Development of a 3D Model for the Human Cannabinoid CB1 Receptor

Salo, Outi M. H.; Lahtela‐Kakkonen, Maija; Gynther, Jukka; Järvinen, Tomi; Poso, Antti

doi:10.1021/jm031052c

Cited by 82 publications

(111 citation statements)

References 65 publications

(126 reference statements)

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“…Since the crystal structure of bovine rhodopsin was solved (Palczewski et al, 2000), many homology models for the rhodopsin-like family A GPCRs, including the cannabinoid receptors, have been proposed (Shim et al, 2003;Salo et al, 2004;Montero et al, 2005). However, the structure and role of the extracellular domains are not clearly defined because of their mobility, resulting in poorly resolved diffraction patterns, and their low sequence homology, relative to the transmembrane domains.…”

mentioning

confidence: 99%

Dual Role of the Second Extracellular Loop of the Cannabinoid Receptor 1: Ligand Binding and Receptor Localization

Ahn

Bertalovitz²,

Mierke³

et al. 2009

Mol Pharmacol

112

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The seven transmembrane ␣-helices of G protein-coupled receptors (GPCRs) are the hallmark of this superfamily. Intrahelical interactions are critical to receptor assembly and, for the GPCR subclass that binds small molecules, ligand binding. Most research has focused on identifying the ligand binding pocket within the helical bundle, whereas the role of the extracellular loops remains undefined. Molecular modeling of the cannabinoid receptor 1 (CB1) extracellular loop 2 (EC2), however, suggests that EC2 is poised for key interactions. To test this possibility, we employed alanine scanning mutagenesis of CB1 EC2 and identified two distinct regions critical for ligand binding, G protein coupling activity, and receptor trafficking. Receptors with mutations in the N terminus of EC2 (W255A, N256A) were retained in the endoplasmic reticulum and did not bind the agonist (1R,3R,In contrast, the C terminus of EC2 differentiates agonist and inverse agonist; the P269A, H270A, and I271A receptors exhibited diminished binding for several agonists but bound inverse agonists SR141716A,, and 4-[6-methoxy-2-(4-methoxyphenyl)-benzofuran-3-carbonyl]benzonitrile (LY320135) with wild-type receptor affinity. The F268A receptor involving substitution in the Cys-X-X-X-Ar motif, displayed both impaired localization and ligand binding. Other amino acid substitutions at position 268 revealed that highly hydrophobic residues are required to accomplish both functions. It is noteworthy that a F268W receptor was trafficked to the cell surface yet displayed differential binding preference for inverse agonists comparable with the P269A, H270A, and I271A receptors. The findings are consistent with a dual role for EC2 in stabilizing receptor assembly and in ligand binding.The human cannabinoid receptor 1 (CB1) is a member of the rhodopsin-like G protein-coupled receptor (GPCR) family, members of which comprise seven transmembrane helices (TMs) connected by three intracellular loops and three extracellular loops. In addition to binding ⌬ 9 -tetrahydrocannabinol (⌬ 9 -THC), the psychoactive constituent of Cannabis sativa, several endogenous cannabinoid receptor agonists have been identified, including anandamide (arachidonoylethanolamide), 2-arachidonoylglycerol, and 2-arachidonylglyceryl ether (noladin ether). CB1 also binds a variety of synthetic cannabimimetic compounds such as the nonclassic agonist CP55940, a bicyclic analog of ⌬ 9 -THC, the classic agonist HU-210, and the selective inverse agonists SR141716A (also known as rimonabant), AM251, and LY320135. Upon activation, CB1 modulates synaptic transmission, ultimately playing a role in analgesia, anxiety, feeding behavior, and movement disorders (Porter and Felder, 2001;Howlett et al., 2002). Thus, understanding the features of CB1 critical for ligand binding and receptor localization is important for developing its therapeutic potential.Molecular modeling analyses of ligand-receptor interactions involving CB1 are consistent with the idea that the N-(piperidin-1-yl)-5-(4-iodophenyl...

