title: Localization of ryanodine receptor 3 in the sinus endothelial cells of the rat spleen.
abstract: The ultrastructural localization of ryanodine receptors (RyR) in sinus endothelial cells of the rat spleen was examined by confocal laser scanning and electron microscopy by using isoform-specific antibodies to each of the RyR isoforms. Immunofluorescence microscopy of tissue cryosections revealed RyR3 to be localized, with a strand-like form, in the superficial layer and within the cytoplasm of endothelial cells. Antibodies to RyR1 and RyR2 did not react indicating RyR3 was the predominant isoform. RyR3 was observed over the cortical layer of actin filaments in the apical part and beneath stress fibers in the basal part of the endothelial cells. The distribution of Ca2+-storing tubulovesicular-structures within endothelial cells was established by tissue sections treated with osmium ferricyanide selectively to stain the sarcoplasmic reticulum and transverse tubules in muscle cells; electron microscopy revealed densely stained tubulovesicular structures located throughout the sinus endothelial cells and interconnected at various sites. These structures closely apposed the plasma membrane at the apical, lateral, and basal surfaces of the cells and occasionally ran closely parallel to the plasma membrane and near to the mitochondria. Immunogold electron microscopy revealed RyR in the membranes of the nucleus, tubulovesicular structures, and subplasmalemmal cisternae. In the subplasmalemmal cisternae at the apical, lateral, and basal surfaces, RyR was detected on the membranes near to the plasma membrane. Labeling was also present on the membranes of tubulovesicular structures near to caveolae and on the cristae of the mitochondria. Thus, RyR probably participates in Ca2+ signal transduction and/or mechanosignal transduction in sinus endothelial cells.
authors.affiliation: Department of Cell Biology, Fukuoka University School of Medicine, Jonann-ku, Fukuoka, Japan. kiyokoue@fukuoka-u.ac.jp
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Uehara
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Onoue
authors.forename: Loice H
authors.initials: LH
authors.lastname: Jeyakumar
authors.forename: Sidney
authors.initials: S
authors.lastname: Fleischer
authors.forename: Akira
authors.initials: A
authors.lastname: Uehara
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology; D021941:Caveolae / Q000378:metabolism / Q000648:ultrastructure; D002450:Cell Communication / Q000502:physiology; D042783:Endothelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D040542:Mechanotransduction, Cellular / Q000502:physiology; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000378:metabolism / Q000648:ultrastructure; D032389:Myocytes, Smooth Muscle / Q000378:metabolism / Q000648:ultrastructure; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D013154:Spleen / Q000166:cytology / Q000378:metabolism*
chemical_list: D020033:Protein Isoforms; D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium