Cellular factors are required to activate bovine papillomavirus-1 early gene transcription and to establish viral plasmid persistence but are not required for cellular transformation.
Transcription from the major upstream early gene promoter, P89, of bovine papillomavirus (BPV)-1 is detectable in transfected cells lacking viral gene products yet also responds to viral E2 proteins. In contrast to human papillomaviruses (HPVs), the BPV upstream regulatory region (URR) functions as a transcriptional enhancer in epithelial cells and fibroblasts of bovine, murine or human origin. Mutations of Sp1 and/or two novel transcriptional enhancer factor (TEF)-1 sites within the 5' URR of the intact BPV-1 genome dramatically reduced P89-initiated mRNA levels, leading to decreased BPV-1 plasmid amplification and inefficient formation of transformed cell foci. However, cell lines transformed with wt or mutant BPV-1 genomes contained similar levels of unintegrated BPV-1 DNA, P89 mRNA and E2-dependent transactivation. We conclude that cellular factors necessary for activating viral early gene transcription, establishment of viral plasmid replication and cell immortalization are not required during the maintenance phase of BPV-1 infection.
Haugen
Thomas H
TH
Veterans Affairs Medical Center, The Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA. thomas-haugen@uiowa.edu
Lace
Michael J
MJ
Ishiji
Takaoki
T
Sameshima
Atsushi
A
Anson
James R
JR
Turek
Lubomir P
LP
D000818:Animals; D052688:Bovine papillomavirus 1 / Q000235:genetics*; D002417:Cattle; D002418:Cattle Diseases / Q000821:virology; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D015967:Gene Expression Regulation, Viral; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D030361:Papillomavirus Infections / Q000821:virology; D011401:Promoter Regions, Genetic; D016329:Sp1 Transcription Factor / Q000378:metabolism; D000091262:TEA Domain Transcription Factors; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D016329:Sp1 Transcription Factor; D000091262:TEA Domain Transcription Factors; C057182:TEAD1 protein, human; D014157:Transcription Factors