[SMaLS/FNS] Creating mazes on cell surfaces: morphogenesis and patterning of microridges in zebrafish skin cells

Speaker: Alvaro Sagasti (Professor, Molecular, Cell and Developmental Biology UCLA)

Title:  “Creating mazes on cell surfaces: morphogenesis and patterning of microridges in zebrafish skin cells”

Abstract: Mucosal epithelial cells make elongated actin- and keratin-based protrusions called microridges, which are arranged in striking maze-like patterns on their apical surfaces. Our lab is studying the cytoskeletal regulatory proteins that build microridges and the physical forces that promote their labyrinthine patterning. We found that non-muscle myosin II (NMII)-mediated contraction of the apical cortex plays crucial roles in both the morphogenesis and patterning of microridges. Initially, NMII-mediated contraction relieves apical membrane tension to enable microridge formation. At later stages, NMII activity promotes microridge rearrangements that cause their pattern to change dynamically: individual NMII minifilaments in the cortex are tethered to microridges and pull on them to break them (fission) or pull them together (fusion). We propose that these stochastic fission and fusion events allow microridge patterns to evolve towards an increasingly energetically favorable nematic organization.