1
|
Lefevre TJ, Wei W, Mukhaleva E, Meda Venkata SP, Chandan NR, Abraham S, Li Y, Dessauer CW, Vaidehi N, Smrcka AV. Stabilization of interdomain interactions in G protein α subunits as a determinant of Gα i subtype signaling specificity. J Biol Chem 2024; 300:107211. [PMID: 38522511 PMCID: PMC11066577 DOI: 10.1016/j.jbc.2024.107211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 03/07/2024] [Accepted: 03/12/2024] [Indexed: 03/26/2024] Open
Abstract
Highly homologous members of the Gαi family, Gαi1-3, have distinct tissue distributions and physiological functions, yet their biochemical and functional properties are very similar. We recently identified PDZ-RhoGEF (PRG) as a novel Gαi1 effector that is poorly activated by Gαi2. In a proteomic proximity labeling screen we observed a strong preference for Gαi1 relative to Gαi2 with respect to engagement of a broad range of potential targets. We investigated the mechanistic basis for this selectivity using PRG as a representative target. Substitution of either the helical domain (HD) from Gαi1 into Gαi2 or substitution of a single amino acid, A230 in Gαi2 with the corresponding D in Gαi1, largely rescues PRG activation and interactions with other potential Gαi targets. Molecular dynamics simulations combined with Bayesian network models revealed that in the GTP bound state, separation at the HD-Ras-like domain (RLD) interface is more pronounced in Gαi2 than Gαi1. Mutation of A230 to D in Gαi2 stabilizes HD-RLD interactions via ionic interactions with R145 in the HD which in turn modify the conformation of Switch III. These data support a model where D229 in Gαi1 interacts with R144 and stabilizes a network of interactions between HD and RLD to promote protein target recognition. The corresponding A230 in Gαi2 is unable to stabilize this network leading to an overall lower efficacy with respect to target interactions. This study reveals distinct mechanistic properties that could underly differential biological and physiological consequences of activation of Gαi1 or Gαi2 by G protein-coupled receptors.
Collapse
Affiliation(s)
- Tyler J Lefevre
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA; Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Wenyuan Wei
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | - Elizaveta Mukhaleva
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | | | - Naincy R Chandan
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA; Genentech, South San Francisco, California, USA
| | - Saji Abraham
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Yong Li
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, Texas, USA
| | - Carmen W Dessauer
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, Texas, USA
| | - Nagarajan Vaidehi
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | - Alan V Smrcka
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
| |
Collapse
|
2
|
Lefevre TJ, Wei W, Mukhaleva E, Venkata SPM, Chandan NR, Abraham S, Li Y, Dessauer CW, Vaidehi N, Smrcka AV. Stabilization of Interdomain Interactions in G protein α i Subunits Determines Gα i Subtype Signaling Specificity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.10.532072. [PMID: 37066214 PMCID: PMC10103935 DOI: 10.1101/2023.03.10.532072] [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: 06/14/2023]
Abstract
Highly homologous members of the Gαi family, Gαi1-3, have distinct tissue distributions and physiological functions, yet the functional properties of these proteins with respect to GDP/GTP binding and regulation of adenylate cyclase are very similar. We recently identified PDZ-RhoGEF (PRG) as a novel Gαi1 effector, however, it is poorly activated by Gαi2. Here, in a proteomic proximity labeling screen we observed a strong preference for Gαi1 relative to Gαi2 with respect to engagement of a broad range of potential targets. We investigated the mechanistic basis for this selectivity using PRG as a representative target. Substitution of either the helical domain (HD) from Gαi1 into Gαi2 or substitution of a single amino acid, A230 in Gαi2 to the corresponding D in Gαi1, largely rescues PRG activation and interactions with other Gαi targets. Molecular dynamics simulations combined with Bayesian network models revealed that in the GTP bound state, dynamic separation at the HD-Ras-like domain (RLD) interface is prevalent in Gαi2 relative to Gαi1 and that mutation of A230s4h3.3 to D in Gαi2 stabilizes HD-RLD interactions through formation of an ionic interaction with R145HD.11 in the HD. These interactions in turn modify the conformation of Switch III. These data support a model where D229s4h3.3 in Gαi1 interacts with R144HD.11 stabilizes a network of interactions between HD and RLD to promote protein target recognition. The corresponding A230 in Gαi2 is unable to form the "ionic lock" to stabilize this network leading to an overall lower efficacy with respect to target interactions. This study reveals distinct mechanistic properties that could underly differential biological and physiological consequences of activation of Gαi1 or Gαi2 by GPCRs.
