Objective Low shear stress and matrix metalloproteinase are involved in atherogenesis and plaque stability. The aim of this study wad to explore the relation and possible mechanism of membrane type-1 matrix metalloproteinase (MT1-MMP) and low shear stress (LSS).
Methods 80 male apoE-/- mice were fed a high-fat diet, and lesions in the left carotid artery were induced by perivascular placement of constrictive collars.
Results Ultrasound-determined shear stress was significantly lower in the left carotid artery than in the right artery (5.61±0.72 vs 9.76±1.48 N/m2, p<0.01). Confocal microscopy and dual staining revealed higher MT1-MMP expression in left common carotid artery. Cultured human umbilical vein endothelial cells (HUVECs) exposed to 0.4 N/cm2 shear stress (LSS) and 1.2 N/cm2 shear stress (PSS). HUVECs subjected to LSS showed a time-dependent increase in MT1-MMP mRNA level. MT1-MMP mRNA level was downregulated under PSS at 3 and 5 h. MT1-MMP protein showed no change in expression at 1-h LSS, but 3-, 5-, 8- and 16-h treatment produced significantly increased expression and activity. NF-κB DNA-binding activity was stronger at 30-min and 1-h LSS exposure than with control treatment. Pretreatment with 18 μM SN50 efficiently inhibited NF-κB DNA binding activity. In the presence of SN50, MT1-MMP mRNA expression, protein level and activity were significantly attenuated (all p<0.01). MT1-MMP mRNA expression, protein level and activity were inhibited by PD98059 (all p<0.01). To determine the relation between ERK1/2 and NF-κB with MT1-MMP induced by LSS, HUVECs were incubated with PD98059 for 2 h before LSS. The level of phosphor-IKKα/β was reduced, whereas that of phosphor-IκBα was increased as compared with no PD98059 treatment. As well, NF-κB DNA-binding activity was decreased. HUVECs were preincubated for 48 h with FAK siRNA and then treated with LSS. The shear stress-induced increase in MT1-MMP mRNA and protein level and activity was significantly inhibited (all p<0.01). As well, LSS-induced ERK1/2 activation was inhibited with 5-min LSS exposure (p<0.01). To examine NF-κB DNA-binding activity, HUVECs were pretreated for 48 h with FAK siRNA before being exposed to LSS. NF-κB DNA-binding activity was inhibited with FAK siRNA pretreatment. HUVECs were preincubated for 48 h with integrin β1 siRNA and then underwent LSS. The shear stress-induced increase in MT1-MMP mRNA expression, protein level and activity was significantly inhibited (all p<0.01). As well, LSS-induced FAK and ERK1/2 activation was inhibited at 5-min exposure (p<0.01). Next, we examined NF-κB DNA-binding activity with 48-h integrin β1 siRNA pretreatment before exposure to LSS; NF-κB DNA binding activity was inhibited by siRNA integrin β1 pretreatment.
Conclusions MT1-MMP induced by LSS is involved in atherosclerotic plaque, via the integrin β1-FAK-ERK1/2-NF-κB pathway.
- Membrane type-1 matrix metalloproteinase (MT1-MMP)
- low shear stress (LSS)
- human umbilical vein endothelial cells (HUVECs)