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Zeng X, Wu C, Cao Y, Li H, Zhang X. Mdm2-mediated ubiquitination of PKCβII is responsible for insulin-induced heterologous desensitization of dopamine D 3 receptor. FEBS Lett 2024; 598:400-414. [PMID: 38302840 DOI: 10.1002/1873-3468.14815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/21/2023] [Accepted: 01/05/2024] [Indexed: 02/03/2024]
Abstract
The insulin and dopaminergic systems in the brain are associated with schizophrenia and Parkinson's disease with respect to etiology and treatment. The present study investigated the crosstalk between the insulin receptor (IR) and dopamine receptor and found that insulin stimulation selectively inhibits signaling of D3 R in a PKCβII-dependent manner. Upon insulin stimulation, E3 ligase enzyme Mdm2 moves out of the nucleus to ubiquitinate PKCβII. Subsequently, ubiquitinated PKCβII translocates to the cell membrane and interacts with D3 R in a phosphorylation-dependent manner at S229/257, resulting in the attenuation of D3 R signaling and initiating clathrin-mediated endocytosis and downregulation. Considering that both IR and D3 R are closely related to some neuropsychosis, this study could provide new molecular insight into the etiology of the disorder.
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Affiliation(s)
- Xingyue Zeng
- School of Pharmaceutical Sciences, Guizhou University, Guiyang, China
| | - ChengYan Wu
- School of Pharmaceutical Sciences, Guizhou University, Guiyang, China
| | - Yongkai Cao
- Department of Neurology, Institute of Translational Medicine, The First Affiliated Hospital of Shenzhen University, China
| | - Huijun Li
- Department of Pharmaceuticals, People's Hospital of Zunyi City Bo Zhou District, China
| | - Xiaohan Zhang
- School of Pharmaceutical Sciences, Guizhou University, Guiyang, China
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Min X, Wang S, Zhang X, Sun N, Kim KM. PKCβII activation requires nuclear trafficking for phosphorylation and Mdm2-mediated ubiquitination. Life Sci Alliance 2023; 6:e202201748. [PMID: 36717249 PMCID: PMC9887771 DOI: 10.26508/lsa.202201748] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 01/11/2023] [Accepted: 01/11/2023] [Indexed: 01/31/2023] Open
Abstract
PKCβII, a conventional PKC family member, plays critical roles in the regulation of a variety of cellular functions. Here, we employed loss-of-function approaches and mutants of PKCβII with altered phosphorylation and protein interaction behaviors to identify the cellular mechanisms underlying the activation of PKCβII. Our results show that 3-phosphoinositide-dependent protein kinase-1 (PDK1)-mediated constitutive phosphorylation of PKCβII at the activation loop (T500) is required for phorbol ester-induced nuclear entry and subsequent Mdm2-mediated ubiquitination of PKCβII, whereas ubiquitination of PKCβII is required for the PDK1-mediated inducible phosphorylation of PKCβII at T500 in the nucleus. After moving out of the nucleus, PKCβII interacts with actin, undergoes inducible mTORC2-mediated phosphorylation at the turn motif (T641), interacts with clathrin, and then translocates to the plasma membrane. This overall cascade of cellular events intertwined with the phosphorylation at critical residues and Mdm2-mediated ubiquitination in the nucleus and along with interactions with actin and clathrin plays roles that encompass the core processes of PKC activation.
