Spatial Variations in Shear Stress Activate klf2a-snai1b Signaling for Bicuspid to Multicuspid Valve Formation

Authors

  • Jing Wang University of California, Los Angeles, Los Angeles, USA
  • Aaron L Brown Stanford University, Stanford, USA
  • Charlie Z Zheng University of California, Los Angeles, Los Angeles, US
  • Alexander D Kaiser Stanford University, Stanford, USA
  • Tomohiro Yokota University of California, Los Angeles, Los Angeles, USA and Greater Los Angeles VA Healthcare System, Los Angeles, USA
  • Seul-Ki Park University of California, Los Angeles, Los Angeles, USA
  • Alison L Marsden Stanford University, Stanford, USA
  • Tzung K Hsiai University of California, Los Angeles, Los Angeles, USA and Greater Los Angeles VA Healthcare System, Los Angeles, USA

DOI:

https://doi.org/10.21542/gcsp.2025.hvbte.21

Abstract

Bicuspid aortic valve (BAV) is the most common congenital heart defect, involving heterogenous contributions from multiple genes and signaling pathways. In zebrafish hearts, the atrioventricular (AV) valve undergoes a transition from 2 cusps to 4 cusps during the larval stage, thus providing a mechano-transduction model to elucidate the de novo leaflet transition from a bicuspid to a quadricuspid valve. Using the Tp1 notch reporter line and EdU assays, we showed that the two new leaflets form at a faster rate than the two pre-existing leaflets from 14 to 45 days post-fertilization (dpf), but the number of proliferating valvular interstitial cells (VIC) significantly reduced in the pre-existing two leaflets between 15 and 18 dpf. In situ hybridization, 2-D computational fluid dynamics (CFD) simulations, and the wea mutants (weak atrium, myh6-/-) revealed that the widening of the commissure at 14 dpf leads to shear stress-activated klf2a-snai1b signaling, which initiates endothelial-to-mesenchymal transition (EndoMT) of the two new leaflets. Reduction in shear stress by disrupting forward flow across the AV canal resulted in a significant decrease of klf2a and snai1bexpression at the commissure, where 80% of the wea hearts (n = 12) remained bicuspid at 14 dpf. Finally, bulk-RNA sequencing laser-dissected AV valve tissue from 28 dpf to 45 dpf revealed no differential expression of EndoMT-related genes, but significant upregulation of chondrogenic genes, implicating the maturation of valvular ECMs in the late-larval stage. In summary, spatial variations in shear stress-activated klf2a-snai1b signaling at the commissure modulate the transition from bicuspid to quadricuspid valves.

Published

2025-10-06

Issue

Vol. 2025 No. HVBTE (2025): Proceedings of the The 10th Heart Valve Biology and Tissue Engineering Meeting

Section

Developmental Biology of Heart Valves

License

Copyright (c) 2025 Jing Wang, Aaron L Brown, Charlie Z Zheng, Alexander D Kaiser, Tomohiro Yokota, Seul-Ki Park, Alison L Marsden, Tzung K Hsiai

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

This is an open access article distributed under the terms of the Creative Commons Attribution license CC BY 4.0, which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited.