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Allosteric Modulation Of The Cb1 Receptor
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Book Synopsis Conformationally Constrained Analogs of Org27569 as Allosteric Modulators of CB1 Cannabinoid Receptor by : Siddhi Honavar
Download or read book Conformationally Constrained Analogs of Org27569 as Allosteric Modulators of CB1 Cannabinoid Receptor written by Siddhi Honavar and published by . This book was released on 2015 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Cannabinoid receptors have become the focus of research due to their importance as targets for treating a number of disorders. These receptors which are a part of the G-protein coupled receptor (GPCR) superfamily are of two subtypes, CB1 receptors which are present abundantly in the brain and in small traces in the peripheral and adipose tissues and CB2 receptors which are predominantly found in the immune cells. The cannabinoid receptors were always known to show its function through the orthosteric ligand binding, but the discovery of allosteric site on the CB1 receptors, has opened up a whole new horizon for research. Three of Organon analogs displayed a noticeable allosterism at the CB1 receptors, wherein they were negative allosteric modulators of function but positive allosteric modulators of binding of orthosteric ligand at the CB1 receptor. The SAR around these three molecules has not been explored as much, and as all three almost shared the same phamacophoric properties, Org 27569 was selected as the lead compound. Org 27569 which is a negative allosteric modulator of CB1 receptor has been found to also show hypophagic effect independent of the presence of the CB1 receptor, and hence pointing towards the possibility of it's off target binding which is a major limitation in its further development as a drug. Exploring the SAR around Org 27569 would give a better insight into the molecules requirements for allosteric modulation at CB1 receptor. The Conformational restriction approach is adopted as a tool for molecular modification and design of the analogs. This projects aims at synthesizing conformationally constrained analogs of Org 27569 as GAT700 and GAT701, to explore the receptor binding and functional selectivity of the allosteric modulators at the CB1 cannabinoid receptor.
Book Synopsis Allosteric Modulation of the CB1 Receptor by : Jamie Kerr
Download or read book Allosteric Modulation of the CB1 Receptor written by Jamie Kerr and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Bioactive compounds from Cannabis sativa have been used for millennia to alleviate the symptoms of a range of diseases. The physiological basis of effects such as analgesia, stimulation of hunger and reduction of inflammation was established in the late 20th century with the discovery of cannabinoid receptors but efforts to synthesise safe and potent drugs targeting these proteins have so far failed. The major barrier to research in this area is the instability of the receptors outside of biological settings, rendering elucidation of the binding sites by traditional means difficult. Certain small molecules can interact with the cannabinoid type 1 receptor (CB1) at locations distinct to the primary ligand docking site. Such allosteric modulation of the endocannabinoid system offers significant advantages over using orthosteric drugs and in this research a range of indole based structures were synthesised and tested in an attempt to improve the activity and drug-like nature of a lead compound. A partial structure-activity relationship was established, including the description of the most potent allosteric enhancer of CB1 so far reported. Efforts were also undertaken to investigate the allosteric binding environments using photoactivatable ligands based on a CB1 inhibitor. In combination with mutation studies and computer modelling this technique could allow the rational design of allosteric modulators, a task which is not trivial at present. Two photoactivatable compounds were synthesised and shown to interact with the receptor, with a method for isolating covalently labelled peptide fragments from other biomolecules demonstrated using "click chemistry" and a modified Wang resin. This work may find application in future investigations aiming to produce allosteric pharmaceuticals targeting CB1. Furthermore, the techniques described may be applied to study the binding site of a recently described allosteric endocannabinoid or could potentially be adapted to look at secondary binding domains in other G protein-coupled receptors.
