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Journal of Virology, September 2002, p. 8710-8721, Vol. 76, No. 17
0022-538X/02/$04.00+0 DOI: 10.1128/JVI.76.17.8710-8721.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
Department of Microbiology and Immunology,1 The Cancer Center, University of Rochester, Rochester, New York 146422
Received 5 March 2002/ Accepted 6 June 2002
Previously, we reported that human papillomavirus (HPV) type 16 E6 binds to C/H1, C/H3, and the C-terminal domains of coactivators p300 and CBP, causing the modulation of the transcription of certain genes controlled by NF-
B (p65 or relA) and p53. To establish the biological significance of these observations, we have focused on the transcriptional regulation of interleukin-8 (IL-8), a potent chemoattractant for T lymphocytes and neutrophils, which is also essential for the initiation of the local immune response. The IL-8 promoter is regulated by NF-
B/p65 in response to tumor necrosis factor alpha and requires the cooperation of the coactivators CBP/p300 and steroid receptor coactivator 1 (SRC-1) and the p300/CBP-associated factor (P/CAF) for optimal activation. Here we report that, in the presence of HPV-16 E6, the promoter activity of IL-8 was repressed. Moreover, from the mutational analysis of the IL-8 promoter, we found that E6 down-regulates the IL-8 promoter activity through the NF-
B/p65 binding site. This inhibition appears to result from the ability of HPV-16 E6 to compete with NF-
B/p65 and SRC-1 for binding to the N terminus and C terminus of CBP, respectively. Reporter data also showed that E7 represses IL-8 promoter activity, though to a lesser extent than E6 but, like E6, the repression by E7 is through the NF-
B/p65 binding site. E7 was shown for the first time to bind to P/CAF, and the binding was necessary for the down regulation of the IL-8 promoter. E6 and E7 together inhibited transcription of the IL-8 promoter to a greater extent than either alone. Finally, by RNase protection assay, we showed that the synthesis of endogenous IL-8 mRNA was repressed in keratinocytes stably expressing E6 and E7. Taken together, the results provide evidence that E6 and E7 can cooperatively disrupt IL-8 transcription through disruption of transcriptional active complexes, and this may have important consequences for immune responses in infected hosts.
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