title: Thrombin receptor activation causes rapid neural cell rounding and neurite retraction independent of classic second messengers.
abstract: The protease thrombin is a potent activator of various cell types. Thrombin cleaves and thereby activates its own seven-transmembrane-domain receptor which couples to G proteins. Thrombin also can inhibit neuronal differentiation, supposedly by degrading components of the extracellular matrix. Here we report that active thrombin induces immediate cell rounding and neurite retraction in differentiating N1E-115 and NG108-15 neural cells in serum-free culture. Serum (0.5-5% vol/vol) evokes similar responses, but the cell-rounding and neurite-retracting activity of serum is not attributable to thrombin. Neural cell rounding is transient, subsiding after 10-15 min, and subject to homologous desensitization, whereas retracted neurites rapidly degenerate. Thrombin action is inhibited by cytochalasin, but not colchicine. A novel 14-amino acid peptide agonist of the thrombin receptor fully mimics thrombin's morphoregulatory activity, indicating that thrombin-induced shape changes are receptor-mediated and not secondary to extracellular matrix degradation. Although thrombin receptors couple to phosphoinositide hydrolysis and Ca2+ mobilization, thrombin-induced shape changes appear to depend neither on the Ca2+/protein kinase C- nor the cyclic nucleotide-mediated signal transduction pathways; however, the morphological response to thrombin is blocked by pervanadate, an inhibitor of tyrosine phosphatases, and by broad-specificity kinase inhibitors. Our results suggest that the thrombin receptor communicates to an as-yet-uncharacterized effector to reorganize the actin cytoskeleton and to reverse the differentiated phenotype of neural cells.
authors.affiliation: Division of Cellular Biochemistry, The Netherlands Cancer Institute, Amsterdam.
authors.forename: K
authors.initials: K
authors.lastname: Jalink
authors.forename: W H
authors.initials: WH
authors.lastname: Moolenaar
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D019833:Genistein; D007529:Isoflavones / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D016501:Neurites / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D009447:Neuroblastoma; D009474:Neurons / Q000166:cytology* / Q000187:drug effects; D009842:Oligopeptides / Q000138:chemical synthesis / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000502:physiology*; D018179:Receptors, Thrombin; D015290:Second Messenger Systems; D015398:Signal Transduction / Q000187:drug effects; D019311:Staurosporine; D013917:Thrombin / Q000378:metabolism / Q000494:pharmacology*; D014638:Vanadates / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D007529:Isoflavones; D009842:Oligopeptides; D011956:Receptors, Cell Surface; D018179:Receptors, Thrombin; D014638:Vanadates; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D013917:Thrombin; D019311:Staurosporine; D002118:Calcium