title: A novel Galphaq/11-selective inhibitor.
abstract: YM-254890, which was isolated from the culture broth of Chromobacterium sp., inhibits ADP-induced platelet aggregation and has antithrombotic and thrombolytic effects. YM-254890 blocks Galpha(q/11)-coupled ADP receptor P2Y1-mediated Ca(2+) mobilization. Here we report that YM-254890 is a selective Galpha(q/11) inhibitor. YM-254890 blocked Ca(2+) mobilization mediated by several Galpha(q/11)-coupled receptors but not by Galpha(i)- or Galpha(15)-coupled receptor, indicating that phospholipase Cbeta activation and subsequent signaling molecules are not the target of YM-254890. YM-254890 completely prevented the serum response factor (SRF)-mediated gene transcription induced by Galpha(q)R183C, which is constitutively active in a receptor-dependent manner because of its reduced k(cat) of GTP hydrolysis. Conversely, YM-254890 had only a modest effect on the SRF-mediated gene transcription by Galpha(q)Q209L, which is GTPase-deficient (activated) Galpha(q). These suggested that the acting point of YM-254890 is receptor-Galpha(q) interaction or the subsequent guanine nucleotide exchange step. The fact that YM-254890 (i) inhibited the SRF-mediated gene transcription by Galpha(qi5), which interacts with Galpha(i)-coupled receptor and possesses the effector function of Galpha(q), and (ii) had no effect on the K(d) value of high affinity [(3)H]2MeSADP binding to P2Y1, which reflects the agonist-receptor-Galpha ternary complex, suggested that receptor-Galpha(q/11) interaction is not the target of YM-254890. On the other hand, specific [(35)S]GTPgammaS binding to Galpha(q/11) stimulated by the M1 muscarinic acetylcholine receptor and P2Y1 were inhibited by YM-254890. These data indicate that YM-254890 blocks the exchange of GDP for GTP in Galpha(q/11) activation. This novel Galpha(q/11)-selective inhibitor is a promising and powerful tool for studying Galpha(q/11) protein activation, Galpha(q/11) -coupled receptor signaling, and Galpha(q/11)-mediated biological events.
authors.affiliation: Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., 21 Miyukigaoka, Tsukuba-shi, Ibaraki 305-8585, Japan. takasaki@yamanouchi.co.jp
authors.forename: Jun
authors.initials: J
authors.lastname: Takasaki
authors.forename: Tetsu
authors.initials: T
authors.lastname: Saito
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Taniguchi
authors.forename: Tomihisa
authors.initials: T
authors.lastname: Kawasaki
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Moritani
authors.forename: Kazumi
authors.initials: K
authors.lastname: Hayashi
authors.forename: Masato
authors.initials: M
authors.lastname: Kobori
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000235:genetics / Q000378:metabolism; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D017930:Genes, Reporter; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015394:Molecular Structure; D010456:Peptides, Cyclic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058472:Receptors, Purinergic P2Y1; D015398:Signal Transduction / Q000502:physiology; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; C546382:P2RY1 protein, human; D010456:Peptides, Cyclic; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; C475455:YM-254890; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000242:Cyclic AMP; C112631:G protein alpha 16; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020962:Heterotrimeric GTP-Binding Proteins; D002118:Calcium