The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform
Benita Sjogren - One of the best experts on this subject based on the ideXlab platform.
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digoxin mediated upregulation of RGS2 Protein protects against cardiac injury
Journal of Pharmacology and Experimental Therapeutics, 2016Co-Authors: Benita Sjogren, Sergio Parra, Kevin B Atkins, Behirda Karaj, Richard R NeubigAbstract:Regulator of G Protein signaling (RGS) Proteins have emerged as novel drug targets since their discovery almost two decades ago. RGS2 has received particular interest in cardiovascular research due to its role in regulating Gq signaling in the heart and vascular smooth muscle. RGS2−/− mice are hypertensive, prone to heart failure, and display accelerated kidney fibrosis. RGS2 is rapidly degraded through the proteasome, and human mutations leading to accelerated RGS2 Protein degradation correlate with hypertension. Hence, stabilizing RGS2 Protein expression could be a novel route in treating cardiovascular disease. We previously identified cardiotonic steroids, including digoxin, as selective stabilizers of RGS2 Protein in vitro. In the current study we investigated the functional effects of digoxin-mediated RGS2 Protein stabilization in vivo. Using freshly isolated myocytes from wild-type and RGS2−/− mice treated with vehicle or low-dose digoxin (2 µg/kg/day for 7 days) we demonstrated that agonist-induced cAMP levels and cardiomyocyte contractility was inhibited by digoxin in wild-type but not in RGS2−/− mice. This inhibition was accompanied by an increase in RGS2 Protein levels in cardiomyocytes as well as in whole heart tissue. Furthermore, digoxin had protective effects in a model of cardiac injury in wild-type mice and this protection was lost in RGS2−/− mice. Digoxin is the oldest known therapy for heart failure; however, beyond its activity at the Na+/K+-ATPase, the exact mechanism of action is not known. The current study adds a novel mechanism, whereby through stabilizing RGS2 Protein levels digoxin could exert its protective effects in the failing heart.
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fbxo44 mediated degradation of RGS2 Protein uniquely depends on a cullin 4b ddb1 complex
PLOS ONE, 2015Co-Authors: Benita Sjogren, Steven Swaney, Richard R NeubigAbstract:The ubiquitin-proteasome system for Protein degradation plays a major role in regulating cell function and many signaling Proteins are tightly controlled by this mechanism. Among these, Regulator of G Protein Signaling 2 (RGS2) is a target for rapid proteasomal degradation, however, the specific enzymes involved are not known. Using a genomic siRNA screening approach, we identified a novel E3 ligase complex containing cullin 4B (CUL4B), DNA damage binding Protein 1 (DDB1) and F-box Protein 44 (FBXO44) that mediates RGS2 Protein degradation. While the more typical F-box partners CUL1 and Skp1 can bind FBXO44, that E3 ligase complex does not bind RGS2 and is not involved in RGS2 degradation. These observations define an unexpected DDB1/CUL4B-containing FBXO44 E3 ligase complex. Pharmacological targeting of this mechanism provides a novel therapeutic approach to hypertension, anxiety, and other diseases associated with RGS2 dysregulation.
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pkc activation leads to increased RGS2 Protein levels
The FASEB Journal, 2015Co-Authors: Lauren Aschermann, Benita SjogrenAbstract:Regulator of G Protein Signaling 2 (RGS2) is a member of a family of Proteins that regulate G Protein-coupled receptor (GPCR) mediated signaling by accelerating GTP hydrolysis on active Gα subunits...
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identification of Protein kinase c activation as a novel mechanism for RGS2 Protein upregulation through phenotypic screening of natural product extracts
Molecular Pharmacology, 2014Co-Authors: Avi Raveh, Richard R Neubig, Pamela J Schultz, Lauren Aschermann, Colleen Carpenter, Giselle Tamayocastillo, Jon Clardy, David H Sherman, Benita SjogrenAbstract:Biochemical high-throughput screening is widely used in drug discovery, using a variety of small molecule libraries. However, broader screening strategies may be more beneficial to identify novel biologic mechanisms. In the current study we used a β-galactosidase complementation method to screen a selection of microbial-derived pre-fractionated natural product extracts for those that increase regulator of G Protein signaling 2 (RGS2) Protein levels. RGS2 is a member of a large family of Proteins that all regulate signaling through G Protein–coupled receptors (GPCRs) by accelerating GTPase activity on active Gα as well as through other mechanisms. RGS2−/− mice are hypertensive, show increased anxiety, and are prone to heart failure. RGS2 has a very short Protein half-life due to rapid proteasomal degradation, and we propose that enhancement of RGS2 Protein levels could be a beneficial therapeutic strategy. Bioassay-guided fractionation of one of the hit strains yielded a pure compound, Indolactam V, a known Protein kinase C (PKC) activator, which selectively increased RGS2 Protein levels in a time- and concentration-dependent manner. Similar results were obtained with phorbol 12-myristate 13-acetate as well as activation of the Gq-coupled muscarinic M3 receptor. The effect on RGS2 Protein levels was blocked by the nonselective PKC inhibitor Go6983 (3-[1-[3-(dimethylamino)propyl]-5-methoxy-1H-indol-3-yl]-4-(1H-indol-3-yl)-1H-pyrrole-2,5-dione), the PKCβ-selective inhibitor Ruboxastaurin, as well as small interfering RNA-mediated knockdown of PKCβ. Indolactam V-mediated increases in RGS2 Protein levels also had functional effects on GPCR signaling. This study provides important proof-of-concept for our screening strategy and could define a negative feedback mechanism in Gq/Phospholipase C signaling through RGS2 Protein upregulation.
