The Experts below are selected from a list of 6717 Experts worldwide ranked by ideXlab platform
Richard R Neubig - One of the best experts on this subject based on the ideXlab platform.
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RGS4 differentially regulates antidepressant and locomotor behaviors in vivo
The FASEB Journal, 2015Co-Authors: Cienna Nielsen, Babak Shirvani, Amanda Baun, John Devilbiss, Lilyann Nyangau, Lena Chung, John R Traynor, Richard R Neubig, Jeffery N TalbotAbstract:Evidence suggests the antidepressant actions of serotonin (5-HT) are modulated by regulators of G Protein signaling (RGS) Proteins. Specifically, we have shown that upregulation of cortical RGS4 (mRNA and Protein) occurs in response to genetic disruption of RGS Protein activity at the GTP-binding Protein Gαi2 and following chronic administration of serotonin-selective reuptake inhibitors (SSRIs). Genetic deletion of RGS4 (RGS4(-/-)) had no effect on basal antidepressant-like behaviors or generalized locomotor activity. However, RGS4(-/-) mice exhibited decreased antidepressant-like responses to the SSRI fluoxetine, whereas desipramine, a selective inhibitor of norepinephrine reuptake, was fully efficacious. Conversely, the regulation of locomotor activity by desipramine was augmented in RGS4(-/-) animals relative to vehicle-treated controls. RGS4 expression had no effect on locomotor activity following fluoxetine administration. Overall, these data suggest altered expression of RGS4 differentially influen...
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the loss of RGS Protein gαi2 interactions results in markedly impaired mouse neutrophil trafficking to inflammatory sites
Molecular and Cellular Biology, 2012Co-Authors: Hyeseon Cho, Richard R Neubig, Il-young Hwang, Chung Park, Olena Kamenyeva, Sunny Yung, Ji Liang Gao, Philip M Murphy, John H KehrlAbstract:Neutrophils are first responders rapidly mobilized to inflammatory sites by a tightly regulated, nonredundant hierarchy of chemoattractants. These chemoattractants engage neutrophil cell surface receptors triggering heterotrimeric G-Protein Gαi subunits to exchange GDP for GTP. By limiting the duration that Gαi subunits remain GTP bound, RGS Proteins modulate chemoattractant receptor signaling. Here, we show that neutrophils with a genomic knock in of a mutation that disables regulator of G-Protein signaling (RGS)-Gαi2 interactions accumulate in the bone marrow and mobilize poorly to inflammatory sites. These defects are attributable to enhanced sensitivity to background signals, prolonged chemoattractant receptor signaling, and inappropriate CXCR2 downregulation. Intravital imaging revealed a failure of the mutant neutrophils to accumulate at and stabilize sites of sterile inflammation. Furthermore, these mice could not control a nonlethal Staphylococcus aureus infection. Neutrophil RGS Proteins establish a threshold for Gαi activation, helping to coordinate desensitization mechanisms. Their loss renders neutrophils functionally incompetent.
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RGS-insensitive Gα subunits: probes of Gα subtype-selective signaling and physiological functions of RGS Proteins.
Methods in molecular biology (Clifton N.J.), 2011Co-Authors: Kuljeet Kaur, Jason M. Kehrl, Raelene A. Charbeneau, Richard R NeubigAbstract:The Regulator of G Protein Signaling (RGS) Proteins were identified as a family in 1996 and humans have more than 30 such Proteins. Their best known function is to suppress G Protein-Coupled Receptors (GPCR) signaling by increasing the rate of Gα turnoff through stimulation of GTPase activity (i.e., GTPase acceleration Protein or GAP activity). The GAP activity of RGS Proteins on the Gαi and Gαq family of G Proteins can terminate signals initiated by both α and βγ subunits. RGS Proteins also serve as scaffolds, assembling signal-regulating modules. Understanding the physiological roles of RGS Proteins is of great importance, as GPCRs are major targets for drug development. The traditional method of using RGS knockout mice has provided some information about the role of RGS Proteins but in many cases effects are modest, perhaps because of redundancy in RGS Protein function. As an alternative approach, we have utilized a glycine-to-serine mutation in the switch 1 region of Gα subunits that prevents RGS binding. The mutation has no known effects on Gα binding to receptor, Gβγ, or effectors. Alterations in function resulting from the G>S mutation imply a role for both the specific mutated Gα subunit and its regulation by RGS Protein activity. Mutant rodents expressing these G>S mutant Gα subunits have strong phenotypes and provide important information about specific physiological functions of Gαi2 and Gαo and their control by RGS. The conceptual framework behind this approach and a summary of recent results is presented in this chapter.
