TOXI 26 |
| The role for the aryl hydrocarbon receptor (AHR) in normal vascular development led us to investigate the interplay between the AHR and fluid shear stress. Using an in vitro system, we show that fluid flow induces a robust AHR-mediated increase in CYP1 expression. Furthermore, we demonstrate that incubation with sheared bovine or human sera is sufficient for AHR activation, indicating that direct cellular exposure to shear stress is not required for this response. Fractionation of sera by size and density revealed the AHR-activating factor to be low-density lipoprotein (LDL). Purified LDL (0.1 mg/ml) from sheared sera induces a 6-fold increase in AHR-mediated signaling as compared with LDL purified from static sera. Similar results were obtained by exposing a purified fraction of LDL to fluid flow, suggesting that shear stress is capable of directly modifying LDL structure and/or function. In addition, we show that LDL can be converted to an AHR-activating species by conventional methods of lipoprotein modification, such as NaOCl oxidation. |
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Frontiers in Chemical Toxicology
1:00 PM-4:45 PM, Monday, August 20, 2007 BCEC -- 258C, Oral
Division of Chemical Toxicology |