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RGS2 Protein degradation is mediated by a novel cullin 4b f box 44 e3 ligase complex 843 8
The FASEB Journal, 2014Co-Authors: Benita Sjogren, Steven Swaney, Richard R NeubigAbstract:Hypertension and heart failure are major health issues and there is a need to identify more effective treatments and novel drug targets. Regulator of G Protein Signaling 2 (RGS2) is highly expresse...
Hannele Laivuori - One of the best experts on this subject based on the ideXlab platform.
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An RGS2 3 ' UTR polymorphism is associated with preeclampsia in overweight women
BMC Genetics, 2016Co-Authors: Tiina Karppanen, Tea Kaartokallio, Miira M. Klemetti, Seppo Heinonen, Eero Kajantie, Juha Kere, Katja Kivinen, Anneli Pouta, Anne Cathrine Staff, Hannele LaivuoriAbstract:Background Preeclampsia is a common and heterogeneous vascular syndrome of pregnancy. Its genetic risk profile is yet unknown and may vary between individuals and populations. The rs4606 3′ UTR polymorphism of the Regulator of G-Protein signaling 2 gene (RGS2) in the mother has been implicated in preeclampsia as well as in the development of chronic hypertension after preeclampsia. The RGS2 Protein acts as an inhibitor of physiological vasoconstrictive pathways, and a low RGS2 level is associated with hypertension and obesity, two conditions that predispose to preeclampsia. We genotyped the rs4606 polymorphism in 1339 preeclamptic patients and in 697 controls from the Finnish Genetics of Preeclampsia Consortium (FINNPEC) cohort to study the association of the variant with preeclampsia.
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An RGS2 3′UTR polymorphism is associated with preeclampsia in overweight women
BMC Genetics, 2016Co-Authors: Tiina Karppanen, Tea Kaartokallio, Miira M. Klemetti, Seppo Heinonen, Eero Kajantie, Juha Kere, Katja Kivinen, Anneli Pouta, Anne Cathrine Staff, Hannele LaivuoriAbstract:Background Preeclampsia is a common and heterogeneous vascular syndrome of pregnancy. Its genetic risk profile is yet unknown and may vary between individuals and populations. The rs4606 3′ UTR polymorphism of the Regulator of G-Protein signaling 2 gene ( RGS2 ) in the mother has been implicated in preeclampsia as well as in the development of chronic hypertension after preeclampsia. The RGS2 Protein acts as an inhibitor of physiological vasoconstrictive pathways, and a low RGS2 level is associated with hypertension and obesity, two conditions that predispose to preeclampsia. We genotyped the rs4606 polymorphism in 1339 preeclamptic patients and in 697 controls from the Finnish Genetics of Preeclampsia Consortium (FINNPEC) cohort to study the association of the variant with preeclampsia. Results No association between rs4606 and preeclampsia was detected in the analysis including all women. However, the polymorphism was associated with preeclampsia in a subgroup of overweight women (body mass index ≥ 25 kg/m^2, and
Richard R Neubig - One of the best experts on this subject based on the ideXlab platform.
