cellular transforming genes produce their changes by at least two different mechanisms: abnormally high production of the normal protein encoded by these genes, or normal levels of an altered form of the protein.

Animals↗
PubMedDate not supplied

Bovine papillomavirus E2 trans-activating gene product binds to specific sites in papillomavirus DNA.

Enhancers are cis-acting elements that activate transcription in higher eukaryotes independently of their position or orientation relative to the promoter that they activate. The mechanisms by which enhancers activate transcription are poorly understood, in part because, with the exception of the glucocorticoid receptor, the proteins that directly interact with enhancers have not been purified, nor have the genes encoding them been cloned. The upstream regulatory region (URR) that immediately precedes the early genes of the bovine papillomavirus type 1 genome (BPV) has enhancer activity when it is activated by a trans-acting gene product of the BPV E2 open reading frame (ORF) (Fig. 1). It is not known whether this enhancement represents a direct or indirect effect of E2 on the URR. We have used an E2 peptide expressed in bacteria and a DNA-protein complex immunoprecipitation assay to study E2-mediated enhancement of transcription by the URR. We show here that this peptide directly binds to four specific sites in the BPV URR, and to one site in the human papillomavirus (H)PV16 URR. All the binding sites contain a related sequence of nucleotides; a 23 base pair (bp) fragment containing this sequence can specifically prevent binding of the E2 protein to the BPV URR. The BPV E2-URR enhancer interaction may therefore represent a useful model system for studying the mechanism of transcriptional enhancement, as both an effector protein and its target enhancer can be purified and genetically manipulated.

Animals↗