Book Synopsis Design and Synthesis of Allosteric Modulators of CB1 Cannabinoid Receptor by : Abhijit R. Kulkarni
Download or read book Design and Synthesis of Allosteric Modulators of CB1 Cannabinoid Receptor written by Abhijit R. Kulkarni and published by . This book was released on 2011 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cannabinoid receptors are a major class of cell-membrane receptors which belong to the super-family of G protein-coupled receptors (GPCRs) and are targeted for the treatment of several diseases including neurodegenerative diseases, cancer, obesity, inflammation and neuropathic and inflammatory pain. Two subtypes of cannabinoid receptors, namely, CB1 and CB2, have been cloned and studied more intensively. CB1 receptor is the most abundant GPCR in the brain, and a wide range of selective and potent CB1-receptor ligands for its orthosteric site have been developed. However, their therapeutic utility has been limited due to side effects associated with indiscriminate cannabinoid receptor activation and propensity for receptor desensitization. This problem is exemplified by the recent cancellation of the Phase III clinical trials of the CB1 antagonists / inverse agonists Taranabant and Otenabant and the manufacturer's (Sanofi-Aventis) voluntary withdrawal of the marketed drug Rimonabant in the European Union. Rimonabant (Acomplia), which was approved as an adjunctive weight-loss drug in Europe, suffered serious-dose related gastrointestinal and psychiatric side effects such as depression and suicidal ideation. Other approaches such as development of CB1 neutral as well as peripherally-acting antagonists have shown therapeutic promise and reduced side effects in recently published preclinical studies.A promising alternative approach is the development of CB1 allosteric modulators which by binding to a sub-type specific and topographically distinct site from the orthosteric site can either enhance or inhibit the action of endocannabinoids and thus act more selectively to tune the CB signaling in a site- and event-specific manner. Recently high-throughput screening (HTS) from two different laboratories has identified two different classes of ligand (e.g., Org27569 and PSNCBAM-1) exhibiting negative allosteric modulation at CB1 receptors. Due to the unavailability of the cannabinoid receptor's crystal structure, characterization of the binding site(s) of these allosteric modulators is lacking. Availability of such data will prove instrumental in elucidating their molecular basis for activity and in developing highly selective, potent CB1 allosteric modulators. The objective of the present study is to develop covalent probes (both photo-activatable and electrophilic) based upon the parent structure of Org27569 bearing azido and isothiocyanate functionality at the judiciously chosen positions. Using Ligand-Assisted Protein Structure approach (LAPS), which involves use of such probes for labeling the receptor covalently followed by MS analysis of the protein and validating the resulting data with site-directed mutagenesis and molecular modeling studies, the chemical nature and tertiary structure of the active allosteric sites of CB1 can be elucidated. Additionally, we propose to synthesize an iodinated analog of Org27569 to facilitate development of radiometric competitive binding assays directed at CB1 allosteric site. We also propose to synthesize two hybrid analogs of Org27569 and PSNCBAM-1 to help understand structural requirements for CB1 allosteric site and facilitate development of future structure-activity relationship studies.
Book Synopsis Allosteric Modulation of Cannabinoid Receptor One by : Jonathan Choiniere
Download or read book Allosteric Modulation of Cannabinoid Receptor One written by Jonathan Choiniere and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cannabinoid receptors and endocannabinoid system play a role in many physiological processes which makes cannabinoid receptor 1 a good target for therapies to a wide range of pathologies such as addiction, obesity, pain, depression, anxiety, and neurodegenerative disorders. Despite all of the therapeutic potential of creating cannabinoid receptor specific drugs, development of such medications has been difficult due to psychoactive side effects that are linked to agonist and antagonist ligands. This thesis work focuses on describing cannabinoid receptor 1, its known ligands, therapeutic potential, and exploring the possibility of using allosteric modulator compounds as a way to maximize medicinal benefit while limiting psychoactive side effects.