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thinking outside of the RGS box new approaches to therapeutic targeting of regulators of g Protein signaling
Molecular Pharmacology, 2010Co-Authors: Benita Sjogren, Richard R NeubigAbstract:Regulators of G Protein signaling (RGS) Proteins are emerging as potentially important drug targets. The mammalian RGS Protein family has more than 20 members and they share a common ∼120-residue RGS homology domain or “RGS box.” RGS Proteins regulate signaling via G Protein-coupled receptors by accelerating GTPase activity at active α subunits of G Proteins of the Gq and Gi/o families. Most studies searching for modulators of RGS Protein function have been focused on inhibiting the GTPase accelerating Protein activity. However, many RGS Proteins contain additional domains that serve other functions, such as interactions with Proteins or subcellular targeting. Here, we discuss a rationale for therapeutic targeting of RGS Proteins by regulation of expression or allosteric modulation to permit either increases or decreases in RGS function. Several RGS Proteins have reduced expression or function in pathophysiological states, so strategies to increase RGS function would be useful. Because several RGS Proteins are rapidly degraded by the N-end rule pathway, finding ways to stabilize them may prove to be an effective way to enhance RGS Protein function.
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Polyplexed flow cytometry Protein interaction assay: a novel high-throughput screening paradigm for RGS Protein inhibitors.
Journal of biomolecular screening, 2009Co-Authors: David L. Roman, Shodai Ota, Richard R NeubigAbstract:Intracellular signaling cascades are a series of regulated Protein-Protein interactions that may provide a number of targets for potential drug discovery. Here, the authors examine the interaction of regulators of G-Protein signaling (RGS) Proteins with the G-Protein Galphao, using a flow cytometry Protein interaction assay (FCPIA). FCPIA accurately measures nanomolar binding constants of this Protein-Protein interaction and has been used in high-throughput screening. This report focuses on 5 RGS Proteins (4, 6, 7, 8, and 16). To increase the content of screens, the authors assessed high-throughput screening of these RGS Proteins in multiplex, by establishing binding constants of each RGS with Galphao in isolation, and then in a multiplex format with 5 RGS Proteins present. To use this methodology as a higher-content multiplex Protein-Protein interaction screen, they established Z-factor values for RGS Proteins in multiplex of 0.73 to 0.92, indicating this method is suitable for screening using FCPIA. To increase throughput, they also compressed a set of 8000 compounds by combining 4 compounds in a single assay well. Subsequent deconvolution of the compounds mixtures verified the identification of active compounds at specific RGS targets in their mixtures using the polyplexed FCPIA method.
David P Siderovski - One of the best experts on this subject based on the ideXlab platform.
