title: Anatomical localization of protease-activated receptor-1 and protease-mediated neuroglial crosstalk on peri-synaptic astrocytic endfeet.
abstract: We studied the localization, activation and function of protease-activated receptor 1 (PAR-1) at the CNS synapse utilizing rat brain synaptosomes and slices. Confocal immunofluoresence and transmission electron microscopy in brain slices with pre-embedding diaminobenzidine (DAB) immunostaining found PAR-1 predominantly localized to the peri-synaptic astrocytic endfeet. Structural confocal immunofluorescence microscopy studies of isolated synaptosomes revealed spherical structures stained with anti-PAR-1 antibody which co-stained mainly for glial-filament acidic protein compared with the neuronal markers synaptophysin and PSD-95. Immunoblot studies of synaptosomes demonstrated an appropriate major band corresponding to PAR-1 and activation of the receptor by a specific agonist peptide (SFLLRN) significantly modulated phosphorylated extracellular signal-regulated kinase. A significant membrane potential depolarization was produced by thrombin (1 U/mL) and the PAR-1 agonist (100 μM) and depolarization by high K(+) elevated extracellular thrombin-like activity in the synaptosomes preparation. The results indicate PAR-1 localized to the peri-synaptic astrocytic endfeet is most likely activated by synaptic proteases and induces cellular signaling and modulation of synaptic electrophysiology. A protease mediated neuron-glia pathway may be important in both physiological and pathological regulation of the synapse.
authors.affiliation: Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Efrat
authors.initials: E
authors.lastname: Shavit
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Michaelson
authors.forename: Joab
authors.initials: J
authors.lastname: Chapman
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure*; D056654:CA3 Region, Hippocampal / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D006801:Humans; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D016253:Microscopy, Immunoelectron; D009457:Neuroglia / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020239:Receptor Cross-Talk / Q000502:physiology*; D044463:Receptor, PAR-1 / Q000172:deficiency / Q000235:genetics / Q000648:ultrastructure*; D013569:Synapses / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure*; D013574:Synaptosomes / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D044463:Receptor, PAR-1