Characterization of UBO-QIC as a Gαq inhibitor in platelets.
Gαq plays an important role in platelet activation by agonists such as thrombin, adenosine diphosphate (ADP) and thromboxane. The significance of Gαq signaling in platelets was established using YM254890, a Gαq/11-specific inhibitor and Gαq knockout murine platelets. However, YM-254890 is no longer available for investigators and there is a need to characterize other Gαq inhibitors. The aim of this study is to characterize the specificity of a compound, {L-threonine,(3R)-N-acetyl-3-hydroxy-L-leucyl-(aR)-a-hydroxybenzenepropanoyl-2,3-idehydro-N-methylalanyl-L-alanyl-N-methyl-L-alanyl-(3R)-3-[[(2S,3R)-3-hydroxy-4-methyl-1-oxo-2-[(1-oxopropyl)amino]pentyl]oxy]-L-leucyl-N,O-dimethyl-,(7 → 1)-lactone (9CI)} (UBO-QIC), as a Gαq inhibitor in platelets. Human platelets treated with UBO-QIC showed a concentration-dependent inhibition of platelet aggregation and secretion by protease-activated receptors (PAR) agonists, U46619 and ADP. UBO-QIC also abolished Gαq pathway signaling events such as calcium mobilization and pleckstrin phosphorylation. UBO-QIC had no nonspecific effects on the Gα12/13 pathway since platelet shape change was intact in Gαq knockout murine platelets stimulated with PAR agonists in the presence of the inhibitor. In addition, UBO-QIC-treated platelets did not affect collagen-related peptide-induced platelet activation suggesting that this inhibitor had no non-specific effects on the GPVI pathway. Furthermore, Akt phosphorylation downstream of the Gαi and Gαz pathways, and vasodilator-stimulated phosphoprotein phosphorylation downstream of the Gαs pathway were not inhibited in UBO-QIC-treated platelets. UBO-QIC is a specific inhibitor for Gαq, which can be a useful tool for investigating Gαq-coupled receptor signaling pathways in platelets.
a Sol Sherry Thrombosis Research Center and Department of Physiology , Temple University School of Medicine , Philadelphia , PA , USA.
Vaishali
V
Inamdar
a Sol Sherry Thrombosis Research Center and Department of Physiology , Temple University School of Medicine , Philadelphia , PA , USA.
Akruti
A
Patel
a Sol Sherry Thrombosis Research Center and Department of Physiology , Temple University School of Medicine , Philadelphia , PA , USA.
Bhanu Kanth
BK
Manne
a Sol Sherry Thrombosis Research Center and Department of Physiology , Temple University School of Medicine , Philadelphia , PA , USA.
Carol
C
Dangelmaier
a Sol Sherry Thrombosis Research Center and Department of Physiology , Temple University School of Medicine , Philadelphia , PA , USA.
Satya P
SP
Kunapuli
D000244:Adenosine Diphosphate; D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D047630:Depsipeptides / Q000494:pharmacology*; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000037:antagonists & inhibitors*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
D047630:Depsipeptides; C000607068:FR900359; D044385:GTP-Binding Protein alpha Subunits; D010975:Platelet Aggregation Inhibitors; D010980:Platelet Membrane Glycoproteins; C098341:platelet membrane glycoprotein VI; D000244:Adenosine Diphosphate; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D001241:Aspirin; D002118:Calcium
GTP-binding protein alpha subunit; Gq; YM-254890; platelet aggregation; platelets; specificity