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J. Virol., Dec 1995, 8051-8056, Vol 69, No. 12
Z Gu and G Matlashewski
The mitogen-activated protein (MAP) kinase signal transduction pathway is
an intracellular signaling cascade which mediates cellular responses to
growth and differentiation factors. The MAP kinase pathway can be activated
by a wide range of stimuli dependent on the cell types, and this is
normally a transient response. Oncogenes such as ras, src, raf, and mos
have been proposed to transform cells in part by prolonging the activated
stage of components within this signaling pathway. The human papillomavirus
(HPV) oncogenes E6 and E7 play an essential role in the in vitro
transformation of primary human keratinocytes and rodent cells. The HPV
type 16 E5 gene has also been shown to have weak transforming activity and
may enhance the epidermal growth factor (EGF)- mediated signal transduction
to the nucleus. In the present study, we have investigated the effects of
the oncogenic HPV type 16 E5, E6, and E7 genes on the induction of the MAP
kinase signaling pathway. The E5 gene induced an increase in the MAP kinase
activity both in the absence and in the presence of EGF. In comparison, the
E6 and E7 oncoproteins do not alter the MAP kinase activity or prolong the
MAP kinase activity induced with EGF. These findings suggest that E5 may
function, at least in part, to enhance the cell response through the MAP
kinase pathway. However, the transforming activity of E6 and E7 is not
associated with alterations in the MAP kinase pathway. These findings are
consistent with E5 enhancing the response to growth factor stimulation.
Copyright © 1995, American Society for Microbiology
Effect of human papillomavirus type 16 oncogenes on MAP kinase activity
Institute of Parasitology, McGill University, Ste. Anne de Bellevue, Quebec, Canada.
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