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Pharmacological Reviews Sep 2023The two -arrestins, -arrestin-1 and -2 (systematic names: arrestin-2 and -3, respectively), are multifunctional intracellular proteins that regulate the activity of a... (Review)
Review
The two -arrestins, -arrestin-1 and -2 (systematic names: arrestin-2 and -3, respectively), are multifunctional intracellular proteins that regulate the activity of a very large number of cellular signaling pathways and physiologic functions. The two proteins were discovered for their ability to disrupt signaling via G protein-coupled receptors (GPCRs) via binding to the activated receptors. However, it is now well recognized that both -arrestins can also act as direct modulators of numerous cellular processes via either GPCR-dependent or -independent mechanisms. Recent structural, biophysical, and biochemical studies have provided novel insights into how -arrestins bind to activated GPCRs and downstream effector proteins. Studies with -arrestin mutant mice have identified numerous physiologic and pathophysiological processes regulated by -arrestin-1 and/or -2. Following a short summary of recent structural studies, this review primarily focuses on -arrestin-regulated physiologic functions, with particular focus on the central nervous system and the roles of -arrestins in carcinogenesis and key metabolic processes including the maintenance of glucose and energy homeostasis. This review also highlights potential therapeutic implications of these studies and discusses strategies that could prove useful for targeting specific -arrestin-regulated signaling pathways for therapeutic purposes. SIGNIFICANCE STATEMENT: The two β-arrestins, structurally closely related intracellular proteins that are evolutionarily highly conserved, have emerged as multifunctional proteins able to regulate a vast array of cellular and physiological functions. The outcome of studies with β-arrestin mutant mice and cultured cells, complemented by novel insights into β-arrestin structure and function, should pave the way for the development of novel classes of therapeutically useful drugs capable of regulating specific β-arrestin functions.
Topics: Mice; Animals; beta-Arrestins; Arrestins; Signal Transduction; Receptors, G-Protein-Coupled; beta-Arrestin 1
PubMed: 37028945
DOI: 10.1124/pharmrev.121.000302 -
Cell Nov 2022Morphine and fentanyl are among the most used opioid drugs that confer analgesia and unwanted side effects through both G protein and arrestin signaling pathways of...
Morphine and fentanyl are among the most used opioid drugs that confer analgesia and unwanted side effects through both G protein and arrestin signaling pathways of μ-opioid receptor (μOR). Here, we report structures of the human μOR-G protein complexes bound to morphine and fentanyl, which uncover key differences in how they bind the receptor. We also report structures of μOR bound to TRV130, PZM21, and SR17018, which reveal preferential interactions of these agonists with TM3 side of the ligand-binding pocket rather than TM6/7 side. In contrast, morphine and fentanyl form dual interactions with both TM3 and TM6/7 regions. Mutations at the TM6/7 interface abolish arrestin recruitment of μOR promoted by morphine and fentanyl. Ligands designed to reduce TM6/7 interactions display preferential G protein signaling. Our results provide crucial insights into fentanyl recognition and signaling of μOR, which may facilitate rational design of next-generation analgesics.
Topics: Humans; Analgesics, Opioid; Arrestin; Fentanyl; GTP-Binding Proteins; Morphine; Receptors, Opioid, mu
PubMed: 36368306
DOI: 10.1016/j.cell.2022.09.041 -
Cell Nov 2022Binding of arrestin to phosphorylated G protein-coupled receptors (GPCRs) is crucial for modulating signaling. Once internalized, some GPCRs remain complexed with...
Binding of arrestin to phosphorylated G protein-coupled receptors (GPCRs) is crucial for modulating signaling. Once internalized, some GPCRs remain complexed with β-arrestins, while others interact only transiently; this difference affects GPCR signaling and recycling. Cell-based and in vitro biophysical assays reveal the role of membrane phosphoinositides (PIPs) in β-arrestin recruitment and GPCR-β-arrestin complex dynamics. We find that GPCRs broadly stratify into two groups, one that requires PIP binding for β-arrestin recruitment and one that does not. Plasma membrane PIPs potentiate an active conformation of β-arrestin and stabilize GPCR-β-arrestin complexes by promoting a fully engaged state of the complex. As allosteric modulators of GPCR-β-arrestin complex dynamics, membrane PIPs allow for additional conformational diversity beyond that imposed by GPCR phosphorylation alone. For GPCRs that require membrane PIP binding for β-arrestin recruitment, this provides a mechanism for β-arrestin release upon translocation of the GPCR to endosomes, allowing for its rapid recycling.
Topics: beta-Arrestins; Phosphatidylinositols; Arrestins; beta-Arrestin 1; Receptors, G-Protein-Coupled
PubMed: 36368322
DOI: 10.1016/j.cell.2022.10.018 -
Nature Structural & Molecular Biology May 2015G protein-coupled receptors (GPCRs) are essential mediators of cellular signaling and are important targets of drug action. Of the approximately 350 nonolfactory human...
