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Abstract
Monoglyceride lipase (MGL), the main enzyme responsible for the hydrolytic deactivation of the endocannabinoid 2-arachidonoyl-sn-glycerol (2-AG), is an intracellular serine hydrolase that plays critical roles in many physiological and pathological processes, such as pain, inflammation, neuroprotection and cancer. The crystal structures of MGL that are currently available provide valuable information about how this enzyme might function and interact with site-directed small-molecule inhibitors. On the other hand, its conformational equilibria and the contribution of regulatory cysteine residues present within the substrate-binding pocket or on protein surface remain open issues. Several classes of MGL inhibitors have been developed, from early reversible ones, such as URB602 and pristimerin, to carbamoylating agents that react with the catalytic serine, such as JZL184 and more recent O-hexafluoroisopropyl carbamates. Other inhibitors that modulate MGL activity by interacting with conserved regulatory cysteines act through mechanisms that deserve to be more thoroughly investigated.
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Affiliation(s)
- Laura Scalvini
- Dipartimento di Farmacia, Università degli Studi di Parma, I-43124 Parma, Italy
| | - Daniele Piomelli
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, CA 92697, United States; Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, United States; Unit of Drug Discovery and Development, Istituto Italiano di Tecnologia, Genova, Italy.
| | - Marco Mor
- Dipartimento di Farmacia, Università degli Studi di Parma, I-43124 Parma, Italy.
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Karageorgos I, Wales TE, Janero DR, Zvonok N, Vemuri VK, Engen JR, Makriyannis A. Active-site inhibitors modulate the dynamic properties of human monoacylglycerol lipase: a hydrogen exchange mass spectrometry study. Biochemistry 2013; 52:5016-26. [PMID: 23795559 DOI: 10.1021/bi400430k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Human monoacylglycerol lipase (hMGL) regulates endocannabinoid signaling primarily by deactivating the lipid messenger 2-arachidonoylglycerol. Agents that carbamylate hMGLs catalytic Ser(122) constitute a leading class of therapeutically promising hMGL inhibitors. We have applied peptide-level hydrogen/deuterium exchange mass spectrometry to characterize hMGL's conformational responses to two potent carbamylating inhibitors, AM6580 (irreversible) and AM6701 (slowly reversible). A dynamic, solvent-exposed lid domain is characteristic of hMGL's solution conformation. Both hMGL inhibitors restricted backbone enzyme motility in the active-site region and increased substrate binding-pocket solvent exposure. Covalent reaction of AM6580 with hMGL generates a bulkier carbamylated Ser(122) residue as compared to the more discrete Ser(122) modification by AM6701, a difference reflected in AM6580's more pronounced effect upon hMGL conformation. We demonstrate that structurally distinct carbamylating hMGL inhibitors generate particular conformational ensembles characterized by region-specific hMGL dynamics. By demonstrating the distinctive influences of two hMGL inhibitors on enzyme conformation, this study furthers our understanding at the molecular level of the dynamic features of hMGL interaction with small-molecule ligands.