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Current Protocols in Pharmacology - Evaluating Modulators of “Regulator of G‐Protein Signaling” (RGS) Proteins
Current Protocols in Pharmacology, 2012Co-Authors: Dustin E Bosch, Robert G. Lowery, Thomas Zielinski, David P SiderovskiAbstract:“Regulator of G-Protein Signaling” (RGS) Proteins constitute a class of intracellular signaling regulators that accelerate GTP hydrolysis by heterotrimeric Gα subunits. In recent years, RGS Proteins have emerged as potential drug targets for modulation by small molecules. Described in this unit are high-throughput screening procedures for identifying modulators of RGS Protein-mediated GTPase acceleration (GAP activity), for assessment of RGS domain/Gα interactions (most avid in vitro when Gα is bound by aluminum tetrafluoride), and for validation of candidate GAP-modulatory molecules with the single-turnover GTP hydrolysis assay. Curr. Protoc. Pharmacol. 56:2.8.1-2.8.15. © 2012 by John Wiley & Sons, Inc. Keywords: regulator of G-Protein signaling (RGS) Proteins; heterotrimeric G-Protein α subunits; Forster resonance energy transfer (FRET); single-turnover GTP hydrolysis; fluorescence polarization (FP)
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evaluating modulators of regulator of g Protein signaling RGS Proteins
Current protocols in pharmacology, 2012Co-Authors: Dustin E Bosch, Robert G. Lowery, Thomas Zielinski, David P SiderovskiAbstract:“Regulator of G-Protein Signaling” (RGS) Proteins constitute a class of intracellular signaling regulators that accelerate GTP hydrolysis by heterotrimeric Gα subunits. In recent years, RGS Proteins have emerged as potential drug targets for modulation by small molecules. Described in this unit are high-throughput screening procedures for identifying modulators of RGS Protein-mediated GTPase acceleration (GAP activity), for assessment of RGS domain/Gα interactions (most avid in vitro when Gα is bound by aluminum tetrafluoride), and for validation of candidate GAP-modulatory molecules with the single-turnover GTP hydrolysis assay. Curr. Protoc. Pharmacol. 56:2.8.1-2.8.15. © 2012 by John Wiley & Sons, Inc. Keywords: regulator of G-Protein signaling (RGS) Proteins; heterotrimeric G-Protein α subunits; Forster resonance energy transfer (FRET); single-turnover GTP hydrolysis; fluorescence polarization (FP)
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Evaluating modulators of "Regulator of G-Protein Signaling" (RGS) Proteins.
Current protocols in pharmacology, 2012Co-Authors: Dustin E Bosch, Robert G. Lowery, Thomas Zielinski, David P SiderovskiAbstract:"Regulator of G-Protein Signaling" (RGS) Proteins constitute a class of intracellular signaling regulators that accelerate GTP hydrolysis by heterotrimeric Gα subunits. In recent years, RGS Proteins have emerged as potential drug targets for modulation by small molecules. Described in this unit are high-throughput screening procedures for identifying modulators of RGS Protein-mediated GTPase acceleration (GAP activity), for assessment of RGS domain/Gα interactions (most avid in vitro when Gα is bound by aluminum tetrafluoride), and for validation of candidate GAP-modulatory molecules with the single-turnover GTP hydrolysis assay.
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Integrating energy calculations with functional assays to decipher the specificity of G Protein–RGS Protein interactions
Nature Structural & Molecular Biology, 2011Co-Authors: Mickey Kosloff, David P Siderovski, Dustin E Bosch, Amanda M Travis, Vadim Y ArshavskyAbstract:The RGS family is involved in regulating G Protein signaling. Using computational analysis coupled with examination of RGS activity, a group of variable residues that together modulate G Protein recognition are now identified. Mutational analysis confirmed the importance of these modulatory residues and generated gain-of-function RGS Proteins. The analysis described is shown to be applicable to uncovering important residues in other Protein families. The diverse Regulator of G Protein Signaling (RGS) family sets the timing of G Protein signaling. To understand how the structure of RGS Proteins determines their common ability to inactivate G Proteins and their selective G Protein recognition, we combined structure-based energy calculations with biochemical measurements of RGS activity. We found a previously unidentified group of variable 'Modulatory' residues that reside at the periphery of the RGS domain–G Protein interface and fine-tune G Protein recognition. Mutations of Modulatory residues in high-activity RGS Proteins impaired RGS function, whereas redesign of low-activity RGS Proteins in critical Modulatory positions yielded complete gain of function. Therefore, RGS Proteins combine a conserved core interface with peripheral Modulatory residues to selectively optimize G Protein recognition and inactivation. Finally, we show that our approach can be extended to analyze interaction specificity across other large Protein families.
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integrating energy calculations with functional assays to decipher the specificity of g Protein RGS Protein interactions
Nature Structural & Molecular Biology, 2011Co-Authors: Mickey Kosloff, David P Siderovski, Dustin E Bosch, Amanda M Travis, Vadim Y ArshavskyAbstract:The RGS family is involved in regulating G Protein signaling. Using computational analysis coupled with examination of RGS activity, a group of variable residues that together modulate G Protein recognition are now identified. Mutational analysis confirmed the importance of these modulatory residues and generated gain-of-function RGS Proteins. The analysis described is shown to be applicable to uncovering important residues in other Protein families.