Collapse
Affiliation(s)
- Tyler J. Lefevre
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI
| | - Wenyuan Wei
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | - Elizaveta Mukhaleva
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | | | - Naincy R. Chandan
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
- Genentech, South San Francisco, CA
| | - Saji Abraham
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
| | - Yong Li
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | - Carmen W. Dessauer
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | - Nagarajan Vaidehi
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, CA
| | - Alan V. Smrcka
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
| |
Collapse
|
3
|
Inazumi H, Kuwahara K. NRSF/REST-Mediated Epigenomic Regulation in the Heart: Transcriptional Control of Natriuretic Peptides and Beyond. BIOLOGY 2022; 11:biology11081197. [PMID: 36009824 PMCID: PMC9405064 DOI: 10.3390/biology11081197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/07/2022] [Accepted: 08/09/2022] [Indexed: 11/17/2022]
Abstract
Simple Summary Reactivation of the fetal cardiac gene program, such as those encoding atrial and brain natriuretic peptides (ANP and BNP, respectively), is a characteristic feature of failing hearts. We previously revealed that a transcriptional repressor, neuron-restrictive silencer factor (NRSF), also called repressor element-1-silencing transcription factor (REST), plays a crucial role in the transcriptional control of ANP, BNP and other fetal cardiac genes through collaboration with various other transcription factors to maintain physiological cardiac function and electrical stability. Increased production of ANP and BNP prevents the progression of heart failure, but reactivation of Gαo and fetal-type cardiac ion channels (T-type Ca2+ and HCN channels) leads to deteriorated cardiac function and lethal arrhythmias observed in mice with disturbed NRSF function. Epigenetic regulators with which NRSF forms a complex modify histone acetylation and methylation, thereby participating in NRSF-mediated transcriptional regulation. Further comprehensive studies will lead to clarification of the molecular mechanisms underlying the development of cardiac dysfunction and heart failure. Abstract Reactivation of fetal cardiac genes, including those encoding atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), is a key feature of pathological cardiac remodeling and heart failure. Intensive studies on the regulation of ANP and BNP have revealed the involvement of numerous transcriptional factors in the regulation of the fetal cardiac gene program. Among these, we identified that a transcriptional repressor, neuron-restrictive silencer factor (NRSF), also named repressor element-1-silencing transcription factor (REST), which was initially detected as a transcriptional repressor of neuron-specific genes in non-neuronal cells, plays a pivotal role in the transcriptional regulation of ANP, BNP and other fetal cardiac genes. Here we review the transcriptional regulation of ANP and BNP gene expression and the role of the NRSF repressor complex in the regulation of cardiac gene expression and the maintenance of cardiac homeostasis.
