MBI Weekly Seminar

Time: 10.00am – 11.00am
Date: Friday, 13 November 2020
Venue: Online seminar via ZOOM

Patterned ECM hydraulics and anisotropic tissue stiffness drives inner ear morphogenesis

by Akankshi Munjal, Research Fellow, Harvard Medical School
Host: Prof. Timothy Saunders

How dogeometrically complex organs take shape from simple cell sheets in embryos? This is a central issue in biology with important implications in regenerative medicine. Many studies across species conclude that the main driving force is cell-intrinsic and generated by actomyosin contractility. The extracellular matrix (ECM) that surrounds most cells is considered to be a passive mechanical scaffold that may shape these forces through differential stiffness. I will present a case which inverts this expectation. Zebrafish semicircular canals form from invaginations in the otic epithelium (buds) that extend and fuse to form the hubs of each canal. We find that conventional actomyosin-driven behaviors are not required. Instead, local secretion of hyaluronan, made by the enzymesugdhandhas3,drives canal morphogenesis. Charged hyaluronate polymers osmotically swell with water and generate isotropic extracellular pressure to deform the overlying epithelium into buds. The mechanical anisotropy needed to shape buds into tubes is conferred by a polarized distribution of cellular protrusions, linked between cells, that we term cytocinches.  Hyaluronate-pressure shaped by anisotropic tissue stiffness may be a widespread mechanism for powering morphological change in organogenesis and tissue engineering.

MBI SPSS Fully Webcasted
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