John H Kehrl - One of the best experts on this subject based on the ideXlab platform.
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Normal Thymocyte Egress, T Cell Trafficking, and CD4+ T Cell Homeostasis Require Interactions between RGS Proteins and Gαi2.
Journal of immunology (Baltimore Md. : 1950), 2017Co-Authors: Il-young Hwang, Chung Park, Kathleen Harrison, John H KehrlAbstract:Adaptive immunity depends on mature thymocytes leaving the thymus to enter the bloodstream and the trafficking of T cells through lymphoid organs. Both of these require heterotrimeric Gα i Protein signaling, whose intensity and duration are controlled by the regulator of G Protein signaling (RGS) Proteins. In this study, we show that RGS Protein/Gα i2 interactions are essential for normal thymocyte egress, T cell trafficking, and homeostasis. Mature thymocytes with a Gα i2 mutation that disables RGS Protein binding accumulated in the perivascular channels of thymic corticomedullary venules. Severe reductions in peripheral naive CD4 + T cells and regulatory T cells occurred. The mutant CD4 + T cells adhered poorly to high endothelial venules and exhibited defects in lymph node entrance and egress. The kinetics of chemokine receptor signaling were disturbed, including chemokine- induced integrin activation. Despite the thymic and lymph node egress defects, sphingosine-1-phosphate signaling was not obviously perturbed. This study reveals how RGS Proteins modulate Gα i2 signaling to facilitate thymocyte egress and T cell trafficking.
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an essential role for RGS Protein gαi2 interactions in b lymphocyte directed cell migration and trafficking
Journal of Immunology, 2015Co-Authors: Il-young Hwang, Chung Park, Kathleen Harrison, Cedric Boularan, Céline Galés, John H KehrlAbstract:Chemokines engage B lymphocyte surface receptors, triggering heterotrimeric G Protein Gαi subunit guanine nucleotide exchange. RGS Proteins limit the duration that Gαi subunits remain GTP bound, and the loss of an individual RGS Protein typically enhances chemokine receptor signaling. In this study, we show that B cells carrying a Gαi2 (G184S/G184S) mutation that disables all RGS Protein/Gαi2 interactions exhibit an unexpectedly severe reduction in chemokine receptor signaling. The Gαi2 (G184S/G184S) B cells have markedly elevated basal calcium levels, but poor chemokine-induced increases, enhanced nonspecific migration, but extremely poor chemotaxis. In striking contrast, the Gαi2 (G184S/G184S) B cells exhibited enhanced sensitivity to sphingosine 1-phosphate (S1P). S1P elicited heightened intracellular calcium responses and enhanced S1P-triggered cell migration. Mice with the Gαi2 (G184S/G184S) mutation displayed excessive numbers of germinal center-like structures; abnormal serum Ig profiles; and aberrant B lymphocyte trafficking. These findings establish an essential role for RGS Proteins in B cell chemoattractant signaling and for the proper position of B lymphocytes in lymphoid organs.
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An essential role for RGS Protein/Gαi2 interactions in B lymphocyte-directed cell migration and trafficking
Journal of immunology (Baltimore Md. : 1950), 2015Co-Authors: Il-young Hwang, Chung Park, Kathleen Harrison, Cedric Boularan, Céline Galés, John H KehrlAbstract:Chemokines engage B lymphocyte surface receptors, triggering heterotrimeric G Protein Gαi subunit guanine nucleotide exchange. RGS Proteins limit the duration that Gαi subunits remain GTP bound, and the loss of an individual RGS Protein typically enhances chemokine receptor signaling. In this study, we show that B cells carrying a Gαi2 (G184S/G184S) mutation that disables all RGS Protein/Gαi2 interactions exhibit an unexpectedly severe reduction in chemokine receptor signaling. The Gαi2 (G184S/G184S) B cells have markedly elevated basal calcium levels, but poor chemokine-induced increases, enhanced nonspecific migration, but extremely poor chemotaxis. In striking contrast, the Gαi2 (G184S/G184S) B cells exhibited enhanced sensitivity to sphingosine 1-phosphate (S1P). S1P elicited heightened intracellular calcium responses and enhanced S1P-triggered cell migration. Mice with the Gαi2 (G184S/G184S) mutation displayed excessive numbers of germinal center-like structures; abnormal serum Ig profiles; and aberrant B lymphocyte trafficking. These findings establish an essential role for RGS Proteins in B cell chemoattractant signaling and for the proper position of B lymphocytes in lymphoid organs.
