Transduction mechanisms involved in thrombin receptor-induced nerve growth factor secretion and cell division in primary cultures of astrocytes.
In astrocytes, thrombin and thrombin receptor-activating peptide (TRAP-14), a 14-amino-acid agonist of the proteolytic activating receptor for thrombin (PART), significantly increased cell division as assessed by [3H]-thymidine incorporation into DNA (EC50 = 1 nM and +650% at 100 nM for thrombin; EC50 = 3 microM and +600% at 100 microM for TRAP-14) and nerve growth factor (NGF) secretion (approximately twofold at 100 nM thrombin or 100 microM TRAP-14). The [3H] thymidine incorporation was prevented by protein kinase C inhibitors (staurosporine and H7) or by down-regulation of this enzyme by chronic exposure of astrocytes to phorbol 12-myristate 13-acetate (PMA). Thrombin-induced NGF secretion was completely inhibited by protein kinase C inhibitors. Treatment with PMA stimulated NGF secretion 19-fold, and this effect was not further enhanced by thrombin. These data suggest an absolute requirement of protein kinase C activity for thrombin-induced NGF secretion and cell division. Pretreatment of astrocytes with pertussis toxin (PTX) reduced thrombin- and TRAP-14-induced DNA synthesis. PART activation caused a decrease in forskolin-stimulated cyclic AMP accumulation. PTX treatment prevented the inhibitory effect of PART activation on cyclic AMP accumulation, suggesting that a PTX-sensitive G protein, such as Gi or G(o), is involved in thrombin-induced cell division. In contrast, thrombin-induced NGF secretion was not inhibited by PTX. Finally, the protein tyrosine kinase inhibitor herbimycin A partially but significantly prevented thrombin- and TRAP-14-induced cell division but was without effect on NGF secretion. Taken together, these results demonstrate that, in astrocytes, PART(s)-triggered cell division or NGF secretion is mediated by distinct transduction mechanisms.
Debeir
T
T
CNS Research Department, Synthélabo Recherche, Bagneux, France.
Gueugnon
J
J
Vigé
X
X
Benavides
J
J
D000067956:Adenylyl Cyclase Inhibitors; D000818:Animals; D001253:Astrocytes / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured / Q000201:enzymology / Q000378:metabolism / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis / Q000378:metabolism; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism; D009414:Nerve Growth Factors / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology; D037342:Pertussis Toxin; D011247:Pregnancy; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018179:Receptors, Thrombin / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D014316:Tritium / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000067956:Adenylyl Cyclase Inhibitors; D009414:Nerve Growth Factors; D010446:Peptide Fragments; D018179:Receptors, Thrombin; D010566:Virulence Factors, Bordetella; C089243:thrombin receptor peptide 14; D014316:Tritium; D005576:Colforsin; D000242:Cyclic AMP; D037342:Pertussis Toxin; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D013917:Thrombin; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate; D013936:Thymidine