Collapse
Affiliation(s)
- Hideaki Inazumi
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Koichiro Kuwahara
- Department of Cardiovascular Medicine, School of Medicine, Shinshu University, 3-1-1 Asahi, Nagano 390-8621, Japan
- Correspondence: ; Tel.: +81-263-37-3191; Fax: +81-263-37-3195
| |
Collapse
|
4
|
Inazumi H, Kuwahara K, Nakagawa Y, Kuwabara Y, Numaga-Tomita T, Kashihara T, Nakada T, Kurebayashi N, Oya M, Nonaka M, Sugihara M, Kinoshita H, Moriuchi K, Yanagisawa H, Nishikimi T, Motoki H, Yamada M, Morimoto S, Otsu K, Mortensen RM, Nakao K, Kimura T. NRSF- GNAO1 Pathway Contributes to the Regulation of Cardiac Ca 2+ Homeostasis. Circ Res 2022; 130:234-248. [PMID: 34875852 DOI: 10.1161/circresaha.121.318898] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND During the development of heart failure, a fetal cardiac gene program is reactivated and accelerates pathological cardiac remodeling. We previously reported that a transcriptional repressor, NRSF (neuron restrictive silencer factor), suppresses the fetal cardiac gene program, thereby maintaining cardiac integrity. The underlying molecular mechanisms remain to be determined, however. METHODS We aim to elucidate molecular mechanisms by which NRSF maintains normal cardiac function. We generated cardiac-specific NRSF knockout mice and analyzed cardiac gene expression profiles in those mice and mice cardiac-specifically expressing a dominant-negative NRSF mutant. RESULTS We found that cardiac expression of Gαo, an inhibitory G protein encoded in humans by GNAO1, is transcriptionally regulated by NRSF and is increased in the ventricles of several mouse models of heart failure. Genetic knockdown of Gnao1 ameliorated the cardiac dysfunction and prolonged survival rates in these mouse heart failure models. Conversely, cardiac-specific overexpression of GNAO1 in mice was sufficient to induce cardiac dysfunction. Mechanistically, we observed that increasing Gαo expression increased surface sarcolemmal L-type Ca2+ channel activity, activated CaMKII (calcium/calmodulin-dependent kinase-II) signaling, and impaired Ca2+ handling in ventricular myocytes, which led to cardiac dysfunction. CONCLUSIONS These findings shed light on a novel function of Gαo in the regulation of cardiac Ca2+ homeostasis and systolic function and suggest Gαo may be an effective therapeutic target for the treatment of heart failure.
Collapse
Affiliation(s)
- Hideaki Inazumi
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
| | - Koichiro Kuwahara
- Cardiovascular Medicine (K.K., M.O., H.M.), School of Medicine, Shinshu University, Matsumoto
| | - Yasuaki Nakagawa
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
| | - Yoshihiro Kuwabara
- Center for Accessing Early Promising Treatment, Kyoto University Hospital (Y.K.)
| | - Takuro Numaga-Tomita
- Molecular Pharmacology (T.N.-T., M.Y.), School of Medicine, Shinshu University, Matsumoto
| | - Toshihide Kashihara
- Molecular Pharmacology, School of Pharmaceutical Sciences, Kitasato University, Tokyo (T. Kashihara)
| | - Tsutomu Nakada
- Research Center for Supports to Advanced Science (T. Nakada), School of Medicine, Shinshu University, Matsumoto
| | - Nagomi Kurebayashi
- Cellular and Molecular Pharmacology, School of Medicine, Juntendo University, Tokyo (N.K.)
| | - Miku Oya
- Cardiovascular Medicine (K.K., M.O., H.M.), School of Medicine, Shinshu University, Matsumoto
| | - Miki Nonaka
- Pain Control Research, The Jikei University School of Medicine (M.N.)
| | - Masami Sugihara
- Clinical Laboratory Medicine, School of Medicine, Juntendo University, Tokyo (M.S.)
| | - Hideyuki Kinoshita
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
| | - Kenji Moriuchi
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
| | | | - Toshio Nishikimi
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
- Wakakusa Tatsuma Rehabilitation Hospital, Osaka (T. Nishikimi)
| | - Hirohiko Motoki
- Cardiovascular Medicine (K.K., M.O., H.M.), School of Medicine, Shinshu University, Matsumoto
| | - Mitsuhiko Yamada
- Molecular Pharmacology (T.N.-T., M.Y.), School of Medicine, Shinshu University, Matsumoto
| | - Sachio Morimoto
- School of Health Sciences Fukuoka, International University of Health and Welfare, Okawa (S.M.)
| | - Kinya Otsu
- The School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, United Kingdom (K.O.)