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the loss of RGS Protein gαi2 interactions results in markedly impaired mouse neutrophil trafficking to inflammatory sites
Molecular and Cellular Biology, 2012Co-Authors: Hyeseon Cho, Richard R Neubig, Il-young Hwang, Chung Park, Olena Kamenyeva, Sunny Yung, Ji Liang Gao, Philip M Murphy, John H KehrlAbstract:Neutrophils are first responders rapidly mobilized to inflammatory sites by a tightly regulated, nonredundant hierarchy of chemoattractants. These chemoattractants engage neutrophil cell surface receptors triggering heterotrimeric G-Protein Gαi subunits to exchange GDP for GTP. By limiting the duration that Gαi subunits remain GTP bound, RGS Proteins modulate chemoattractant receptor signaling. Here, we show that neutrophils with a genomic knock in of a mutation that disables regulator of G-Protein signaling (RGS)-Gαi2 interactions accumulate in the bone marrow and mobilize poorly to inflammatory sites. These defects are attributable to enhanced sensitivity to background signals, prolonged chemoattractant receptor signaling, and inappropriate CXCR2 downregulation. Intravital imaging revealed a failure of the mutant neutrophils to accumulate at and stabilize sites of sterile inflammation. Furthermore, these mice could not control a nonlethal Staphylococcus aureus infection. Neutrophil RGS Proteins establish a threshold for Gαi activation, helping to coordinate desensitization mechanisms. Their loss renders neutrophils functionally incompetent.
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chapter 9 regulation of immune function by g Protein coupled receptors trimeric g Proteins and RGS Proteins
Progress in Molecular Biology and Translational Science, 2009Co-Authors: Hyeseon Cho, John H KehrlAbstract:Receptors for chemokines and a variety of ligands such as histamine, nucleosides, and bioactive lipids signal through heterotrimeric G Proteins and play critical roles in immune function. Heterotrimeric G Protein signaling pathways are subjected to many layers of regulation including regulators of G Protein signaling (RGS) Proteins that mainly function to attenuate these signaling pathways. This review focuses on the overall importance of G Protein‐coupled receptor‐heterotrimeric G Protein‐RGS Protein signaling in immune function with emphasis on lymphocyte trafficking and motility. Considerable portion is devoted to discussing mechanisms by which chemoattractant receptors activate downstream signaling pathways that function during leukocyte migration. Studies using intravital imaging techniques to monitor lymphocyte trafficking and motility as well as ones probing intracellular spatiotemporal dynamics of trimeric signaling components are also discussed as they increasingly provide mechanistic insights into trimeric G Protein signaling networks.
David L. Roman - One of the best experts on this subject based on the ideXlab platform.
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screen targeting lung and prostate cancer oncogene identifies novel inhibitors of RGS17 and problematic chemical substructures
SLAS DISCOVERY: Advancing the Science of Drug Discovery, 2018Co-Authors: Christopher R Bodle, Josephine H Schamp, Joseph B Obrien, Michael P. Hayes, Jonathan A Doorn, Meng Wu, David L. RomanAbstract:Regulator of G Protein signaling (RGS) Proteins temporally regulate heterotrimeric G Protein signaling cascades elicited by G Protein–coupled receptor activation and thus are essential for cell homeostasis. The dysregulation of RGS Protein expression has been linked to several pathologies, spurring discovery efforts to identify small-molecule inhibitors of these Proteins. Presented here are the results of a high-throughput screening (HTS) campaign targeting RGS17, an RGS Protein reported to be inappropriately upregulated in several cancers. A screen of over 60,000 small molecules led to the identification of five hit compounds that inhibit the RGS17-Gαo Protein-Protein interaction. Chemical and biochemical characterization demonstrated that three of these hits inhibited the interaction through the decomposition of parent compound into reactive products under normal chemical library storage/usage conditions. Compound substructures susceptible to decomposition are reported and the decomposition process char...
