1
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Walker AR, Parkin HA, Hye Kim S, Terzidou V, Woodward DF, Bennett PR, Hanyaloglu AC. Constitutive internalisation of EP2 differentially regulates G protein signalling. J Mol Endocrinol 2024; 73:e230153. [PMID: 38639976 PMCID: PMC11227035 DOI: 10.1530/jme-23-0153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 04/19/2024] [Indexed: 04/20/2024]
Abstract
The prostanoid G protein-coupled receptor (GPCR) EP2 is widely expressed and implicated in endometriosis, osteoporosis, obesity, pre-term labour and cancer. Internalisation and intracellular trafficking are critical for shaping GPCR activity, yet little is known regarding the spatial programming of EP2 signalling and whether this can be exploited pharmacologically. Using three EP2-selective ligands that favour activation of different EP2 pathways, we show that EP2 undergoes limited agonist-driven internalisation but is constitutively internalised via dynamin-dependent, β-arrestin-independent pathways. EP2 was constitutively trafficked to early and very early endosomes (VEE), which was not altered by ligand activation. APPL1, a key adaptor and regulatory protein of the VEE, did not impact EP2 agonist-mediated cAMP. Internalisation was required for ~70% of the acute butaprost- and AH13205-mediated cAMP signalling, yet PGN9856i, a Gαs-biased agonist, was less dependent on receptor internalisation for its cAMP signalling, particularly in human term pregnant myometrial cells that endogenously express EP2. Inhibition of EP2 internalisation partially reduced calcium signalling activated by butaprost or AH13205 and had no effect on PGE2 secretion. This indicates an agonist-dependent differential spatial requirement for Gαs and Gαq/11 signalling and a role for plasma membrane-initiated Gαq/11-Ca2+-mediated PGE2 secretion. These findings reveal a key role for EP2 constitutive internalisation in its signalling and potential spatial bias in mediating its downstream functions. This, in turn, could highlight important considerations for future selective targeting of EP2 signalling pathways.
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Affiliation(s)
- Abigail R Walker
- Institute of Reproductive and Developmental Biology, Department Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Holly A Parkin
- Institute of Reproductive and Developmental Biology, Department Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Sung Hye Kim
- Institute of Reproductive and Developmental Biology, Department Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Vasso Terzidou
- Institute of Reproductive and Developmental Biology, Department Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - David F Woodward
- Department of Bioengineering, Imperial College London, London, UK
| | - Phillip R Bennett
- Institute of Reproductive and Developmental Biology, Department Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Aylin C Hanyaloglu
- Institute of Reproductive and Developmental Biology, Department Metabolism, Digestion and Reproduction, Imperial College London, London, UK
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2
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Semesta KM, Garces A, Tsvetanova NG. The psychosis risk factor RBM12 encodes a novel repressor of GPCR/cAMP signal transduction. J Biol Chem 2023; 299:105133. [PMID: 37543364 PMCID: PMC10502367 DOI: 10.1016/j.jbc.2023.105133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 07/20/2023] [Accepted: 07/31/2023] [Indexed: 08/07/2023] Open
Abstract
RBM12 is a high-penetrance risk factor for familial schizophrenia and psychosis, yet its precise cellular functions and the pathways to which it belongs are not known. We utilize two complementary models, HEK293 cells and human iPSC-derived neurons, and delineate RBM12 as a novel repressor of the G protein-coupled receptor/cAMP/PKA (GPCR/cAMP/PKA) signaling axis. We establish that loss of RBM12 leads to hyperactive cAMP production and increased PKA activity as well as altered neuronal transcriptional responses to GPCR stimulation. Notably, the cAMP and transcriptional signaling steps are subject to discrete RBM12-dependent regulation. We further demonstrate that the two RBM12 truncating variants linked to familial psychosis impact this interplay, as the mutants fail to rescue GPCR/cAMP signaling hyperactivity in cells depleted of RBM12. Lastly, we present a mechanism underlying the impaired signaling phenotypes. In agreement with its activity as an RNA-binding protein, loss of RBM12 leads to altered gene expression, including that of multiple effectors of established significance within the receptor pathway. Specifically, the abundance of adenylyl cyclases, phosphodiesterase isoforms, and PKA regulatory and catalytic subunits is impacted by RBM12 depletion. We note that these expression changes are fully consistent with the entire gamut of hyperactive signaling outputs. In summary, the current study identifies a previously unappreciated role for RBM12 in the context of the GPCR-cAMP pathway that could be explored further as a tentative molecular mechanism underlying the functions of this factor in neuronal physiology and pathophysiology.
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Affiliation(s)
- Khairunnisa M Semesta
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - Angelica Garces
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - Nikoleta G Tsvetanova
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA.
