Prolonged shear stress and KLF2 suppress constitutive proinflammatory transcription through inhibition of ATF2.

Absence of shear stress due to disturbed blood flow at arterial bifurcations and curvatures leads to endothelial dysfunction and proinflammatory gene expression, ultimately resulting in atherogenesis. KLF2 has recently been implicated as a transcription factor involved in mediating the anti-inflammatory effects of flow. We investigated the effect of shear on basal and TNF-alpha-induced genomewide expression profiles of human umbilical vein endothelial cells (HUVECs). Cluster analysis confirmed that shear stress induces expression of protective genes including KLF2, eNOS, and thrombomodulin, whereas basal expression of TNF-alpha-responsive genes was moderately decreased. Promoter analysis of these genes showed enrichment of binding sites for ATF transcription factors, whereas TNF-alpha-induced gene expression was mostly NF-kappaB dependent. Furthermore, human endothelial cells overlying atherosclerotic plaques had increased amounts of phosphorylated nuclear ATF2 compared with endothelium at unaffected sites. In HUVECs, a dramatic reduction of nuclear binding activity of ATF2 was observed under shear and appeared to be KLF2 dependent. Reduction of ATF2 with siRNA potently suppressed basal proinflammatory gene expression under no-flow conditions. In conclusion, we demonstrate that shear stress and KLF2 inhibit nuclear activity of ATF2, providing a potential mechanism by which endothelial cells exposed to laminar flow are protected from basal proinflammatory, atherogenic gene expression.

[1]  P. Majumder,et al.  Kruppel-like factor 2 (KLF2) regulates proinflammatory activation of monocytes. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[2]  Aiqing He,et al.  Identification of inflammatory gene modules based on variations of human endothelial cell responses to oxidized lipids , 2006, Proceedings of the National Academy of Sciences.

[3]  R. Kaufman,et al.  Signaling the Unfolded Protein Response from the Endoplasmic Reticulum* , 2004, Journal of Biological Chemistry.

[4]  Johannes Roth,et al.  Transcriptional profiling of IKK2/NF-kappa B- and p38 MAP kinase-dependent gene expression in TNF-alpha-stimulated primary human endothelial cells. , 2004, Blood.

[5]  J. T. ten Cate,et al.  Vascular Endothelial Genes That Are Responsive to Tumor Necrosis Factor-a In Vitro Are Expressed in Atherosclerotic Lesions , Including Inhibitor of Apoptosis Protein-1 , Stannin , and Two Novel Genes , 1998 .

[6]  P. D. de Groot,et al.  Prolonged fluid shear stress induces a distinct set of endothelial cell genes, most specifically lung Krüppel-like factor (KLF2). , 2002, Blood.

[7]  Jurgen Seppen,et al.  Endothelial KLF2 links local arterial shear stress levels to the expression of vascular tone-regulating genes. , 2005, The American journal of pathology.

[8]  Yuzhi Zhang,et al.  Integration of flow-dependent endothelial phenotypes by Kruppel-like factor 2. , 2005, The Journal of clinical investigation.

[9]  Yuzhi Zhang,et al.  Distinct endothelial phenotypes evoked by arterial waveforms derived from atherosclerosis-susceptible and -resistant regions of human vasculature. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[10]  J. van Marle,et al.  The Human Kinesin-Like Protein RB6K Is under Tight Cell Cycle Control and Is Essential for Cytokinesis , 2001, Molecular and Cellular Biology.

[11]  Aiqing He,et al.  The Unfolded Protein Response Is an Important Regulator of Inflammatory Genes in Endothelial Cells , 2006, Arteriosclerosis, thrombosis, and vascular biology.

[12]  G. Garcı́a-Cardeña,et al.  Endothelial Dysfunction, Hemodynamic Forces, and Atherogenesis a , 2000, Annals of the New York Academy of Sciences.

[13]  Y. Nakatani,et al.  ATF-2 has intrinsic histone acetyltransferase activity which is modulated by phosphorylation , 2000, Nature.