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RGS17 an emerging therapeutic target for lung and prostate cancers
Future Medicinal Chemistry, 2013Co-Authors: Christopher R Bodle, Duncan I Mackie, David L. RomanAbstract:Ligands for G-Protein-coupled receptors (GPCRs) represent approximately 50% of currently marketed drugs. RGS Proteins modulate heterotrimeric G Proteins and, thus, GPCR signaling, by accelerating the intrinsic GTPase activity of the Gα subunit. Given the prevalence of GPCR targeted therapeutics and the role RGS Proteins play in G Protein signaling, some RGS Proteins are emerging as targets in their own right. One such RGS Protein is RGS17. Increased RGS17 expression in some prostate and lung cancers has been demonstrated to support cancer progression, while reduced expression of RGS17 can lead to development of chemotherapeutic resistance in ovarian cancer. High-throughput screening is a powerful tool for lead compound identification, and utilization of high-throughput technologies has led to the discovery of several RGS inhibitors, thus far. As screening technologies advance, the identification of novel lead compounds the subsequent development of targeted therapeutics appears promising.
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A High Throughput Screen for RGS Proteins Using Steady State Monitoring of Free Phosphate Formation
PLOS ONE, 2013Co-Authors: C. Aaron Monroy, Duncan I Mackie, David L. RomanAbstract:G-Protein coupled receptors are a diverse group that are the target of over 50% of marketed drugs. Activation of these receptors results in the exchange of bound GDP for GTP in the Gα subunit of the heterotrimeric G-Protein. The Gα subunit dissociates from the β/γ subunits and both proceed to affect downstream signaling targets. The signal terminates by the hydrolysis of GTP to GDP and is temporally regulated by Regulators of G-Protein Signaling (RGS) Proteins that act as GTPase Activating Proteins (GAPs). This makes RGS Proteins potentially desirable targets for “tuning” the effects of current therapies as well as developing novel pharmacotherapies. Current methods for evaluating RGS activity depend on laborious and/or expensive techniques. In this study we developed a simple and inexpensive assay for the steady state analysis of RGS Protein GAP activity, using RGS4, RGS8 and RGS17 as models. Additionally, we report the use of RGS4 as a model for high throughput assay development. After initial setup, this assay can be conducted in a highly parallel fashion with a read time of less than 8 minutes for a 1536-well plate. The assay exhibited a robust Z-factor of 0.6 in a 1536-well plate. We conducted a pilot screen for inhibitors using a small, 2320 compound library. From this screen, 13 compounds were identified as compounds for further analysis. The successful development of this assay for high-throughput screening provides a low cost, high speed, simple method for assessing RGS Protein activity.
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Polyplexed flow cytometry Protein interaction assay: a novel high-throughput screening paradigm for RGS Protein inhibitors.
Journal of biomolecular screening, 2009Co-Authors: David L. Roman, Shodai Ota, Richard R NeubigAbstract:Intracellular signaling cascades are a series of regulated Protein-Protein interactions that may provide a number of targets for potential drug discovery. Here, the authors examine the interaction of regulators of G-Protein signaling (RGS) Proteins with the G-Protein Galphao, using a flow cytometry Protein interaction assay (FCPIA). FCPIA accurately measures nanomolar binding constants of this Protein-Protein interaction and has been used in high-throughput screening. This report focuses on 5 RGS Proteins (4, 6, 7, 8, and 16). To increase the content of screens, the authors assessed high-throughput screening of these RGS Proteins in multiplex, by establishing binding constants of each RGS with Galphao in isolation, and then in a multiplex format with 5 RGS Proteins present. To use this methodology as a higher-content multiplex Protein-Protein interaction screen, they established Z-factor values for RGS Proteins in multiplex of 0.73 to 0.92, indicating this method is suitable for screening using FCPIA. To increase throughput, they also compressed a set of 8000 compounds by combining 4 compounds in a single assay well. Subsequent deconvolution of the compounds mixtures verified the identification of active compounds at specific RGS targets in their mixtures using the polyplexed FCPIA method.