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3
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Semesta KM, Garces A, Tsvetanova NG. The psychosis risk factor RBM12 encodes a novel repressor of GPCR/cAMP signal transduction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.12.523776. [PMID: 36711667 PMCID: PMC9882185 DOI: 10.1101/2023.01.12.523776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
RBM12 is a high-penetrance risk factor for familial schizophrenia and psychosis, yet its precise cellular functions and the pathways to which it belongs are not known. We utilize two complementary models, HEK293 cells and human iPSC-derived neurons, and delineate RBM12 as a novel repressor of the G protein-coupled receptor/cyclic AMP/protein kinase A (GPCR/cAMP/PKA) signaling axis. We establish that loss of RBM12 leads to hyperactive cAMP production and increased PKA activity as well as altered neuronal transcriptional responses to GPCR stimulation. Notably, the cAMP and transcriptional signaling steps are subject to discrete RBM12-dependent regulation. We further demonstrate that the two RBM12 truncating variants linked to familial psychosis impact this interplay, as the mutants fail to rescue GPCR/cAMP signaling hyperactivity in cells depleted of RBM12. Lastly, we present a mechanism underlying the impaired signaling phenotypes. In agreement with its activity as an RNA-binding protein, loss of RBM12 leads to altered gene expression, including that of multiple effectors of established significance within the receptor pathway. Specifically, the abundance of adenylyl cyclases, phosphodiesterase isoforms, and PKA regulatory and catalytic subunits is impacted by RBM12 depletion. We note that these expression changes are fully consistent with the entire gamut of hyperactive signaling outputs. In summary, the current study identifies a previously unappreciated role for RBM12 in the context of the GPCR/cAMP pathway that could be explored further as a tentative molecular mechanism underlying the functions of this factor in neuronal physiology and pathophysiology.
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Affiliation(s)
- Khairunnisa M Semesta
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, United States
| | - Angelica Garces
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, United States
| | - Nikoleta G Tsvetanova
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, United States
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4
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The emerging role of mass spectrometry-based proteomics in drug discovery. Nat Rev Drug Discov 2022; 21:637-654. [PMID: 35351998 DOI: 10.1038/s41573-022-00409-3] [Citation(s) in RCA: 118] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2022] [Indexed: 12/14/2022]
Abstract
Proteins are the main targets of most drugs; however, system-wide methods to monitor protein activity and function are still underused in drug discovery. Novel biochemical approaches, in combination with recent developments in mass spectrometry-based proteomics instrumentation and data analysis pipelines, have now enabled the dissection of disease phenotypes and their modulation by bioactive molecules at unprecedented resolution and dimensionality. In this Review, we describe proteomics and chemoproteomics approaches for target identification and validation, as well as for identification of safety hazards. We discuss innovative strategies in early-stage drug discovery in which proteomics approaches generate unique insights, such as targeted protein degradation and the use of reactive fragments, and provide guidance for experimental strategies crucial for success.
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5
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Peng GE, von Zastrow M. A Live-Cell Imaging Assay for Nuclear Entry of cAMP-Dependent Protein Kinase Catalytic Subunits Stimulated by Endogenous GPCR Activation. Methods Mol Biol 2022; 2483:339-349. [PMID: 35286686 DOI: 10.1007/978-1-0716-2245-2_21] [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] [Indexed: 06/14/2023]
Abstract
Nuclear entry of cAMP-dependent protein kinase catalytic subunits is typically inferred from changes in net protein amount or kinase activity in the nucleus. Previous methods to directly assess nuclear entry require kinase subunit overexpression and/or supraphysiological cAMP elevation. We describe a method to detect nuclear entry of catalytic subunits expressed at an endogenous level in living cells, stimulated by cAMP in a physiological range, and in real time.
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Affiliation(s)
- Grace E Peng
- Program in Cell Biology, University of California, San Francisco, San Francisco, CA, USA
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Mark von Zastrow
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, USA.
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA.
- Quantitative Biology Institute, University of California, San Francisco, San Francisco, CA, USA.
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6
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Endosomal cAMP production broadly impacts the cellular phosphoproteome. J Biol Chem 2021; 297:100907. [PMID: 34166681 PMCID: PMC8294583 DOI: 10.1016/j.jbc.2021.100907] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 06/14/2021] [Accepted: 06/18/2021] [Indexed: 12/21/2022] Open
Abstract
Endosomal signaling downstream of G-protein-coupled receptors (GPCRs) has emerged as a novel paradigm with important pharmacological and physiological implications. However, our knowledge of the functional consequences of intracellular signaling is incomplete. To begin to address this gap, we combined an optogenetic approach for site-specific generation of the prototypical second messenger generated by active GPCRs, cyclic AMP (cAMP), with unbiased mass-spectrometry-based analysis of the phosphoproteome. We identified 218 unique, high-confidence sites whose phosphorylation is either increased or decreased in response to cAMP elevation. We next determined that the same amount of cAMP produced from the endosomal membrane led to more robust changes in phosphorylation than the plasma membrane. Remarkably, this was true for the entire repertoire of 218 identified targets and irrespective of their annotated subcellular localizations (endosome, cell surface, nucleus, cytosol). Furthermore, we identified a particularly strong endosome bias for a subset of proteins that are dephosphorylated in response to cAMP. Through bioinformatics analysis, we established these targets as putative substrates for protein phosphatase 2A (PP2A), and we propose compartmentalized activation of PP2A by cAMP-responsive kinases as the likely underlying mechanism. Altogether, our study extends the concept that endosomal signaling is a significant functional contributor to cellular responsiveness to cAMP by establishing a unique role for localized cAMP production in defining categorically distinct phosphoresponses.