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digoxin mediated upregulation of RGS2 Protein protects against cardiac injury
Journal of Pharmacology and Experimental Therapeutics, 2016Co-Authors: Benita Sjogren, Sergio Parra, Kevin B Atkins, Behirda Karaj, Richard R NeubigAbstract:Regulator of G Protein signaling (RGS) Proteins have emerged as novel drug targets since their discovery almost two decades ago. RGS2 has received particular interest in cardiovascular research due to its role in regulating Gq signaling in the heart and vascular smooth muscle. RGS2−/− mice are hypertensive, prone to heart failure, and display accelerated kidney fibrosis. RGS2 is rapidly degraded through the proteasome, and human mutations leading to accelerated RGS2 Protein degradation correlate with hypertension. Hence, stabilizing RGS2 Protein expression could be a novel route in treating cardiovascular disease. We previously identified cardiotonic steroids, including digoxin, as selective stabilizers of RGS2 Protein in vitro. In the current study we investigated the functional effects of digoxin-mediated RGS2 Protein stabilization in vivo. Using freshly isolated myocytes from wild-type and RGS2−/− mice treated with vehicle or low-dose digoxin (2 µg/kg/day for 7 days) we demonstrated that agonist-induced cAMP levels and cardiomyocyte contractility was inhibited by digoxin in wild-type but not in RGS2−/− mice. This inhibition was accompanied by an increase in RGS2 Protein levels in cardiomyocytes as well as in whole heart tissue. Furthermore, digoxin had protective effects in a model of cardiac injury in wild-type mice and this protection was lost in RGS2−/− mice. Digoxin is the oldest known therapy for heart failure; however, beyond its activity at the Na+/K+-ATPase, the exact mechanism of action is not known. The current study adds a novel mechanism, whereby through stabilizing RGS2 Protein levels digoxin could exert its protective effects in the failing heart.
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fbxo44 mediated degradation of RGS2 Protein uniquely depends on a cullin 4b ddb1 complex
PLOS ONE, 2015Co-Authors: Benita Sjogren, Steven Swaney, Richard R NeubigAbstract:The ubiquitin-proteasome system for Protein degradation plays a major role in regulating cell function and many signaling Proteins are tightly controlled by this mechanism. Among these, Regulator of G Protein Signaling 2 (RGS2) is a target for rapid proteasomal degradation, however, the specific enzymes involved are not known. Using a genomic siRNA screening approach, we identified a novel E3 ligase complex containing cullin 4B (CUL4B), DNA damage binding Protein 1 (DDB1) and F-box Protein 44 (FBXO44) that mediates RGS2 Protein degradation. While the more typical F-box partners CUL1 and Skp1 can bind FBXO44, that E3 ligase complex does not bind RGS2 and is not involved in RGS2 degradation. These observations define an unexpected DDB1/CUL4B-containing FBXO44 E3 ligase complex. Pharmacological targeting of this mechanism provides a novel therapeutic approach to hypertension, anxiety, and other diseases associated with RGS2 dysregulation.
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identification of Protein kinase c activation as a novel mechanism for RGS2 Protein upregulation through phenotypic screening of natural product extracts
Molecular Pharmacology, 2014Co-Authors: Avi Raveh, Richard R Neubig, Pamela J Schultz, Lauren Aschermann, Colleen Carpenter, Giselle Tamayocastillo, Jon Clardy, David H Sherman, Benita SjogrenAbstract:Biochemical high-throughput screening is widely used in drug discovery, using a variety of small molecule libraries. However, broader screening strategies may be more beneficial to identify novel biologic mechanisms. In the current study we used a β-galactosidase complementation method to screen a selection of microbial-derived pre-fractionated natural product extracts for those that increase regulator of G Protein signaling 2 (RGS2) Protein levels. RGS2 is a member of a large family of Proteins that all regulate signaling through G Protein–coupled receptors (GPCRs) by accelerating GTPase activity on active Gα as well as through other mechanisms. RGS2−/− mice are hypertensive, show increased anxiety, and are prone to heart failure. RGS2 has a very short Protein half-life due to rapid proteasomal degradation, and we propose that enhancement of RGS2 Protein levels could be a beneficial therapeutic strategy. Bioassay-guided fractionation of one of the hit strains yielded a pure compound, Indolactam V, a known Protein kinase C (PKC) activator, which selectively increased RGS2 Protein levels in a time- and concentration-dependent manner. Similar results were obtained with phorbol 12-myristate 13-acetate as well as activation of the Gq-coupled muscarinic M3 receptor. The effect on RGS2 Protein levels was blocked by the nonselective PKC inhibitor Go6983 (3-[1-[3-(dimethylamino)propyl]-5-methoxy-1H-indol-3-yl]-4-(1H-indol-3-yl)-1H-pyrrole-2,5-dione), the PKCβ-selective inhibitor Ruboxastaurin, as well as small interfering RNA-mediated knockdown of PKCβ. Indolactam V-mediated increases in RGS2 Protein levels also had functional effects on GPCR signaling. This study provides important proof-of-concept for our screening strategy and could define a negative feedback mechanism in Gq/Phospholipase C signaling through RGS2 Protein upregulation.
