Endothelial cell TIMP-1 is upregulated by shear stress via Sp-1 and the TGFβ1 signaling pathways.
Laminar shear stress promotes vascular integrity by inhibiting proteolysis of the extracellular matrix (ECM) surrounding the microvasculature. We hypothesized that the matrix metalloproteinase inhibitor TIMP-1 would be upregulated in endothelial cells exposed to shear stress. Microvascular endothelial cells isolated from rat or mouse skeletal muscles were exposed to laminar shear stress for 2, 4, or 24 h. A biphasic increase in TIMP-1 protein was observed at 2 and 24 h of shear stress exposure. Sp-1 siRNA prevented the increase in TIMP-1 after 2, but not 24, hours of shear exposure. TGFβ production and Smad2/3 phosphorylation are increased by shear stress. Inhibition of TGFβ signaling, either by use of the TGFβ receptor 1 inhibitor SB-431542 or with Smad 2/3 siRNA, abrogated the shear stress-induced increase in TIMP-1 mRNA after 24 h of shear stress exposure. These results suggest that both acute and chronic elevated laminar shear stress act to maintain vessel integrity through increasing TIMP-1 production, but that the TGFβ signaling pathway is essential to maintain TIMP-1 expression during chronic shear stress.
Angiogenesis Research Group, Faculty of Health, York University, 4700 Keele St., Toronto, ON M3J 1P3, Canada.
Cassandra
C
Uchida
Tara L
TL
Haas
D000818:Animals; D042783:Endothelial Cells / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013312:Stress, Physiological / Q000502:physiology*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
D019715:Tissue Inhibitor of Metalloproteinase-1; D014157:Transcription Factors; D053773:Transforming Growth Factor beta1