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Affiliation(s)
- Ioannis Karageorgos
- Center for Drug Discovery and Departments of Pharmaceutical Sciences and Chemistry and Chemical Biology, Northeastern University , Boston, Massachusetts 02115-5000, United States
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Nasr ML, Shi X, Bowman AL, Johnson M, Zvonok N, Janero DR, Vemuri VK, Wales TE, Engen JR, Makriyannis A. Membrane phospholipid bilayer as a determinant of monoacylglycerol lipase kinetic profile and conformational repertoire. Protein Sci 2013; 22:774-87. [PMID: 23553709 DOI: 10.1002/pro.2257] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 03/07/2013] [Accepted: 03/19/2013] [Indexed: 11/10/2022]
Abstract
The membrane-associated serine hydrolase, monoacylglycerol lipase (MGL), is a well-recognized therapeutic target that regulates endocannabinoid signaling. Crystallographic studies, while providing structural information about static MGL states, offer no direct experimental insight into the impact of MGL's membrane association upon its structure-function landscape. We report application of phospholipid bilayer nanodiscs as biomembrane models with which to evaluate the effect of a membrane system on the catalytic properties and conformational dynamics of human MGL (hMGL). Anionic and charge-neutral phospholipid bilayer nanodiscs enhanced hMGL's kinetic properties [apparent maximum velocity (Vmax) and substrate affinity (Km)]. Hydrogen exchange mass spectrometry (HX MS) was used as a conformational analysis method to profile experimentally the extent of hMGL-nanodisc interaction and its impact upon hMGL structure. We provide evidence that significant regions of hMGL lid-domain helix α4 and neighboring helix α6 interact with the nanodisc phospholipid bilayer, anchoring hMGL in a more open conformation to facilitate ligand access to the enzyme's substrate-binding channel. Covalent modification of membrane-associated hMGL by the irreversible carbamate inhibitor, AM6580, shielded the active site region, but did not increase solvent exposure of the lid domain, suggesting that the inactive, carbamylated enzyme remains intact and membrane associated. Molecular dynamics simulations generated conformational models congruent with the open, membrane-associated topology of active and inhibited, covalently-modified hMGL. Our data indicate that hMGL interaction with a phospholipid membrane bilayer induces regional changes in the enzyme's conformation that favor its recruiting lipophilic substrate/inhibitor from membrane stores to the active site via the lid, resulting in enhanced hMGL catalytic activity and substrate affinity.
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Affiliation(s)
- Mahmoud L Nasr
- Center for Drug Discovery and Department of Chemistry, Northeastern University, Boston, Massachusetts 02115-5000, USA
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1,3,4-Oxadiazol-2-ones as fatty-acid amide hydrolase and monoacylglycerol lipase inhibitors: Synthesis, in vitro evaluation and insight into potency and selectivity determinants by molecular modelling. Eur J Pharm Sci 2013; 49:423-33. [PMID: 23557840 DOI: 10.1016/j.ejps.2013.03.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 02/28/2013] [Accepted: 03/18/2013] [Indexed: 01/15/2023]
Abstract
Inhibition of the key hydrolytic enzymes of the endocannabinoid system, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), has been proposed as potential mode of action for various therapeutic applications. Continuing our previous work, we take the first steps of structure-activity relationship exploration and show that 1,3,4-oxadiazol-2-ones can serve as scaffold for both selective FAAH and MAGL inhibitors, and also function as a dual FAAH/MAGL inhibitor at sub-micromolar IC50 values. Moreover, 10-fold selectivity against MAGL over FAAH was achieved with compound 3d (FAAH and MAGL IC50; 2.0 and 0.22 μM). Lastly, enzyme and ligand features contributing to the potency and selectivity differences are analysed by molecular docking.
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Naidoo V, Karanian DA, Vadivel SK, Locklear JR, Wood JT, Nasr M, Quizon PMP, Graves EE, Shukla V, Makriyannis A, Bahr BA. Equipotent inhibition of fatty acid amide hydrolase and monoacylglycerol lipase - dual targets of the endocannabinoid system to protect against seizure pathology. Neurotherapeutics 2012; 9:801-13. [PMID: 22270809 PMCID: PMC3480564 DOI: 10.1007/s13311-011-0100-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Advances in the understanding of the endogenous cannabinoid system have led to several therapeutic indications for new classes of compounds that enhance cannabinergic responses. Endocannabinoid levels are elevated during pathogenic conditions, and inhibitors of endocannabinoid inactivation promote such on-demand responses. The endocannabinoids anandamide and 2-arachidonoyl glycerol have been implicated in protective signaling against excitotoxic episodes, including seizures. To better understand modulatory pathways that can exploit such responses, we used the new generation compound AM6701 that blocks both the anandamide-deactivating enzyme fatty acid amide hydrolase (FAAH) and the 2-arachidonoyl glycerol-deactivating enzyme monoacylglycerol lipase (MAGL) with equal potency. Also studied was the structural isomer AM6702 which is 44-fold more potent for inhibiting FAAH versus MAGL. When applied before and during kainic acid (KA) exposure to cultured hippocampal slices, AM6701 protected against the resulting excitotoxic events of calpain-mediated cytoskeletal damage, loss of presynaptic and postsynaptic proteins, and pyknotic changes in neurons. The equipotent inhibitor was more effective than its close relative AM6702 at protecting against the neurodegenerative cascade assessed in the slice model. In vivo, AM6701 was also the more effective compound for reducing the severity of KA-induced seizures and protecting against behavioral deficits linked to seizure damage. Corresponding with the behavioral improvements, cytoskeletal and synaptic protection was elicited by AM6701, as found in the KA-treated hippocampal slice model. It is proposed that the influence of AM6701 on FAAH and MAGL exerts a synergistic action on the endocannabinoid system, thereby promoting the protective nature of cannabinergic signaling to offset excitotoxic brain injury.