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RGS2 Protein degradation is mediated by a novel cullin 4b f box 44 e3 ligase complex 843 8
The FASEB Journal, 2014Co-Authors: Benita Sjogren, Steven Swaney, Richard R NeubigAbstract:Hypertension and heart failure are major health issues and there is a need to identify more effective treatments and novel drug targets. Regulator of G Protein Signaling 2 (RGS2) is highly expresse...
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Cardiotonic Steroids Stabilize Regulator of G Protein Signaling 2 Protein Levels
Molecular Pharmacology, 2012Co-Authors: Benita Sjogren, Sergio Parra, Kevin B Atkins, Lauren Heath, Richard R NeubigAbstract:Regulator of G Protein signaling 2 (RGS2), a Gq-specific GTPase-activating Protein, is strongly implicated in cardiovascular function. RGS2(−/−) mice are hypertensive and prone to heart failure, and several rare human mutations that accelerate RGS2 degradation have been identified among patients with hypertension. Therefore, pharmacological up-regulation of RGS2 Protein levels might be beneficial. We used a β-galactosidase complementation method to screen several thousand compounds with known pharmacological functions for those that increased RGS2 Protein levels. Several cardiotonic steroids (CTSs), including ouabain and digoxin, increased RGS2 but not RGS4 Protein levels. CTSs increased RGS2 Protein levels through a post-transcriptional mechanism, by slowing Protein degradation. RGS2 mRNA levels in primary vascular smooth muscle cells were unaffected by CTS treatment, whereas Protein levels were increased 2- to 3-fold. Na+/K+-ATPase was required for the increase in RGS2 Protein levels, because the effect was lost in Na+/K+-ATPase-knockdown cells. Furthermore, we demonstrated that CTS-induced increases in RGS2 levels were functional and reduced receptor-stimulated, Gq-dependent, extracellular signal-regulated kinase phosphorylation. Finally, we showed that in vivo treatment with digoxin led to increased RGS2 Protein levels in heart and kidney. CTS-induced increases in RGS2 Protein levels and function might modify several deleterious mechanisms in hypertension and heart failure. This novel CTS mechanism might contribute to the beneficial actions of low-dose digoxin treatment in heart failure. Our results support the concept of small-molecule modulation of RGS2 Protein levels as a new strategy for cardiovascular therapy.
Ulrike Mende - One of the best experts on this subject based on the ideXlab platform.
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selective loss of fine tuning of gq 11 signaling by RGS2 Protein exacerbates cardiomyocyte hypertrophy
Journal of Biological Chemistry, 2006Co-Authors: Wei Zhang, Thomas Anger, Jialin Su, Xiaomei Xu, Agnieszka Gach, Ronglih Liao, Ulrike MendeAbstract:Abstract Alterations in cardiac G Protein-mediated signaling, most prominently Gq/11 signaling, are centrally involved in hypertrophy and heart failure development. Several RGS Proteins that can act as negative regulators of G Protein signaling are expressed in the heart, but their functional roles are still poorly understood. RGS expression changes have been described in hypertrophic and failing hearts. In this study, we report a marked decrease in RGS2 (but not other major cardiac RGS Proteins (RGS3-RGS5)) that occurs prior to hypertrophy development in different models with enhanced Gq/11 signaling (transgenic expression of activated Gαq* and pressure overload due to aortic constriction). To assess functional consequences of selective down-regulation of endogenous RGS2, we identified targeting sequences for effective RGS2 RNA interference and used lipid-based transfection to achieve uptake of fluorescently labeled RGS2 small interfering RNA in >90% of neonatal and adult ventricular myocytes. Endogenous RGS2 expression was dose-dependently suppressed (up to 90%) with no major change in RGS3-RGS5. RGS2 knockdown increased phenylephrine- and endothelin-1-induced phospholipase Cβ stimulation in both cell types and exacerbated the hypertrophic effect (increase in cell size and radiolabeled Protein) in neonatal myocytes, with no major change in Gq/11-mediated ERK1/2, p38, or JNK activation. Taken together, this study demonstrates that endogenous RGS2 exerts functionally important inhibitory restraint on Gq/11-mediated phospholipase Cβ activation and hypertrophy in ventricular myocytes. Our findings point toward a potential pathophysiological role of loss of fine tuning due to selective RGS2 down-regulation in Gq/11-mediated remodeling. Furthermore, this study shows the feasibility of effective RNA interference in cardiomyocytes using lipid-based small interfering RNA transfection.
