title: Development of Photoactivatable Allosteric Modulators for the Chemokine Receptor CXCR3.
abstract: The CXCR3 receptor, a class A G protein-coupled receptor (GPCR), is involved in the regulation and trafficking of various immune cells. CXCR3 antagonists have been proposed to be beneficial for the treatment of a wide range of disorders including but not limited to inflammatory and autoimmune diseases. The structure-based design of CXCR3 ligands remains, however, hampered by a lack of structural information describing in detail the interactions between an allosteric ligand and the receptor. We designed and synthesized photoactivatable probes for the structural and functional characterization, using photoaffinity labeling followed by mass spectrometry, of the CXCR3 allosteric binding pocket of AMG 487 and RAMX3, two potent and selective CXCR3 negative allosteric modulators. Photoaffinity labeling is a common approach to elucidate binding modes of small-molecule ligands of GPCRs through the aid of photoactivatable probes that convert to extremely reactive intermediates upon photolysis. The photolabile probe N-[({1-[3-(4-ethoxyphenyl)-4-oxo-3,4-dihydropyrido[2,3-d]pyrimidin-2-yl]ethyl}-2-[4-fluoro-3-(trifluoromethyl)phenyl]-N-{1-[4-(3-(trifluoromethyl)-3H-diazirin-3-yl]benzyl}piperidin-4-yl)methyl]acetamide (10) showed significant labeling of the CXCR3 receptor (80%) in a [(3) H]RAMX3 radioligand displacement assay. Compound 10 will serve as an important tool compound for the detailed investigation of the binding pocket of CXCR3 by mass spectrometry.
authors.affiliation: Department of Chemistry & Pharmacy, Emil Fischer Center, Friedrich Alexander University Erlangen-Nürnberg, Schuhstr. 19, 91052, Erlangen, Germany.
authors.forename: Tizita Haimanot
authors.initials: TH
authors.lastname: Admas
authors.affiliation: Department of Chemistry & Pharmacy, Emil Fischer Center, Friedrich Alexander University Erlangen-Nürnberg, Schuhstr. 19, 91052, Erlangen, Germany.|Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, 3A1, 33458, Jupiter, FL, USA.
authors.forename: Viachaslau
authors.initials: V
authors.lastname: Bernat
authors.affiliation: Department of Chemistry & Pharmacy, Emil Fischer Center, Friedrich Alexander University Erlangen-Nürnberg, Schuhstr. 19, 91052, Erlangen, Germany.
authors.forename: Markus R
authors.initials: MR
authors.lastname: Heinrich
authors.affiliation: Department of Chemistry & Pharmacy, Emil Fischer Center, Friedrich Alexander University Erlangen-Nürnberg, Schuhstr. 19, 91052, Erlangen, Germany. nuska.tschammer@nanotemper.de.|NanoTemper Technologies GmbH, Flößergasse 4, 81369, München, Germany. nuska.tschammer@nanotemper.de.
authors.forename: Nuska
authors.identifier: http://orcid.org/0000-0003-2433-3355
authors.initials: N
authors.lastname: Tschammer
mesh_terms: D000081:Acetamides / Q000138:chemical synthesis / Q000494:pharmacology* / Q000528:radiation effects*; D054371:Chemokine CXCL11 / Q000378:metabolism; D000242:Cyclic AMP / Q000737:chemistry; D057809:HEK293 Cells; D006801:Humans; D013058:Mass Spectrometry; D019920:Photoaffinity Labels / Q000138:chemical synthesis / Q000494:pharmacology* / Q000528:radiation effects; D010782:Photolysis; D010880:Piperidines / Q000138:chemical synthesis / Q000494:pharmacology* / Q000528:radiation effects*; D011744:Pyrimidinones / Q000494:pharmacology; D054367:Receptors, CXCR3 / Q000037:antagonists & inhibitors* / Q000737:chemistry; D014316:Tritium
chemical_list: D000081:Acetamides; C515202:CXCL11 protein, human; C515187:CXCR3 protein, human; D054371:Chemokine CXCL11; C000618497:N-(((1-(3-(4-ethoxyphenyl)-4-oxo-3,4-dihydropyrido(2,3-d)pyrimidin-2-yl)ethyl)-2-(4-fluoro-3-(trifluoromethyl)phenyl)N-(1-(4-(3-(trifluoromethyl)-3H-diazirin-3-yl)benzyl))piperidin-4-yl)methyl)acetamide; C541505:N-(1-(3-(4-ethoxyphenyl)-4-oxo-3,4-dihydropyrido(2,3-d)pyrimidin-2-yl)ethyl)-N-pyridin-3-ylmethyl-2-(4-trifluoromethoxyphenyl)acetamide; D019920:Photoaffinity Labels; D010880:Piperidines; D011744:Pyrimidinones; C576504:RAMX3; D054367:Receptors, CXCR3; D014316:Tritium; D000242:Cyclic AMP
keywords: CXCR3; chemokine receptors; irreversible binding; photoactivatable ligands; photoaffinity labelling