[14]  Michael Kracht,et al.  Transcriptional and post-transcriptional control of gene expression in inflammation. , 2002, Cytokine.

[15]  M. Adachi,et al.  Expression of transcriptional repressor ATF3/LRF1 in human atherosclerosis: colocalization and possible involvement in cell death of vascular endothelial cells. , 2002, Atherosclerosis.

[16]  M. Cybulsky,et al.  The NF-kappa B signal transduction pathway in aortic endothelial cells is primed for activation in regions predisposed to atherosclerotic lesion formation. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[17]  M. Rondaij,et al.  KLF2 provokes a gene expression pattern that establishes functional quiescent differentiation of the endothelium. , 2006, Blood.

[18]  G. Garcı́a-Cardeña,et al.  Kruppel-Like Factor 2 (KLF2) Regulates Endothelial Thrombotic Function , 2005, Circulation research.

[19]  C F Dewey,et al.  Vascular endothelial cells respond to spatial gradients in fluid shear stress by enhanced activation of transcription factors. , 1999, Arteriosclerosis, thrombosis, and vascular biology.

[20]  T. Collins,et al.  Tumor Necrosis Factor α-Induced E-selectin Expression Is Activated by the Nuclear Factor-κB and c-JUN N-terminal Kinase/p38 Mitogen-activated Protein Kinase Pathways* , 1997, The Journal of Biological Chemistry.

[21]  E. Wagner,et al.  AP-1: a double-edged sword in tumorigenesis , 2003, Nature Reviews Cancer.

[22]  M. Karin.  The Regulation of AP-1 Activity by Mitogen-activated Protein Kinases (*) , 1995, The Journal of Biological Chemistry.

[23]  H. Yamawaki,et al.  Chronic Physiological Shear Stress Inhibits Tumor Necrosis Factor–Induced Proinflammatory Responses in Rabbit Aorta Perfused Ex Vivo , 2003, Circulation.

[24]  S. Usami,et al.  Shear stress regulates gene expression in vascular endothelial cells in response to tumor necrosis factor-alpha: a study of the transcription profile with complementary DNA microarray. , 2005, Journal of biomedical science.

[25]  Johannes Roth,et al.  Transcriptional profiling of IKK2/NF-κB— and p38 MAP kinasedependent gene expression in TNF-α—stimulated primary human endothelial cells , 2004 .

[26]  L. Pachter,et al.  rVista for comparative sequence-based discovery of functional transcription factor binding sites. , 2002, Genome research.

[27]  Jian Jian Li,et al.  Mutual regulation of c‐Jun and ATF2 by transcriptional activation and subcellular localization , 2006, The EMBO journal.

[28]  F. Luscinskas,et al.  KLF2 Is a Novel Transcriptional Regulator of Endothelial Proinflammatory Activation , 2004, The Journal of experimental medicine.

[29]  Shuchien,et al.  Shear Stress Increases ICAM-1 and Decreases VCAM-1 and E-selectin Expressions Induced by Tumor Necrosis Factor-α in Endothelial Cells , 2004 .

[30]  C. Stoeckert,et al.  Coexisting proinflammatory and antioxidative endothelial transcription profiles in a disturbed flow region of the adult porcine aorta. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[31]  S. Usami,et al.  Shear Stress Increases ICAM-1 and Decreases VCAM-1 and E-selectin Expressions Induced by Tumor Necrosis Factor-&agr; in Endothelial Cells , 2004, Arteriosclerosis, thrombosis, and vascular biology.

[32]  W. Min,et al.  TNF initiates E-selectin transcription in human endothelial cells through parallel TRAF-NF-kappa B and TRAF-RAC/CDC42-JNK-c-Jun/ATF2 pathways. , 1997, Journal of immunology.

[33]  Tsonwin Hai,et al.  Transcription factor ATF cDNA clones: an extensive family of leucine zipper proteins able to selectively form DNA-binding heterodimers. , 1989, Genes & development.