title: Neuroproteomics in the auditory brainstem: candidate proteins for ultrafast and precise information processing.
abstract: In the mammalian auditory brainstem, the cochlear nuclear complex (CN) and the superior olivary complex (SOC) feature structural and functional specializations for ultrafast (<1 ms) and precise information processing. Their proteome, the basis for structure and function, has been rarely analyzed so far. Here we identified and quantified the protein profiles of three major auditory brainstem regions of adult rats, the CN, the SOC, and the inferior colliculus (IC). The rest of the brain served as a reference. Via label-free quantitative mass spectrometry and 2-D DIGE/MALDI-MS, we identified 584 and 297 proteins in the plasma membrane/synaptic vesicle proteome and the cytosolic proteome, respectively. 'Region-typical' proteins, i.e., those with higher abundance in one region than in the other three, were considered candidates for functional specializations. Key proteins were validated via Western blots and immunohistochemistry. Functional annotation clustering revealed an overrepresentation of neurofilament proteins among the CN+SOC-typical proteins. These are related to regulation of axon diameter and, thereby, conduction velocity. Interestingly, the sets of synapse-associated proteins differed between regions. For example, synaptotagmin-2 (Syt2), a Ca2+ sensor for fast exocytosis, was CN+SOC+IC-typical, whereas Syt1 was CN+SOC+IC-atypical. Together, our quantitative comparison of protein profiles has revealed several interesting candidate proteins for ultrafast and precise information processing.
authors.affiliation: Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin-Schroedinger-Straße 13, 67663 Kaiserslautern, Germany. Electronic address: christian.moritz@biologie.uni-kl.de.
authors.forename: Christian P
authors.initials: CP
authors.lastname: Moritz
authors.affiliation: Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin-Schroedinger-Straße 13, 67663 Kaiserslautern, Germany. Electronic address: eugenia.eckstein@googlemail.com.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Eckstein
authors.affiliation: Institute of Immunology, University Medical Center of the Johannes Gutenberg University Mainz, Langenbeckstr. 1, 55131 Mainz, Germany. Electronic address: tenzer@uni-mainz.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Tenzer
authors.affiliation: Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin-Schroedinger-Straße 13, 67663 Kaiserslautern, Germany. Electronic address: eckhard.friauf@biologie.uni-kl.de.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Friauf
mesh_terms: D000818:Animals; D017626:Cochlear Nucleus / Q000378:metabolism*; D007245:Inferior Colliculi / Q000378:metabolism*; D008297:Male; D009928:Organ Specificity; D020543:Proteome; D051381:Rats; D017207:Rats, Sprague-Dawley; D065832:Superior Olivary Complex / Q000378:metabolism*
chemical_list: D020543:Proteome
keywords: Auditory brainstem; Axon diameter regulation; E-Syt1; Kir4.1; Neurofilament; Synaptotagmin