Plexin-B2 regulates mechanotension during multicellular organization

During multicellular organization, individual cells need to constantly adjust intracellular contractility and junctional adhesive properties in order to maintain tissue cohesion and mechanotension. The membrane receptors linking external biochemical cues and internal cell mechanics are incompletely understood. Here, we reveal that the axon guidance receptor Plexin-B2 regulates intracellular mechanotension, and this in turn impacts cell-cell/cell-matrix adhesiveness during self-assembly of human embryonic stem cells (hESCs) and neuroprogenitor cells (hNPCs) into epithelial structures. The altered tissue mechanics caused by Plexin-B2 deficiency or over expression affects stem cell behaviors as well as β-catenin and YAP mechanosensing. Strikingly, Plexin-B2 deficiency results in accelerated neuronal differentiation, while proper levels of Plexin-B2 activity are required for maintaining cytoarchitectural integrity of the neuroepithelium as modeled in cerebral organoids. Mechanistically, Plexin-B2 engages its extracellular and Ras-GAP domains for mechanoregulation via RAP1/2. Our studies establish mechanoregulation as a key function of Plexin-B2 during multicellular organization, thereby solidifying the principle of force- mediated regulation of stem cell biology and tissue morphogenesis. RNA-sequencing of hESC colonies of WT, PLXNB2 KO, and PLXNB2 OE condition, with three independent replicates for each condition.