| | | | - Kazuwa Nakao
- Medical Innovation Center (K.N.), Graduate School of Medicine, Kyoto University
| | - Takeshi Kimura
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
| |
Collapse
|
5
|
Lymperopoulos A, Wertz SL, Pollard CM, Desimine VL, Maning J, McCrink KA. Not all arrestins are created equal: Therapeutic implications of the functional diversity of the β-arrestins in the heart. World J Cardiol 2019; 11:47-56. [PMID: 30820275 PMCID: PMC6391623 DOI: 10.4330/wjc.v11.i2.47] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 11/28/2018] [Accepted: 01/10/2019] [Indexed: 02/06/2023] Open
Abstract
The two ubiquitous, outside the retina, G protein-coupled receptor (GPCR) adapter proteins, β-arrestin-1 and -2 (also known as arrestin-2 and -3, respectively), have three major functions in cells: GPCR desensitization, i.e., receptor decoupling from G-proteins; GPCR internalization via clathrin-coated pits; and signal transduction independently of or in parallel to G-proteins. Both β-arrestins are expressed in the heart and regulate a large number of cardiac GPCRs. The latter constitute the single most commonly targeted receptor class by Food and Drug Administration-approved cardiovascular drugs, with about one-third of all currently used in the clinic medications affecting GPCR function. Since β-arrestin-1 and -2 play important roles in signaling and function of several GPCRs, in particular of adrenergic receptors and angiotensin II type 1 receptors, in cardiac myocytes, they have been a major focus of cardiac biology research in recent years. Perhaps the most significant realization coming out of their studies is that these two GPCR adapter proteins, initially thought of as functionally interchangeable, actually exert diametrically opposite effects in the mammalian myocardium. Specifically, the most abundant of the two β-arrestin-1 exerts overall detrimental effects on the heart, such as negative inotropy and promotion of adverse remodeling post-myocardial infarction (MI). In contrast, β-arrestin-2 is overall beneficial for the myocardium, as it has anti-apoptotic and anti-inflammatory effects that result in attenuation of post-MI adverse remodeling, while promoting cardiac contractile function. Thus, design of novel cardiac GPCR ligands that preferentially activate β-arrestin-2 over β-arrestin-1 has the potential of generating novel cardiovascular therapeutics for heart failure and other heart diseases.
Collapse
Affiliation(s)
- Anastasios Lymperopoulos
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
| | - Shelby L Wertz
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
| | - Celina M Pollard
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
| | - Victoria L Desimine
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
| | - Jennifer Maning
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
- Jackson Memorial Hospital, Miami, FL 33136, United States
| | - Katie A McCrink
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
- Massachusetts General Hospital, Boston, MA 02114, United States
| |
Collapse
|
6
|
Desimine VL, McCrink KA, Parker BM, Wertz SL, Maning J, Lymperopoulos A. Biased Agonism/Antagonism of Cardiovascular GPCRs for Heart Failure Therapy. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 339:41-61. [PMID: 29776604 DOI: 10.1016/bs.ircmb.2018.02.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
G protein-coupled receptors (GPCRs) are among the most important drug targets currently used in clinic, including drugs for cardiovascular indications. We now know that, in addition to activating heterotrimeric G protein-dependent signaling pathways, GPCRs can also activate G protein-independent signaling, mainly via the βarrestins. The major role of βarrestin1 and -2, also known as arrestin2 or -3, respectively, is to desensitize GPCRs, i.e., uncoupled them from G proteins, and to subsequently internalize the receptor. As the βarrestin-bound GPCR recycles inside the cell, it serves as a signalosome transducing signals in the cytoplasm. Since both G proteins and βarrestins can transduce signals from the same receptor independently of each other, any given GPCR agonist might selectively activate either pathway, which would make it a biased agonist for that receptor. Although this selectivity is always relative (never absolute), in cases where the G protein- and βarrestin-dependent signals emanating from the same GPCR result in different cellular effects, pharmacological exploitation of GPCR-biased agonism might have therapeutic potential. In this chapter, we summarize the GPCR signaling pathways and their biased agonism/antagonism examples discovered so far that can be exploited for heart failure treatment. We also highlight important issues that need to be clarified along the journey of these ligands from bench to the clinic.
