The Interferon Regulatory Factors (IRFs) are a family of interferon-inducible proteins which play distinct roles in diverse processes such as pathogen response, cytokine signalling, cell growth regulation and hematopoietic development. The objective of this research was to investigate the mechanisms by which IRF-1 and IRF-2 regulate gene expression and cell growth. Structure-function analyses of the IRF-2 protein demonstrate that transcriptional repression by IRF-2 is contained within the first 125 N-terminal amino acids and correlates directly with IRF-2 DNA binding. Overexpression of functional IRF-2 deletion mutant proteins in NIH3T3 cells results in oncogenic transformation and tumorigenesis, suggesting that IRF-2 oncogenicity correlates directly with transcriptional repression. Similar structure-function analyses localize IRF-1 transactivation to the C-terminus. Like IRF-1, hybrid constructs which fuse the DNA binding domain of IRF-1 and IRF-2 to the transactivation domain of NF-kappaB RelA(p65) are transcriptional activators. Inducible expression of IRF-1 and IRF/RelA in NIH3T3 cells results in reduced cellular growth and induction of apoptosis. Furthermore, expression of the PKR, STAT1(p91), and WAF1 growth regulatory proteins are elevated following induction of IRF-1 or IRF/RelA, correlating transactivation function and tumor suppressor activity of IRF-1 or IRF/RelA. By RNA fingerprinting, the secretory leukocyte protease inhibitor (SLPI) was identified as the first gene whose expression is downregulated by IRF-1 or IRF-1/RelA. A region in the SLPI promoter was identified that bound IRF-1, suggesting a direct mechanism for IRF-1 regulation of SLPI expression.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.35028 |
| Date | January 1998 |
| Creators | Nguyen, Hannah Anh-Quan. |
| Contributors | Hiscott, John (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Microbiology and Immunology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001635424, proquestno: NQ44532, Theses scanned by UMI/ProQuest. |
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