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7
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von Zastrow M, Sorkin A. Mechanisms for Regulating and Organizing Receptor Signaling by Endocytosis. Annu Rev Biochem 2021; 90:709-737. [PMID: 33606955 DOI: 10.1146/annurev-biochem-081820-092427] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Intricate relationships between endocytosis and cellular signaling, first recognized nearly 40 years ago through the study of tyrosine kinase growth factor receptors, are now known to exist for multiple receptor classes and to affect myriad physiological and developmental processes. This review summarizes our present understanding of how endocytosis orchestrates cellular signaling networks, with an emphasis on mechanistic underpinnings and focusing on two receptor classes-tyrosine kinase and G protein-coupled receptors-that have been investigated in particular detail. Together, these examples provide a useful survey of the current consensus, uncertainties, and controversies in this rapidly advancing area of cell biology.
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Affiliation(s)
- Mark von Zastrow
- Department of Psychiatry, University of California, San Francisco, California 94143, USA;
| | - Alexander Sorkin
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA;
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8
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von Zastrow M. Proteomic Approaches to Investigate Regulated Trafficking and Signaling of G Protein-Coupled Receptors. Mol Pharmacol 2020; 99:392-398. [PMID: 33361190 DOI: 10.1124/molpharm.120.000178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 11/09/2020] [Indexed: 12/14/2022] Open
Abstract
Advances in proteomic methodologies based on quantitative mass spectrometry are now transforming pharmacology and experimental biology more broadly. The present review will discuss several examples based on work in the author's laboratory, which focuses on delineating relationships between G protein-coupled receptor signaling and trafficking in the endocytic network. The examples highlighted correspond to those discussed in a talk presented at the 2019 EB/ASPET meeting, which was organized by Professor Joe Beavo to commemorate his receipt of the Julius Axelrod Award. SIGNIFICANCE STATEMENT: GPCRs are allosteric machines that signal by interacting with other cellular proteins, and this, in turn, is determined by a complex interplay between the biochemical, subcellular localization, and membrane trafficking properties of receptors relative to transducer and regulatory proteins. The present minireview highlights recent advances and challenges in elucidating this dynamic cell biology and toward delineating the cellular basis of drug action at the level of defined GPCR interaction networks using proteomic approaches enabled by quantitative mass spectrometry.
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Affiliation(s)
- Mark von Zastrow
- Departments of Cellular and Molecular Pharmacology, and Psychiatry and Behavioral Science, San Francisco School of Medicine, and Quantitative Biology Institute, University of California, San Francisco, California
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9
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Kaur S, Chen Y, Shenoy SK. Agonist-activated glucagon receptors are deubiquitinated at early endosomes by two distinct deubiquitinases to facilitate Rab4a-dependent recycling. J Biol Chem 2020; 295:16630-16642. [PMID: 32967969 PMCID: PMC7864061 DOI: 10.1074/jbc.ra120.014532] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 09/17/2020] [Indexed: 01/08/2023] Open
Abstract
The glucagon receptor (GCGR) activated by the peptide hormone glucagon is a seven-transmembrane G protein-coupled receptor (GPCR) that regulates blood glucose levels. Ubiquitination influences trafficking and signaling of many GPCRs, but its characterization for the GCGR is lacking. Using endocytic colocalization and ubiquitination assays, we have identified a correlation between the ubiquitination profile and recycling of the GCGR. Our experiments revealed that GCGRs are constitutively ubiquitinated at the cell surface. Glucagon stimulation not only promoted GCGR endocytic trafficking through Rab5a early endosomes and Rab4a recycling endosomes, but also induced rapid deubiquitination of GCGRs. Inhibiting GCGR internalization or disrupting endocytic trafficking prevented agonist-induced deubiquitination of the GCGR. Furthermore, a Rab4a dominant negative (DN) that blocks trafficking at recycling endosomes enabled GCGR deubiquitination, whereas a Rab5a DN that blocks trafficking at early endosomes eliminated agonist-induced GCGR deubiquitination. By down-regulating candidate deubiquitinases that are either linked with GPCR trafficking or localized on endosomes, we identified signal-transducing adaptor molecule-binding protein (STAMBP) and ubiquitin-specific protease 33 (USP33) as cognate deubiquitinases for the GCGR. Our data suggest that USP33 constitutively deubiquitinates the GCGR, whereas both STAMBP and USP33 deubiquitinate agonist-activated GCGRs at early endosomes. A mutant GCGR with all five intracellular lysines altered to arginines remains deubiquitinated and shows augmented trafficking to Rab4a recycling endosomes compared with the WT, thus affirming the role of deubiquitination in GCGR recycling. We conclude that the GCGRs are rapidly deubiquitinated after agonist-activation to facilitate Rab4a-dependent recycling and that USP33 and STAMBP activities are critical for the endocytic recycling of the GCGR.
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Affiliation(s)
- Suneet Kaur
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Yuqing Chen
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Sudha K Shenoy
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA; Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA.
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10
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Crilly SE, Puthenveedu MA. Compartmentalized GPCR Signaling from Intracellular Membranes. J Membr Biol 2020; 254:259-271. [PMID: 33231722 DOI: 10.1007/s00232-020-00158-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 11/11/2020] [Indexed: 12/21/2022]
Abstract
G protein-coupled receptors (GPCRs) are integral membrane proteins that transduce a wide array of inputs including light, ions, hormones, and neurotransmitters into intracellular signaling responses which underlie complex processes ranging from vision to learning and memory. Although traditionally thought to signal primarily from the cell surface, GPCRs are increasingly being recognized as capable of signaling from intracellular membrane compartments, including endosomes, the Golgi apparatus, and nuclear membranes. Remarkably, GPCR signaling from these membranes produces functional effects that are distinct from signaling from the plasma membrane, even though often the same G protein effectors and second messengers are activated. In this review, we will discuss the emerging idea of a "spatial bias" in signaling. We will present the evidence for GPCR signaling through G protein effectors from intracellular membranes, and the ways in which this signaling differs from canonical plasma membrane signaling with important implications for physiology and pharmacology. We also highlight the potential mechanisms underlying spatial bias of GPCR signaling, including how intracellular membranes and their associated lipids and proteins affect GPCR activity and signaling.