Collapse
Affiliation(s)
- Victoria L Desimine
- From the Laboratory for the Study of Neurohormonal Control of the Circulation, Nova Southeastern University College of Pharmacy, Fort Lauderdale, FL, United States
| | - Katie A McCrink
- From the Laboratory for the Study of Neurohormonal Control of the Circulation, Nova Southeastern University College of Pharmacy, Fort Lauderdale, FL, United States
| | - Barbara M Parker
- From the Laboratory for the Study of Neurohormonal Control of the Circulation, Nova Southeastern University College of Pharmacy, Fort Lauderdale, FL, United States
| | - Shelby L Wertz
- From the Laboratory for the Study of Neurohormonal Control of the Circulation, Nova Southeastern University College of Pharmacy, Fort Lauderdale, FL, United States
| | - Jennifer Maning
- From the Laboratory for the Study of Neurohormonal Control of the Circulation, Nova Southeastern University College of Pharmacy, Fort Lauderdale, FL, United States
| | - Anastasios Lymperopoulos
- From the Laboratory for the Study of Neurohormonal Control of the Circulation, Nova Southeastern University College of Pharmacy, Fort Lauderdale, FL, United States.
| |
Collapse
|
7
|
Arrestins in the Cardiovascular System: An Update. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 159:27-57. [DOI: 10.1016/bs.pmbts.2018.07.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
8
|
Saddic LA, Muehlschlegel JD. Sarco"MiR" friend or foe: a perspective on the mechanisms of doxorubicin-induced cardiomyopathy. ANNALS OF TRANSLATIONAL MEDICINE 2016; 4:203. [PMID: 27294099 DOI: 10.21037/atm.2016.05.30] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Anthracyclines are a class of chemotherapeutics used to treat a variety of human cancers including both solid tumors such as breast, ovarian, and lung, as well as malignancies of the blood including leukemia and lymphoma. Despite being extremely effective anti-cancer agents, the application of these drugs is offset by side effects, most notably cardiotoxicity. Many patients treated with doxorubicin (DOX), one of the most common anthracyclines used in oncology, will develop radiographic signs and/or symptoms of cardiomyopathy. Since more and more patients treated with these drugs are surviving their malignancies and manifesting with heart disease, there is particular interest in understanding the mechanisms of anthracycline-induced injury and developing ways to prevent and treat its most feared complication, heart failure. MicroRNAs (miRNAs) are small noncoding RNAs that regulate the expression of mRNAs. Since miRNAs can regulate many mRNAs in a single network they tend to play a crucial role in the pathogenesis of several diseases, including heart failure. Here we present a perspective on a recent work by Roca-Alonso and colleagues who demonstrate a cardioprotective function of the miR-30 family members following DOX-induced cardiac injury. They provide evidence for direct targeting of these miRNAs on key elements of the β-adrenergic pathway and further show that this interaction regulates cardiac function and apoptosis. These experiments deliver fresh insights into the biology of toxin-induced cardiomyopathy and suggest the potential for novel therapeutic targets.
Collapse
Affiliation(s)
- Louis A Saddic
- Department of Anesthesiology, Perioperative, and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, USA
| | - Jochen D Muehlschlegel
- Department of Anesthesiology, Perioperative, and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, USA
| |
Collapse
|
9
|
Keller K, Maass M, Dizayee S, Leiss V, Annala S, Köth J, Seemann WK, Müller-Ehmsen J, Mohr K, Nürnberg B, Engelhardt S, Herzig S, Birnbaumer L, Matthes J. Lack of Gαi2 leads to dilative cardiomyopathy and increased mortality in β1-adrenoceptor overexpressing mice. Cardiovasc Res 2015; 108:348-56. [PMID: 26464333 DOI: 10.1093/cvr/cvv235] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 09/28/2015] [Indexed: 01/05/2023] Open
Abstract
