Screening a plant extract library for inhibitors of cholecystokinin receptor CCK1 pathways.
This study describes the screening of a plant extract library for inhibitors of signal transduction pathways mediated by the cholecystokinin receptor, CCK1. CCK1 receptors are coupled to Galpha(q/11)-proteins, localized mainly in the gastrointestinal tract, and implicated in the regulation of various digestive functions. A primary screen was performed using a cell-based assay that used the beta-lactamase gene reporter controlled by the transcriptional activator NFAT. The assay was validated with the CCK1 receptor antagonist, lorglumide, and automated by the use of a liquid-handling robot MultiProbe II. Off-target hits were triaged by counterscreening against gene reporter cells activated by a combination of thapsigargin and phorbol ester. Purification of active compounds was guided by the beta-lactamase gene reporter and Ca2+ mobilization assays. Pure compounds were characterized by Ca2+ mobilization, radioligand binding, inositol-1 phosphate formation, and Eu-GTP binding assays. The selectivity of inhibition was tested against a panel of Galpha(q/11), Galpha(s), and Galpha(i/0)-coupled receptors. These studies led to the identification of a novel Galpha(q/11)-selective inhibitor.
Nesterov
Alexandre
A
Unigen Pharmaceuticals, Inc., Lacey, WA 98516, USA. alexandre_nesterov@yahoo.com
Hong
Mei
M
Hertel
Carmen
C
Jiao
Ping
P
Brownell
Lidia
L
Cannon
Edward
E
D000818:Animals; D031644:Ardisia / Q000737:chemistry; D001681:Biological Assay / Q000379:methods*; D002460:Cell Line; D002766:Cholecystokinin / Q000378:metabolism; D017930:Genes, Reporter; D010936:Plant Extracts / Q000737:chemistry*; D010940:Plant Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D054852:Small Molecule Libraries
D010936:Plant Extracts; D010940:Plant Proteins; D011949:Receptors, Cholecystokinin; D054852:Small Molecule Libraries; D002766:Cholecystokinin