Book Synopsis The Study of Allosteric Modulator Sites at the Cannabinoid CB1 Receptor by : Teresa S. Barber
Download or read book The Study of Allosteric Modulator Sites at the Cannabinoid CB1 Receptor written by Teresa S. Barber and published by . This book was released on 2009 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Org 27569, Org 27759 and Org 29647 are the first discovered allosteric modulators of the cannabinoid CB1 receptor. These ligands are thought to bind to "accessory binding sites" at the receptor . Binding of the Org allosteric modulators has been shown to affect the affinities of various CB1 ligands, but to reduce the efficacy of these ligands. The goal of this research project was to understand at a molecular level, the origins of the effects produced by the Org allosteric modulators. The study was begun by performing AM1 conformational searches for each allosteric modulator using the Spartan molecular modeling suite . Those conformers within 2.00 kcal/mol of the global minimum energy conformer of each modulator were subjected to geometry optimization in Jaguar (Schrodinger, Inc). Org27569 was then targeted for further study. Org 27569 has been reported to increase the CB1 affinity of the non-classical cannabinoid, (1R3R4R)-3-[2-hydroxy-4-(1,1-dimethylheptylphenyl]-4-(3-hydroxy-propyl)cyclohexab-1-ol, CP-55,940, but to reduce its efficacy. Since the binding site of Org27569 is unknown, the MMC program was then employed to identify potential binding sites. The MMC program is a cavity biased method that uses Monte Carlo simulated annealing of chemical potential to identify small-molecule binding sites in protein structures via a molecular fragment approach [F. Guarnieri and M. Mezei, JACS 118, 8493, 1996]. The receptor was placed in a virtual cell. At high chemical potentials, the box is filled with completely with the fragment of interest. As the chemical potential decreases, fragments with less favorable interactions are stripped away. Indole and piperidine rings were used as fragments because they constitute the two major structural features of Org 27569. Three common binding sites for both the indole and piperidine fragments were identified. These areas were R3.50 (intracellular domain), W4.50 (possible homodimer interface) and in the transmembrane region between helices 1 and 2 (interacting with CP55,940). These were considered possible interaction sites for the following reasons: (1) If interactions occurred between the allosteric modulator and R3.50, this would block the interaction site of the G-protein and thus impair signalling. (2) W4.50 is commonly found in GPCR dimer interfaces. If the CB1 receptor functions as a dimer, Org27569 would impair activation by blocking dimer formation. (3) The TMH1-2 site site would allow the affinity of CP55940 to increase because it would block CP55940 exit from CB1. At the same time, the TMH1-2 site dock would constrain TMH6 from moving during activation by tethering the EC-3 loop. This should also result in impaired signal transduction. Future studies will involve mutation studies of each allosteric binding site identified in this project to determine the allosteric binding site for Org 27569"--Abstract from author supplied metadata.
Book Synopsis Ligand-Induced Modulation of the Cannabinoid Receptor 1 by : Rachel Dopart
Download or read book Ligand-Induced Modulation of the Cannabinoid Receptor 1 written by Rachel Dopart and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Allosteric Modulation of G Protein-Coupled Receptors by : Robert Laprairie
Download or read book Allosteric Modulation of G Protein-Coupled Receptors written by Robert Laprairie and published by Academic Press. This book was released on 2022-02-05 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Allosteric Modulation of G Protein-Coupled Receptors reviews fundamental information on G protein-coupled receptors (GPCRs) and allosteric modulation, presenting original research in the area and collectively providing a comprehensive description of key issues in GPCR allosteric modulation. The book provides background on core concepts of molecular pharmacology while also introducing the most important advances and studies in the area. It also discusses key methodologies. This is an essential book for researchers and advanced students engaged in pharmacology, toxicology and pharmaceutical sciences training and research. Many of the GPCR-targeted drugs released in the past decade have specifically worked via allosteric mechanisms. Unlike direct orthosteric-acting compounds that occupy a similar receptor site to that of endogenous ligands, allosteric modulators alter GPCR-dependent signaling at a site apart from the endogenous ligand. Recent methodological and analytical advances have greatly improved our ability to understand the signaling mechanisms of GPCRs. We now know that allostery is a common regulatory mechanism for all GPCRs and not – as we once believed – unique to a few receptor subfamilies. Introduces background on core concepts of molecular pharmacology, including statistical analyses, non-linear regression, complex models and GPCR-dependent signal transduction as they relate to allosteric modulation Discusses critical advances and landmark studies, including discoveries in the area of GPCR allosteric modulation, which are reviewed for their importance in positive and negative regulation, protein-protein interactions, and small molecule drug discovery Includes key methodologies used to study allosteric modulation at the in silico, in vitro, and in vivo levels of drug discovery and characterization
Book Synopsis Allosteric Modulation of the Human Cannabinoid-1 Receptor by : Derek M. Shore
