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Dissertation
Impact of a downstream C/EBP site on HIV-1 gene expression and pathogenesis
Doctor of Philosophy (Ph.D.), Drexel University
Dec 2007
DOI:
https://doi.org/10.17918/00010172
Abstract
Previous studies have shown that two CCAAT enhancer binding protein (C/EBP) sites, upstream of the transcriptional start site, are necessary for subtype B human immunodeficiency virus type 1 (HIV-1) gene expression in cells of the monocytemacrophage lineage. However, no studies have been reported concerning the C/EBP sites within the non-subtype B HIV-1 LTRs or downstream of the transcriptional start site within the subtype B LTR. Electrophoretic mobility shift (EMS) analyses demonstrated that one of three putative downstream C/EBP binding sites (downstream element three, DS3) within the subtype B LTR was able to form a DNA-protein complex containing C/EBP[beta]. By utilizing the DS3-9C variant, which exhibits low DNA binding affinity for C/EBP[beta], it has been shown that the DS3 binding site is important for HIV-1 basal transcription. The DS3-9C-containing LTR exhibits a lower basal transcription level and is able to be transactivated by C/EBP[beta]-2 to a lower extent compared to the parental HIV-1 subtype B LTR. However, upon activation with Tat alone or with C/EBP[beta]-2 together, the DS3-9C-containing LTRs exhibit a similar or even greater transcriptional activation than that of the parental LTR. HIV-1 molecular clone viruses containing the DS3-9C C/EBP binding site variant have revealed a decreased replication capacity and a delayed rate of replication. These results suggest that the DS3-9C configuration might be related to virual persistence and reactivation in cells of the monocyte-macrophage lineage. Furthermore, one C/EBP binding site has been identified within the subtype C LTR. Subtype B and C LTRs are able to be activated by C/EBP[beta]-2 to similar levels in the monocytic cell line, U-937. The interaction observed between C/EBP[beta]-2 and Tat with the subtype B and C LTRs suggest the functionally important transactivation ability of C/EBP[beta] among different subtypes that, under certain circumstances, may be cell type dependent.
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Details
- Title
- Impact of a downstream C/EBP site on HIV-1 gene expression and pathogenesis
- Creators
- Yujie Liu
- Contributors
- Brian Wigdahl (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xx, 273 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Microbiology and Immunology; College of Medicine; Drexel University
- Other Identifier
- 991021888945604721