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Wu C, Hu L, Liu B, Zeng X, Ma H, Cao Y, Li H, Zhang X. TRAF6-mediated ubiquitination of AKT in the nucleus is a critical event underlying the desensitization of G protein-coupled receptors. Cell Commun Signal 2024; 22:213. [PMID: 38566235 PMCID: PMC10986131 DOI: 10.1186/s12964-024-01592-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Accepted: 03/23/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND Desensitization of G protein-coupled receptors (GPCRs) refers to the attenuation of receptor responsiveness by prolonged or intermittent exposure to agonists. The binding of β-arrestin to the cytoplasmic cavity of the phosphorylated receptor, which competes with the G protein, has been widely accepted as an extensive model for explaining GPCRs desensitization. However, studies on various GPCRs, including dopamine D2-like receptors (D2R, D3R, D4R), have suggested the existence of other desensitization mechanisms. The present study employed D2R/D3R variants with different desensitization properties and utilized loss-of-function approaches to uncover the mechanisms underlying GPCRs homologous desensitization, focusing on the signaling cascade that regulates the ubiquitination of AKT. RESULTS AKT undergoes K8/14 ubiquitination by TRAF6, which occurs in the nucleus and promotes its membrane recruitment, phosphorylation and activation under receptor desensitization conditions. The nuclear entry of TRAF6 relies on the presence of the importin complex. Src regulates the nuclear entry of TRAF6 by mediating the interaction between TRAF6 and importin β1. Ubiquitinated AKT translocates to the plasma membrane where it associates with Mdm2 to phosphorylate it at the S166 and S186 residues. Thereafter, phosphorylated Mdm2 is recruited to the nucleus, resulting in the deubiquitination of β-Arr2. The deubiquitinated β-Arr2 then forms a complex with Gβγ, which serves as a biomarker for GPCRs desensitization. Like in D3R, ubiquitination of AKT is also involved in the desensitization of β2 adrenoceptors. CONCLUSION Our study proposed that the property of a receptor that causes a change in the subcellular localization of TRAF6 from the cytoplasm to the nucleus to mediate AKT ubiquitination could initiate the desensitization of GPCRs.
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Affiliation(s)
- Chengyan Wu
- School of Pharmaceutical Sciences, Guizhou University, Guiyang, 550025, China
| | - Li Hu
- School of Pharmaceutical Sciences, Guizhou University, Guiyang, 550025, China
| | - Bing Liu
- School of Pharmaceutical Sciences, Guizhou University, Guiyang, 550025, China
| | - Xingyue Zeng
- School of Pharmaceutical Sciences, Guizhou University, Guiyang, 550025, China
| | - Haixiang Ma
- School of Pharmaceutical Sciences, Guizhou University, Guiyang, 550025, China
| | - Yongkai Cao
- Institute of Translational Medicine, The First Affiliated Hospital of Shenzhen University, Shenzhen, 518035, China
| | - Huijun Li
- Department of Pharmaceuticals, People's Hospital of Zunyi City Bo Zhou District, Zunyi, 563000, China
| | - Xiaohan Zhang
- School of Pharmaceutical Sciences, Guizhou University, Guiyang, 550025, China.
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Kim KM. Unveiling the Differences in Signaling and Regulatory Mechanisms between Dopamine D2 and D3 Receptors and Their Impact on Behavioral Sensitization. Int J Mol Sci 2023; 24:ijms24076742. [PMID: 37047716 PMCID: PMC10095578 DOI: 10.3390/ijms24076742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 03/25/2023] [Accepted: 03/28/2023] [Indexed: 04/09/2023] Open
Abstract
Dopamine receptors are classified into five subtypes, with D2R and D3R playing a crucial role in regulating mood, motivation, reward, and movement. Whereas D2R are distributed widely across the brain, including regions responsible for motor functions, D3R are primarily found in specific areas related to cognitive and emotional functions, such as the nucleus accumbens, limbic system, and prefrontal cortex. Despite their high sequence homology and similar signaling pathways, D2R and D3R have distinct regulatory properties involving desensitization, endocytosis, posttranslational modification, and interactions with other cellular components. In vivo, D3R is closely associated with behavioral sensitization, which leads to increased dopaminergic responses. Behavioral sensitization is believed to result from D3R desensitization, which removes the inhibitory effect of D3R on related behaviors. Whereas D2R maintains continuous signal transduction through agonist-induced receptor phosphorylation, arrestin recruitment, and endocytosis, which recycle and resensitize desensitized receptors, D3R rarely undergoes agonist-induced endocytosis and instead is desensitized after repeated agonist exposure. In addition, D3R undergoes more extensive posttranslational modifications, such as glycosylation and palmitoylation, which are needed for its desensitization. Overall, a series of biochemical settings more closely related to D3R could be linked to D3R-mediated behavioral sensitization.
