Multi-isotope imaging mass spectrometry reveals slow protein turnover in hair-cell stereocilia
| Autor: | Agnieszka K. Rzadzinska, Benjamin J. Perrin, Duan Sun Zhang, J. Collin Poczatek, Claude Lechene, James M. Ervasti, David P. Corey, Valeria Piazza, Mei Wang, Haydn M. Prosser |
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| Rok vydání: | 2011 |
| Předmět: |
Biology
Cleavage (embryo) Article Epithelium Mass Spectrometry Stereocilia 03 medical and health sciences Bleaching Agents Mice 0302 clinical medicine Fiducial Markers otorhinolaryngologic diseases medicine Animals Inner ear Mechanotransduction Homologous Recombination Actin 030304 developmental biology 0303 health sciences Multidisciplinary Hair Cells Auditory Inner Rana catesbeiana Protein turnover Proteins Anatomy Actins Cell biology Mice Inbred C57BL Tamoxifen medicine.anatomical_structure Treadmilling Animals Newborn sense organs Hair cell Chickens 030217 neurology & neurosurgery |
| Zdroj: | Nature |
| ISSN: | 1476-4687 |
| Popis: | Multi-isotope imaging mass spectrometry is used to quantify protein turnover in animal stereocilia, showing that rapid turnover occurs only in stereocilia tips. In the auditory system, the mechanosensory hair cells of the inner ear convert sound-induced vibrations into electrical signals. The apical surface of a hair cell consists of stereocilia with a core of actin filaments that function as mechanosensors. It has been suggested that these actin filaments are replaced within two to three days by a treadmilling process. Using the newly developed multi-isotope imaging mass spectrometry (MIMS) technique, Zhang et al. quantify protein turnover in hair-cell stereocilia in vivo and find that turnover is slow throughout the stereocilia, except for the tip region, and does not involve a treadmilling process. Hair cells of the inner ear are not normally replaced during an animal’s life, and must continually renew components of their various organelles1. Among these are the stereocilia, each with a core of several hundred actin filaments that arise from their apical surfaces and that bear the mechanotransduction apparatus at their tips. Actin turnover in stereocilia has previously been studied2 by transfecting neonatal rat hair cells in culture with a β-actin–GFP fusion, and evidence was found that actin is replaced, from the top down, in 2–3 days. Overexpression of the actin-binding protein espin causes elongation of stereocilia within 12–24 hours, also suggesting rapid regulation of stereocilia lengths3. Similarly, the mechanosensory ‘tip links’ are replaced in 5–10 hours after cleavage in chicken and mammalian hair cells4,5. In contrast, turnover in chick stereocilia in vivo is much slower6. It might be that only certain components of stereocilia turn over quickly, that rapid turnover occurs only in neonatal animals, only in culture, or only in response to a challenge like breakage or actin overexpression. Here we quantify protein turnover by feeding animals with a 15N-labelled precursor amino acid and using multi-isotope imaging mass spectrometry to measure appearance of new protein. Surprisingly, in adult frogs and mice and in neonatal mice, in vivo and in vitro, the stereocilia were remarkably stable, incorporating newly synthesized protein at |
| Databáze: | OpenAIRE |
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