Multiple cis-elements mediate shear stress-induced gene expression

Shyy, John Y.-J.; Li, Yi-Shan; Lin, Ming-Chao; Chen, Wayne; Yuan, Suli; Usami, Schunichi; Chien, Shu

doi:10.1016/0021-9290(95)00093-3

Cited by 84 publications

References 20 publications

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“…12 AP-1 was shown to mediate shear-induced monocyte chemotactic protein-1 expression. 13 Further characterization of the role of these sites in the shear-induced eNOS expression is underway in our laboratory.…”

Section: Discussionmentioning

confidence: 99%

Nitric Oxide Synthase Expression in Endothelial Cells Exposed to Mechanical Forces

et al. 1998

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Abstract-Nitric oxide (NO) has been demonstrated to play a central role in vascular biology and pathobiology. The expression of endothelial NO synthase (eNOS) is regulated in part by blood flow-induced mechanical factors. The purpose of this study was to evaluate how the expression of eNOS mRNA correlates with the activation of its promoter in both arterial and venous endothelial cells (ECs) exposed to mechanical forces, ie, shear stress and cyclic circumferential stretch. Bovine aortic ECs (BAECs) and EA hy.926, a cell line derived from human umbilical vein ECs, were grown on the inside of elastic tubes and subjected to combinations of pressure, pulsatile shear stress, and cyclic circumferential stretch for 24 hours. Two patterns of shear stress were used: unidirectional (mean of 6, ranging from 3 to 9 dyne/cm 2 ) and oscillatory (mean of 0.3, ranging from Ϫ3 to ϩ3 dyne/cm 2 ). The expression of eNOS mRNA was quantified by Northern blot analysis. Activation of the promoter was assessed by luciferase activity after the cells were transiently transfected before the flow experiments with a plasmid construct containing the fully functional eNOS promoter coupled to a luciferase reporter gene. Expression of eNOS mRNA was increased and promoter activity was enhanced by unidirectional shear stress compared with static control. Oscillatory shear slightly upregulated eNOS mRNA in BAECs, whereas it downregulated eNOS mRNA in EA hy.926. In both BAECs and EA hy.926, there was a good correlation between the increase in eNOS mRNA expression and promoter activation by unidirectional shear stress. In contrast, in both BAECs and EA hy.926 cells exposed to shear stress, cyclic stretch did not change eNOS mRNA expression, but the activation of eNOS promoter was significantly lower. Moreover, when ECs were exposed to oscillatory shear stress, there was a dramatic activation of the eNOS promoter. These results demonstrate that unidirectional shear stress increases eNOS mRNA expression via a transcriptional mechanism. However, oscillatory shear stress and cyclic stretch appear to control eNOS expression through posttranscriptional regulatory events. NO has been demonstrated to interfere with key events involved in atherogenesis.1 Not only is NO the most potent vasodilator, it also inhibits platelet aggregation and leukocyte adhesion to ECs and suppresses vascular smooth muscle cell proliferation and migration. The production of NO, as well as the expression of eNOS by ECs, has been shown to be dependent on mechanical factors.2-4 Shear stress and cyclic circumferential stretch have been demonstrated to increase NO release as well as upregulate eNOS mRNA and protein. 2,3More recently, using an in vitro tube model in which pressure, shear stress, and cyclic circumferential stretch can be combined, we have shown that shear stress represents the major mechanical factor inducing an increase in eNOS expression in BAECs. Pressure and cyclic stretch, however, did not significantly alter changes in eNOS expression in cells exposed to shear str...

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Section: Discussionmentioning

confidence: 99%

Nitric Oxide Synthase Expression in Endothelial Cells Exposed to Mechanical Forces

et al. 1998

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“…26,58 Furthermore, multiple cis elements that mediate transcriptional regulation by shear stress have now been identified. 61,62 The robust nature of the Cx43 response to both stretch and shear implies that this gap junction protein is important in communicating alterations in mechanical environment in both endothelial cells and smooth muscle cells, and it may impart functional changes to these cells. Several investigators have proposed that changes in gap junctional activity contribute to the increased vascular reactivity that is observed in hypertension.…”

Section: Discussionmentioning

confidence: 99%

Regulation of Vascular Connexin43 Gene Expression by Mechanical Loads

Cowan¹,

Lye

Langille

1998

Circulation Research

132

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Abstract-Vascular tissues respond to changes in the mechanical forces imposed on them with changes in vasomotor tone in the short term and with structural remodeling in the long term. Since these responses involve intercellular communication, we have investigated regulation of the gap junction proteins, connexin26 (Cx26), connexin37 (Cx37), connexin40 (Cx40), and connexin43 (Cx43), by mechanical loads. Results were compared with parallel experiments on c-fos and GAPDH. Twenty percent stretch of cultured vascular smooth muscle cells caused a 3-fold increase in Cx43 mRNA levels by 2 hours. Cx26 was expressed at low levels but failed to respond to stretch, and Cx37 and Cx40 were not detected. c-fos mRNA levels increased after 30 minutes of stretch, whereas GAPDH mRNA did not change. Protein levels of Cx43 increased by 4 hours and remained elevated for 16 hours. Nuclear run-on experiments confirmed that Cx43 and c-fos were transcriptionally regulated by stretch. New protein synthesis was not a requirement for the stretch-induced rise in Cx43 expression, since mRNA levels were unaffected by treatment with cycloheximide. To examine transcriptional control of Cx43, stretched and unstretched vascular smooth muscle cells were transfected with a variety of promoter-reporter gene constructs. Cx43 sequences extending from within exon 1 (ϩ162) to Ϫ1686 in the 5Ј-flanking region were coupled to the chloramphenicol acetyl transferase reporter gene. Deletions from the 5Ј end of these sequences differentially regulated reporter gene expression and indicated multiple potential regulatory sites. In particular, a putative activator protein-1 site at the Ϫ42 to Ϫ48 region was required for basal reporter activity. None of the promoter constructs revealed stretch sensitivity, indicating that the site of transcriptional control by stretch lies outside the Ϫ1686 to ϩ162 region. Finally, Cx43 mRNA levels were assessed in cultured endothelial cells subjected to laminar shear stress of 15 dynes/cm 2 . Cx43 mRNA levels increased by Ϸ4-fold at 1 hour and remained elevated for the duration of shear force. In conclusion, both mechanical strain and fluid shear stress caused increased expression of the gap junction protein Cx43. (Circ Res. 1998;82:786-793.)

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“…These include several proadhesive, proinflammatory, or prothrombotic genes such as intercellular adhesion molecule-1 (14), monocyte chemoattractant protein-1 (15), and tissue factor (TF) (16). Transcriptional activation of these genes has been shown to proceed via cis -acting sequences that bind transcription factors Sp1 (16), NF-B (17), AP1 (18,15), and early growth response-1 (Egr-1) (12,13). Transcription factors AP1 and NF-B are themselves upregulated by shear stress (19).…”

Section: Introductionmentioning

confidence: 99%