title: Evidence that protease-activated receptor-2 mediates trypsin-induced reversal of stellation in cultured rat astrocytes.
abstract: Serine proteases such as thrombin and trypsin play a key role in the development and repair processes in the central nervous system. Molecular actions of serine proteases include multiple cellular events like activation of protease-activated receptors (PARs). PARs belong to a family of G protein-coupled receptors that can be stimulated through their proteolytic cleavage by ligands. PAR-2 has been implicated in neurodegenerative diseases including astrogliosis. Although recent studies have shown that low concentration of trypsin activates PAR-2, its role in morphological changes in primary astrocytes has not been studied. In the present study, we investigated the effects of PAR-2 in astrocyte stellation in rat primary astrocyte culture. Both trypsin (0.1-1 U/ml) and a PAR-2-activating peptide SLIGRL-NH2 (1-50 microM) significantly reversed the stellation induced by serum deprivation in rat astrocytes. Treatment of astrocytes with trypsin or SLIGRL-NH2 resulted in a transient rise of the intracellular Ca2+ level and trypsin-induced morphological changes were blocked by BAPTA, a Ca2+ chelator. In addition, a protein kinase C (PKC) inhibitor, bisindolylmaleimide significantly inhibited the trypsin-induced morphological changes, whereas activation of PKC by phorbol-12-myristate-13-acetate acted as trypsin. Taken together, these results suggest that activation of PAR-2 by trypsin caused reversal of stellation in cultured astrocytes, in part, via the mobilization of intracellular Ca2+ and activation of PKC.
authors.affiliation: Department of Pharmacology, College of Pharmacy, Seoul National University, San 56-1, Shillim-Dong, Kwanak-Gu, Seoul 151-742, South Korea.
authors.forename: Gyu Hwan
authors.initials: GH
authors.lastname: Park
authors.forename: Jae Ryun
authors.initials: JR
authors.lastname: Ryu
authors.forename: Chan Young
authors.initials: CY
authors.lastname: Shin
authors.forename: Min Sik
authors.initials: MS
authors.lastname: Choi
authors.forename: Byoung-Hee
authors.initials: BH
authors.lastname: Han
authors.forename: Won-Ki
authors.initials: WK
authors.lastname: Kim
authors.forename: Hyoung-Chun
authors.initials: HC
authors.lastname: Kim
authors.forename: Kwang Ho
authors.initials: KH
authors.lastname: Ko
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism*; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007150:Immunohistochemistry; D009842:Oligopeptides / Q000494:pharmacology; D011493:Protein Kinase C / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044464:Receptor, PAR-2 / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014357:Trypsin / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D009842:Oligopeptides; D044464:Receptor, PAR-2; C112356:seryl-leucyl-isoleucyl-glycyl--arginyl-leucinamide; D011493:Protein Kinase C; D014357:Trypsin; D002118:Calcium