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Leo LM, Al-Zoubi R, Hurst DP, Stephan AP, Zhao P, Tilley DG, Miess E, Schulz S, Abood ME, Reggio PH. The NPXXY Motif Regulates β-Arrestin Recruitment by the CB1 Cannabinoid Receptor. Cannabis Cannabinoid Res 2023; 8:731-748. [PMID: 35792570 PMCID: PMC10589503 DOI: 10.1089/can.2021.0223] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Background: Activation of signaling effectors by G-protein coupled receptors (GPCRs) depends on different molecular mechanisms triggered by conserved amino acid residues. Although studies have focused on the G-protein signaling state, the mechanism for β-arrestin signaling by CB1 is not yet well defined. Studies have indicated that transmembrane helix 7 (TMH7) and the highly conserved NPXXY motif can be subject to different conformational changes in response to biased ligands and could therefore participate in a molecular mechanism to trigger β-arrestin recruitment. Objective: To investigate the effect of mutations in the NPXXY motif on different signaling pathways activated by the CB1 receptor. Materials and Methods: Point mutations of the NPXXY motif and associated residues were generated in the CB1 receptor using site-directed mutagenesis and transfection into HEK-293 cells. Signaling by wild-type and mutant receptors was analyzed by quantifying inhibition of cAMP, and by β-arrestin recruitment assays. Results: We found that N7.49 and Y7.53 are essential for β-arrestin recruitment by CB1. N7.49A and Y7.53F impair β-arrestin signaling, with no effect on G-protein signaling. We found a regulatory role for residue I2.43; I2.43 interacts with Y7.53, affecting its positioning. Reducing steric bulk at I2.43 (I2.43A) enhances β-arrestin1 recruitment, while introducing a polar residue (I2.43T) reduces β-arrestin recruitment. Conclusions: These findings point to a novel mechanism for β-arrestin recruitment, implicating amino acids in the NPXXY motif as critical for the putative β-arrestin biased conformational state of Class A GPCRs.
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Affiliation(s)
- Luciana M. Leo
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Rufaida Al-Zoubi
- Department of Medicinal Chemistry and Pharmacognosy, Faculty of Pharmacy, Jordan University of Science & Technology, Irbid, Jordan
| | - Dow P. Hurst
- Chemistry and Biochemistry Department, UNC Greensboro, Greensboro, North Carolina, USA
| | - Anna P. Stephan
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Pingwei Zhao
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Douglas G. Tilley
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Elke Miess
- Department of Pharmacology and Toxicology, Jena University Hospital-Friedrich Schiller University Jena, Jena, Germany
| | - Stefan Schulz
- Department of Pharmacology and Toxicology, Jena University Hospital-Friedrich Schiller University Jena, Jena, Germany
| | - Mary E. Abood
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Patricia H. Reggio
- Chemistry and Biochemistry Department, UNC Greensboro, Greensboro, North Carolina, USA
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Pulgar VM, Howlett AC, Eldeeb K. WIN55212-2 Modulates Intracellular Calcium via CB 1 Receptor-Dependent and Independent Mechanisms in Neuroblastoma Cells. Cells 2022; 11:2947. [PMID: 36230909 PMCID: PMC9563019 DOI: 10.3390/cells11192947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/13/2022] [Accepted: 09/16/2022] [Indexed: 11/29/2022] Open
Abstract
The CB1 cannabinoid receptor (CB1R) and extracellular calcium (eCa2+)-stimulated Calcium Sensing receptor (CaSR) can exert cellular signaling by modulating levels of intracellular calcium ([Ca2+]i). We investigated the mechanisms involved in the ([Ca2+]i) increase in N18TG2 neuroblastoma cells, which endogenously express both receptors. Changes in [Ca2+]i were measured in cells exposed to 0.25 or 2.5 mM eCa2+ by a ratiometric method (Fura-2 fluorescence) and expressed as the difference between baseline and peak responses (ΔF340/380). The increased ([Ca2+]i) in cells exposed to 2.5 mM eCa2+ was blocked by the CaSR antagonist, NPS2143, this inhibition was abrogated upon stimulation with WIN55212-2. WIN55212-2 increased [Ca2+]i at 0.25 and 2.5 mM eCa2+ by 700% and 350%, respectively, but this increase was not replicated by CP55940 or methyl-anandamide. The store-operated calcium entry (SOCE) blocker, MRS1845, attenuated the WIN55212-2-stimulated increase in [Ca2+]i at both levels of eCa2+. Simultaneous perfusion with the CB1 antagonist, SR141716 or NPS2143 decreased the response to WIN55212-2 at 0.25 mM but not 2.5 mM eCa2+. Co-perfusion with the non-CB1/CB2 antagonist O-1918 attenuated the WIN55212-2-stimulated [Ca2+]i increase at both eCa2+ levels. These results are consistent with WIN55212-2-mediated intracellular Ca2+ mobilization from store-operated calcium channel-filled sources that could occur via either the CB1R or an O-1918-sensitive non-CB1R in coordination with the CaSR. Intracellular pathway crosstalk or signaling protein complexes may explain the observed effects.
