The 67-kDa laminin-binding protein is involved in shear stress-dependent endothelial nitric-oxide synthase expression

It has been suggested that the mechanical forces acting on endothelial cell s may be sensed in part by cell-matrix connections. We therefore studied th e role of different matrix proteins, in particular laminin I, on a shear st ress-dependent endothelial response, namely nitric-oxide synthase (eNOS) ex pression. Primary porcine aortic endothelial cells were seeded onto glass p lates either noncoated (NC cells) or precoated with fibronectin (FN cells), laminin (LN cells), or collagen I (CN cells). Western blots were used to d etect differences in the final matrix composition of these cells. A shear s tress of 16 dyn/cm(2) was applied for 6 h, Only LN cells showed detectable amounts of laminin I in their underlying matrix when they reached confluenc e. They reacted with a a-fold increase of eNOS expression (n = 16, p < 0.00 1) to the exposure of shear stress, which went along with enhanced eNOS pro tein and NO release. In contrast, neither FN cells (n = 9) nor NC cells (n = 13) showed a significant increase of eNOS expression under shear stress, The increase in CN cells was borderline (1.4-fold; n = 9, p < 0.05) and was not associated with an increase of eNOS protein. The shear-induced increas e in eNOS expression of LN cells was abolished by the peptide YIGSR, which blocks the cellular binding to laminin I via a 67-kDa laminin-binding prote in, whereas a control peptide (YIGSK) had no effect. The induction of eNOS expression by shear stress is stimulated by an interaction of endothelial c ells with laminin which is, at least in part, mediated by a 67-kDa laminin- binding protein.