Functional characterization of the transforming genes of adenovirus and papillomavirus
Abstract
To determine whether the transcription regulatory activities of the adenoviral E1a gene play a role in its ability to transform primary cells an extensive series of mutations within the E1a gene have been constructed. The mutants were characterized for their ability to transactivate the adenoviral early promoters, repress the transcriptional stimulation of the polyoma virus enhancer, establish primary baby rat kidney cells in culture, cooperate with the activated Ha-ras oncogene in morphologically transforming these cells, permit efficient growth in both quiescent and proliferating W138 cells and induce quiescent rodent cells to enter S phase. The mutant phenotypes reveal that: (1) the two transcription regulatory activities of E1a are separable since essential protein domains map within different regions of the protein, (2) transactivation is unlikely to contribute significantly to E1a mediated transformation since several isolated mutants lost the ability to transactivate but were nevertheless efficient at transformation, (3) establishment, oncogene cooperation and the ability to induce S phase progression are linked to enhancer repression suggesting that E1a transforms cells by the repression of a cellular enhancer, and (4) transformation is a consequence of E1a activities normally used by the virus to insure efficient growth in quiescent cells. The close association of human papillomavirus type-16 DNA with a majority of human cervical carcinomas implies some role for the virus in this type of cancer. This study demonstrates that the human papillomavirus type-16 genome when cloned into a molony retrovirus expression vector is capable of cooperating with the cellular ras oncogene in the morphological transformation of primary baby rat kidney cells. Deletion mutants localize this activity to either/both the E6 or E7 open reading frames of the virus.
Degree
Ph.D.
Advisors
Jones, Purdue University.
Subject Area
Molecular biology
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