Protein profile of mouse endolymph suggests a role in controlling cochlear homeostasis
The cochlea contains two extracellular fluids, perilymph and endolymph. Endolymph exhibits high potential of approximately +80 to +110 mV (depending on species), which sensitizes sensory hair cells. Other properties of this unique fluid remain elusive, owing to its minuscule volume in rodent cochlea. We therefore developed a technique to collect high-purity endolymph from mouse cochleae. Comprehensive proteomic analysis of sampled endolymph using liquid chromatography with mass spectrometry identified 301 proteins, dominated by molecules engaged in immunity and proteostasis. Approximately 30% of these proteins were undetectable in our perilymph. A combination of mass spectrometry and different approaches revealed that, compared to perilymph, endolymph was enriched with α<sub>2</sub>-macroglobulin, osteopontin, apolipoprotein D, apolipoprotein E, and apolipoprotein J/clusterin. In other cells or tissues, α<sub>2</sub>-macroglobulin, apolipoprotein E, and apolipoprotein J contribute to the clearance of degraded proteins from extracellular fluid. Altogether, with the proteins described here, endolymph may play a protective role in stabilizing cochlear homeostasis.
Authors
- T. Ōta (ORCID: https://orcid.org/0000-0003-0011-8925)
- Yoshiaki Kikkawa (ORCID: https://orcid.org/0000-0001-8859-4998)
- Eri Wakai (ORCID: https://orcid.org/0000-0001-5207-9898)
- Daisuke Ino (ORCID: https://orcid.org/0000-0002-8112-0746)
- Hiroki Okanishi
- Yoshikatsu Kanai
- Hidenori Inohara (ORCID: https://orcid.org/0000-0003-4473-1203)
- Yumi Ohta (ORCID: https://orcid.org/0000-0002-5059-0876)
- Hiroshi Hibino (ORCID: https://orcid.org/0000-0003-0688-1489)
- Kazuya Ono
- Takashi Sato (ORCID: https://orcid.org/0000-0002-7623-9021)
- Masatoshi Fukuda
Institutions
- Japan Agency for Medical Research and Development (JP)
- Tokyo Metropolitan Institute of Medical Science (JP)
- Development Initiatives (GB)
- Osaka Research Institute of Industrial Science and Technology (JP)
- Niigata University (JP)
- The University of Osaka (JP)
Publication Details
- Journal
- iScience
- Published
- 2024-10-19
- DOI
- https://doi.org/10.1016/j.isci.2024.111214
- Citations
- 2
- Primary Topic
- Hearing, Cochlea, Tinnitus, Genetics
- Type
- article
- Field-Weighted Citation Impact
- 0.72
Funders
- Takeda Science Foundation
- Japan Agency for Medical Research and Development
- Brain Science Foundation
- Ministry of Education, Culture, Sports, Science and Technology
- Inamori Foundation
- Japan Society for the Promotion of Science
- Institute for Protein Research, Osaka University
- Core Research for Evolutional Science and Technology
- Moonshot Research and Development Program