Hypoxia and glucocorticoid signaling converge to regulate macrophage migration inhibitory factor gene expression

Laura Elsby, Rachelle Donn, Zaynab Alourfi, Laura Green, Elaine Beaulieu, David Ray

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Objective. Macrophage migration inhibitory factor (MIF) is a proinflammatory mediator involved in the pathogenesis of rheumatoid arthritis. This study was undertaken to identify the MIF promoter elements responsible for regulating gene expression. Methods. Luciferase reporter gene assays were used to identify the MIF promoter sequence responsible for basal activity. Bioinformatic analysis was used to predict transcription factor binding sites, and electrophoretic mobility shift assay (EMSA) was used to demonstrate transcription factor binding. Chromatin immunoprecipitation (ChIP) was used to demonstrate transcription factor loading on the MIF promoter. Results. We identified the minimal promoter sequence required for basal MIF promoter activity that was also capable of conferring glucocorticoid-dependent inhibition in a T lymphocyte model cell line. Deletion studies and EMSA revealed 2 elements in the MIF promoter that were responsible for basal promoter activity. The 5′ element binds CREB/activating transcription factor 1, and the 3′ element is a functional hypoxia-responsive element binding hypoxia-inducible factor 1α. Further studies demonstrated that the cis elements are both required for glucocorticoid-dependent inhibition. ChIP demonstrated glucocorticoid-dependent recruitment of glucocorticoid receptor α to the MIF promoter in lymphocytes within 1 hour of treatment and a concomitant decrease in acetylated histone H3. Conclusion. Our findings indicate that hypoxia and glucocorticoid signaling converge on a single element regulating MIF; this regulatory unit is a potential interacting node for microenvironment sensing of oxygen tension and glucocorticoid action in foci of inflammation. © 2009, American College of Rheumatology.
    Original languageEnglish
    Pages (from-to)2220-2231
    Number of pages11
    JournalArthritis Care & Research
    Volume60
    Issue number8
    Early online date30 Jul 2009
    DOIs
    Publication statusPublished - Aug 2009

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