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Affiliation(s)
- Stephanie E Crilly
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, 48109, USA.
| | - Manojkumar A Puthenveedu
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, 48109, USA.,Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
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11
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Jones EM, Lubock NB, Venkatakrishnan AJ, Wang J, Tseng AM, Paggi JM, Latorraca NR, Cancilla D, Satyadi M, Davis JE, Babu MM, Dror RO, Kosuri S. Structural and functional characterization of G protein-coupled receptors with deep mutational scanning. eLife 2020; 9:54895. [PMID: 33084570 PMCID: PMC7707821 DOI: 10.7554/elife.54895] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 10/16/2020] [Indexed: 01/14/2023] Open
Abstract
The >800 human G protein–coupled receptors (GPCRs) are responsible for transducing diverse chemical stimuli to alter cell state- and are the largest class of drug targets. Their myriad structural conformations and various modes of signaling make it challenging to understand their structure and function. Here, we developed a platform to characterize large libraries of GPCR variants in human cell lines with a barcoded transcriptional reporter of G protein signal transduction. We tested 7800 of 7828 possible single amino acid substitutions to the beta-2 adrenergic receptor (β2AR) at four concentrations of the agonist isoproterenol. We identified residues specifically important for β2AR signaling, mutations in the human population that are potentially loss of function, and residues that modulate basal activity. Using unsupervised learning, we identify residues critical for signaling, including all major structural motifs and molecular interfaces. We also find a previously uncharacterized structural latch spanning the first two extracellular loops that is highly conserved across Class A GPCRs and is conformationally rigid in both the inactive and active states of the receptor. More broadly, by linking deep mutational scanning with engineered transcriptional reporters, we establish a generalizable method for exploring pharmacogenomics, structure and function across broad classes of drug receptors.
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Affiliation(s)
- Eric M Jones
- Department of Chemistry and Biochemistry, UCLA-DOE Institute for Genomics and Proteomics, Molecular Biology Institute, Quantitative and Computational Biology Institute, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, and Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, United States
| | - Nathan B Lubock
- Department of Chemistry and Biochemistry, UCLA-DOE Institute for Genomics and Proteomics, Molecular Biology Institute, Quantitative and Computational Biology Institute, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, and Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, United States
| | - A J Venkatakrishnan
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.,Department of Computer Science, Stanford University, Department of Computer Science, Institute for Computational and Mathematical Engineering, Stanford University, Department of Computer Science, Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Department of Computer Science, Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
| | - Jeffrey Wang
- Department of Chemistry and Biochemistry, UCLA-DOE Institute for Genomics and Proteomics, Molecular Biology Institute, Quantitative and Computational Biology Institute, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, and Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, United States
| | - Alex M Tseng
- Department of Computer Science, Stanford University, Department of Computer Science, Institute for Computational and Mathematical Engineering, Stanford University, Department of Computer Science, Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Department of Computer Science, Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
| | - Joseph M Paggi
- Department of Computer Science, Stanford University, Department of Computer Science, Institute for Computational and Mathematical Engineering, Stanford University, Department of Computer Science, Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Department of Computer Science, Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
| | - Naomi R Latorraca
- Department of Computer Science, Stanford University, Department of Computer Science, Institute for Computational and Mathematical Engineering, Stanford University, Department of Computer Science, Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Department of Computer Science, Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
| | - Daniel Cancilla
- Department of Chemistry and Biochemistry, UCLA-DOE Institute for Genomics and Proteomics, Molecular Biology Institute, Quantitative and Computational Biology Institute, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, and Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, United States
| | - Megan Satyadi
- Department of Chemistry and Biochemistry, UCLA-DOE Institute for Genomics and Proteomics, Molecular Biology Institute, Quantitative and Computational Biology Institute, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, and Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, United States
| | - Jessica E Davis
- Department of Chemistry and Biochemistry, UCLA-DOE Institute for Genomics and Proteomics, Molecular Biology Institute, Quantitative and Computational Biology Institute, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, and Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, United States
| | - M Madan Babu
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Ron O Dror
- Department of Computer Science, Stanford University, Department of Computer Science, Institute for Computational and Mathematical Engineering, Stanford University, Department of Computer Science, Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Department of Computer Science, Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
| | - Sriram Kosuri
- Department of Chemistry and Biochemistry, UCLA-DOE Institute for Genomics and Proteomics, Molecular Biology Institute, Quantitative and Computational Biology Institute, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, and Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, United States
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12
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Semesta KM, Tian R, Kampmann M, von Zastrow M, Tsvetanova NG. A high-throughput CRISPR interference screen for dissecting functional regulators of GPCR/cAMP signaling. PLoS Genet 2020; 16:e1009103. [PMID: 33052901 PMCID: PMC7588078 DOI: 10.1371/journal.pgen.1009103] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 10/26/2020] [Accepted: 09/08/2020] [Indexed: 12/27/2022] Open
Abstract
G protein-coupled receptors (GPCRs) allow cells to respond to chemical and sensory stimuli through generation of second messengers, such as cyclic AMP (cAMP), which in turn mediate a myriad of processes, including cell survival, proliferation, and differentiation. In order to gain deeper insights into the complex biology and physiology of these key cellular pathways, it is critical to be able to globally map the molecular factors that shape cascade function. Yet, to this date, efforts to systematically identify regulators of GPCR/cAMP signaling have been lacking. Here, we combined genome-wide screening based on CRISPR interference with a novel sortable transcriptional reporter that provides robust readout for cAMP signaling, and carried out a functional screen for regulators of the pathway. Due to the sortable nature of the platform, we were able to assay regulators with strong and moderate phenotypes by analyzing sgRNA distribution among three fractions with distinct reporter expression. We identified 45 regulators with strong and 50 regulators with moderate phenotypes not previously known to be involved in cAMP signaling. In follow-up experiments, we validated the functional effects of seven newly discovered mediators (NUP93, PRIM1, RUVBL1, PKMYT1, TP53, SF3A2, and HRAS), and showed that they control distinct steps of the pathway. Thus, our study provides proof of principle that the screening platform can be applied successfully to identify bona fide regulators of GPCR/second messenger cascades in an unbiased and high-throughput manner, and illuminates the remarkable functional diversity among GPCR regulators.
