DOI: 10.5061/dryad.2fqz612q6
title: Wasp controls oriented migration of endothelial cells to achieve functional vascular patterning

description: Endothelial cell migration and proliferation are essential for the
 establishment of a hierarchical organization of blood vessels and optimal
 distribution of blood. However, how these cellular processes are
 quantitatively coordinated to drive vascular network morphogenesis remains
 unknown. Here, using the zebrafish vasculature as a model system, we
 demonstrate that the balanced distribution of endothelial cells as well as
 the resulting regularity of vessel caliber, is a result of migration of
 cells from veins connected to arteries and cell proliferation in veins. We
 identify the Wiskott-Aldrich Syndrome protein (WASp) as an
 important molecular regulator of this process and show that loss of
 coordinated migration from veins to arteries
 upon wasb depletion results in aberrant vessel
 morphology and the formation of persistent arteriovenous shunts. We
 demonstrate that WASp achieves its function through the coordination of
 junctional actin assembly and PECAM1 recruitment and provide evidence that
 this is conserved in human. Together, we demonstrate that functional
 vascular patterning in the zebrafish trunk utilizes differential cell
 movement regulated by junctional actin, and that interruption of
 differential migration may represent a pathomechanism in vascular
 malformations.
description: Segmentation and tracking of endothelial
 nuclei Segmentation and tracking of nuclei
 from live imaging in zebrafish and cultured HUVECs was performed with
 Imaris Image Tracking Package (Bitplane). Tracking data was formatted
 according to community standards for open cell migration
 data (Gonzalez-Beltran et al., 2020). For each zebrafish the cell tracking
 data was oriented in three-dimensional space such that the aorta is
 parallel to the x-axis and the DLAV in the positive-y half plane. In this
 way, the y-component of the transformed trajectories serve as a read-out
 for the ventral to dorsal positions of the nuclei. In order to determine
 the orientation of the aorta we used positional data of all nuclei in the
 aorta over the whole time period and performed linear regression. The
 tracking was subsequently rotated and translated in three-dimensional
 space (see https://github.com/wgiese/zebrafish_ec_migration/wiki for details). We extracted ventral to dorsal velocities over the developmental process, by calculating the signed displacement in y-direction over time windows of 2 h. This process was repeated over the whole time period from 26 h to 44 h in 10 min time steps for all cell tracks. In HUVECs cell trajectory data was aligned such that the y-axis followed the outer edge of the scratch-wound, while the cell-free space is on the positive-x half plane. We calculated the effective speed as the quotient of the distance from start to end point and the tracking time. Furthermore, we determined the directionality of each trajectory from the vector pointing from start to end point and calculated the angle with the y-axis. The data that support the findings of this study are available from the corresponding author upon reasonable request<i>.</i>