The characterization of transcriptional regulation of murinefgl2 gene.
Published: 2005
Language: eng
Number of pages: 233
Description: Fgl2 is plays an important role in MHV-3 induced fulminant hepatitis, as well as many other inflammatory diseases both through its ability to directly cleave prothrombin to thrombin (prothrombinase activity) and by its immunomodulatory activity. The mechanisms controlling fgl2 expression, especially at the transcriptional level, are still poorly understood. The elucidation of mechanisms that regulate fgl2 expression will allow for better understanding of the relevance of fgl2 in fgl2 related immune mediated diseases. This thesis presents the details on the characterization of the regulation of fgl2 gene expression at the transcriptional level.Finally, it was found that IFN-gamma, but not IFN-alpha, LPS, TNF-alpha and IL-1 induced fgl2 mRNA and protein expression in macrophage cells. (Abstract shortened by UMI.)To this end, the genomic DNA of fgl2 was cloned from BALB/cJ mice. The transcriptional initiation site was mapped to nine nucleotides upstream of the translation start codon. A comparison of fgl2 genomic sequence from the MHV-3 susceptible BALB/cJ mice with the resistant A/J mice did not show significant differences and the promoter sequences from both strains of mice (1.3kb) were identical. Thus one cannot account for differences in fgl2 transcription and disease outcome between resistant and susceptible strains based on DNA structure.To understand the mechanism controlling fgl2 constitutive expression, fgl2 transcription was examined in murine vascular endothelial cells known to constitutively express fgl2. A complex positive regulatory domain (PRD) spanning a 39 bp sequence from -87 to -49 (relative to the transcription start site) was identified. The nucleoprotein complexes that form on this PRD contain Sp1/Sp3 family members, OCT-1, and ETS-1. Heterologous expression in Drosophila Schneider cells confirmed that the constitutive expression of this gene is controlled by ETS-1 in the presence of both the Sp1 and Sp3 transcription factors. These results suggested a multiple cis DNA elements in a clustered region function cooperatively to regulate constitutive fgl2 expression.I showed that the induction of fgl2 in MHV-3 infected macrophages is at least in part due to increased transcription. Nucleocapsid (N) protein of viral strains producing fulminant hepatitis was then found to induce transcription of the fgl2 gene and to elevate procoagulant activity (PCA). Preliminary mapping of the fgl2 promoter has defined a region from -372 to -306 upstream from the transcription initiation site to be responsive to N protein and also requires the Sp1/Sp3 binding site.
Notes: Thesis (Ph.D.)--University of Toronto, 2005.

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Source: Dissertation Abstracts International, Volume: 66-06, Section: B, page: 2962.