Download or read book Allosteric Modulation of the Human Cannabinoid-1 Receptor written by Derek M. Shore and published by . This book was released on 2014 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The human cannabinoid-1 (CB1) receptor is a Class A, rhodopsin-like G protein-coupled receptor (GPCR). CB1 is found primarily in the central nervous system (CNS) where it participates in the regulation of neuronal activity; consequently, it is not surprising that this receptor has been implicated in numerous pathologies, including Alzheimer's disease, cancer, obesity, and pain. Unfortunately, many attempts at therapeutically targeting CB1 have failed, due to unacceptable CNS-related side effects; specifically, attempts to target CB1's orthosteric binding site (i.e. the primary binding site of endogenous, non-allosteric ligands) have been unsuccessful. These failures may be due to problems involving receptor subtype selectivity, a lack of functional selectivity, as well as a pathological interference with basal signaling. The ultimate goal of this research is to expand our understanding of CB1 signal transduction, at a molecular level, and to employ this knowledge in the development of CB1-based drug therapies. In pursuing this goal, we have used computational methods together with mutagenesis, synthesis, and pharmacological studies. The results of this work are presented here in four chapters, with each chapter acting as a foundation for subsequent investigation. In Chapter 1, we present results involving the importance of CB1's extracellular (EC) loops to its G protein-mediated signaling. Specifically, these results suggest that an ionic interaction between Lys-373 (of the EC-3 loop) and D2.63176 is important for G protein-mediated signaling. Our computational results suggest this salt bridge is important because it promotes an active conformation of the EC-3 loop, such that the EC-3 loop is pulled across the top of the receptor, `tethering' the EC-3 loop and transmembrane helix (TMH) 2. In addition, we report results that suggest that the EC-2 loop moves down (into the transmembrane core) upon activation. In Chapter 2, we report the binding site and mechanism of action of the negative CB1 allosteric modulator ORG27569. This compound has the paradoxical effects of increasing the equilibrium binding of CP55,940 (an orthosteric agonist), while at the same time antagonizing its G protein-mediated signaling. When applied alone, ORG27569 acts as an inverse agonist of G protein-mediated signaling, as well as an agonist of the ERK signaling pathway. Our results suggest that ORG27569 binds in the TMH3/6/7 region of CB1 (extending extracellularly), and promotes an intermediate conformation of CB1. In addition, ORG27569 may antagonize the G protein-mediated signaling of CP55,940 by sterically blocking conformational changes of the EC-2 and EC-3 loops, as well as by packing tightly against TMH6. We also reported that ORG27569's inverse agonism is dependent upon the formation of a hydrogen bond between its piperidine nitrogen and K3.28192. In Chapter 3, we use our model of ORG27569 docked at CB1 (in the presence of CP55,940) to design, synthesize, and characterize four analogs of ORG27569. These compounds were designed using three different strategies: 1) to form a new hydrogen bond between the analog(s) and D6.58366; 2) to form a new aromatic stack between the analog(s) an F3.25189; and 3) to test steric packing between the analog(s) and TMH6/7. The experimental results revealed that these four compounds have a unique and rich pharmacological profile. The analog PHR018 is a more efficacious negative allosteric modulator than ORG27569 (whereas PHR017 is a less efficacious modulator). The analog PHR016 is a `classical' allosteric modulator (i.e. an allosteric modulator that only affects the binding/signaling of an orthosteric ligand, with no functional effects when applied alone); PHR016's sole functional effect is to antagonize the G protein-mediated signaling of CP55,940. Finally, the analog PHR019 was observed to be a completely biased agonist for CB1 ERK signaling. To our knowledge, PHR019 is the only completely biased agonist for the ERK signaling pathway that targets a GPCR. In addition, none of these analogs acted as inverse agonists of G protein-mediated signaling. Altogether, these results suggest the remarkable therapeutic potential of CB1 allosteric-based therapies, due to the analogs' unprecedented level of functional control, as well the analogs' noninterference with basal G protein-mediated signaling. In Chapter 4, we report the binding site and mechanism of action of lipoxin A4, a positive allosteric modulator of CB1. Specifically, we used the Forced-Biased Metropolis Monte Carlo simulated annealing method (MMC), Glide docking studies, as well as molecular dynamics to identify lipoxin A4's binding site at CB1. These results suggest that lipoxin A4 binds in the TMH3/6/7 region of CB1, extending extracellularly. Unlike ORG27569 (which sterically blocks conformational changes of the EC loops), lipoxin A4 forms several electrostatic interactions with the EC loops. By forming these interactions, lipoxin A4 promotes an active conformation of the EC-3 (and EC-2) loops, thereby stabilizing an active conformation of CB1. Together, these results describe important conformational changes in the extracellular region of CB1, the binding site and mechanism of action of ORG27569, the development of unique ORG27569 analogs (including a biased agonist of the ERK pathway), and finally the binding site and mechanism of action of the positive allosteric modulator, lipoxin A4. Hopefully, this work (and future studies) will aid in the development of new therapies that target CB1."--Abstract from author supplied metadata.