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Affiliation(s)
- Xiao Min
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
| | - Shujie Wang
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
| | - Xiaohan Zhang
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
| | - Ningning Sun
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
| | - Kyeong-Man Kim
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
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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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Min X, Zhang X, Wang S, Kim KM. Activation of PKCβII through nuclear trafficking guided by βγ subunits of trimeric G protein and 14-3-3ε. Life Sci 2022; 312:121245. [PMID: 36503900 DOI: 10.1016/j.lfs.2022.121245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 11/22/2022] [Accepted: 11/23/2022] [Indexed: 11/27/2022]
Abstract
AIMS Conventional members of protein kinase C (PKC) family, including PKCβII, are constitutively phosphorylated on three major motifs and located in the cytosol in a primed state. In response to cellular stimuli, PKCβII is activated through inducible phosphorylation and Mdm2-mediated ubiquitination. In this study, we aimed to identify the activation mechanism of PKCβII, focusing on the signaling cascade that regulate the phosphorylation and ubiquitination. MATERIALS AND METHODS Loss-of-function approaches and mutants of PDK1/PKCβII that display different regulatory properties were used to identify the cellular components and processes responsible for endocytosis. KEY FINDINGS Phorbol 12-myristate 13-acetate (PMA)-induced phosphorylation and ubiquitination of PKCβII, which are needed for its translocation to the plasma membrane, required the presence of both Gβγ and 14-3-3ε. Gβγ and 14-3-3ε mediated the constitutive phosphorylation of PKCβII by scaffolding PI3K and PDK1 in the cytosol, which is an inactive but required state for the activation of PKCβII by subsequent signals. In response to PMA treatment, the signaling complex translocated to the nucleus with dissociation of PI3K from it. Thereafter, PDK1 stably interacted with 14-3-3ε and was dephosphorylated; PKCβII interacted with Mdm2 along with Gβγ, leading to its ubiquitination at two lysine residues on its C-tail. Finally, PDK1/14-3-3ε and ubiquitinated PKCβII translocated to the plasma membrane. SIGNIFICANCE As PKCβII mediates a wide range of cellular functions and plays important roles in the pathogenesis of various diseases, our results will provide clues to understand the pathogenesis of PKCβII-related disorders and facilitate their treatment.
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Affiliation(s)
- Xiao Min
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
| | - Xiaohan Zhang
- School of Pharmaceutical Sciences, Guizhou University, Guiyang 550025, China
| | - Shujie Wang
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
| | - Kyeong-Man Kim
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea.
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Acharya S, Kundu D, Kim KM. β-Arrestin1 and GPCR kinase2 play permissive roles in Src-mediated endocytosis of α4β2 nicotinic ACh receptors. Br J Pharmacol 2021; 178:3498-3516. [PMID: 33844281 DOI: 10.1111/bph.15495] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 04/02/2021] [Accepted: 04/06/2021] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND AND PURPOSE The α4β2 nicotinic ACh receptor (nAChR), a subtype of the ligand-gated ion channel, is abundantly expressed in the brain and is implicated in several neurological disorders. The endocytosis of nAChRs plays important roles in the pathogenesis of neurological diseases, but the underlying molecular mechanisms remain poorly understood. EXPERIMENTAL APPROACH Loss-of-function approaches and mutants of α4β2 nAChRs that display different endocytic properties were used to identify the cellular components and processes responsible for endocytosis. The signalling cascade that leads to endocytosis was deduced via protein interactions in predicted cellular components. The endocytosis of α4β2 nAChRs was determined and crosschecked using an ELISA and radioligand assay. KEY RESULTS Endocytosis of α4β2 nAChRs occurred through clathrin-mediated endocytosis in a dynamin-dependent manner. 14-3-3η-dependent Src-mediated phosphorylation of the nAChR α4 subunit at Y575 was required for nAChR endocytosis, and this occurred with the assistance of β-arrestin1 and GPCR kinase 2 (GRK2) without the need for kinase activity. Endocytosis triggered the mouse double minute 2 homologue-mediated ubiquitination and subsequent down-regulation of α4β2 nAChRs. CONCLUSIONS AND IMPLICATIONS α4β2 nAChR, an ionophore receptor, employs the metabotropic signalling pathway required for endocytosis, which leads to ubiquitination and down-regulation. Further, GRK2 and β-arrestin1, usually associated with GPCR signalling, are involved in the endocytosis of α4β2 nAChRs via different mechanisms. Considering the functional and pathological implications of nAChR endocytosis, results obtained in this study are crucial for the progression of basic research and clinical investigations.