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Affiliation(s)
- Kyeong-Man Kim
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 61186, Republic of Korea
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Burström V, Ågren R, Betari N, Valle-León M, Garro-Martínez E, Ciruela F, Sahlholm K. Dopamine-induced arrestin recruitment and desensitization of the dopamine D4 receptor is regulated by G protein-coupled receptor kinase-2. Front Pharmacol 2023; 14:1087171. [PMID: 36778010 PMCID: PMC9911804 DOI: 10.3389/fphar.2023.1087171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 01/18/2023] [Indexed: 01/28/2023] Open
Abstract
The dopamine D4 receptor (D4R) is expressed in the retina, prefrontal cortex, and autonomic nervous system and has been implicated in attention deficit hyperactivity disorder (ADHD), substance use disorders, and erectile dysfunction. D4R has also been investigated as a target for antipsychotics due to its high affinity for clozapine. As opposed to the closely related dopamine D2 receptor (D2R), dopamine-induced arrestin recruitment and desensitization at the D4R have not been studied in detail. Indeed, some earlier investigations could not detect arrestin recruitment and desensitization of this receptor upon its activation by agonist. Here, we used a novel nanoluciferase complementation assay to study dopamine-induced recruitment of β-arrestin2 (βarr2; also known as arrestin3) and G protein-coupled receptor kinase-2 (GRK2) to the D4R in HEK293T cells. We also studied desensitization of D4R-evoked G protein-coupled inward rectifier potassium (GIRK; also known as Kir3) current responses in Xenopus oocytes. Furthermore, the effect of coexpression of GRK2 on βarr2 recruitment and GIRK response desensitization was examined. The results suggest that coexpression of GRK2 enhanced the potency of dopamine to induce βarr2 recruitment to the D4R and accelerated the rate of desensitization of D4R-evoked GIRK responses. The present study reveals new details about the regulation of arrestin recruitment to the D4R and thus increases our understanding of the signaling and desensitization of this receptor.
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Affiliation(s)
- Viktor Burström
- Department of Integrative Medical Biology, Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Richard Ågren
- Department of Neuroscience, Karolinska Institutet, Solna, Sweden
| | - Nibal Betari
- Department of Integrative Medical Biology, Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Marta Valle-León
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, Barcelona, Spain,Neuropharmacology and Pain Group, Neuroscience Program, Institut d'Investigació Biomèdica de Bellvitge, IDIBELL, Barcelona, Spain
| | - Emilio Garro-Martínez
- Department of Integrative Medical Biology, Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Francisco Ciruela
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, Barcelona, Spain,Neuropharmacology and Pain Group, Neuroscience Program, Institut d'Investigació Biomèdica de Bellvitge, IDIBELL, Barcelona, Spain
| | - Kristoffer Sahlholm
- Department of Integrative Medical Biology, Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden,Department of Neuroscience, Karolinska Institutet, Solna, Sweden,Pharmacology Unit, Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, Barcelona, Spain,Neuropharmacology and Pain Group, Neuroscience Program, Institut d'Investigació Biomèdica de Bellvitge, IDIBELL, Barcelona, Spain,*Correspondence: Kristoffer Sahlholm,
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Min X, Sun N, Wang S, Zhang X, Kim KM. Sequestration of Gβγ by deubiquitinated arrestins into the nucleus as a novel desensitization mechanism of G protein-coupled receptors. Cell Commun Signal 2023; 21:11. [PMID: 36658650 PMCID: PMC9854190 DOI: 10.1186/s12964-022-01013-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 12/10/2022] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Desensitization of G protein-coupled receptors (GPCRs) refers to a rapid attenuation of responsiveness that occurs with repeated or continuous exposure to agonists. GRK-mediated phosphorylation and subsequent binding with arrestins in the activated receptor cytoplasmic cavity in competition with G proteins has been suggested as the