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mentioning

confidence: 99%

Dual Role of the Second Extracellular Loop of the Cannabinoid Receptor 1: Ligand Binding and Receptor Localization

Ahn

Bertalovitz²,

Mierke³

et al. 2009

Mol Pharmacol

112

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“…Earlier models have been proposed based on the structures of bovine rhodopsin (Hurst et al, 2002;McAllister et al, 2003;Shim et al, 2003;Salo et al, 2004;Silvestri et al, 2008) or the b2-adrenergic receptor (Shim et al, 2012). The more recent structure used here as template affords a sequence alignment that is almost devoid of insertions and deletions.…”

Section: Resultsmentioning

confidence: 99%

Structural Basis of Species-Dependent Differential Affinity of 6-Alkoxy-5-Aryl-3-Pyridinecarboxamide Cannabinoid-1 Receptor Antagonists

et al. 2015

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6-Alkoxy-5-aryl-3-pyridincarboxamides, including the brain-, have been recently introduced as selective, high-affinity antagonists of the human cannabinoid-1 receptor (hCB 1 R). Binding analyses revealed two orders of magnitude lower affinity of these compounds for mouse and rat versus human CB 1 R, whereas the affinity of rimonabant is comparable for all three CB 1 Rs. Modeling of ligand binding to CB 1 R and binding assays with native and mutant (Ile105Met) hCB 1 Rs indicate that the Ile105 to Met mutation in rodent CB 1 Rs accounts for the species-dependent affinity of 14g and 14h. Our work identifies Ile105 as a new pharmacophore component for developing better hCB 1 R antagonists and invalidates rodent models for assessing the antiobesity efficacy of 14g and 14h.

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“…3 Such a computational approach has been widely used to study the structural characteristics of experimental-structure-unavailable proteins, including cannabinoid receptors. 41,46,47 The defined homology model was then employed to analyze the CB2 structural characterization of the 7-TM helical bundle for its helix tilt angles, interhelix hydrophobic interaction, interhelix H-bonding network, conserved residues and motifs, and a possible disulfide bond between residues Cys174 and Cys179. 41 The structures of the associated amphipathic cytoplasmic helix domain VIII in both CB1 and CB2 receptors were verified and compared using a NMR method to study the solution structures of relative peptides in membrane mimetic dodecylphosphocholine (DPC) micelles.…”

Section: Resultsmentioning

confidence: 99%

GPCR Structure‐Based Virtual Screening Approach for CB2 Antagonist Search.

Chen¹,

Wang²,

Xie³

2007

ChemInform

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The potential for therapeutic specificity in regulating diseases has made cannabinoid (CB) receptors one of the most important G-protein-coupled receptor (GPCR) targets in search for new drugs. Considering the lack of related 3D experimental structures, we have established a structure-based virtual screening protocol to search for CB2 bioactive antagonists based on the 3D CB2 homology structure model. However, the existing homology-predicted 3D models often deviate from the native structure and therefore may incorrectly bias the in silico design. To overcome this problem, we have developed a 3D testing database query algorithm to examine the constructed 3D CB2 receptor structure model as well as the predicted binding pocket. In the present study, an antagonist-bound CB2 receptor complex model was initially generated using flexible docking simulation and then further optimized by molecular dynamic and mechanical (MD/MM) calculations. The refined 3D structural model of the CB2-ligand complex was then inspected by exploring the interactions between the receptor and ligands in order to predict the potential CB2 binding pocket for its antagonist. The ligand-receptor complex model and the predicted antagonist binding pockets were further processed and validated by FlexX-Pharm docking against a testing compound database that contains known antagonists. Furthermore, a consensus scoring (CScore) function algorithm was established to rank the binding interaction modes of a ligand on the CB2 receptor. Our results indicated that the known antagonists seeded in the testing database can be distinguished from a significant amount of randomly chosen molecules. Our studies demonstrated that the established GPCR structure-based virtual screening approach provided a new strategy with a high potential for in silico identifying novel CB2 antagonist leads based on the homology-generated 3D CB2 structure model.

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Development of a 3D Model for the Human Cannabinoid CB1 Receptor

Cited by 82 publications

References 65 publications

Dual Role of the Second Extracellular Loop of the Cannabinoid Receptor 1: Ligand Binding and Receptor Localization

Dual Role of the Second Extracellular Loop of the Cannabinoid Receptor 1: Ligand Binding and Receptor Localization

Structural Basis of Species-Dependent Differential Affinity of 6-Alkoxy-5-Aryl-3-Pyridinecarboxamide Cannabinoid-1 Receptor Antagonists

GPCR Structure‐Based Virtual Screening Approach for CB2 Antagonist Search.

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