Book Synopsis Modulation of Cannabinoid Receptor Activity by Allosteric Modulators, Inverse Agonists and Receptor Binding Partners by : Mariam Mohammed Mahmoud
Download or read book Modulation of Cannabinoid Receptor Activity by Allosteric Modulators, Inverse Agonists and Receptor Binding Partners written by Mariam Mohammed Mahmoud and published by . This book was released on 2015 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Allosteric Modulation of the Cannabinoid Receptor One: Evaluation of Analogs of Indole-2-carboxamide and Pyrimidinyl Biphenylurea by : Leepakshi Khurana
Download or read book Allosteric Modulation of the Cannabinoid Receptor One: Evaluation of Analogs of Indole-2-carboxamide and Pyrimidinyl Biphenylurea written by Leepakshi Khurana and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Computational Study of RTI - 371, a Positive Allosteric Modulator of the Cannabinoid CB1 Receptor by : Michael D. Foster
Download or read book Computational Study of RTI - 371, a Positive Allosteric Modulator of the Cannabinoid CB1 Receptor written by Michael D. Foster and published by . This book was released on 2011 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modulation of Cannabinoid Receptor Activity by Allosteric Modulators, Inverse Agonists and Receptor Binding Partners by : Mariam Mohammed Mahmoud
Download or read book Modulation of Cannabinoid Receptor Activity by Allosteric Modulators, Inverse Agonists and Receptor Binding Partners written by Mariam Mohammed Mahmoud and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Design and Synthesis of Positive Allosteric Modulators of CB1 Cannabinoid Receptor by : Ameya V. Ranade
Download or read book Design and Synthesis of Positive Allosteric Modulators of CB1 Cannabinoid Receptor written by Ameya V. Ranade and published by . This book was released on 2013 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis In Vivo Effects of the CB1 Allosteric Modulator LDK1258, a Structural Analog of ORG-27569 by : Mohammed Ali Mustafa
Download or read book In Vivo Effects of the CB1 Allosteric Modulator LDK1258, a Structural Analog of ORG-27569 written by Mohammed Ali Mustafa and published by . This book was released on 2020 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: CB1 receptor allosteric modulators are an area of growing interest for their potential novel therapeutic actions. In the present study, we examined LDK1258 in a series of pharmacological in vivo tests sensitive to CB1 receptor stimulation. In the tetrad assay, LDK1258 produced significant decreases in locomotor activity and body temperature measures but did not produce either antinociception as measured in the tail-withdrawal assay or catalepsy as assessed in the bar test. These same effects were observed in both CB1 ( -/- ) and (+/+) mice. Moreover, LDK1258 failed to shift the dose-response curves of two orthosteric CB1 receptor agonists in the triad assay. In the mouse drug discrimination assay, LDK1258 failed to substitute or shift the dose-response curve for either CP55,940 or anandamide, but dose-dependently suppressed response rates. In addition, LDK1258 reduced food consumption in both CB1 ( -/- ) and (+/+) mice. Unexpectedly, LDK1258 elicited a delayed antinociceptive effect in the CCI model, an effect not blocked by the CB1 receptor antagonist rimonabant. LCM. S.-MS analysis detected significant levels of the drug in blood and brain tissue 30 min post-administration and remained stable up to 4 hours in the brain. The results of the present study demonstrate that LDK1258 produces a variety of pharmacological effects, including antinociception, but these effects do not require CB1 receptor activation. These findings underscore the need for translational studies to examine newly developed CB1 receptor allosteric modulators that are characterized in in vitro assays to the whole animal, as has been done with other CB1 receptor allosteric modulators.
