University of Geneva, Switzerland
Sphingolipid control of oriented mitosis
The orientation of cell division is a fundamental mechanism to control asymmetric stem cell division, elongation of the neural tube and the extension of the body axis, among other processes. During zebrafish gastrulation, when the body axis extends, dorsal epiblast cells display divisions that are robustly oriented along the animal-vegetal embryonic axis. Here, we used a combination of mass-spectrometry-based lipidomics and quantitative image analysis to show that sphingolipids mediate spindle positioning during oriented division of epiblast cells. We have identified the Wnt signaling as a regulator of sphingolipid synthesis that mediates the activity of serine palmitoyltransferase (SPT), the first and rate-limiting enzyme in sphingolipid production. Sphingolipids determine the palmitoylation state of the Anthrax receptor, which then positions the mitotic spindle of dividing epiblast cells. Our data show how Wnt signaling mediates sphingolipid-dependent oriented division and how sphingolipids determine Anthrax receptor palmitoylation, which ultimately controls the activation of Diaphanous to mediate spindle rotation and oriented mitosis.