Display Settings:


Send to:

Choose Destination
See comment in PubMed Commons below
Circ Res. 2002 Sep 6;91(5):398-405.

Galpha(q) and Gbetagamma regulate PAR-1 signaling of thrombin-induced NF-kappaB activation and ICAM-1 transcription in endothelial cells.

Author information

  • 1Department of Pharmacology, College of Medicine, The University of Illinois, Chicago, Ill 60612-7343, USA. ARahman@uic.edu


As thrombin binding to the G protein-coupled proteinase activated receptor-1 (PAR-1) induces endothelial adhesivity to leukocytes through NF-kappaB activation and intercellular adhesion molecule-1 (ICAM-1) expression, we determined the signaling pathways mediating the response. Studies showed that the heterotrimeric G proteins, Galpha(q), and the Gbetagamma dimer were key determinants of the PAR-1 agonist peptide (TFLLRNPNDK)-induced NF-kappaB activation and ICAM-1 expression in endothelial cells. Cotransfection of RGS3T, a regulator of G-protein signaling that inhibits Galpha(q), or alpha-transducin (Galpha(t)), a scavenger of the Gbetagamma, markedly decreased NF-kappaB activity induced by PAR-1 activation. We determined the downstream signaling targets activated by Galpha(q) and Gbetagamma that mediate NF-kappaB activation. Expression of the kinase-defective protein kinase C (PKC)-delta mutant inhibited NF-kappaB activation induced by the constitutively active Galpha(q) mutant, but had no effect on NF-kappaB activity induced by Gbeta(1)gamma(2). In related experiments, NF-kappaB as well as ICAM-1 promoter activation induced by Gbeta(1)gamma(2) were inhibited by the expression of the dominant-negative mutant of 85-kDa regulatory subunit of PI 3-kinase; however, the expression of this mutant had no effect on the response induced by activated Galpha(q). Cotransfection of the catalytically inactive Akt mutant inhibited the NF-kappaB activation induced by the constitutively active PI 3-kinase mutant as well as that by the activated forms of Galpha(q) and PKC-delta. These results support a model in which ligation of PAR-1 induces NF-kappaB activation and ICAM-1 transcription by the engagement of parallel Galphaq/PKC-delta and Gbetagamma/PI3-kinase pathways that converge at Akt.

[PubMed - indexed for MEDLINE]
Free full text

Publication Types, MeSH Terms, Substances, Grant Support

PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire
    Loading ...
    Write to the Help Desk