title: The decrease in histone methyltransferase EZH2 in response to fluid shear stress alters endothelial gene expression and promotes quiescence.
abstract: High uniform fluid shear stress (FSS) is atheroprotective and preserves the endothelial phenotype and function through activation of downstream mediators such as MAPK7 (Erk5). Endothelial cells respond to FSS thanks to mechanotransduction. However, how the resulting signaling is integrated and resolved at the epigenetic level remains elusive. We hypothesized that Polycomb methyltransferase EZH2 is involved in the effects of FSS in human endothelial cells. We showed that FSS decreases the expression of the Polycomb methyltransferase EZH2. Despite simultaneous activation of MAPK7, MAPK7 pathway does not directly influence the transcription of EZH2. Interestingly though, the knockdown of EZH2 activates the protective MAPK7 signaling in endothelial cells, even in the absence of FSS. To understand the influence of the FSS-decreased expression of EZH2 on endothelial transcriptome, we performed RNA-seq and differential gene expression analysis. We identified candidate groups of genes dependent on both EZH2 and FSS. Among those, Gene Ontology overrepresentation analysis revealed highly significant enrichment of the cell cycle-related genes, suggesting changes in proliferation. Indeed, the depletion of EZH2 strongly inhibited endothelial proliferation, indicating cell cycle arrest. The concomitant decrease in CCNA expression suggests the transition of endothelial cells into a quiescent phenotype. Further bioinformatical analysis suggested TXNIP as a possible mediator between EZH2 and cell cycle-related gene network. Our data show that EZH2 is a FSS-responsive gene. Decreased EZH2 levels enhance the activation of the atheroprotective MAPK7 signaling. Decrease in EZH2 under FSS mediates the decrease in the expression of the network of cell cycle-related genes, which allows the cells to enter quiescence. EZH2 is therefore important for the protective effects of FSS in endothelium.
authors.affiliation: Cardiovascular Regenerative Medicine Research Group, Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Hanzeplein 1 (EA11), 9713 GZ, Groningen, The Netherlands. m.maleszewska@gmail.com.|Max Planck Research Group Chromatin and Ageing, Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931, Cologne, Germany. m.maleszewska@gmail.com.
authors.forename: Monika
authors.initials: M
authors.lastname: Maleszewska
authors.affiliation: Cardiovascular Regenerative Medicine Research Group, Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Hanzeplein 1 (EA11), 9713 GZ, Groningen, The Netherlands.
authors.forename: Byambasuren
authors.initials: B
authors.lastname: Vanchin
authors.affiliation: Cardiovascular Regenerative Medicine Research Group, Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Hanzeplein 1 (EA11), 9713 GZ, Groningen, The Netherlands.
authors.forename: Martin C
authors.initials: MC
authors.lastname: Harmsen
authors.affiliation: Cardiovascular Regenerative Medicine Research Group, Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Hanzeplein 1 (EA11), 9713 GZ, Groningen, The Netherlands. g.krenning@umcg.nl.
authors.forename: Guido
authors.initials: G
authors.lastname: Krenning
mesh_terms: D002448:Cell Adhesion / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D049109:Cell Proliferation; D015536:Down-Regulation / Q000235:genetics; D000071221:Enhancer of Zeste Homolog 2 Protein; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D063990:Gene Ontology; D053263:Gene Regulatory Networks; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000201:enzymology*; D006801:Humans; D048054:Mitogen-Activated Protein Kinase 7 / Q000378:metabolism; D008954:Models, Biological; D063151:Polycomb Repressive Complex 2 / Q000235:genetics / Q000378:metabolism*; D012212:Rheology; D013314:Stress, Mechanical
chemical_list: C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2; C481581:MAPK7 protein, human; D048054:Mitogen-Activated Protein Kinase 7
keywords: Chromatin; Endothelial cell; Enhancer of zeste homolog-2 (EZH2); Fluid shear stress (FSS); Mechanotransduction