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Affiliation(s)
- Victor M. Pulgar
- Department of Pharmaceutical and Clinical Sciences, College of Pharmacy and Health Sciences, Campbell University, Buies Creek, NC 27506, USA
- Biomedical Research and Infrastructure Center, Winston-Salem State University, Winston-Salem, NC 27101, USA
- Department of Obstetrics & Gynecology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Allyn C. Howlett
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Khalil Eldeeb
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
- Jerry M. Wallace School of Osteopathic Medicine, Campbell University, Buies Creek, NC 27506, USA
- AL Azhar Faculty of Medicine, New Damietta 34518, Egypt
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Leo LM, Abood ME. CB1 Cannabinoid Receptor Signaling and Biased Signaling. Molecules 2021; 26:molecules26175413. [PMID: 34500853 PMCID: PMC8433814 DOI: 10.3390/molecules26175413] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/30/2021] [Accepted: 09/03/2021] [Indexed: 12/11/2022] Open
Abstract
The CB1 cannabinoid receptor is a G-protein coupled receptor highly expressed throughout the central nervous system that is a promising target for the treatment of various disorders, including anxiety, pain, and neurodegeneration. Despite the wide therapeutic potential of CB1, the development of drug candidates is hindered by adverse effects, rapid tolerance development, and abuse potential. Ligands that produce biased signaling—the preferential activation of a signaling transducer in detriment of another—have been proposed as a strategy to dissociate therapeutic and adverse effects for a variety of G-protein coupled receptors. However, biased signaling at the CB1 receptor is poorly understood due to a lack of strongly biased agonists. Here, we review studies that have investigated the biased signaling profile of classical cannabinoid agonists and allosteric ligands, searching for a potential therapeutic advantage of CB1 biased signaling in different pathological states. Agonist and antagonist bound structures of CB1 and proposed mechanisms of action of biased allosteric modulators are used to discuss a putative molecular mechanism for CB1 receptor activation and biased signaling. Current studies suggest that allosteric binding sites on CB1 can be explored to yield biased ligands that favor or hinder conformational changes important for biased signaling.
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Oliver EE, Hughes EK, Puckett MK, Chen R, Lowther WT, Howlett AC. Cannabinoid Receptor Interacting Protein 1a (CRIP1a) in Health and Disease. Biomolecules 2020; 10:biom10121609. [PMID: 33261012 PMCID: PMC7761089 DOI: 10.3390/biom10121609] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 11/23/2020] [Accepted: 11/24/2020] [Indexed: 12/15/2022] Open
Abstract
Endocannabinoid signaling depends upon the CB1 and CB2 cannabinoid receptors, their endogenous ligands anandamide and 2-arachidonoylglycerol, and intracellular proteins that mediate responses via the C-terminal and other intracellular receptor domains. The CB1 receptor regulates and is regulated by associated G proteins predominantly of the Gi/o subtypes, β-arrestins 1 and 2, and the cannabinoid receptor-interacting protein 1a (CRIP1a). Evidence for a physiological role for CRIP1a is emerging as data regarding the cellular localization and function of CRIP1a are generated. Here we summarize the neuronal distribution and role of CRIP1a in endocannabinoid signaling, as well as discuss investigations linking CRIP1a to development, vision and hearing sensory systems, hippocampus and seizure regulation, and psychiatric disorders including schizophrenia. We also examine the genetic and epigenetic association of CRIP1a within a variety of cancer subtypes. This review provides evidence upon which to base future investigations on the function of CRIP1a in health and disease.
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Affiliation(s)
- Emily E. Oliver
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 20157, USA; (E.E.O.); (E.K.H.); (M.K.P.); (R.C.)
- Department of Biochemistry and Center for Structural Biology, Wake Forest School of Medicine, Winston-Salem, NC 20157, USA;
| | - Erin K. Hughes
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 20157, USA; (E.E.O.); (E.K.H.); (M.K.P.); (R.C.)
- Department of Biochemistry and Center for Structural Biology, Wake Forest School of Medicine, Winston-Salem, NC 20157, USA;
| | - Meaghan K. Puckett
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 20157, USA; (E.E.O.); (E.K.H.); (M.K.P.); (R.C.)
| | - Rong Chen
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 20157, USA; (E.E.O.); (E.K.H.); (M.K.P.); (R.C.)
| | - W. Todd Lowther
- Department of Biochemistry and Center for Structural Biology, Wake Forest School of Medicine, Winston-Salem, NC 20157, USA;
| | - Allyn C. Howlett
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 20157, USA; (E.E.O.); (E.K.H.); (M.K.P.); (R.C.)
