Shear stress activation of the glucocorticoid receptor transcription pathway

Summary form only given. Steroid hormones have profound physiological effects, controlling the transcription of genes involved in areas such as development, differentiation, metabolism, and reproduction. This study focuses on interactions between shear stress-induced and hormone-induced transcription pathways. Specifically, the present study tests the hypothesis that steady laminar shear stress activates the glucocorticoid receptor signaling pathway in endothelial cells. A functional chimeric protein of the green fluorescent protein (GFP) and the glucocorticoid receptor (GR) is used to track translocation of the receptors in cells. In both bovine aortic endothelial (BAEC) and 3T3 fibroblast cells, shear stress at 10 and 25 dynes/cm² activates the receptors, causing GFP-GR to nuclear localize in a manner similar to induction with 25 μM dexamethasone, a potent glucocorticoid. However, in BAEC cells, but not in 3T3 cells, GFP-GR nuclear localization is blocked substantially by kinase inhibitors (PD098059 and LY294002). Promoter studies using a secreted alkaline phosphatase (SEAP) reporter plasmid with glucocorticoid response elements as enhancer sequence indicate that SEAP production in BAEC cells exposed to shear stress of 10 and 25 dynes/cm² for up to 8 hrs produces SEAP at a level comparable to induction with 25 μM dexamethasone. These results indicate the potential role glucocorticoid receptors play in shear-induced anti-inflammatory responses and transcriptional changes in endothelial cells. Potential impact of this project can be considered in terms of biotechnology, gene therapy, drug delivery, and tissue engineering.