Shear stress-induced Ets-1 modulates protease inhibitor expression in microvascular endothelial cells

✍ Scribed by Malgorzata Milkiewicz; Cassandra Uchida; Eric Gee; Tomasz Fudalewski; Tara L. Haas

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 280 KB
• Volume: 217
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.21526

✦ Synopsis

Abstract

Elevated shear stress within the skeletal muscle microvasculature is implicated in the induction of a longitudinal splitting form of angiogenesis, which is characterized by the lack of basement membrane breakage. We investigated whether the transcriptional regulator, Ets‐1, is responsive to changes in hemodynamic forces and if so, whether Ets‐1 controls microvascular endothelial cell integrity by inducing the expression of inhibitors of matrix degrading proteases. Rats were treated with prazosin for 2, 4, and 7 days to increase in microvascular shear stress in hindlimb skeletal muscles. In complimentary in vitro experiments, rat microvascular skeletal muscle endothelial cells were exposed to laminar shear stress (15 dyne/cm^2^) for 0.5, 2, and 24 h. TaqMan PCR analysis of laser microdissected capillaries isolated from EDL muscles demonstrated transient (after 2 days) induction of Ets‐1 gene expression. In cultured cells, a transient up‐regulation of Ets‐1 mRNA was observed after 2 h shear stimulation, accompanied by increased phosphorylation of Ets‐1 and enhanced Ets‐1 DNA binding activity. This response was modulated by ERK1/2 and p38 MAP kinases, but was not dependent on NOS or COX‐2 activity. PAI‐1, TIMP‐1 and TIMP‐3 mRNA were elevated significantly in prazosin treated EDL, and in response to shear stimulation in vitro. In cultured endothelial cells, Ets‐1 RNA interference abolished the shear‐induced increases in Ets‐1, PAI‐1, TIMP‐1, and TIMP‐3 mRNA expression. These results suggest that enhanced laminar shear stress may act to preserve the integrity of microvascular walls in part through Ets‐1‐dependent induction of protease inhibitors. J. Cell. Physiol. 217: 502–510, 2008. © 2008 Wiley‐Liss, Inc.