Activity and intracellular localization of the human cytomegalovirus protein pp71.
The human cytomegalovirus (HCMV) tegument phosphoprotein pp71 activates viral immediate early (IE) transcription and thus has a role in initiating lytic infection. Protein pp71 stimulates expression from a range of promoters in a sequence-independent manner, and in this respect behaves similarly to the herpes simplex virus type 1 (HSV-1) IE protein ICP0. The intracellular localization of pp71 was investigated after its expression from transfected plasmids or from HSV-1 mutants constructed to produce pp71 transiently. The protein colocalized with the cell promyelocytic leukaemia (PML) protein at nuclear domain 10 (ND10) structures but, unlike ICP0, pp71 did not induce disruption of ND10. The activity of pp71 in mouse sensory neurons in vivo was investigated after co-inoculation of animals with pairs of HSV-1 mutants, one expressing pp71 and the second containing the E. coli lacZ gene controlled by various promoters. In this system, pp71 stimulated beta-galactosidase expression from a range of viral IE promoters when mice were analysed at 4 days postinoculation. At later times, expression of pp71 resulted in a reduction in numbers of neurons containing beta-galactosidase, indicating cytotoxicity or promoter shutoff. The HSV-1 latency-active promoter was not responsive to pp71, demonstrating specificity in the activity of the protein. Pp71 was as active in mice lacking both copies of the PML gene (PML-/-) as in control animals, and in PML-/- fibroblasts pp71 stimulated gene expression as effectively as in other cell types. Therefore, neither the PML protein nor the normal ND10 structure is necessary for pp71 to stimulate gene expression.
Marshall
Ker R
KR
Medical Research Council Virology Unit, Church Street, Glasgow G11 5JR, UK1.
Rowley
Kate V
KV
Medical Research Council Virology Unit, Church Street, Glasgow G11 5JR, UK1.
Rinaldi
Angela
A
Medical Research Council Virology Unit, Church Street, Glasgow G11 5JR, UK1.
Nicholson
Iain P
IP
Medical Research Council Virology Unit, Church Street, Glasgow G11 5JR, UK1.
Ishov
Alexander M
AM
The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA2.
Maul
Gerd G
GG
The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA2.
Preston
Chris M
CM
Medical Research Council Virology Unit, Church Street, Glasgow G11 5JR, UK1.
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D003587:Cytomegalovirus / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D015967:Gene Expression Regulation, Viral; D017781:Genes, Immediate-Early; D005822:Genetic Vectors; D018259:Herpesvirus 1, Human / Q000235:genetics; D006801:Humans; D007763:Lac Operon; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D009363:Neoplasm Proteins / Q000172:deficiency / Q000235:genetics; D009474:Neurons / Q000378:metabolism; D009687:Nuclear Proteins; D010957:Plasmids; D000071156:Promyelocytic Leukemia Protein; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics; D014158:Transcription, Genetic; D025521:Tumor Suppressor Proteins; D014709:Vero Cells / Q000378:metabolism; D014764:Viral Proteins / Q000032:analysis / Q000378:metabolism*; D001616:beta-Galactosidase / Q000378:metabolism
D009363:Neoplasm Proteins; D009687:Nuclear Proteins; C513293:Pml protein, mouse; D000071156:Promyelocytic Leukemia Protein; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D014764:Viral Proteins; C051298:cytomegalovirus phosphoprotein 71kDa; C070576:PML protein, human; D001616:beta-Galactosidase