G protein-coupled receptors (GPCRs) are essential mediators of cellular signaling and are important targets of drug action. Of the approximately 350 nonolfactory human GPCRs, more than 100 are still considered to be 'orphans' because their endogenous ligands remain unknown. Here, we describe a unique open-source resource that allows interrogation of the druggable human GPCRome via a G protein-independent β-arrestin-recruitment assay. We validate this unique platform at more than 120 nonorphan human GPCR targets, demonstrate its utility for discovering new ligands for orphan human GPCRs and describe a method (parallel receptorome expression and screening via transcriptional output, with transcriptional activation following arrestin translocation (PRESTO-Tango)) for the simultaneous and parallel interrogation of the entire human nonolfactory GPCRome.
Topics: Amino Acid Sequence; Arrestins; Biological Assay; Humans; Ligands; RNA Interference; RNA, Small Interfering; Receptors, G-Protein-Coupled; Transcription, Genetic; Transcriptional Activation; beta-Arrestins
PubMed: 25895059
DOI: 10.1038/nsmb.3014 -
American Journal of Physiology. Cell... Sep 2022G protein-coupled receptors (GPCRs) are of considerable interest due to their importance in a wide range of physiological functions and in a large number of Food and... (Review)
Review
G protein-coupled receptors (GPCRs) are of considerable interest due to their importance in a wide range of physiological functions and in a large number of Food and Drug Administration (FDA)-approved drugs as therapeutic entities. With continued study of their function and mechanism of action, there is a greater understanding of how effector molecules interact with a receptor to initiate downstream effector signaling. This review aims to explore the signaling pathways, dynamic structures, and physiological relevance in the cardiovascular system of the three most important GPCR signaling effectors: heterotrimeric G proteins, GPCR kinases (GRKs), and β-arrestins. We will first summarize their prominent roles in GPCR pharmacology before transitioning into less well-explored areas. As new technologies are developed and applied to studying GPCR structure and their downstream effectors, there is increasing appreciation for the elegance of the regulatory mechanisms that mediate intracellular signaling and function.
Topics: Arrestins; Receptors, G-Protein-Coupled; Signal Transduction; Transducers; beta-Arrestins
PubMed: 35816644
DOI: 10.1152/ajpcell.00210.2022 -
Cell May 2022β-arrestins bind G protein-coupled receptors to terminate G protein signaling and to facilitate other downstream signaling pathways. Using single-molecule fluorescence...
β-arrestins bind G protein-coupled receptors to terminate G protein signaling and to facilitate other downstream signaling pathways. Using single-molecule fluorescence resonance energy transfer imaging, we show that β-arrestin is strongly autoinhibited in its basal state. Its engagement with a phosphopeptide mimicking phosphorylated receptor tail efficiently releases the β-arrestin tail from its N domain to assume distinct conformations. Unexpectedly, we find that β-arrestin binding to phosphorylated receptor, with a phosphorylation barcode identical to the isolated phosphopeptide, is highly inefficient and that agonist-promoted receptor activation is required for β-arrestin activation, consistent with the release of a sequestered receptor C tail. These findings, together with focused cellular investigations, reveal that agonism and receptor C-tail release are specific determinants of the rate and efficiency of β-arrestin activation by phosphorylated receptor. We infer that receptor phosphorylation patterns, in combination with receptor agonism, synergistically establish the strength and specificity with which diverse, downstream β-arrestin-mediated events are directed.
Topics: Phosphopeptides; Phosphorylation; Receptors, G-Protein-Coupled; beta-Arrestin 1; beta-Arrestins
PubMed: 35483373
DOI: 10.1016/j.cell.2022.03.042 -
Nature Oct 2022The initial step in the sensory transduction pathway underpinning hearing and balance in mammals involves the conversion of force into the gating of a mechanosensory...
The initial step in the sensory transduction pathway underpinning hearing and balance in mammals involves the conversion of force into the gating of a mechanosensory transduction channel. Despite the profound socioeconomic impacts of hearing disorders and the fundamental biological significance of understanding mechanosensory transduction, the composition, structure and mechanism of the mechanosensory transduction complex have remained poorly characterized. Here we report the single-particle cryo-electron microscopy structure of the native transmembrane channel-like protein 1 (TMC-1) mechanosensory transduction complex isolated from Caenorhabditis elegans. The two-fold symmetric complex is composed of two copies each of the pore-forming TMC-1 subunit, the calcium-binding protein CALM-1 and the transmembrane inner ear protein TMIE. CALM-1 makes extensive contacts with the cytoplasmic face of the TMC-1 subunits, whereas the single-pass TMIE subunits reside on the periphery of the complex, poised like the handles of an accordion. A subset of complexes additionally includes a single arrestin-like protein, arrestin domain protein (ARRD-6), bound to a CALM-1 subunit. Single-particle reconstructions and molecular dynamics simulations show how the mechanosensory transduction complex deforms the membrane bilayer and suggest crucial roles for lipid-protein interactions in the mechanism by which mechanical force is transduced to ion channel gating.