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Affiliation(s)
- Khairunnisa Mentari Semesta
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
| | - Ruilin Tian
- Institute for Neurodegenerative Diseases, Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
- Chen-Zuckerberg Biohub, San Francisco, California, United States of America
- Biophysics Graduate Program, University of California, San Francisco, California, United States of America
| | - Martin Kampmann
- Institute for Neurodegenerative Diseases, Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
- Chen-Zuckerberg Biohub, San Francisco, California, United States of America
| | - Mark von Zastrow
- Department of Psychiatry, University of California, San Francisco, California, United States of America
- Department of Cellular & Molecular Pharmacology, University of California, San Francisco, California, United States of America
| | - Nikoleta G. Tsvetanova
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
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13
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Lazar AM, Irannejad R, Baldwin TA, Sundaram AB, Gutkind JS, Inoue A, Dessauer CW, Von Zastrow M. G protein-regulated endocytic trafficking of adenylyl cyclase type 9. eLife 2020; 9:e58039. [PMID: 32515353 PMCID: PMC7332294 DOI: 10.7554/elife.58039] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 06/08/2020] [Indexed: 12/14/2022] Open
Abstract
GPCRs are increasingly recognized to initiate signaling via heterotrimeric G proteins as they move through the endocytic network, but little is known about how relevant G protein effectors are localized. Here we report selective trafficking of adenylyl cyclase type 9 (AC9) from the plasma membrane to endosomes while adenylyl cyclase type 1 (AC1) remains in the plasma membrane, and stimulation of AC9 trafficking by ligand-induced activation of Gs-coupled GPCRs. AC9 transits a similar, dynamin-dependent early endocytic pathway as ligand-activated GPCRs. However, unlike GPCR traffic control which requires β-arrestin but not Gs, AC9 traffic control requires Gs but not β-arrestin. We also show that AC9, but not AC1, mediates cAMP production stimulated by endogenous receptor activation in endosomes. These results reveal dynamic and isoform-specific trafficking of adenylyl cyclase in the endocytic network, and a discrete role of a heterotrimeric G protein in regulating the subcellular distribution of a relevant effector.
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Affiliation(s)
- André M Lazar
- Program in Biochemistry and Cell Biology, University of California San FranciscoSan FranciscoUnited States
| | - Roshanak Irannejad
- Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California San FranciscoSan FranciscoUnited States
| | - Tanya A Baldwin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science CenterHoustonUnited States
| | - Aparna B Sundaram
- Lung Biology Center, Department of Medicine, University of California San FranciscoSan FranciscoUnited States
| | - J Silvio Gutkind
- Department of Pharmacology and Moores Cancer Center, University of California San DiegoSan DiegoUnited States
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-kuSendaiJapan
| | - Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, University of Texas Health Science CenterHoustonUnited States
| | - Mark Von Zastrow
- Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California San FranciscoSan FranciscoUnited States
- Department of Psychiatry and Department of Cellular and Molecular Pharmacology, University of California San FranciscoSan FranciscoUnited States
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14
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Fernandez TJ, De Maria M, Lobingier BT. A cellular perspective of bias at G protein-coupled receptors. Protein Sci 2020; 29:1345-1354. [PMID: 32297394 DOI: 10.1002/pro.3872] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/10/2020] [Accepted: 04/10/2020] [Indexed: 12/17/2022]
Abstract
G protein-coupled receptors (GPCRs) modulate cell function over short- and long-term timescales. GPCR signaling depends on biochemical parameters that define the what, when, and where of receptor function: what proteins mediate and regulate receptor signaling, where within the cell these interactions occur, and how long these interactions persist. These parameters can vary significantly depending on the activating ligand. Collectivity, differential agonist activity at a GPCR is called bias or functional selectivity. Here we review agonist bias at GPCRs with a focus on ligands that show dramatically different cellular responses from their unbiased counterparts.
