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dc.contributor.authorFalquet, Mar
dc.contributor.authorPrezioso, Carla
dc.contributor.authorLudvigsen, Maria A.
dc.contributor.authorBruun, Jack-Ansgar
dc.contributor.authorPasserini, Sara
dc.contributor.authorSveinbjørnsson, Baldur
dc.contributor.authorPietropaolo, Valeria
dc.contributor.authorMoens, Ugo
dc.date.accessioned2023-08-29T07:57:16Z
dc.date.available2023-08-29T07:57:16Z
dc.date.issued2023-01-03
dc.description.abstractMerkel cell polyomavirus (MCPyV) is the major cause of Merkel cell carcinoma (MCC), an aggressive skin cancer. MCPyV large T-antigen (LTag) and small T-antigen (sTag) are the main oncoproteins involved in MCPyV-induced MCC. A hallmark of MCPyV-positive MCC cells is the expression of a C-terminal truncated LTag. Protein kinase A (PKA) plays a fundamental role in a variety of biological processes, including transcription by phosphorylating and thereby regulating the activity of transcription factors. As MCPyV LTag has been shown to be phosphorylated and acts as a transcription factor for the viral early and late promoter, we investigated whether LTag can be phosphorylayted by PKA, and whether this affects the transcript activity of LTag. Using a phosphorylation prediction algorithm, serine 191, 203, and 265 were identified as putative phosphorylation sites for PKA. Mass spectrometry of in vitro PKA-phosphorylated peptides confirmed phosphorylation of S203 and S265, but not S191. Full-length LTag inhibited early and late promoter activity of MCPyV, whereas the truncated MKL2 LTag variant stimulated both promoters. Single non-phosphorylable, as well as phosphomimicking mutations did not alter the inhibitory effect of full-length LTag. However, the non-phosphorylable mutations abrogated transactivation of the MCPyV promoters by MKL2 LTag, whereas phosphomimicking substitutions restored the ability of MKL2 LTag to activate the promoters. Triple LTag and MKL2 LTag mutants had the same effect as the single mutants. Activation of the PKA signaling pathway did not enhance MCPyV promoter activity, nor did it affect LTag expression levels in MCPyV-positive Merkel cell carcinoma (MCC) cells. Our results show that phosphorylation of truncated LTag stimulates viral promoter activity, which may contribute to higher levels of the viral oncoproteins LTag and sTag. Interfering with PKA-induced LTag phosphorylation/activity may be a therapeutic strategy to treat MCPyV-positive MCC patients.en_US
dc.identifier.citationFalquet, Prezioso C, Ludvigsen M, Bruun JA, Passerini S, Sveinbjørnsson B, Pietropaolo V, Moens u. Regulation of Transcriptional Activity of Merkel Cell Polyomavirus Large T-Antigen by PKA-Mediated Phosphorylation. International Journal of Molecular Sciences. 2023;24(1)en_US
dc.identifier.cristinIDFRIDAID 2100224
dc.identifier.doi10.3390/ijms24010895
dc.identifier.issn1661-6596
dc.identifier.issn1422-0067
dc.identifier.urihttps://hdl.handle.net/10037/30493
dc.language.isoengen_US
dc.publisherMDPIen_US
dc.relation.journalInternational Journal of Molecular Sciences
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2023 The Author(s)en_US
dc.rights.urihttps://creativecommons.org/licenses/by/4.0en_US
dc.rightsAttribution 4.0 International (CC BY 4.0)en_US
dc.titleRegulation of Transcriptional Activity of Merkel Cell Polyomavirus Large T-Antigen by PKA-Mediated Phosphorylationen_US
dc.type.versionpublishedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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Attribution 4.0 International (CC BY 4.0)
Except where otherwise noted, this item's license is described as Attribution 4.0 International (CC BY 4.0)