Reversing blood flows act through klf2a to ensure normal valvulogenesis in the developing heart

Vermot, J., Forouhar, A.S., Liebling, M., Wu, D., Plummer, D., Gharib, M., and Fraser, S.E.
PLoS Biology   7(11): e1000246 (Journal)
Registered Authors
Forouhar, Arian S., Fraser, Scott E., Liebling, Michael, Vermot, Julien
Embryos, Blood flow, Heart, Endothelial cells, Gene flow, Heart rate, Cardiac atria, Zebrafish
MeSH Terms
  • Animals
  • Blood Circulation/drug effects
  • Blood Circulation/genetics
  • Embryo, Nonmammalian
  • Gene Expression Regulation, Developmental/drug effects
  • Gene Expression Regulation, Developmental/genetics
  • Heart/embryology*
  • Heart Valves/embryology*
  • Hemodynamics/drug effects
  • In Situ Hybridization
  • Kruppel-Like Transcription Factors/genetics
  • Kruppel-Like Transcription Factors/metabolism*
  • Lidocaine/pharmacology
  • Microscopy, Confocal
  • Reverse Transcriptase Polymerase Chain Reaction
  • Temperature
  • Zebrafish
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism*
19924233 Full text @ PLoS Biol.
Heart valve anomalies are some of the most common congenital heart defects, yet neither the genetic nor the epigenetic forces guiding heart valve development are well understood. When functioning normally, mature heart valves prevent intracardiac retrograde blood flow; before valves develop, there is considerable regurgitation, resulting in reversing (or oscillatory) flows between the atrium and ventricle. As reversing flows are particularly strong stimuli to endothelial cells in culture, an attractive hypothesis is that heart valves form as a developmental response to retrograde blood flows through the maturing heart. Here, we exploit the relationship between oscillatory flow and heart rate to manipulate the amount of retrograde flow in the atrioventricular (AV) canal before and during valvulogenesis, and find that this leads to arrested valve growth. Using this manipulation, we determined that klf2a is normally expressed in the valve precursors in response to reversing flows, and is dramatically reduced by treatments that decrease such flows. Experimentally knocking down the expression of this shear-responsive gene with morpholine antisense oligonucleotides (MOs) results in dysfunctional valves. Thus, klf2a expression appears to be necessary for normal valve formation. This, together with its dependence on intracardiac hemodynamic forces, makes klf2a expression an early and reliable indicator of proper valve development. Together, these results demonstrate a critical role for reversing flows during valvulogenesis and show how relatively subtle perturbations of normal hemodynamic patterns can lead to both major alterations in gene expression and severe valve dysgenesis.
Genes / Markers
Show all Figures
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Engineered Foreign Genes