Transcription factor Sp1 phosphorylation induced by shear stress inhibits membrane type 1-matrix metalloproteinase expression in endothelium.
Membrane type 1-matrix metalloproteinase (MT1-MMP) plays a key role in endothelial cell migration, matrix remodeling, and angiogenesis. Previous studies demonstrated that a mechanical force, cyclic strain, increases MT1-MMP expression by displacing Sp1 with increased Egr-1 expression and binding to the promoter site. However, the effect of shear stress (SS) on MT1-MMP expression is poorly understood. Although Egr-1 mRNA transcription and protein was induced (7.6-fold) in response to SS (n = 5, 0-8 h, p < 0.05), SS decreased MT1-MMP mRNA transcription and protein levels in a time-dependent fashion (10, 50, and 90% reduction at 1, 4, and 8 h, respectively; n = 5, p < 0.05). Egr-1 protein was increased after SS and cyclic strain, but Sp1 was serine-phosphorylated only after SS. SS increased Sp1 DNA binding (3.8-, 5.8-, and 2.4-fold increase at 1, 4, and 8 h, respectively; n = 5, p < 0.05) that was inhibitable by calf intestinal phosphatase. Thus, SS inhibits MT1-MMP expression despite Egr-1 up-regulation by inducing the serine phosphorylation of Sp1, which in turn increases its binding affinity for its site on the MT1-MMP promoter, reducing the ability of Egr-1 to displace it. These data illustrate the complex control of microvascular endothelial cell MT1-MMP expression in response to distinct environmental stimuli (cyclic strain versus shear stress), consisting of both the modulation of specific transcription factor expression (Egr-1) as well as transcription factor post-translational modification (serine phosphorylation of Sp1).
Yun
Sangseob
S
Department of Surgery, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Dardik
Alan
A
Haga
Masae
M
Yamashita
Akimasa
A
Yamaguchi
Seiichi
S
Koh
Yongbok
Y
Madri
Joseph A
JA
Sumpio
Bauer E
BE
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D004247:DNA; D004268:DNA-Binding Proteins / Q000378:metabolism; D051766:Early Growth Response Protein 1; D024202:Electrophoretic Mobility Shift Assay; D004730:Endothelium, Vascular / Q000201:enzymology*; D017874:Immediate-Early Proteins; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000502:physiology*; D009621:Nogalamycin / Q000494:pharmacology; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D017874:Immediate-Early Proteins; D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D004247:DNA; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D009621:Nogalamycin