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A covalent peptide inhibitor of RGS4 identified in a focused one-bead, one compound library screen
BMC Pharmacology, 2009Co-Authors: Rebecca A Roof, David L. Roman, Shodai Ota, Samuel T Clements, Katarzyna Sobczyk-kojiro, Levi L Blazer, Henry I Mosberg, Richard R NeubigAbstract:Background Regulators of G Protein signaling (RGSs) accelerate GTP hydrolysis by Gα subunits and profoundly inhibit signaling by G Protein-coupled receptors (GPCRs). The distinct expression patterns and pathophysiologic regulation of RGS Proteins suggest that inhibitors may have therapeutic potential. We recently described a focused one-bead, one-compound (OBOC) library screen to identify peptide inhibitors of RGS4. Here we extend our observations to include another peptide with a different mechanism of action. Results Peptide 5nd (Tyr-Trp-c [Cys-Lys-Gly-Leu-Cys]-Lys-NH_2, S-S) blocks the RGS4-Gα_o interaction with an IC_50 of 28 μM. It forms a covalent, dithiothreitol (DTT) sensitive adduct with a mass consistent with the incorporation of one peptide per RGS. Peptide 5nd activity is abolished by either changing its disulfide bridge to a methylene dithioether bridge, which cannot form disulfide bridges to the RGS, or by removing all cysteines from the RGS Protein. However, no single cysteine in RGS4 is completely necessary or sufficient for 5nd activity. Conclusion Though it has some RGS selectivity, 5nd appears to be a partially random cysteine modifier. These data suggest that it inhibits RGS4 by forming disulfide bridges with the Protein.
Kirill A. Martemyanov - One of the best experts on this subject based on the ideXlab platform.
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RGS Proteins as targets in the treatment of intestinal inflammation and visceral pain: New insights and future perspectives.
BioEssays : news and reviews in molecular cellular and developmental biology, 2016Co-Authors: Maciej Sałaga, Kirill A. Martemyanov, Martin Storr, Jakub FichnaAbstract:Regulators of G Protein signaling (RGS) Proteins provide timely termination of G Protein-coupled receptor (GPCR) responses. Serving as a central control point in GPCR signaling cascades, RGS Proteins are promising targets for drug development. In this review, we discuss the involvement of RGS Proteins in the pathophysiology of the gastrointestinal inflammation and their potential to become a target for anti-inflammatory drugs. Specifically, we evaluate the emerging evidence for modulation of selected receptor families: opioid, cannabinoid and serotonin by RGS Proteins. We discuss how the regulation of RGS Protein level and activity may modulate immunological pathways involved in the development of intestinal inflammation. Finally, we propose that RGS Proteins may serve as a prognostic factor for survival rate in colorectal cancer. The ideas introduced in this review set a novel conceptual framework for the utilization of RGS Proteins in the treatment of gastrointestinal inflammation, a growing major concern worldwide.
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The R7 RGS Protein Family: Multi-Subunit Regulators of Neuronal G Protein Signaling
Cell Biochemistry and Biophysics, 2009Co-Authors: Garret R Anderson, Ekaterina Posokhova, Kirill A. MartemyanovAbstract:G Protein-coupled receptor signaling pathways mediate the transmission of signals from the extracellular environment to the generation of cellular responses, a process that is critically important for neurons and neurotransmitter action. The ability to promptly respond to rapidly changing stimulation requires timely inactivation of G Proteins, a process controlled by a family of specialized Proteins known as regulators of G Protein signaling (RGS). The R7 group of RGS Proteins (R7 RGS) has received special attention due to their pivotal roles in the regulation of a range of crucial neuronal processes such as vision, motor control, reward behavior, and nociception in mammals. Four Proteins in this group, RGS6, RGS7, RGS9, and RGS11, share a common molecular organization of three modules: (i) the catalytic RGS domain, (ii) a GGL domain that recruits Gβ_5, an outlying member of the G Protein beta subunit family, and (iii) a DEP/DHEX domain that mediates interactions with the membrane anchor Proteins R7BP and R9AP. As heterotrimeric complexes, R7 RGS Proteins not only associate with and regulate a number of G Protein signaling pathway components, but have also been found to form complexes with Proteins that are not traditionally associated with G Protein signaling. This review summarizes our current understanding of the biology of the R7 RGS complexes including their structure/functional organization, Protein–Protein interactions, and physiological roles.
