@article{mbs:/content/journal/jgv/10.1099/vir.0.83224-0, author = "Kofod-Olsen, Emil and Ross-Hansen, Katrine and Mikkelsen, Jacob Giehm and Höllsberg, Per", title = "Human herpesvirus 6B U19 protein is a PML-regulated transcriptional activator that localizes to nuclear foci in a PML-independent manner", journal= "Journal of General Virology", year = "2008", volume = "89", number = "1", pages = "106-116", doi = "https://doi.org/10.1099/vir.0.83224-0", url = "https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.83224-0", publisher = "Microbiology Society", issn = "1465-2099", type = "Journal Article", abstract = "Human herpesvirus 6B (HHV-6B) contains an IE-B domain spanning open reading frames U16/17–U19, based on homology with human cytomegalovirus. Here, the protein product, U19, of the HHV-6B U19 gene is identified as a 47 kDa transcriptional activator. HHV-6B infection or overexpression of U19 transactivated the RANTES promoter. Mutational analysis of the promoter indicated that transactivation was not critically dependent on the promoter sites CRE, NF-κB, ISRE or NF-IL6. ND10 are nuclear substructures that are involved in several cellular regulatory pathways, including those controlling gene expression. HHV-6B infection resulted in a reduced number of ND10 structures, but with a concomitantly increased level of promyelocytic leukaemia (PML) protein expression and mRNA induction. The U19 protein co-located to ND10 with PML and heterochromatin protein 1 (HP1), but whilst PML formed a ring structure, U19 also localized to the centre of ND10. Knockdown of PML by small interfering RNA did not prevent U19 localization to ND10-like foci, but instead led to a fourfold increase in U19-induced transcription from the RANTES promoter. Generation of four truncated U19 proteins indicated that the N-terminal portion of the protein contains a sequence responsible for nuclear localization; a domain in the N-terminal half of U19 is responsible for its ND10 localization, whereas the C-terminal portion contains the transactivation domain. None of the truncated proteins retained full transactivating ability on the RANTES promoter. Thus, U19 is a transcriptional activator that co-localizes with PML and localizes to ND10-like foci independently of PML, yet is regulated negatively by PML or its associated proteins.", }