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Affiliation(s)
- Thomas J Fernandez
- Department of Chemical Physiology and Biochemistry, Oregon Health and Sciences University, Portland, Oregon, USA
| | - Monica De Maria
- Department of Chemical Physiology and Biochemistry, Oregon Health and Sciences University, Portland, Oregon, USA
| | - Braden T Lobingier
- Department of Chemical Physiology and Biochemistry, Oregon Health and Sciences University, Portland, Oregon, USA
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15
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Budayeva HG, Kirkpatrick DS. Monitoring protein communities and their responses to therapeutics. Nat Rev Drug Discov 2020; 19:414-426. [PMID: 32139903 DOI: 10.1038/s41573-020-0063-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/24/2020] [Indexed: 12/19/2022]
Abstract
Most therapeutics are designed to alter the activities of proteins. From metabolic enzymes to cell surface receptors, connecting the function of a protein to a cellular phenotype, to the activity of a drug and to a clinical outcome represents key mechanistic milestones during drug development. Yet, even for therapeutics with exquisite specificity, the sequence of events following target engagement can be complex. Interconnected communities of structural, metabolic and signalling proteins modulate diverse downstream effects that manifest as interindividual differences in efficacy, adverse effects and resistance to therapy. Recent advances in mass spectrometry proteomics have made it possible to decipher these complex relationships and to understand how factors such as genotype, cell type, local environment and external perturbations influence them. In this Review, we explore how proteomic technologies are expanding our understanding of protein communities and their responses to large- and small-molecule therapeutics.
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Affiliation(s)
- Hanna G Budayeva
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, South San Francisco, CA, USA
| | - Donald S Kirkpatrick
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, South San Francisco, CA, USA.
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16
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Stoeber M, Jullié D, Li J, Chakraborty S, Majumdar S, Lambert NA, Manglik A, von Zastrow M. Agonist-selective recruitment of engineered protein probes and of GRK2 by opioid receptors in living cells. eLife 2020; 9:54208. [PMID: 32096468 PMCID: PMC7041944 DOI: 10.7554/elife.54208] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 01/29/2020] [Indexed: 12/21/2022] Open
Abstract
G protein-coupled receptors (GPCRs) signal through allostery, and it is increasingly clear that chemically distinct agonists can produce different receptor-based effects. It has been proposed that agonists selectively promote receptors to recruit one cellular interacting partner over another, introducing allosteric ‘bias’ into the signaling system. However, the underlying hypothesis - that different agonists drive GPCRs to engage different cytoplasmic proteins in living cells - remains untested due to the complexity of readouts through which receptor-proximal interactions are typically inferred. We describe a cell-based assay to overcome this challenge, based on GPCR-interacting biosensors that are disconnected from endogenous transduction mechanisms. Focusing on opioid receptors, we directly demonstrate differences between biosensor recruitment produced by chemically distinct opioid ligands in living cells. We then show that selective recruitment applies to GRK2, a biologically relevant GPCR regulator, through discrete interactions of GRK2 with receptors or with G protein beta-gamma subunits which are differentially promoted by agonists. About a third of all drugs work by targeting a group of proteins known as G-protein coupled receptors, or GPCRs for short. These receptors are found on the surface of cells and transmit messages across the cell’s outer barrier. When a signaling molecule, like a hormone, is released in the body, it binds to a GPCR and changes the receptor’s shape. The change in structure affects how the GPCR interacts and binds to other proteins on the inside of the cell, triggering a series of reactions that alter the cell’s activity. Scientists have previously seen that a GPCR can trigger different responses depending on which signaling molecule is binding on the surface of the cell. However, the mechanism for this is unknown. One hypothesis is that different signaling molecules change the GPCR’s preference for binding to different proteins on the inside of the cell. The challenge has been to observe this happening without interfering with the process. Stoeber et al. have now tested this idea by attaching fluorescent tags to proteins that bind to activated GPCRs directly and without binding other signaling proteins. This meant these proteins could be tracked under a microscope as they made their way to bind to the GPCRs. Stoeber et al. focused on one particular GPCR, known as the opioid receptor, and tested the binding of two different opioid signaling molecules, etorphine and Dynorphin A. The experiments revealed that the different opioids did affect which of the engineered proteins would preferentially bind to the opioid receptor. This was followed by a similar experiment, where the engineered proteins were replaced with another protein called GRK2, which binds to the opioid receptor under normal conditions in the cell. This showed that GRK2 binds much more strongly to the opioid receptor when Dynorphin A is added compared to adding etorphine. These findings show that GPCRs can not only communicate that a signaling molecule is binding but can respond differently to convey what molecule it is more specifically. This could be important in developing drugs, particularly to specifically trigger the desired response and reduce side effects. Stoeber et al. suggest that an important next step for research is to understand how the GPCRs preferentially bind to different proteins.
