Impaired thromboxane receptor dimerization reduces signaling efficiency: A potential mechanism for reduced platelet function in vivo

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• 作者：Valé ; rie Capra^a ; ^b ; ¹ ; ^{Valerie.Capra@unimi.it} ; Mario Mauri^c ; ¹ ; ^{mario.mauri@unimib.it} ; Francesca Guzzi^c ; ^{francesca.guzzi@unimib.it} ; Marta Busnelli^d ; ^e ; ^{m.busnelli@in.cnr.com} ; Maria Rosa Accomazzo^a ; ^{Maria.Accomazzo@unimi.it} ; Pascale Gaussem^f ; ^{pascale.gaussem@univ-paris5.fr} ; Shaista P. Nisar^g ; ^{shaista.nisar@bristol.ac.uk} ; Stuart J. Mundell^g ; ^{s.j.mundell@bristol.ac.uk} ; Marco Parenti^c ; ^{marco.parenti@unimib.it} ; G. Enrico Rovati^a ; ^{Genrico.Rovati@unimi.it}
• 关键词：U46619 (PubChem CID ; 5311493) ; (Z)-7-[(1S ; 2S ; 3R ; 4R)-3-[(E ; 3S)-3-hydroxyoct-1-enyl]-5-oxabicyclo[2.2.1]heptan-2-yl]hept-5-enoic acid ; I-BOP (PubChem CID ; 51015454) ; (Z)-7-[(1S ; 2S ; 3S ; 4R)-3-[(E ; 3R)-3-hydroxy-4-(4-iodophenoxy)but-1-enyl]-7-oxabicyclo[2.2.1]heptan-2-yl]hept-5-enoic acid ; Pinane Thromboxane A2 (PTA2) (PubChem CID ; 25834471) ; (Z)-7-[(1S ; 3R ; 4R ; 5S)-3-[(E ; 3R)-3-hydroxyoct-1-enyl]-6 ; 6-dimethyl-4-bicyclo[3.1.1]heptanyl]hept-5-enoic acid ; SQ29 ; 548 (PubChem CID ; 6437074) ; (Z)-7-[(1R ; 2R ; 3R ; 4S)
• 刊名：Biochemical Pharmacology
• 出版年：2017
• 出版时间：15 January 2017
• 年：2017
• 卷：124
• 期：Complete
• 页码：43-56
• 全文大小：2133 K
• 卷排序：124

文摘

Thromboxane A2 is a potent mediator of inflammation and platelet aggregation exerting its effects through the activation of a G protein-coupled receptor (GPCR), termed TP. Although the existence of dimers/oligomers in Class A GPCRs is widely accepted, their functional significance still remains controversial. Recently, we have shown that TPα and TPβ homo-/hetero-dimers interact through an interface of residues in transmembrane domain 1 (TM1) whose disruption impairs dimer formation. Here, biochemical and pharmacological characterization of this dimer deficient mutant (DDM) in living cells indicates a significant impairment in its response to agonists. Interestingly, two single loss-of-function TPα variants, namely W29C and N42S recently identified in two heterozygous patients affected by bleeding disorders, match some of the residues mutated in our DDM. These two naturally occurring variants display a reduced potency to TP agonists and are characterized by impaired dimer formation in transfected HEK-293T cells. These findings provide proofs that lack of homo-dimer formation is a crucial process for reduced TPα function in vivo, and might represent one molecular mechanism through which platelet TPα receptor dysfunction affects the patient(s) carrying these mutations.