title: Characterization of shear-sensitive genes in the normal rat aorta identifies Hand2 as a major flow-responsive transcription factor.
abstract: OBJECTIVE
  Shear forces play a key role in the maintenance of vessel wall integrity. Current understanding regarding shear-dependent gene expression is mainly based on in vitro or in vivo observations with experimentally deranged shear, hence reflecting acute molecular events in relation to flow. Our objective was to combine computational fluid dynamic (CFD) simulations with global microarray analysis to study flow-dependent vessel wall biology in the aortic wall under physiological conditions.
  
  
  RESULTS
  Male Wistar rats were used. Animal-specific wall shear stress (WSS) magnitude and vector direction were estimated using CFD based on aortic geometry and flow information acquired by magnetic resonance imaging. Two distinct flow pattern regions were identified in the normal rat aortic arch; the distal part of the lesser curvature being exposed to low WSS and a non-uniform vector direction, and a region along the greater curvature being subjected to markedly higher levels of WSS and a uniform vector direction. Microarray analysis identified numerous novel mechanosensitive genes, including Trpc4 and Fgf12, and confirmed well-known ones, e.g. Klf2 and Nrf2. Gene ontology analysis revealed an over-representation of genes involved in transcriptional regulation. The most differentially expressed gene, Hand2, is a transcription factor previously shown to be involved in extracellular matrix remodeling. HAND2 protein was endothelial specific and showed higher expression in the regions exposed to low WSS with disturbed flow.
  
  
  CONCLUSIONS
  Microarray analysis validated the CFD-defined WSS regions in the rat aortic arch, and identified numerous novel shear-sensitive genes. Defining the functional importance of these genes in relation to atherosusceptibility may provide important insight into the understanding of vascular pathology.
authors.affiliation: Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University, Linköping, Sweden. hanna.bjorck@ki.se
authors.forename: Hanna M
authors.initials: HM
authors.lastname: Björck
authors.forename: Johan
authors.initials: J
authors.lastname: Renner
authors.forename: Shohreh
authors.initials: S
authors.lastname: Maleki
authors.forename: Siv F E
authors.initials: SF
authors.lastname: Nilsson
authors.forename: Johan
authors.initials: J
authors.lastname: Kihlberg
authors.forename: Lasse
authors.initials: L
authors.lastname: Folkersen
authors.forename: Matts
authors.initials: M
authors.lastname: Karlsson
authors.forename: Tino
authors.initials: T
authors.lastname: Ebbers
authors.forename: Per
authors.initials: P
authors.lastname: Eriksson
authors.forename: Toste
authors.initials: T
authors.lastname: Länne
mesh_terms: D000818:Animals; D001011:Aorta / Q000378:metabolism* / Q000502:physiology*; D001013:Aorta, Thoracic / Q000378:metabolism / Q000502:physiology; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D051381:Rats; D017208:Rats, Wistar; D033081:Shear Strength / Q000502:physiology*; D013314:Stress, Mechanical
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; C498767:Hand2 protein, rat