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Selective Loss of Fine Tuning of Gq/11 Signaling by RGS2 Protein Exacerbates Cardiomyocyte Hypertrophy
Journal of Biological Chemistry, 2005Co-Authors: Wei Zhang, Thomas Anger, Jialin Su, Xiaomei Xu, Agnieszka Gach, Ronglih Liao, Ulrike MendeAbstract:Abstract Alterations in cardiac G Protein-mediated signaling, most prominently Gq/11 signaling, are centrally involved in hypertrophy and heart failure development. Several RGS Proteins that can act as negative regulators of G Protein signaling are expressed in the heart, but their functional roles are still poorly understood. RGS expression changes have been described in hypertrophic and failing hearts. In this study, we report a marked decrease in RGS2 (but not other major cardiac RGS Proteins (RGS3-RGS5)) that occurs prior to hypertrophy development in different models with enhanced Gq/11 signaling (transgenic expression of activated Gαq* and pressure overload due to aortic constriction). To assess functional consequences of selective down-regulation of endogenous RGS2, we identified targeting sequences for effective RGS2 RNA interference and used lipid-based transfection to achieve uptake of fluorescently labeled RGS2 small interfering RNA in >90% of neonatal and adult ventricular myocytes. Endogenous RGS2 expression was dose-dependently suppressed (up to 90%) with no major change in RGS3-RGS5. RGS2 knockdown increased phenylephrine- and endothelin-1-induced phospholipase Cβ stimulation in both cell types and exacerbated the hypertrophic effect (increase in cell size and radiolabeled Protein) in neonatal myocytes, with no major change in Gq/11-mediated ERK1/2, p38, or JNK activation. Taken together, this study demonstrates that endogenous RGS2 exerts functionally important inhibitory restraint on Gq/11-mediated phospholipase Cβ activation and hypertrophy in ventricular myocytes. Our findings point toward a potential pathophysiological role of loss of fine tuning due to selective RGS2 down-regulation in Gq/11-mediated remodeling. Furthermore, this study shows the feasibility of effective RNA interference in cardiomyocytes using lipid-based small interfering RNA transfection.
Tiina Karppanen - One of the best experts on this subject based on the ideXlab platform.
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An RGS2 3 ' UTR polymorphism is associated with preeclampsia in overweight women
BMC Genetics, 2016Co-Authors: Tiina Karppanen, Tea Kaartokallio, Miira M. Klemetti, Seppo Heinonen, Eero Kajantie, Juha Kere, Katja Kivinen, Anneli Pouta, Anne Cathrine Staff, Hannele LaivuoriAbstract:Background Preeclampsia is a common and heterogeneous vascular syndrome of pregnancy. Its genetic risk profile is yet unknown and may vary between individuals and populations. The rs4606 3′ UTR polymorphism of the Regulator of G-Protein signaling 2 gene (RGS2) in the mother has been implicated in preeclampsia as well as in the development of chronic hypertension after preeclampsia. The RGS2 Protein acts as an inhibitor of physiological vasoconstrictive pathways, and a low RGS2 level is associated with hypertension and obesity, two conditions that predispose to preeclampsia. We genotyped the rs4606 polymorphism in 1339 preeclamptic patients and in 697 controls from the Finnish Genetics of Preeclampsia Consortium (FINNPEC) cohort to study the association of the variant with preeclampsia.
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An RGS2 3′UTR polymorphism is associated with preeclampsia in overweight women
BMC Genetics, 2016Co-Authors: Tiina Karppanen, Tea Kaartokallio, Miira M. Klemetti, Seppo Heinonen, Eero Kajantie, Juha Kere, Katja Kivinen, Anneli Pouta, Anne Cathrine Staff, Hannele LaivuoriAbstract:Background Preeclampsia is a common and heterogeneous vascular syndrome of pregnancy. Its genetic risk profile is yet unknown and may vary between individuals and populations. The rs4606 3′ UTR polymorphism of the Regulator of G-Protein signaling 2 gene ( RGS2 ) in the mother has been implicated in preeclampsia as well as in the development of chronic hypertension after preeclampsia. The RGS2 Protein acts as an inhibitor of physiological vasoconstrictive pathways, and a low RGS2 level is associated with hypertension and obesity, two conditions that predispose to preeclampsia. We genotyped the rs4606 polymorphism in 1339 preeclamptic patients and in 697 controls from the Finnish Genetics of Preeclampsia Consortium (FINNPEC) cohort to study the association of the variant with preeclampsia. Results No association between rs4606 and preeclampsia was detected in the analysis including all women. However, the polymorphism was associated with preeclampsia in a subgroup of overweight women (body mass index ≥ 25 kg/m^2, and