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Affiliation(s)
- Srijan Acharya
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwangju, Republic of Korea.,Mitchell Cancer Institute, Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
| | - Dooti Kundu
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwangju, Republic of Korea
| | - Kyeong-Man Kim
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwangju, Republic of Korea
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GRK2-mediated receptor phosphorylation and Mdm2-mediated β-arrestin2 ubiquitination drive clathrin-mediated endocytosis of G protein-coupled receptors. Biochem Biophys Res Commun 2020; 533:383-390. [DOI: 10.1016/j.bbrc.2020.09.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 09/11/2020] [Indexed: 01/07/2023]
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Zheng M, Zhang X, Sun N, Min X, Acharya S, Kim KM. A novel molecular mechanism responsible for phosphorylation-independent desensitization of G protein-coupled receptors exemplified by the dopamine D 3 receptor. Biochem Biophys Res Commun 2020; 528:432-439. [PMID: 32505358 DOI: 10.1016/j.bbrc.2020.05.197] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 05/26/2020] [Indexed: 10/24/2022]
Abstract
GRK-mediated receptor phosphorylation followed by association with β-arrestins has been proposed to be the molecular mechanism involved in the desensitization of G protein-coupled receptors (GPCRs). However, this mechanism does not explain the desensitization of some GPCRs, such as dopamine D3 receptor (D3R), which does not undergo GRK-mediated phosphorylation. Loss-of-function approaches and mutants of dopamine D2 receptor and D3R, which exhibit different desensitization properties, were used to identify the cellular components and processes responsible for desensitization. D3R mediated the recruitment of Mdm2 to the cytosol, which resulted in the constitutive ubiquitination of β-arrestin2 in the resting state. Under desensitization conditions, cytosolic Mdm2 returned to the nucleus, resulting in the deubiquitination of cytosolic β-arrestins. Deubiquitinated β-arrestins formed a tight complex with Gβγ, thereby sequestering it, causing interference in D3R signaling. In conclusion, this study shows that β-arrestins, depending on their ubiquitination status, control the G protein cycling by regulating their interactions with Gβγ. This is a novel mechanism proposed to explain how certain GPCRs can undergo desensitization without receptor phosphorylation.
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Affiliation(s)
- Mei Zheng
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, 61186, Republic of Korea
| | - Xiaohan Zhang
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, 61186, Republic of Korea
| | - Ningning Sun
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, 61186, Republic of Korea
| | - Xiao Min
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, 61186, Republic of Korea
| | - Srijan Acharya
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, 61186, Republic of Korea
| | - Kyeong-Man Kim
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, 61186, Republic of Korea.
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Zhang X, Min X, Wang S, Sun N, Kim KM. Mdm2-mediated ubiquitination of β-arrestin2 in the nucleus occurs in a Gβγ- and clathrin-dependent manner. Biochem Pharmacol 2020; 178:114049. [PMID: 32450252 DOI: 10.1016/j.bcp.2020.114049] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 05/19/2020] [Indexed: 01/03/2023]
Abstract
The fate and activity of β-arrestin2, a key player in the regulation of desensitization and endocytosis of G protein-coupled receptors (GPCRs), are regulated by mouse double minute 2 homolog (Mdm2)-mediated ubiquitination. However, details of the molecular mechanisms of β-arrestin2 ubiquitination remain unclear. Studies on β-arrestin2 and Mdm2 mutants with modified nucleocytoplasmic shuttling properties have revealed that β-arrestin2 ubiquitination occurs in the nucleus in a Gβγ- and clathrin-dependent manner. The nuclear entry of both β-arrestin2 and Mdm2 commonly relies on the presence of importin complex but can occur independently of each other. Gβγ and clathrin regulated the nuclear entry of β-arrestin2 by mediating the interaction between β-arrestin2 and importin β1. In contrast, Akt-mediated phosphorylation of two serine residues of Mdm2 partly regulated the nuclear entry of Mdm2. Ubiquitinated β-arrestin2 along with Mdm2 translocated to the cytoplasm where they play various functional roles including receptor endocytosis and ubiquitination of other cytoplasmic proteins. The nuclear export of Mdm2 required nuclear entry and interaction of β-arrestin2 with Mdm2. Ubiquitination was required for the translocation of β-arrestin2 toward activated receptors on the plasma membrane and for its endocytic activity. The current study revealed the cellular components and processes involved in the ubiquitination of β-arrestin2, and these findings could be quintessential for providing directions and detailed strategies for the manipulation of GPCR functions and development of GPCR-related therapeutics.
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Affiliation(s)
- Xiaohan Zhang
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 61186, Republic of Korea
| | - Xiao Min
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 61186, Republic of Korea
| | - Shujie Wang
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 61186, Republic of Korea
| | - Ningning Sun
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 61186, Republic of Korea
| | - Kyeong-Man Kim
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 61186, Republic of Korea.
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