- Correspondence: ; Tel.: +1-336-716-8545
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5
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Eldeeb K, Wittmann TG, Leone-Kabler S, Howlett AC. The CB1 cannabinoid receptor‐mediated inhibition of cAMP accumulation in neuroblastoma cells: role of different Gi/o protein subtypes. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.04298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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6
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Schurman LD, Lu D, Kendall DA, Howlett AC, Lichtman AH. Molecular Mechanism and Cannabinoid Pharmacology. Handb Exp Pharmacol 2020; 258:323-353. [PMID: 32236882 PMCID: PMC8637936 DOI: 10.1007/164_2019_298] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Since antiquity, Cannabis has provoked enormous intrigue for its potential medicinal properties as well as for its unique pharmacological effects. The elucidation of its major cannabinoid constituents, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), led to the synthesis of new cannabinoids (termed synthetic cannabinoids) to understand the mechanisms underlying the pharmacology of Cannabis. These pharmacological tools were instrumental in the ultimate discovery of the endogenous cannabinoid system, which consists of CB1 and CB2 cannabinoid receptors and endogenously produced ligands (endocannabinoids), which bind and activate both cannabinoid receptors. CB1 receptors mediate the cannabimimetic effects of THC and are highly expressed on presynaptic neurons in the nervous system, where they modulate neurotransmitter release. In contrast, CB2 receptors are primarily expressed on immune cells. The endocannabinoids are tightly regulated by biosynthetic and hydrolytic enzymes. Accordingly, the endocannabinoid system plays a modulatory role in many physiological processes, thereby generating many promising therapeutic targets. An unintended consequence of this research was the emergence of synthetic cannabinoids sold for human consumption to circumvent federal laws banning Cannabis use. Here, we describe research that led to the discovery of the endogenous cannabinoid system and show how knowledge of this system benefitted as well as unintentionally harmed human health.
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Affiliation(s)
- Lesley D Schurman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Dai Lu
- Rangel College of Pharmacy, Health Science Center, Texas A&M University, Kingsville, TX, USA
| | - Debra A Kendall
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, USA
| | - Allyn C Howlett
- Department of Physiology and Pharmacology and Center for Research on Substance Use and Addiction, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Aron H Lichtman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA.
- Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond, VA, USA.
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7
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Eldeeb K, Leone‐Kabler S, Howlett AC. Cannabinoid receptor antagonists and G protein subtypes. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.lb392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Khalil Eldeeb
- School of Osteopathic MedicineCampbell UniversityLillingtonNC
- Wake Forest University Health SciencesWinston‐SalemNC
- AlAzhar Faculty of MedicineNew DamiettaEgypt
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8
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Eldeeb K, Ganjiwale AD, Chandrashekaran IR, Padgett LW, Burgess J, Howlett AC, Cowsik SM. CB1 cannabinoid receptor-phosphorylated fourth intracellular loop structure-function relationships. Pept Sci (Hoboken) 2018; 111. [PMID: 32411924 DOI: 10.1002/pep2.24104] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A peptide comprising the juxtamembrane C-terminal intracellular loop 4 (IL4) of the CB1 cannabinoid receptor possesses three Serine residues (Ser402, Ser411 and Ser415). Here we report the effect of Ser phosphorylation on the CB1 IL4 peptide conformation and cellular signaling functions using nuclear magnetic resonance spectroscopy, circular dichroism, G protein activation and cAMP production. Circular dichroism studies indicated that phosphorylation at various Ser residues induced helical structure in different environments. NMR data indicates that helical content varies in the order of IL4pSer411 > IL4pSer415 > IL4 > IL4pSer402. The efficacy of phosphorylated IL4 peptides in activating Go and Gi3 ([35S]GTPγS binding) and inhibiting cAMP accumulation in N18TG2 cells were correlated with helicity changes. Treatment of cells with bradykinin, which activates PKC, augmented CB1-mediated inhibition of cAMP accumulation, and this was reversed by a PKC inhibitor, suggesting that phosphorylation of serine might be a physiologically relevant modification in vivo. We conclude that phosphorylation-dependent alterations of helicity of CB1 IL4 peptides can increase efficacy of G protein signaling.
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Affiliation(s)
- Khalil Eldeeb
- Wake Forest University Health Sciences, Winston-Salem, NC, USA.,Al Azhar Faculty of Medicine, New Damietta, Egypt
| | - Anjali D Ganjiwale
- Department of Life Sciences, Bangalore University, Bangalore, Karnataka, India
| | | | - Lea W Padgett
- J.L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA
| | | | - Allyn C Howlett
- Wake Forest University Health Sciences, Winston-Salem, NC, USA.,J.L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA
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