AIMS Inhibitory G (Gi) proteins have been proposed to be cardioprotective. We investigated effects of Gαi2 knockout on cardiac function and survival in a murine heart failure model of cardiac β1-adrenoceptor overexpression. METHODS AND RESULTS β1-transgenic mice lacking Gαi2 (β1-tg/Gαi2 (-/-)) were compared with wild-type mice and littermates either overexpressing cardiac β1-adrenoceptors (β1-tg) or lacking Gαi2 (Gαi2 (-/-)). At 300 days, mortality of mice only lacking Gαi2 was already higher compared with wild-type or β1-tg, but similar to β1-tg/Gαi2 (-/-), mice. Beyond 300 days, mortality of β1-tg/Gαi2 (-/-) mice was enhanced compared with all other genotypes (mean survival time: 363 ± 21 days). At 300 days of age, echocardiography revealed similar cardiac function of wild-type, β1-tg, and Gαi2 (-/-) mice, but significant impairment for β1-tg/Gαi2 (-/-) mice (e.g. ejection fraction 14 ± 2 vs. 40 ± 4% in wild-type mice). Significantly increased ventricle-to-body weight ratio (0.71 ± 0.06 vs. 0.48 ± 0.02% in wild-type mice), left ventricular size (length 0.82 ± 0.04 vs. 0.66 ± 0.03 cm in wild types), and atrial natriuretic peptide and brain natriuretic peptide expression (mRNA: 2819 and 495% of wild-type mice, respectively) indicated hypertrophy. Gαi3 was significantly up-regulated in Gαi2 knockout mice (protein compared with wild type: 340 ± 90% in Gαi2 (-/-) and 394 ± 80% in β1-tg/Gαi2 (-/-), respectively). CONCLUSIONS Gαi2 deficiency combined with cardiac β1-adrenoceptor overexpression strongly impaired survival and cardiac function. At 300 days of age, β1-adrenoceptor overexpression alone had not induced cardiac hypertrophy or dysfunction while there was overt cardiomyopathy in mice additionally lacking Gαi2. We propose an enhanced effect of increased β1-adrenergic drive by the lack of protection via Gαi2. Gαi3 up-regulation was not sufficient to compensate for Gαi2 deficiency, suggesting an isoform-specific or a concentration-dependent mechanism.
Collapse
Affiliation(s)
- Kirsten Keller
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Martina Maass
- Department of Internal Medicine III, University Hospital of Cologne, Cologne, Germany
| | - Sara Dizayee
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Veronika Leiss
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Suvi Annala
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Jessica Köth
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Wiebke K Seemann
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | | | - Klaus Mohr
- Pharmacology and Toxicology Section, Institute of Pharmacy, University of Bonn, Bonn, Germany
| | - Bernd Nürnberg
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Stefan Engelhardt
- Institute of Pharmacology and Toxicology, Technische Universität München, Munich, Germany
| | - Stefan Herzig
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Lutz Birnbaumer
- Laboratory of Neurobiology, NIEHS, NIH (Department of Health and Human Services), Durham, USA
| | - Jan Matthes
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| |
Collapse
|
10
|
Neubig RR. RGS-Insensitive G Proteins as In Vivo Probes of RGS Function. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 133:13-30. [PMID: 26123300 DOI: 10.1016/bs.pmbts.2015.04.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Guanine nucleotide-binding proteins of the inhibitory (Gi/o) class play critical physiological roles and the receptors that activate them are important therapeutic targets (e.g., mu opioid, serotonin 5HT1a, etc.). Gi/o proteins are negatively regulated by regulator of G protein signaling (RGS) proteins. The redundant actions of the 20 different RGS family members have made it difficult to establish their overall physiological role. A unique G protein mutation (G184S in Gαi/o) prevents RGS binding to the Gα subunit and blocks all RGS action at that particular Gα subunit. The robust phenotypes of mice expressing these RGS-insensitive (RGSi) mutant G proteins illustrate the profound action of RGS proteins in cardiovascular, metabolic, and central nervous system functions. Specifically, the enhanced Gαi2 signaling through the RGSi Gαi2(G184S) mutant knock-in mice shows protection against cardiac ischemia/reperfusion injury and potentiation of serotonin-mediated antidepressant actions. In contrast, the RGSi Gαo mutant knock-in produces enhanced mu-opioid receptor-mediated analgesia but also a seizure phenotype. These genetic models provide novel insights into potential therapeutic strategies related to RGS protein inhibitors and/or G protein subtype-biased agonists at particular GPCRs.
