title: Ultrastructural analysis of nanogold-labeled cell surface microvilli in liquid by atmospheric scanning electron microscopy and their relevance in cell adhesion.
abstract: The adhesion of leukocytes circulating in the blood to vascular endothelium is critical for their trafficking in the vasculature, and CD44 is an important cell surface receptor for rolling adhesion. In this study, we demonstrate the correlative observation of CD44 distribution at the lymphocyte cell surface in liquid by fluorescence optical microscopy and immuno-electron microscopy using an atmospheric scanning electron microscope (ASEM). The ultrastructure of the cell surface was clearly imaged by ASEM using positively charged Nanogold particles. ASEM analysis demonstrated microvilli projections around the cell surface and the localization of CD44 on the microvilli. Treatment of cells with cytochalasin D resulted in a loss of the microvilli projections and concomitantly abrogated CD44-mediated adhesion to its ligand hyaluronan. These results suggest the functional relevance of microvilli in CD44-mediated rolling adhesion under shear flow.
authors.affiliation: Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan. murai@orgctl.med.osaka-u.ac.jp.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Murai
authors.forename: Mari
authors.initials: M
authors.lastname: Sato
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Nishiyama
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Suga
authors.forename: Chikara
authors.initials: C
authors.lastname: Sato
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000502:physiology*; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D006046:Gold / Q000008:administration & dosage*; D018960:Hyaluronan Receptors / Q000378:metabolism; D006820:Hyaluronic Acid / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D053768:Metal Nanoparticles / Q000008:administration & dosage*; D051379:Mice; D008855:Microscopy, Electron, Scanning / Q000379:methods; D008871:Microvilli / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure*
chemical_list: C476399:Cd44 protein, mouse; D018960:Hyaluronan Receptors; D006046:Gold; D006820:Hyaluronic Acid