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Affiliation(s)
- Vinogran Naidoo
- Biotechnology Research and Training Center, William C. Friday Laboratory, University of North Carolina Pembroke, Pembroke, North Carolina 28372 USA
- Department of Biology, University of North Carolina Pembroke, Pembroke, North Carolina USA
| | - David A. Karanian
- Department of Pharmaceutical Sciences and the Neurosciences Program, University of Connecticut, Storrs, Connecticut USA
- Center for Drug Discovery, Northeastern University, Boston, Massachusetts USA
| | | | - Johnathan R. Locklear
- Biotechnology Research and Training Center, William C. Friday Laboratory, University of North Carolina Pembroke, Pembroke, North Carolina 28372 USA
| | - JodiAnne T. Wood
- Center for Drug Discovery, Northeastern University, Boston, Massachusetts USA
| | - Mahmoud Nasr
- Center for Drug Discovery, Northeastern University, Boston, Massachusetts USA
| | - Pamela Marie P. Quizon
- Biotechnology Research and Training Center, William C. Friday Laboratory, University of North Carolina Pembroke, Pembroke, North Carolina 28372 USA
| | - Emily E. Graves
- Biotechnology Research and Training Center, William C. Friday Laboratory, University of North Carolina Pembroke, Pembroke, North Carolina 28372 USA
| | - Vidyanand Shukla
- Center for Drug Discovery, Northeastern University, Boston, Massachusetts USA
| | | | - Ben A. Bahr
- Biotechnology Research and Training Center, William C. Friday Laboratory, University of North Carolina Pembroke, Pembroke, North Carolina 28372 USA
- Department of Biology, University of North Carolina Pembroke, Pembroke, North Carolina USA
- Department of Pharmaceutical Sciences and the Neurosciences Program, University of Connecticut, Storrs, Connecticut USA
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Karageorgos I, Tyukhtenko S, Zvonok N, Janero DR, Sallum C, Makriyannis A. Identification by nuclear magnetic resonance spectroscopy of an active-site hydrogen-bond network in human monoacylglycerol lipase (hMGL): implications for hMGL dynamics, pharmacological inhibition, and catalytic mechanism. MOLECULAR BIOSYSTEMS 2010; 6:1381-8. [PMID: 20464001 PMCID: PMC3697746 DOI: 10.1039/c004515b] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Intramolecular hydrogen bonding is an important determinant of enzyme structure, catalysis, and inhibitor action. Monoacylglycerol lipase (MGL) modulates cannabinergic signaling as the main enzyme responsible for deactivating 2-arachidonoylglycerol (2-AG), a primary endocannabinoid lipid messenger. By enhancing tissue-protective 2-AG tone, targeted MGL inhibitors hold therapeutic promise for managing pain and treating inflammatory and neurodegenerative diseases. We report study of purified, solubilized human MGL (hMGL) to explore the details of hMGL catalysis by using two known covalent hMGL inhibitors, the carbamoyl tetrazole AM6701 and N-arachidonoylmaleimide (NAM), that act through distinct mechanisms. Using proton nuclear magnetic resonance spectroscopy (NMR) with purified wild-type and mutant hMGLs, we have directly observed a strong hydrogen-bond network involving Asp239 and His269 of the catalytic triad and neighboring Leu241 and Cys242 residues. hMGL inhibition by AM6701 alters this hydrogen-bonding pattern through subtle active-site structural rearrangements without influencing hydrogen-bond occupancies. Rapid carbamoylation of hMGL Ser122 by AM6701 and elimination of the leaving group is followed by a slow hydrolysis of the carbamate group, ultimately regenerating catalytically competent hMGL. In contrast, hMGL titration with NAM, which leads to cysteine alkylation, stoichiometrically decreases the population of the active-site hydrogen bonds. NAM prevents reformation of this network, and in this manner inhibits hMGL irreversibly. These data provide detailed molecular insight into the distinctive mechanisms of two covalent hMGL inhibitors and implicate a hydrogen-bond network as a structural feature of hMGL catalytic function.
