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Your search keyword '"Müller-Schiffmann, A."' showing total 4 results
Start Over Author "Müller-Schiffmann, A." Journal journal of virology
4 results on '"Müller-Schiffmann, A."'

1. The E6 Protein of the Cutaneous Human Papillomavirus Type 8 Can Stimulate the Viral Early and Late Promoters by Distinct Mechanisms

Author

Julia Beckmann, Andreas Müller-Schiffmann, and Gertrud Steger

Subjects
Gene Expression Regulation, Viral, Keratinocytes, Immunology, P300-CBP Transcription Factors, Biology, Transfection, Microbiology, Cell Line, Virology, Gene expression, Coactivator, medicine, Transcriptional regulation, Humans, p300-CBP Transcription Factors, Promoter Regions, Genetic, Papillomaviridae, Promoter, Oncogene Proteins, Viral, Epidermodysplasia verruciformis, medicine.disease, Molecular biology, Genome Replication and Regulation of Viral Gene Expression, Insect Science, Mutagenesis, Site-Directed, Trans-Activators
Abstract

The expression of the proteins encoded by human papillomaviruses (HPVs) is tightly linked to the differentiation program of the infected keratinocytes. The late promoter, expressing the structural proteins, becomes activated in the differentiated keratinocytes, while the early promoter is also active in the basal layers. We have shown previously that the viral transcriptional regulator E2 and the cellular coactivator p300 cooperate in activation of gene expression of HPV8, which infects the skin and is associated with epidermodysplasia verruciformis. Here we demonstrate that this activation is further stimulated after overexpression of the E6 oncoprotein of HPV8 (8E6). RNase protection experiments revealed that 8E6 efficiently cooperates with 8E2 and p300 in activation of the late promoter. In addition, the early promoter, which did not respond to 8E2 and/or p300, was stimulated more than fourfold by 8E6. Our data suggest that both promoters are activated via distinct mechanisms, since the activation of the early promoter was achieved by the N-terminal moiety of 8E6; in contrast, its C-terminal half was sufficient for late promoter activation. This was markedly reduced by the deletion of amino acids 132 to 136 of 8E6, which also abolished the binding to p300, indicating that a direct interaction between 8E6 and p300 is involved. Moreover, a 45-amino-acid segment within the C/H3 region of p300 is required for 8E6 to stimulate the coactivator function of p300. Our results demonstrate for the first time that an E6 oncoprotein of HPV directly contributes to the regulation of HPV gene expression.

Published
2006
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4. Biological effects and use of PrPSc- and PrP-specific antibodies generated by immunization with purified full-length native mouse prions.

Author

Petsch B, Müller-Schiffmann A, Lehle A, Zirdum E, Prikulis I, Kuhn F, Raeber AJ, Ironside JW, Korth C, and Stitz L

Subjects
Animals, Antibodies, Monoclonal isolation & purification, Antibodies, Monoclonal metabolism, Cell Line, Infectious Disease Incubation Period, Mice, Mice, Inbred BALB C, Mice, Knockout, Prion Proteins, Protein Binding, Time Factors, Antibodies, Monoclonal therapeutic use, Prion Diseases prevention & control, Prions immunology, Prions isolation & purification
Abstract

The prion agent is the infectious particle causing spongiform encephalopathies in animals and humans and is thought to consist of an altered conformation (PrP(Sc)) of the normal and ubiquitous prion protein PrP(C). The interaction of the prion agent with the immune system, particularly the humoral immune response, has remained unresolved. Here we investigated the immunogenicity of full-length native and infectious prions, as well as the specific biological effects of the resulting monoclonal antibodies (MAbs) on the binding and clearance of prions in cell culture and in in vivo therapy. Immunization of prion knockout (Prnp(0/0)) mice with phosphotungstic acid-purified mouse prions resulted in PrP-specific monoclonal antibodies with binding specificities selective for PrP(Sc) or for both PrP(C) and PrP(Sc). PrP(Sc)-specific MAb W261, of the IgG1 isotype, reacted with prions from mice, sheep with scrapie, deer with chronic wasting disease (CWD), and humans with sporadic and variant Creutzfeldt-Jakob disease (CJD) in assays including a capture enzyme-linked immunosorbent assay (ELISA) system. This PrP(Sc)-specific antibody was unable to clear prions from mouse neuroblastoma cells (ScN2a) permanently infected with scrapie, whereas the high-affinity MAb W226, recognizing both isoforms, PrP(Sc) and PrP(C), did clear prions from ScN2a cells, as determined by a bioassay. However, an attempt to treat intraperitoneally prion infected mice with full-length W226 or with a recombinant variable-chain fragment (scFv) from W226 could only slightly delay the incubation time. We conclude that (i) native, full-length PrP(Sc) elicits a prion-specific antibody response in PrP knockout mice, (ii) a PrP(Sc)-specific antibody had no prion-clearing effect, and (iii) even a high-affinity MAb that clears prions in vitro (W226) may not necessarily protect against prion infection, contrary to previous reports using different antibodies.

Published
2011
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