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Affiliation(s)
- Miriam Stoeber
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Damien Jullié
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Joy Li
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Soumen Chakraborty
- Center for Clinical Pharmacology, Washington University School of Medicine, St. Louis, United States.,St Louis College of Pharmacy, St. Louis, United States
| | - Susruta Majumdar
- Center for Clinical Pharmacology, Washington University School of Medicine, St. Louis, United States.,St Louis College of Pharmacy, St. Louis, United States
| | - Nevin A Lambert
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, United States
| | - Aashish Manglik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States.,Department of Anesthesia, University of California, San Francisco, San Francisco, United States
| | - Mark von Zastrow
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
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17
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Lobingier BT, von Zastrow M. When trafficking and signaling mix: How subcellular location shapes G protein-coupled receptor activation of heterotrimeric G proteins. Traffic 2019; 20:130-136. [PMID: 30578610 DOI: 10.1111/tra.12634] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 12/14/2022]
Abstract
G protein-coupled receptors (GPCRs) physically connect extracellular information with intracellular signal propagation. Membrane trafficking plays a supportive role by "bookending" signaling events: movement through the secretory pathway delivers GPCRs to the cell surface where receptors can sample the extracellular environment, while endocytosis and endolysosomal membrane trafficking provide a versatile system to titrate cellular signaling potential and maintain homeostatic control. Recent evidence suggests that, in addition to these important effects, GPCR trafficking actively shapes the cellular signaling response by altering the location and timing of specific receptor-mediated signaling reactions. Here, we review key experimental evidence underlying this expanding view, focused on GPCR signaling mediated through activation of heterotrimeric G proteins located in the cytoplasm. We then discuss lingering and emerging questions regarding the interface between GPCR signaling and trafficking.
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Affiliation(s)
- Braden T Lobingier
- Department of Psychiatry and Department of Cellular and Molecular Pharmacology, University of California, San Francisco School of Medicine, San Francisco, California
| | - Mark von Zastrow
- Department of Psychiatry and Department of Cellular and Molecular Pharmacology, University of California, San Francisco School of Medicine, San Francisco, California
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18
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Filadi R, Basso E, Lefkimmiatis K, Pozzan T. Beyond Intracellular Signaling: The Ins and Outs of Second Messengers Microdomains. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 981:279-322. [PMID: 29594866 DOI: 10.1007/978-3-319-55858-5_12] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A typical characteristic of eukaryotic cells compared to prokaryotes is represented by the spatial heterogeneity of the different structural and functional components: for example, most of the genetic material is surrounded by a highly specific membrane structure (the nuclear membrane), continuous with, yet largely different from, the endoplasmic reticulum (ER); oxidative phosphorylation is carried out by organelles enclosed by a double membrane, the mitochondria; in addition, distinct domains, enriched in specific proteins, are present in the plasma membrane (PM) of most cells. Less obvious, but now generally accepted, is the notion that even the concentration of small molecules such as second messengers (Ca2+ and cAMP in particular) can be highly heterogeneous within cells. In the case of most organelles, the differences in the luminal levels of second messengers depend either on the existence on their membrane of proteins that allow the accumulation/release of the second messenger (e.g., in the case of Ca2+, pumps, exchangers or channels), or on the synthesis and degradation of the specific molecule within the lumen (the autonomous intramitochondrial cAMP system). It needs stressing that the existence of a surrounding membrane does not necessarily imply the existence of a gradient between the cytosol and the organelle lumen. For example, the nuclear membrane is highly permeable to both Ca2+ and cAMP (nuclear pores are permeable to solutes up to 50 kDa) and differences in [Ca2+] or [cAMP] between cytoplasm and nucleoplasm are not seen in steady state and only very transiently during cell activation. A similar situation has been observed, as far as Ca2+ is concerned, in peroxisomes.
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Affiliation(s)
- Riccardo Filadi
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Emy Basso
- Institute of Neuroscience, Padova Section, National Research Council, Padova, Italy
| | - Konstantinos Lefkimmiatis
- Institute of Neuroscience, Padova Section, National Research Council, Padova, Italy
- Venetian Institute of Molecular Medicine, Padova, Italy
| | - Tullio Pozzan
- Department of Biomedical Sciences, University of Padova, Padova, Italy.
- Institute of Neuroscience, Padova Section, National Research Council, Padova, Italy.
- Venetian Institute of Molecular Medicine, Padova, Italy.
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19
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Integration of GPCR Signaling and Sorting from Very Early Endosomes via Opposing APPL1 Mechanisms. Cell Rep 2018; 21:2855-2867. [PMID: 29212031 PMCID: PMC5732320 DOI: 10.1016/j.celrep.2017.11.023] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 10/18/2017] [Accepted: 11/03/2017] [Indexed: 01/10/2023] Open
Abstract
Endocytic trafficking is a critical mechanism for cells to decode complex signaling pathways, including those activated by G-protein-coupled receptors (GPCRs). Heterogeneity in the endosomal network enables GPCR activity to be spatially restricted between early endosomes (EEs) and the recently discovered endosomal compartment, the very early endosome (VEE). However, the molecular machinery driving GPCR activity from the VEE is unknown. Using luteinizing hormone receptor (LHR) as a prototype GPCR for this compartment, along with additional VEE-localized GPCRs, we identify a role for the adaptor protein APPL1 in rapid recycling and endosomal cAMP signaling without impacting the EE-localized β2-adrenergic receptor. LHR recycling is driven by receptor-mediated Gαs/cAMP signaling from the VEE and PKA-dependent phosphorylation of APPL1 at serine 410. Receptor/Gαs endosomal signaling is localized to microdomains of heterogeneous VEE populations and regulated by APPL1 phosphorylation. Our study uncovers a highly integrated inter-endosomal communication system enabling cells to tightly regulate spatially encoded signaling. GPCRs that internalize to very early endosomes (VEEs) require APPL1 to recycle Receptor recycling is driven by cAMP/PKA to phosphorylate serine 410 on APPL1 cAMP signaling from GPCRs, such as LHR, occurs from distinct VEE microdomains APPL1 limits VEE cAMP signaling via opposing mechanisms required for GPCR sorting
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20
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Hanyaloglu AC. Advances in Membrane Trafficking and Endosomal Signaling of G Protein-Coupled Receptors. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 339:93-131. [PMID: 29776606 DOI: 10.1016/bs.ircmb.2018.03.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The integration of GPCR signaling with membrane trafficking, as a single orchestrated system, is a theme increasingly evident with the growing reports of GPCR endosomal signaling. Once viewed as a mechanism to regulate cell surface heterotrimeric G protein signaling, the endocytic trafficking system is complex, highly compartmentalized, yet deeply interconnected with cell signaling. The organization of receptors into distinct plasma membrane signalosomes, biochemically distinct endosomal populations, endosomal microdomains, and its communication with distinct subcellular organelles such as the Golgi provides multiple unique signaling platforms that are critical for specifying receptor function physiologically and pathophysiologically. In this chapter I discuss our emerging understanding in the endocytic trafficking systems employed by GPCRs and their novel roles in spatial control of signaling. Given the extensive roles that GPCRs play in vivo, these evolving models are starting to provide mechanistic understanding of distinct diseases and provide novel therapeutic avenues that are proving to be viable targets.
