title: Endocytosis of MPO in marginal cells is regulated by PKC, protein phosphatase, ERK and PI3-K signaling cascades, but not by PKA and MEK signaling cascades.
abstract: Endocytosis of marginal cells plays a key role in maintaining the homeostasis of endocytosis and function of the organ of Corti. How the signaling cascade is involved in the regulation of endocytosis is an important issue at present. To investigate the regulation of endocytosis in marginal cells of the stria vascularis by the signaling network, we perfused MPO, an endocytosis tracer, with PMA, OA, staurosporin, PAO, PD98059, SB20580 or wortmannin into the cochlear duct. After 30 min endolymphatic perfusion, the tissues were fixed and the distribution of MPO was examined by electron microscopy. We explored the functions of PKC, RTK, PI3-K, PTP, and PP1/2A in MPO endocytosis and defined the MPO endocytic route. MPO endocytosis was strongly dependent on PKC, ERK, PTP, PP1/2A and PI3-K signaling networks, but not on PKA and MEK signaling networks. The MPO endocytic pathways are clathrin-, GPI-AP-, and caveolae-independent.
authors.affiliation: Department of Otolaryngology, Faculty of Medicine, University of Tokyo, Tokyo, Japan. kakigi-tky@umin.ac.jp
authors.forename: Akinobu
authors.initials: A
authors.lastname: Kakigi
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Okada
authors.forename: Taizo
authors.initials: T
authors.lastname: Takeda
authors.forename: Setsuko
authors.initials: S
authors.lastname: Takeda
authors.forename: Daizo
authors.initials: D
authors.lastname: Taguchi
authors.forename: Masahiko
authors.initials: M
authors.lastname: Nishimura
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Yamasoba
mesh_terms: D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004195:Disease Models, Animal; D004705:Endocytosis / Q000502:physiology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006168:Guinea Pigs; D008854:Microscopy, Electron; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009842:Oligopeptides; D009925:Organ of Corti / Q000378:metabolism* / Q000648:ultrastructure; D010544:Peroxidases / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013316:Stria Vascularis / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D009842:Oligopeptides; D010544:Peroxidases; C021799:microperoxidase; D019869:Phosphatidylinositol 3-Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D017027:Protein Tyrosine Phosphatases