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Calcium mobilization and protease-activated receptor cleavage after thrombin stimulation in motor neurons

Authors
  • Smirnova, Irina V.1, 2
  • Vamos, Suzanne3, 4
  • Wiegmann, Thomas3, 4
  • Citron, Bruce A.1, 2
  • Arnold, Paul M.1, 5
  • Festoff, Barry W.1, 2
  • 1 Neurobiology Research, USA
  • 2 University of Kansas Medical Center, Department of Neurology, Kansas City, KS, 66103 , Kansas City
  • 3 Fluorescence Imaging Laboratories Department of Veterans Affairs Medical Center, Kansas City, MO, 64128 , Kansas City
  • 4 University of Kansas Medical Center, Internal Medicine, Kansas City, KS, 66103 , Kansas City
  • 5 Surgery (Neurosurgery) University of Kansas Medical Center, Kansas City, KS, 66103 , Kansas City
Type
Published Article
Journal
Journal of Molecular Neuroscience
Publisher
Springer-Verlag
Publication Date
Feb 01, 1998
Volume
10
Issue
1
Pages
31–44
Identifiers
DOI: 10.1007/BF02737083
Source
Springer Nature
Keywords
License
Yellow

Abstract

Thrombin, the ultimate enzyme in the blood coagulation cascade, has prominent actions on various cells, including neurons. As in platelets, thrombin increases [Ca2+i mobilization in neurons, and also retracts neurites. Both these effects are mediated through a G protein-coupled, proteolytically activated receptor for thrombin (PAR-1). Prolonged exposure to thrombin kills neurons via apoptosis, that may also involve PAR-1 activation. Increased [Ca2+]i has been a unifying mechanism proposed for cell death in several neurodegenerative diseases. Thrombin-elevated calcium levels may activate intracellular cascades in neurons leading to cell death. Since thrombin mediates its diverse effects on cells through both heterotrimeric and monomeric G proteins, we also explored what effect altering differential G protein coupling would have on the neuronal response to thrombin. We studied calcium mobilization by thrombin in a model motor neuronal cell line, NSC19, using fluorescence image analysis. Confirming effects in other neuronal types, thrombin caused dramatic increases in [Ca2+]i levels, both transiently and after prolonged exposure, which involved activation and cleavage of the PAR-1 receptor. Using enzyme linked immunosorbent assay (ELISA) and dot-blot analysis, we found that the N-terminal fragment of PAR-1 was released into the medium after exposure to thrombin. We confirmed that PAR-1 protein and mRNA expression occurred in motor neurons. We found that cholera toxin inhibited thrombin-mediated Ca2+ influx, pertussis toxin did not significantly alter thrombin action, and lovastatin, a small 21-kDa Ras GTPase (Rho) modulator, showed a tendency to reduce the thrombin effect. These data indicate that thrombin-increased [Ca2+]i, sufficient to trigger cell death in motor neurons, might be approached in vivo by modulating thrombin signaling through PAR-1.

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