Collapse
Affiliation(s)
- Richard R Neubig
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan, USA.
| |
Collapse
|
11
|
Stewart A, Fisher RA. Introduction: G Protein-coupled Receptors and RGS Proteins. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 133:1-11. [PMID: 26123299 DOI: 10.1016/bs.pmbts.2015.03.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Here, we provide an overview of the role of regulator of G protein-signaling (RGS) proteins in signaling by G protein-coupled receptors (GPCRs), the latter of which represent the largest class of cell surface receptors in humans responsible for transducing diverse extracellular signals into the intracellular environment. Given that GPCRs regulate virtually every known physiological process, it is unsurprising that their dysregulation plays a causative role in many human diseases and they are targets of 40-50% of currently marketed pharmaceuticals. Activated GPCRs function as GTPase exchange factors for Gα subunits of heterotrimeric G proteins, promoting the formation of Gα-GTP and dissociated Gβγ subunits that regulate diverse effectors including enzymes, ion channels, and protein kinases. Termination of signaling is mediated by the intrinsic GTPase activity of Gα subunits leading to reformation of the inactive Gαβγ heterotrimer. RGS proteins determine the magnitude and duration of cellular responses initiated by many GPCRs by functioning as GTPase-accelerating proteins (GAPs) for specific Gα subunits. Twenty canonical mammalian RGS proteins, divided into four subfamilies, act as functional GAPs while almost 20 additional proteins contain nonfunctional RGS homology domains that often mediate interaction with GPCRs or Gα subunits. RGS protein biochemistry has been well elucidated in vitro, but the physiological functions of each RGS family member remain largely unexplored. This book summarizes recent advances employing modified model organisms that reveal RGS protein functions in vivo, providing evidence that RGS protein modulation of G protein signaling and GPCRs can be as important as initiation of signaling by GPCRs.
Collapse
Affiliation(s)
- Adele Stewart
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Rory A Fisher
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA.
| |
Collapse
|
12
|
Parra S, Huang X, Charbeneau RA, Wade SM, Kaur K, Rorabaugh BR, Neubig RR. Conditional disruption of interactions between Gαi2 and regulator of G protein signaling (RGS) proteins protects the heart from ischemic injury. BMC Pharmacol Toxicol 2014; 15:29. [PMID: 24899231 PMCID: PMC4059092 DOI: 10.1186/2050-6511-15-29] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 05/28/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Regulator of G protein signaling (RGS) proteins suppress G protein coupled receptor signaling by catalyzing the hydrolysis of Gα-bound guanine nucleotide triphosphate. Transgenic mice in which RGS-mediated regulation of Gαi2 is lost (RGS insensitive Gαi2G184S) exhibit beneficial (protection against ischemic injury) and detrimental (enhanced fibrosis) cardiac phenotypes. This mouse model has revealed the physiological significance of RGS/Gαi2 interactions. Previous studies of the Gαi2G184S mutation used mice that express this mutant protein throughout their lives. Thus, it is unclear whether these phenotypes result from chronic or acute Gαi2G184S expression. We addressed this issue by developing mice that conditionally express Gαi2G184S. METHODS Mice that conditionally express RGS insensitive Gαi2G184S were generated using a floxed minigene strategy. Conditional expression of Gαi2G184S was characterized by reverse transcription polymerase chain reaction and by enhancement of agonist-induced inhibition of cAMP production in isolated cardiac fibroblasts. The impact of conditional RGS insensitive Gαi2G184S expression on ischemic injury was assessed by measuring contractile recovery and infarct sizes in isolated hearts subjected to 30 min ischemia and 2 hours reperfusion. RESULTS We demonstrate tamoxifen-dependent expression of Gαi2G184S, enhanced inhibition of cAMP production, and cardioprotection from ischemic injury in hearts conditionally expressing Gαi2G184S. Thus the cardioprotective phenotype previously reported in mice expressing Gαi2G184S does not require embryonic or chronic Gαi2G184S expression. Rather, cardioprotection occurs following acute (days rather than months) expression of Gαi2G184S. CONCLUSIONS These data suggest that RGS proteins might provide new therapeutic targets to protect the heart from ischemic injury. We anticipate that this model will be valuable for understanding the time course (chronic versus acute) and mechanisms of other phenotypic changes that occur following disruption of interactions between Gαi2 and RGS proteins.
