Dr. Beaulieu is recipient of a Frederik Craven Moore award.
Hypoxia and glucocorticoid signaling converge to regulate macrophage migration inhibitory factor gene expression
Article first published online: 30 JUL 2009
Copyright © 2009 by the American College of Rheumatology
Arthritis & Rheumatism
Volume 60, Issue 8, pages 2220–2231, August 2009
How to Cite
Elsby, L. M., Donn, R., Alourfi, Z., Green, L. M., Beaulieu, E. and Ray, D. W. (2009), Hypoxia and glucocorticoid signaling converge to regulate macrophage migration inhibitory factor gene expression. Arthritis & Rheumatism, 60: 2220–2231. doi: 10.1002/art.24659
- Issue published online: 30 JUL 2009
- Article first published online: 30 JUL 2009
- Manuscript Accepted: 7 APR 2009
- Manuscript Received: 8 JAN 2009
- Arthritis Research Campaign. Grant Numbers: ARC grants 16404, 17900
- Manchester Academic Health Sciences Centre
- NIHR Manchester Biomedical Research Centre
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.
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.
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.
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.