title: Actin filaments and microtubules regulate endocytosis in marginal cells of the stria vascularis.
abstract: CONCLUSIONS
  Cationized ferritin (CF) was internalized via clathrin-mediated endocytosis. This process depends on clathrin, actin filaments, and microtubules. Microperoxidase (MPO) was internalized via a clathrin- and caveolin-independent endocytic pathway, which was partially dependent on microtubules but independent of clathrin and actin filaments.
  
  
  OBJECTIVE
  We investigated the role of actin filaments and microtubules in the transport of endocytic carrier vesicles (ECVs) from the plasma membrane to the early sorting endosomes, using CF and MPO as tracers.
  
  
  METHODS
  Fifty-five guinea pigs were used. The animals were divided into a CF endocytosis group and an MPO endocytosis group. These groups consisted of control, nocodazole-treated, cytochalasin (Cyt D)-treated, Cyt D + nocodazole-treated, and geldanamycin-treated subgroups.
  
  
  RESULTS
  For CF endocytosis, the following results were obtained. In the nocodazole experiment, in which microtubules were disrupted to form monomeric tubulin, the number of ECVs loaded with CF was greatly decreased. In the Cyt D experiment, in which the actin filaments were disrupted to form monomers, the number of ECVs labeled with CF was also greatly decreased. In the geldanamycin experiment, in which clathrin-mediated endocytosis was regulated and actin stress fibers were dissolved, the endocytosis of CF was severely inhibited. For MPO endocytosis, in the nocodazole experiment, the endocytosis of MPO was markedly suppressed.
authors.affiliation: Department of Otolaryngology, Kochi Medical School, Kochi, Japan. kakigia@med.kochi-u.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: Daizo
authors.initials: D
authors.lastname: Taguchi
authors.forename: Rie
authors.initials: R
authors.lastname: Nishioka
authors.forename: Masahiko
authors.initials: M
authors.lastname: Nishimura
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology*; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism; D005260:Female; D005293:Ferritins / Q000493:pharmacokinetics; D006168:Guinea Pigs; D008870:Microtubules / Q000502:physiology*; D010544:Peroxidases / Q000493:pharmacokinetics; D013316:Stria Vascularis / Q000166:cytology* / Q000502:physiology
chemical_list: C010297:polycationic ferritin; D005293:Ferritins; D010544:Peroxidases; C021799:microperoxidase