Collapse
Affiliation(s)
| | | | | | | | | | - Boyd R Rorabaugh
- Department of Pharmaceutical and Biomedical Sciences, Ohio Northern University College of Pharmacy, Ada, OH 45810, USA.
| | | |
Collapse
|
13
|
Competition for Gβγ dimers mediates a specific cross-talk between stimulatory and inhibitory G protein α subunits of the adenylyl cyclase in cardiomyocytes. Naunyn Schmiedebergs Arch Pharmacol 2013; 386:459-69. [PMID: 23615874 DOI: 10.1007/s00210-013-0876-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Accepted: 04/17/2013] [Indexed: 12/20/2022]
Abstract
Heterotrimeric G proteins are key regulators of signaling pathways in mammalian cells. Beyond G protein-coupled receptors, the amount and mutual ratio of specific G protein α, β, and γ subunits determine the G protein signaling. However, little is known about mechanisms that regulate the concentration and composition of G protein subunits at the plasma membrane. Here, we show a novel cross-talk between stimulatory and inhibitory G protein α subunits (Gα) that is mediated by G protein βγ dimers and controls the abundance of specific Gα subunits at the plasma membrane. Firstly, we observed in heart tissue from constitutively Gαi2- and Gαi3-deficient mice that the loss of Gαi2 and Gαi3 was accompanied by a slight increase in the protein content of the nontargeted Gαi isoform. Therefore, we analyzed whether overexpression of selected Gα subunits conversely impairs endogenous G protein α and β subunit levels in cardiomyocytes. Integration of overexpressed Gαi2 subunits into heterotrimeric G proteins was verified by co-immunoprecipitation. Adenoviral expression of increasing amounts of Gαi2 led to a reduction of Gαi3 (up to 90 %) and Gαs (up to 75 %) protein levels. Likewise, increasing amounts of adenovirally expressed Gαs resulted in a linear 75 % decrease in both Gαi2 and Gαi3 protein levels. In contrast, overexpression of either Gαi or Gαs isoform did not influence the amount of Gαo and Gαq, both of which are not involved in the regulation of adenylyl cyclase activity. The mRNA expression of the disappearing endogenous Gα subunits was not affected, indicating a posttranslational mechanism. Interestingly, the amount of endogenous G protein βγ dimers was not altered by any Gα overexpression. However, the increase of Gβγ level by adenoviral expression prevented the loss of endogenous Gαs and Gαi3 in Gαi2 overexpressing cardiomyocytes. Thus, our results provide evidence for a novel mechanism cross-regulating adenylyl cyclase-modulating Gαi isoforms and Gαs proteins. The Gα subunits apparently compete for a limited amount of Gβγ dimers, which are required for G protein heterotrimer formation at the plasma membrane.
Collapse
|
14
|
Seifert R. Regulation of G protein subunit composition in cardiomyocytes: pharmacological implications. Naunyn Schmiedebergs Arch Pharmacol 2013; 386:455-7. [PMID: 23568551 DOI: 10.1007/s00210-013-0864-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 03/31/2013] [Indexed: 10/27/2022]
|
15
|
Bratton MR, Antoon JW, Duong BN, Frigo DE, Tilghman S, Collins-Burow BM, Elliott S, Tang Y, Melnik LI, Lai L, Alam J, Beckman BS, Hill SM, Rowan BG, McLachlan JA, Burow ME. Gαo potentiates estrogen receptor α activity via the ERK signaling pathway. J Endocrinol 2012; 214:45-54. [PMID: 22562654 PMCID: PMC3614348 DOI: 10.1530/joe-12-0097] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The estrogen receptor α (ERα) is a transcription factor that mediates the biological effects of 17β-estradiol (E(2)). ERα transcriptional activity is also regulated by cytoplasmic signaling cascades. Here, several Gα protein subunits were tested for their ability to regulate ERα activity. Reporter assays revealed that overexpression of a constitutively active Gα(o) protein subunit potentiated ERα activity in the absence and presence of E(2). Transient transfection of the human breast cancer cell line MCF-7 showed that Gα(o) augments the transcription of several ERα-regulated genes. Western blots of HEK293T cells transfected with ER±Gα(o) revealed that Gα(o) stimulated phosphorylation of ERK 1/2 and subsequently increased the phosphorylation of ERα on serine 118. In summary, our results show that Gα(o), through activation of the MAPK pathway, plays a role in the regulation of ERα activity.
Collapse
Affiliation(s)
- Melyssa R Bratton
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane University, 1430 Tulane Avenue, SL-78, New Orleans, Louisiana 70112, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|