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Affiliation(s)
- Aylin C Hanyaloglu
- Institute of Reproductive and Developmental Biology, Department of Surgery and Cancer, Imperial College London, London, United Kingdom.
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21
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Evolving View of Membrane Trafficking and Signaling Systems for G Protein-Coupled Receptors. ENDOCYTOSIS AND SIGNALING 2018; 57:273-299. [DOI: 10.1007/978-3-319-96704-2_10] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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22
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Spatial encryption of G protein-coupled receptor signaling in endosomes; Mechanisms and applications. Biochem Pharmacol 2017; 143:1-9. [DOI: 10.1016/j.bcp.2017.04.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 04/25/2017] [Indexed: 01/14/2023]
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23
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Grundmann M, Kostenis E. Temporal Bias: Time-Encoded Dynamic GPCR Signaling. Trends Pharmacol Sci 2017; 38:1110-1124. [PMID: 29074251 DOI: 10.1016/j.tips.2017.09.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 09/24/2017] [Accepted: 09/25/2017] [Indexed: 12/21/2022]
Abstract
Evidence suggests that cells can time-encode signals for secure transport and perception of information, and it appears that this dynamic signaling is a common principle of nature to code information in time. G-protein-coupled receptor (GPCR) signaling networks are no exception as their composition and signal transduction appear temporally flexible. In this review, we discuss the potential mechanisms by which GPCRs code biological information in time to create 'temporal bias.' We highlight dynamic signaling patterns from the second messenger to the receptor-ligand level and shed light on the dynamics of G-protein cycles, the kinetics of ligand-receptor interaction, and the occurrence of distinct signaling waves within the cell. A dynamic feature such as temporal bias adds to the complexity of GPCR signaling bias and gives rise to the question whether this trait could be exploited to gain control over time-encoded cell physiology.
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Affiliation(s)
- Manuel Grundmann
- Molecular-, Cellular- and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany; Kidney Disease Research, Bayer Pharma AG, Aprather Weg 18a, 42113 Wuppertal, Germany
| | - Evi Kostenis
- Molecular-, Cellular- and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany.
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24
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Altszyler E, Ventura AC, Colman-Lerner A, Chernomoretz A. Ultrasensitivity in signaling cascades revisited: Linking local and global ultrasensitivity estimations. PLoS One 2017; 12:e0180083. [PMID: 28662096 PMCID: PMC5491127 DOI: 10.1371/journal.pone.0180083] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 05/23/2017] [Indexed: 01/04/2023] Open
Abstract
Ultrasensitive response motifs, capable of converting graded stimuli into binary responses, are well-conserved in signal transduction networks. Although it has been shown that a cascade arrangement of multiple ultrasensitive modules can enhance the system's ultrasensitivity, how a given combination of layers affects a cascade's ultrasensitivity remains an open question for the general case. Here, we introduce a methodology that allows us to determine the presence of sequestration effects and to quantify the relative contribution of each module to the overall cascade's ultrasensitivity. The proposed analysis framework provides a natural link between global and local ultrasensitivity descriptors and it is particularly well-suited to characterize and understand mathematical models used to study real biological systems. As a case study, we have considered three mathematical models introduced by O'Shaughnessy et al. to study a tunable synthetic MAPK cascade, and we show how our methodology can help modelers better understand alternative models.
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Affiliation(s)
- Edgar Altszyler
- Laboratorio de Inteligencia Artificial Aplicada, Universidad de Buenos Aires, Departamento de Computación - CONICET, Ciudad Universitaria, Pabellón I, Buenos Aires, C1428EHA, Argentina
| | - Alejandra C. Ventura
- IFIBYNE-UBA-CONICET and Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, Buenos Aires, C1428EHA, Argentina
| | - Alejandro Colman-Lerner
- IFIBYNE-UBA-CONICET and Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, Buenos Aires, C1428EHA, Argentina
| | - Ariel Chernomoretz
- Departamento de Física FCEN UBA - IFIBA CONICET, Ciudad Universitaria, Pabellón I, Buenos Aires, C1428EHA, Argentina
- Fundación Instituto Leloir, Av Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
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