conventional mechanism of desensitization. Along with widely accepted conventional mechanism of desensitization, studies of various GPCRs including dopamine D2-like receptors (D2R, D3R, D4R) have suggested the existence of another desensitization mechanism. In this study, loss-of-function approaches and D2-like receptor mutants that display different desensitization properties were used to elucidate the molecular mechanisms responsible for desensitization. RESULTS Desensitization development entailed the signaling cascade composed of Src, PDK1, and Akt, the latter of which in turn interacted with USP33, an arrestin deubiquitinase, to promote arrestin deubiquitination. The deubiquitinated arrestin subsequently formed a complex with Gβγ and translocated to the nucleus via an importin complex, wherein it sequestered Gβγ from the receptor and Gα, thereby attenuating receptor signaling. As in D2-like receptors, both USP33 and importin β1 were involved in the desensitization of the β2 adrenoceptor. CONCLUSIONS In addition to the conventional mechanism of desensitization, which occurs on the plasma membrane and in the cytosol, this study provides a new insight that another desensitization pathway in which nuclear trafficking plays a critical role is operating. It is plausible that multiple, complementary desensitization measures are in place to properly induce desensitization depending on receptor characteristics or the surrounding environment. Video Abstract.
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Affiliation(s)
- Xiao Min
- grid.14005.300000 0001 0356 9399Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwangju, 61186 Republic of Korea
| | - Ningning Sun
- grid.14005.300000 0001 0356 9399Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwangju, 61186 Republic of Korea
| | - Shujie Wang
- grid.14005.300000 0001 0356 9399Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwangju, 61186 Republic of Korea
| | - Xiaohan Zhang
- grid.14005.300000 0001 0356 9399Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwangju, 61186 Republic of Korea ,grid.443382.a0000 0004 1804 268XCollege of Pharmaceutical Sciences, Guizhou University, Guiyang, 550025 Guizhou China
| | - Kyeong-Man Kim
- grid.14005.300000 0001 0356 9399Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwangju, 61186 Republic of Korea
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Mechanistic diversity involved in the desensitization of G protein-coupled receptors. Arch Pharm Res 2021; 44:342-353. [PMID: 33761113 DOI: 10.1007/s12272-021-01320-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 03/14/2021] [Indexed: 01/14/2023]
Abstract
The desensitization of G protein-coupled receptors (GPCRs), which involves rapid loss of responsiveness due to repeated or chronic exposure to agonists, can occur through various mechanisms at different levels of signaling pathways. In this review, the mechanisms of GPCR desensitization are classified according to their occurrence at the receptor level and downstream to the receptor. The desensitization at the receptor level occurs in a phosphorylation-dependent manner, wherein the activated receptors are phosphorylated by GPCR kinases (GRKs), thereby increasing their affinities for arrestins. Arrestins bind to receptors through the cavity on the cytoplasmic region of heptahelical domains and interfere with the binding and activation of G-protein. Diverse mechanisms are involved in the desensitization that occurs downstream of the receptor. Some of these include the sequestration of G proteins, such as Gq and Gi/o by GRK2/3 and deubiquitinated arrestins, respectively. Mechanistically, GRK2/3 attenuates GPCR signaling by sequestering the Gα subunits of the Gq family and Gβγ via regulators of G protein signaling and pleckstrin homology domains, respectively. Moreover, studies on Gi/o-coupled D2-like receptors have reported that arrestins are deubiquitinated under desensitization condition and form a stable complex with Gβγ, thereby preventing them from coupling with Gα and the receptor, eventually leading to receptor signaling inhibition. Notably, the desensitization mechanism that involves arrestin deubiquitination is interesting; however, this is a new mechanism and needs to be explored further.
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