Book Synopsis Pharmacological Characterisation of a Novel Cannabinoid CB1 Receptor Allosteric Modulator by : James G. Horswill
Download or read book Pharmacological Characterisation of a Novel Cannabinoid CB1 Receptor Allosteric Modulator written by James G. Horswill and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Biased Signaling at the CB1 Cannabinoid Receptor by : Luciana Magalhaes Leo
Download or read book Biased Signaling at the CB1 Cannabinoid Receptor written by Luciana Magalhaes Leo and published by . This book was released on 2021 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: The CB1 cannabinoid receptor is a G-protein coupled receptor highly expressed throughout the central nervous system, that has been suggested as a target for the treatment of various disorders, including anxiety, pain and neurodegeneration. Despite the wide therapeutic potential of CB1, development of potential drug candidates has long been hindered by concerns about adverse effects, rapid tolerance development and abuse potential. Ligands that produce biased signaling have been proposed as a strategy to dissociate therapeutic and adverse effects for a variety of G-protein coupled receptors. Biased signaling involves selective activation of a signaling transducer in detriment of another, mainly involving selective activation of G-protein signaling or b-arrestin signaling. However, biased signaling at the CB1 receptor is poorly understood due to the lack of strongly biased agonists. The development of biased agonists would be aided by understanding the molecular mechanism that leads to biased signaling. Although the structure of CB1 has been resolved in the inactive state and in the canonical active state, which allows G-protein signaling, little is known about the alternative active state that allows b-arrestin biased signaling. Therefore, we set out to investigate molecular and pharmacological tools that could shed light on the mechanism of CB1 biased signaling and to characterize novel allosteric ligands with a biased signaling profile. Using molecular dynamics stimulation of CB1 bound to a ORG27569, an allosteric ligand that stimulates b-arrestin signaling and inhibits G-protein signaling, we proposed single amino acid mutations that were predicted to impact b-arrestin signaling, and expressed wild-type and mutated CB1 receptor in HEK293 cells to measure signaling through different signaling transducers. We found that N7.49 and Y7.53, two amino acids in the highly conserved NPXXY motif, were essential for b-arrestin recruitment and signaling, but mutating them to Ala and Phe, respectively, did not impact G-protein signaling. We also found that I2.43, a functionally conserved amino acid on transmembrane helix 2, negatively regulates a switch in the rotameric position of Y7.53, as mutating I2.43 to Ala reduced steric hindrance upon Y7.53 and enhanced b-arrestin1 recruitment and signaling, while mutating it to Thr, a polar residue that would further hinder Y7.53, partially inhibited b-arrestin recruitment. Therefore, we concluded that N7.49 and Y7.53 form a hydrogen bond network along with D2.50 that is essential for the alternative active state that stimulates b-arrestin biased signaling. N7.49 acts as a fulcrum on which transmembrane helix 7 can bend, and Y7.53 acts as a rotamer toggle switch, stabilizing conformational changes on the intracellular end of transmembrane helix 7. This is the first record of a molecular mechanism for CB1 b-arrestin biased signaling involving the NPXXY motif. Due to the highly conserved character of these residues, it is possible that this mechanism can also be applied to other class A G-protein coupled receptors. In addition, we characterized novel biased allosteric ligands that stimulate or inhibit b-arrestin1 signaling. Two ORG27569 analogs were found to enhance orthosteric agonist induced b-arrestin1 recruitment and extracellular-signal regulated kinase 1/2 phosphorylation (pERK), with no effect on G-protein signaling. Two pregnenolone analogs absent of the steroid scaffold were found to inhibit pERK signaling independent of Gprotein signaling, indicating that they hinder b-arrestin dependent signaling. Since these analogs are believed to mediate their effects via stimulation or inhibition of conformational changes on transmembrane helix 7, our findings support a role for this domain on the alternative active state of CB1. In contrast, a GAT211 analog, GAT1601, had no effect on recruitment of b-arrestin1, but stimulated G-protein signaling and slightly enhanced barrestin2 recruitment. This compound binds to an allosteric site, where it stimulates the canonical active state of CB1 by facilitating the outward movement of transmembrane helix 6. Altogether, the results presented in this dissertation suggest that CB1 b-arrestin biased signaling is regulated by the NPXXY motif, which stimulates conformational changes on the transmembrane helix 7/helix 8 elbow, and that stimulating or hindering these conformational changes can enhance or disrupt CB1 b-arrestin biased signaling. However, facilitating the movement of transmembrane helix 6 favors G-protein biased signaling. Our findings provide molecular and pharmacological tools that will be of great importance to structure guided drug design and to future studies on the functional consequences of biased signaling at the CB1 receptor.
Book Synopsis Design, Synthesis, and SAR of Novel Allosteric Modulators of the Cannabinoid CB1 Receptor by : Mostafa Hamed Abdelrahman
Download or read book Design, Synthesis, and SAR of Novel Allosteric Modulators of the Cannabinoid CB1 Receptor written by Mostafa Hamed Abdelrahman and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
