title: Correlation of actin crosslinker and capper expression levels with stereocilia growth phases.
abstract: During development of the chick cochlea, actin crosslinkers and barbed-end cappers presumably influence growth and remodeling of the actin paracrystal of hair cell stereocilia. We used mass spectrometry to identify and quantify major actin-associated proteins of the cochlear sensory epithelium from E14 to E21, when stereocilia widen and lengthen. Tight actin crosslinkers (i.e. fascins, plastins, and espin) are expressed dynamically during cochlear epithelium development between E7 and E21, with FSCN2 replacing FSCN1 and plastins remaining low in abundance. Capping protein, a barbed-end actin capper, is located at stereocilia tips; it is abundant during growth phase II, when stereocilia have ceased elongating and are increasing in diameter. Capping protein levels then decline during growth phase III, when stereocilia reinitiate barbed-end elongation. Although actin crosslinkers are readily detected by electron microscopy in developing chick cochlea stereocilia, quantitative mass spectrometry of stereocilia isolated from E21 chick cochlea indicated that tight crosslinkers are present there in stoichiometric ratios relative to actin that are much lower than their ratios for vestibular stereocilia. These results demonstrate the value of quantitation of global protein expression in chick cochlea during stereocilia development.
authors: Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, Oregon 97239;
authors: Matthew R
authors: MR
authors: Avenarius
authors: Katherine W
authors: KW
authors: Saylor
authors: Megan R
authors: MR
authors: Lundeberg
authors: Phillip A
authors: PA
authors: Wilmarth
authors: Jung-Bum
authors: JB
authors: Shin
authors: Kateri J
authors: KJ
authors: Spinelli
authors: James M
authors: JM
authors: Pagana
authors: Leonardo
authors: L
authors: Andrade
authors: Bechara
authors: B
authors: Kachar
authors: Dongseok
authors: D
authors: Choi
authors: Larry L
authors: LL
authors: David
authors: Peter G
authors: PG
authors: Barr-Gillespie
mesh_terms: D051344:Actin Capping Proteins / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D002642:Chick Embryo / Q000378:metabolism; D003051:Cochlea / Q000196:embryology / Q000378:metabolism; D047108:Embryonic Development / Q000502:physiology; D004848:Epithelium / Q000196:embryology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006198:Hair Cells, Auditory / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D059547:Stereocilia / Q000378:metabolism* / Q000502:physiology
chemical_list: D051344:Actin Capping Proteins; D000199:Actins; D008840:Microfilament Proteins