Topics: Animals; Arrestins; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Calcium-Binding Proteins; Cryoelectron Microscopy; Ion Channel Gating; Ion Channels; Lipids; Mechanotransduction, Cellular
PubMed: 36224384
DOI: 10.1038/s41586-022-05314-8 -
Developmental Cell Nov 2015While cilia are recognized as important signaling organelles, the extent of ciliary functions remains unknown because of difficulties in cataloguing proteins from...
While cilia are recognized as important signaling organelles, the extent of ciliary functions remains unknown because of difficulties in cataloguing proteins from mammalian primary cilia. We present a method that readily captures rapid snapshots of the ciliary proteome by selectively biotinylating ciliary proteins using a cilia-targeted proximity labeling enzyme (cilia-APEX). Besides identifying known ciliary proteins, cilia-APEX uncovered several ciliary signaling molecules. The kinases PKA, AMPK, and LKB1 were validated as bona fide ciliary proteins and PKA was found to regulate Hedgehog signaling in primary cilia. Furthermore, proteomics profiling of Ift27/Bbs19 mutant cilia correctly detected BBSome accumulation inside Ift27(-/-) cilia and revealed that β-arrestin 2 and the viral receptor CAR are candidate cargoes of the BBSome. This work demonstrates that proximity labeling can be applied to proteomics of non-membrane-enclosed organelles and suggests that proteomics profiling of cilia will enable a rapid and powerful characterization of ciliopathies.
Topics: AMP-Activated Protein Kinases; Amino Acid Sequence; Animals; Arrestins; Ascorbate Peroxidases; Biological Transport; Cells, Cultured; Cilia; Cyclic AMP-Dependent Protein Kinases; Embryo, Mammalian; Fibroblasts; Hedgehog Proteins; Image Processing, Computer-Assisted; Mice; Mice, Knockout; Microscopy; Microtubule-Associated Proteins; Molecular Sequence Data; Organelles; Protein Serine-Threonine Kinases; Proteome; Proteomics; Retinal Pigment Epithelium; Sequence Homology, Amino Acid; Signal Transduction; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; beta-Arrestin 2; beta-Arrestins; rab GTP-Binding Proteins
PubMed: 26585297
DOI: 10.1016/j.devcel.2015.10.015 -
Nature Communications Apr 2023In sexual reproduction, sperm contribute half the genomic material required for creation of offspring yet core molecular mechanisms essential for their formation are...
In sexual reproduction, sperm contribute half the genomic material required for creation of offspring yet core molecular mechanisms essential for their formation are undefined. Here, the α-arrestin molecule arrestin-domain containing 5 (ARRDC5) is identified as an essential regulator of mammalian spermatogenesis. Multispecies testicular tissue transcriptome profiling indicates that expression of Arrdc5 is testis enriched, if not specific, in mice, pigs, cattle, and humans. Knockout of Arrdc5 in mice leads to male specific sterility due to production of low numbers of sperm that are immotile and malformed. Spermiogenesis, the final phase of spermatogenesis when round spermatids transform to spermatozoa, is defective in testes of Arrdc5 deficient mice. Also, epididymal sperm in Arrdc5 knockouts are unable to capacitate and fertilize oocytes. These findings establish ARRDC5 as an essential regulator of mammalian spermatogenesis. Considering the role of arrestin molecules as modulators of cellular signaling and ubiquitination, ARRDC5 is a potential male contraceptive target.
Topics: Animals; Cattle; Humans; Male; Mice; Arrestins; Infertility, Male; Mice, Knockout; Morphogenesis; Semen; Spermatogenesis; Spermatozoa; Swine; Testis
PubMed: 37069147
DOI: 10.1038/s41467-023-37735-y -
Biomolecules Feb 2021Arrestins are a small family of four proteins in most vertebrates that bind hundreds of different G protein-coupled receptors (GPCRs). Arrestin binding to a GPCR has at... (Review)
Review
Arrestins are a small family of four proteins in most vertebrates that bind hundreds of different G protein-coupled receptors (GPCRs). Arrestin binding to a GPCR has at least three functions: precluding further receptor coupling to G proteins, facilitating receptor internalization, and initiating distinct arrestin-mediated signaling. The molecular mechanism of arrestin-GPCR interactions has been extensively studied and discussed from the "arrestin perspective", focusing on the roles of arrestin elements in receptor binding. Here, we discuss this phenomenon from the "receptor perspective", focusing on the receptor elements involved in arrestin binding and emphasizing existing gaps in our knowledge that need to be filled. It is vitally important to understand the role of receptor elements in arrestin activation and how the interaction of each of these elements with arrestin contributes to the latter's transition to the high-affinity binding state. A more precise knowledge of the molecular mechanisms of arrestin activation is needed to enable the construction of arrestin mutants with desired functional characteristics.
Topics: Animals; Arrestin; Arrestins; Binding Sites; Cattle; Crystallography, X-Ray; Fishes; Humans; Hydrophobic and Hydrophilic Interactions; Mice; Models, Molecular; Mutation; Phosphorylation; Protein Binding; Protein Conformation; Protein Domains; Protein Isoforms; Receptors, G-Protein-Coupled; Signal Transduction
PubMed: 33557162
DOI: 10.3390/biom11020218