Albumin-Like Protein is the Major Protein Constituent of Luminal Fluid in the Human Endolymphatic Sac
Open Access
- 29 June 2011
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLOS ONE
- Vol. 6 (6), e21656
- https://doi.org/10.1371/journal.pone.0021656
Abstract
The endolymphatic sac (ES) is an inner ear organ that is connected to the cochleo-vestibular system through the endolymphatic duct. The luminal fluid of the ES contains a much higher concentration of proteins than any other compartment of the inner ear. This high protein concentration likely contributes to inner ear fluid volume regulation by creating an osmotic gradient between the ES lumen and the interstitial fluid. We characterized the protein profile of the ES luminal fluid of patients (n = 11) with enlarged vestibular aqueducts (EVA) by proteomics. In addition, we investigated differences in the protein profiles between patients with recent hearing deterioration and patients without hearing deterioration. The mean total protein concentration of the luminal fluid was 554.7±94.6 mg/dl. A total of 58 out of 517 spots detected by 2-DE were analyzed by MALDI-TOF MS. The protein profile of the luminal fluid was different from the profile of plasma. Proteins identified from 29 of the spots were also present in the MARC-filtered human plasma; however, the proteins identified from the other 25 spots were not detected in the MARC-filtered human plasma. The most abundant protein in the luminal fluid was albumin-like proteins, but most of them were not detected in MARC-filtered human plasma. The concentration of albumin-like proteins was higher in samples from patients without recent hearing deterioration than in patients with recent hearing deterioration. Consequently, the protein of ES luminal fluid is likely to be originated from both the plasma and the inner ear and considering that inner ear fluid volumes increase abnormally in patients with EVA following recent hearing deterioration, it is tempting to speculate that albumin-like proteins may be involved in the regulation of inner ear fluid volume through creation of an osmotic gradient during pathological conditions such as endolymphatic hydrops.Keywords
This publication has 27 references indexed in Scilit:
- Large vestibular aqueduct syndrome and endolymphatic hydrops: two presentations of a common primary inner-ear dysfunction?The Journal of Laryngology & Otology, 2009
- Visualization of a high protein concentration in the cochlea of a patient with a large endolymphatic duct and sac, using three-dimensional fluid-attenuated inversion recovery magnetic resonance imagingThe Journal of Laryngology & Otology, 2006
- Microscale analysis of proteins in inner ear tissues and fluids with emphasis on endolymphatic sac, otoconia, and organ of CortiElectrophoresis, 2006
- Efficient prefractionation of low‐abundance proteins in human plasma and construction of a two‐dimensional mapProteomics, 2005
- Origins and frequencies of SLC26A4 (PDS) mutations in east and south Asians: global implications for the epidemiology of deafnessJournal of Medical Genetics, 2003
- Endocytotic activity of the free floating cells and epithelial cells in the endolymphatic sac: An electron microscopic studyThe Anatomical Record, 1991
- Uptake of Radioactive Sulphur in the Endolymphatic Sac:An Autoradiographic StudyActa Oto-Laryngologica, 1989
- Serum albuminHepatology, 1988
- Degradation of the Homogeneous Substance in the Endolymphatic SacActa Oto-Laryngologica, 1988
- Effect of Labyrinthectomy on the Endolymphatic Sac:A Histological, Ultrastractural and Computer-Aided Morphometric Investigation in the MouseActa Oto-Laryngologica, 1986