ZFIN ID: ZDB-PUB-180622-24
Lamellar projections in the endolymphatic sac act as a relief valve to regulate inner ear pressure
Swinburne, I.A., Mosaliganti, K.R., Upadhyayula, S., Liu, T.L., Hildebrand, D.G.C., Tsai, T.Y., Chen, A., Al-Obeidi, E., Fass, A.K., Malhotra, S., Engert, F., Lichtman, J.W., Kirchausen, T., Betzig, E., Megason, S.G.
Date: 2018
Source: eLIFE   7: (Journal)
Registered Authors: Chen, Anzhi, Engert, Florian, Megason, Sean, Mosaliganti, Kishore, Swinburne, Ian
Keywords: cell biology, developmental biology, inner ear, lamella, pressure, stem cells, timelapse, valve, zebrafish
MeSH Terms:
  • Animals
  • Animals, Genetically Modified
  • Embryo, Nonmammalian
  • Endolymphatic Sac/anatomy & histology
  • Endolymphatic Sac/physiology
  • Endolymphatic Sac/ultrastructure*
  • Female
  • Gene Expression
  • Hearing/physiology*
  • Homeostasis/physiology
  • Hydrostatic Pressure
  • In Situ Hybridization, Fluorescence
  • Larva/anatomy & histology
  • Larva/physiology
  • Larva/ultrastructure*
  • Male
  • Microscopy, Electron
  • Mutation
  • Time-Lapse Imaging
  • Transcription Factors/genetics*
  • Transcription Factors/metabolism
  • Zebrafish
  • Zebrafish Proteins/genetics*
  • Zebrafish Proteins/metabolism
PubMed: 29916365 Full text @ Elife
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.