title: Accumulated caveolae constitute subcellular compartments for glial calcium signaling in lanceolate sensory endings innervating rat vibrissae.
abstract: The terminal Schwann cells that accompany lanceolate sensory endings in the rat vibrissal follicle are known to display the small plasma membrane invaginations termed caveolae, which concentrate Ca(2+) signaling molecules. We have previously shown that these cells generate Ca(2+) signals at the lamellar processes covering the receptor axons through activation of the metabotropic purinoceptor P2Y(2). To investigate the roles of caveolae in the spatiotemporal organization of Ca(2+) signals, terminal Schwann cells were observed by immunohistochemistry for the caveola protein caveolin-1, and by transmission and scanning electron microscopy. In addition, immunohistochemical detection of P2Y(2) and its coupling partner G(q/11) along with confocal image analysis of the purinergically induced glial Ca(2+) responses was performed in isolated tissue preparations either treated or untreated with the caveolae eliminator methyl-β-cyclodextrin. Results showed the Schwann lamellae to be characterized by the presence of dense caveolae accompanying a fine tubular network of the endoplasmic reticulum Ca(2+) store and by intense expression of the signaling molecules P2Y(2) and G(q/11). Loss of caveolae diffusely redistributed these molecules throughout the entire cell and impaired the lamellar Ca(2+) signals, both in chronological priority (preceding the global cell response) and in spatial integrity (involving the entire length of the processes). To our knowledge, this is the first report of a subcellular accumulation of caveolae underlying compartmentalized glial Ca(2+) signals that can couple with local effects on the accompanying axon terminals.
authors.affiliation: Laboratory of Histology and Cytology, Graduate School of Medicine, Hokkaido University, Sapporo 060-8638, Japan. hiromiva@med.hokudai.ac.jp
authors.forename: Hiromi
authors.initials: H
authors.lastname: Takahashi-Iwanaga
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Iwanaga
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D051242:Caveolin 1 / Q000378:metabolism*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D009457:Neuroglia / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D058470:Receptors, Purinergic P2Y / Q000378:metabolism; D009418:S100 Proteins / Q000378:metabolism; D012583:Schwann Cells / Q000378:metabolism* / Q000648:ultrastructure; D014738:Vibrissae / Q000294:innervation* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D051242:Caveolin 1; D058470:Receptors, Purinergic P2Y; D009418:S100 Proteins; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D002118:Calcium