Lamellar projections in the endolymphatic sac act as a relief valve to regulate inner ear pressure

Ian A. Swinburne, Kishore R. Mosaliganti, Srigokul Upadhyayula, Tsung Li Liu, David G.C. Hildebrand, Tony Y.C. Tsai, Anzhi Chen, Ebaa Al-Obeidi, Anna K. Fass, Samir Malhotra, Florian Engert, Jeff W. Lichtman, Tomas Kirchhausen, Eric Betzig, Sean G. Megason

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

The inner ear is a fluid-filled closed-epithelial structure whose function requires maintenance of an internal hydrostatic pressure and fluid composition. The endolymphatic sac (ES) is a dead-end epithelial tube connected to the inner ear whose function is unclear. ES defects can cause distended ear tissue, a pathology often seen in hearing and balance disorders. Using live imaging of zebrafish larvae, we reveal that the ES undergoes cycles of slow pressure-driven inflation followed by rapid deflation. Absence of these cycles in lmx1bb mutants leads to distended ear tissue. Using serial-section electron microscopy and adaptive optics lattice light-sheet microscopy, we find a pressure relief valve in the ES comprised of partially separated apical junctions and dynamic overlapping basal lamellae that separate under pressure to release fluid. We propose that this lmx1-dependent pressure relief valve is required to maintain fluid homeostasis in the inner ear and other fluid-filled cavities.

Original languageEnglish
Article numbere37131
JournaleLife
Volume7
DOIs
StatePublished - Jun 19 2018

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