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Affiliation(s)
- Ioannis Karageorgos
- Center for Drug Discovery, Northeastern University, 360 Huntington Avenue, 116 Mugar Hall, Boston, MA 02115-5000, USA 617-373-2208. Fax: +1 617-373-7493
| | - Sergiy Tyukhtenko
- Center for Drug Discovery, Northeastern University, 360 Huntington Avenue, 116 Mugar Hall, Boston, MA 02115-5000, USA 617-373-2208. Fax: +1 617-373-7493
| | - Nikolai Zvonok
- Center for Drug Discovery, Northeastern University, 360 Huntington Avenue, 116 Mugar Hall, Boston, MA 02115-5000, USA 617-373-2208. Fax: +1 617-373-7493
| | - David R. Janero
- Center for Drug Discovery, Northeastern University, 360 Huntington Avenue, 116 Mugar Hall, Boston, MA 02115-5000, USA 617-373-2208. Fax: +1 617-373-7493
| | - Christine Sallum
- Center for Drug Discovery, Northeastern University, 360 Huntington Avenue, 116 Mugar Hall, Boston, MA 02115-5000, USA 617-373-2208. Fax: +1 617-373-7493
| | - Alexandros Makriyannis
- Center for Drug Discovery, Northeastern University, 360 Huntington Avenue, 116 Mugar Hall, Boston, MA 02115-5000, USA 617-373-2208. Fax: +1 617-373-7493
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Käsnänen H, Myllymäki MJ, Minkkilä A, Kataja AO, Saario SM, Nevalainen T, Koskinen AMP, Poso A. 3-Heterocycle-phenyl N-alkylcarbamates as FAAH inhibitors: design, synthesis and 3D-QSAR studies. ChemMedChem 2010; 5:213-31. [PMID: 20024981 DOI: 10.1002/cmdc.200900390] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Carbamates are a well-established class of fatty acid amide hydrolase (FAAH) inhibitors. Here we describe the synthesis of meta-substituted phenolic N-alkyl/aryl carbamates and their in vitro FAAH inhibitory activities. The most potent compound, 3-(oxazol-2yl)phenyl cyclohexylcarbamate (2 a), inhibited FAAH with a sub-nanomolar IC(50) value (IC(50)=0.74 nM). Additionally, we developed and validated three-dimensional quantitative structure-activity relationships (QSAR) models of FAAH inhibition combining the newly disclosed carbamates with our previously published inhibitors to give a total set of 99 compounds. Prior to 3D-QSAR modeling, the degree of correlation between FAAH inhibition and in silico reactivity was also established. Both 3D-QSAR methods used, CoMSIA and GRID/GOLPE, produced statistically significant models with coefficient of correlation for external prediction (R(2) (PRED)) values of 0.732 and 0.760, respectively. These models could be of high value in further FAAH inhibitor design.
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Affiliation(s)
- Heikki Käsnänen
- Department of Pharmaceutical Chemistry, University of Kuopio, P.O.Box 1627, 70211 Kuopio, Finland
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