title: Immunocytochemical localization of the translocase of the outer mitochondrial membrane (Tom20) in the human cochlea.
abstract: Mitochondrial degeneration in the inner ear is likely a contributing factor in age-related hearing loss and other otopathologies such as Meniere's disease. Most mitochondrial proteins are synthesized in the cytosol and imported through the mitochondrial membranes by translocators. The translocase of the outer membrane (Tom) is the universal entry gate for all proteins that are imported into mitochondria. Altered function of the translocator could alter protein transport into the mitochondria, and disrupt function. In this study, we determined the immunolocalization of Tom20, a major mitochondrial protein import receptor, in microdissected human cochlea frozen sections obtained from postmortem autopsy and celloidin-embedded archival specimens. We used affinity purified rabbit polyclonal antibodies against Tom20. We also determined the Tom20 immunolocalization in the mouse inner ear. In the human and mouse cochlea, Tom20 was ubiquitously distributed in the organ of Corti, allowing well-delineated visualization of inner and outer hair cells. Tom20 immunoreactivity localized in the cytoplasm of spiral ganglia neurons. In the inner ear of aged subjects with Meniere's disease, there was decreased expression of Tom20. These results suggest that Tom20 can be used in the inner ear as a marker for mitochondrial protein import.
authors.affiliation: Department of Head and Neck Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-1624, USA.
authors.forename: Ashley E
authors.initials: AE
authors.lastname: Balaker
authors.forename: Paul
authors.initials: P
authors.lastname: Ishiyama
authors.forename: Ivan A
authors.initials: IA
authors.lastname: Lopez
authors.forename: Gail
authors.initials: G
authors.lastname: Ishiyama
authors.forename: Akira
authors.initials: A
authors.lastname: Ishiyama
mesh_terms: D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002648:Child; D003051:Cochlea / Q000201:enzymology*; D005260:Female; D005404:Fixatives; D005557:Formaldehyde; D005629:Frozen Sections; D006198:Hair Cells, Auditory / Q000201:enzymology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D026901:Membrane Transport Proteins / Q000032:analysis*; D008575:Meniere Disease / Q000201:enzymology*; D051379:Mice; D008808:Mice, Inbred CBA; D042282:Microdissection; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology*; D051336:Mitochondrial Membranes / Q000201:enzymology*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D051381:Rats; D011956:Receptors, Cell Surface / Q000032:analysis*; D013136:Spiral Ganglion / Q000201:enzymology; D016707:Tissue Fixation / Q000379:methods
chemical_list: D015415:Biomarkers; D005404:Fixatives; D026901:Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D011956:Receptors, Cell Surface; C084008:TOMM20 protein, human; C489997:Tomm20 protein, mouse; D005557:Formaldehyde