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The R7 RGS Protein family: multi-subunit regulators of neuronal G Protein signaling.
Cell biochemistry and biophysics, 2009Co-Authors: Garret R Anderson, Ekaterina Posokhova, Kirill A. MartemyanovAbstract:G Protein-coupled receptor signaling pathways mediate the transmission of signals from the extracellular environment to the generation of cellular responses, a process that is critically important for neurons and neurotransmitter action. The ability to promptly respond to rapidly changing stimulation requires timely inactivation of G Proteins, a process controlled by a family of specialized Proteins known as regulators of G Protein signaling (RGS). The R7 group of RGS Proteins (R7 RGS) has received special attention due to their pivotal roles in the regulation of a range of crucial neuronal processes such as vision, motor control, reward behavior, and nociception in mammals. Four Proteins in this group, RGS6, RGS7, RGS9, and RGS11, share a common molecular organization of three modules: (i) the catalytic RGS domain, (ii) a GGL domain that recruits G beta(5), an outlying member of the G Protein beta subunit family, and (iii) a DEP/DHEX domain that mediates interactions with the membrane anchor Proteins R7BP and R9AP. As heterotrimeric complexes, R7 RGS Proteins not only associate with and regulate a number of G Protein signaling pathway components, but have also been found to form complexes with Proteins that are not traditionally associated with G Protein signaling. This review summarizes our current understanding of the biology of the R7 RGS complexes including their structure/functional organization, Protein-Protein interactions, and physiological roles.
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the membrane anchor r7bp controls the proteolytic stability of the striatal specific RGS Protein RGS9 2
Journal of Biological Chemistry, 2007Co-Authors: Garret R Anderson, Arthur Semenov, Joseph H Song, Kirill A. MartemyanovAbstract:A member of the RGS (regulators of G Protein signaling) family, RGS9-2 is a critical regulator of G Protein signaling pathways that control locomotion and reward signaling in the brain. RGS9-2 is specifically expressed in striatal neurons where it forms complexes with its newly discovered partner, R7BP (R7 family binding Protein). Interaction with R7BP is important for the subcellular targeting of RGS9-2, which in native neurons is found in plasma membrane and its specializations, postsynaptic densities. Here we report that R7BP plays an additional important role in determining proteolytic stability of RGS9-2. We have found that co-expression with R7BP dramatically elevates the levels of RGS9-2 and its constitutive subunit, Gbeta5. Measurement of the RGS9-2 degradation kinetics in cells indicates that R7BP markedly reduces the rate of RGS9-2.Gbeta5 proteolysis. Lentivirus-mediated RNA interference knockdown of the R7BP expression in native striatal neurons results in the corresponding decrease in RGS9-2 Protein levels. Analysis of the molecular determinants that mediate R7BP/RGS9-2 binding to result in proteolytic protection have identified that the binding site for R7BP in RGS Proteins is formed by pairing of the DEP (Disheveled, EGL-10, Pleckstrin) domain with the R7H (R7 homology), a domain of previously unknown function that interacts with four putative alpha-helices of the R7BP core. These findings provide a mechanism for the regulation of the RGS9 Protein stability in the striatal neurons.
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specificity of g Protein RGS Protein recognition is regulated by affinity adapters
Neuron, 2003Co-Authors: Kirill A. Martemyanov, Johnathan A Hopp, Vadim Y ArshavskyAbstract:RGS Proteins regulate the duration of cell signaling by modulating the lifetime of activated G Proteins. The specificity of RGS-G Protein mutual recognition is critical for meeting unique timing requirements of numerous G Protein-mediated pathways. Our study of two splice isoforms of RGS9 expressed in different types of neurons revealed a novel mechanism whereby this specificity is determined by specialized Protein domains or subunits acting as affinity adapters. The long RGS9 isoform contains a C-terminal domain that provides high-affinity interaction with its target G Protein. The lack of this domain in the short RGS9 isoform is compensated by the action of a G Protein effector subunit that is structurally similar to this C-terminal domain. This allows the short isoform to specifically target the complex between the G Protein and its effector. Thus, the specific timing needs of different signaling pathways can be accommodated by affinity adapters positioned at various pathway components.