title: A substrate-free activity-based protein profiling screen for the discovery of selective PREPL inhibitors.
abstract: Peptidases play vital roles in physiology through the biosynthesis, degradation, and regulation of peptides. Prolyl endopeptidase-like (PREPL) is a newly described member of the prolyl peptidase family, with significant homology to mammalian prolyl endopeptidase and the bacterial peptidase oligopeptidase B. The biochemistry and biology of PREPL are of fundamental interest due to this enzyme's homology to the biomedically important prolyl peptidases and its localization in the central nervous system. Furthermore, genetic studies of patients suffering from hypotonia-cystinuria syndrome (HCS) have revealed a deletion of a portion of the genome that includes the PREPL gene. HCS symptoms thought to be caused by lack of PREPL include neuromuscular and mild cognitive deficits. A number of complementary approaches, ranging from biochemistry to genetics, will be required to understand the biochemical, cellular, physiological, and pathological mechanisms regulated by PREPL. We are particularly interested in investigating physiological substrates and pathways controlled by PREPL. Here, we use a fluorescence polarization activity-based protein profiling (fluopol-ABPP) assay to discover selective small-molecule inhibitors of PREPL. Fluopol-ABPP is a substrate-free approach that is ideally suited for studying serine hydrolases for which no substrates are known, such as PREPL. After screening over 300,000 compounds using fluopol-ABPP, we employed a number of secondary assays to confirm assay hits and characterize a group of 3-oxo-1-phenyl-2,3,5,6,7,8-hexahydroisoquinoline-4-carbonitrile and 1-alkyl-3-oxo-3,5,6,7-tetrahydro-2H-cyclopenta[c]pyridine-4-carbonitrile PREPL inhibitors that are able to block PREPL activity in cells. Moreover, when administered to mice, 1-isobutyl-3-oxo-3,5,6,7-tetrahydro-2H-cyclopenta[c]pyridine-4-carbonitrile distributes to the brain, indicating that it may be useful for in vivo studies. The application of fluopol-ABPP has led to the first reported PREPL inhibitors, and these inhibitors will be of great value in studying the biochemistry of PREPL and in eventually understanding the link between PREPL and HCS.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
authors.forename: Anna Mari
authors.initials: AM
authors.lastname: Lone
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Bachovchin
authors.forename: David B
authors.initials: DB
authors.lastname: Westwood
authors.forename: Anna E
authors.initials: AE
authors.lastname: Speers
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Spicer
authors.forename: Virneliz
authors.initials: V
authors.lastname: Fernandez-Vega
authors.forename: Peter
authors.initials: P
authors.lastname: Chase
authors.forename: Peter S
authors.initials: PS
authors.lastname: Hodder
authors.forename: Hugh
authors.initials: H
authors.lastname: Rosen
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Cravatt
authors.forename: Alan
authors.initials: A
authors.lastname: Saghatelian
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D055808:Drug Discovery; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D005454:Fluorescence Polarization / Q000379:methods*; D020869:Gene Expression Profiling; D057166:High-Throughput Screening Assays; D051379:Mice; D008810:Mice, Inbred C57BL; D015394:Molecular Structure; D000085822:Prolyl Oligopeptidases; D012697:Serine Endopeptidases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D004791:Enzyme Inhibitors; D012697:Serine Endopeptidases; D000085822:Prolyl Oligopeptidases