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Wattiez AS, Walder RY, Sande CM, White SR, Hammond DL. Peripheral inflammatory injury alters the relative abundance of Gα subunits in the dorsal horn of the spinal cord and in the rostral ventromedial medulla of male rats. Mol Pain 2017; 13:1744806917715210. [PMID: 28604220 PMCID: PMC5486491 DOI: 10.1177/1744806917715210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Abstract A diverse array of G protein-coupled receptors (GPCRs) is implicated in the modulation of nociception. The efficacy and potency of several GPCR agonists change as a consequence of peripheral inflammatory injury. Whether these changes reflect alterations in expression of the G proteins themselves is not known. This study examined the expression of transcripts and proteins for the α subunits of three classes of heteromeric G proteins in the dorsal horn of the spinal cord and the rostral ventromedial medulla (RVM) of male rats four days and two weeks after intraplantar injection of complete Freund’s adjuvant (CFA) or saline. Levels of Gα transcript in the dorsal horn or RVM were unchanged by CFA treatment. However, in the dorsal horn, Gαi protein decreased in cytosolic and membrane fractions four days after CFA treatment. Levels of Gαz protein decreased in the membrane fraction. Levels of the other Gα subunits did not differ. Levels of the Gα subunits were unchanged two weeks after CFA treatment. In the RVM, Gαz protein levels decreased in the cytosolic fraction four days after CFA treatment. No other differences were observed. Two weeks after CFA, the levels for all Gα subunits trended higher in the RVM. These data indicate that peripheral inflammatory injury induces subtle changes in the abundance of Gα subunits that is specific with respect to class, subcellular compartment, tissue, and time after injury. These changes have the potential to alter the balance of the different subcellular signaling pathways through which GPCR agonists act to modulate nociception.
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Torres M. Chapter Two - Heterotrimeric G Protein Ubiquitination as a Regulator of G Protein Signaling. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 141:57-83. [PMID: 27378755 DOI: 10.1016/bs.pmbts.2016.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Ubiquitin-mediated regulation of G proteins has been known for over 20 years as a result of discoveries made independently in yeast and vertebrate model systems for pheromone and photoreception, respectively. Since that time, several details underlying the cause and effect of G protein ubiquitination have been determined-including the initiating signals, responsible enzymes, trafficking pathways, and their effects on protein structure, function, interactions, and cell signaling. The collective body of evidence suggests that Gα subunits are the primary targets of ubiquitination. However, longstanding and recent results suggest that Gβ and Gγ subunits are also ubiquitinated, in some cases impacting cell polarization-a process essential for chemotaxis and polarized cell growth. More recently, evidence from mass spectrometry (MS)-based proteomics coupled with advances in PTM bioinformatics have revealed that protein families representing G protein subunits contain several structural hotspots for ubiquitination-most of which have not been investigated for a functional role in signal transduction. Taken together, our knowledge and understanding of heterotrimeric G protein ubiquitination as a regulator of G protein signaling-despite 20 years of research-is still emerging.
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Affiliation(s)
- M Torres
- Georgia Institute of Technology, School of Biology, Atlanta, GA, United States.
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Ogasawara J, Izawa T, Sakurai T, Sakurai T, Shirato K, Ishibashi Y, Ishida H, Ohno H, Kizaki T. The Molecular Mechanism Underlying Continuous Exercise Training-Induced Adaptive Changes of Lipolysis in White Adipose Cells. J Obes 2015; 2015:473430. [PMID: 26075089 PMCID: PMC4444571 DOI: 10.1155/2015/473430] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 04/04/2015] [Accepted: 04/27/2015] [Indexed: 01/04/2023] Open
Abstract
Physical exercise accelerates the mobilization of free fatty acids from white adipocytes to provide fuel for energy. This happens in several tissues and helps to regulate a whole-body state of metabolism. Under these conditions, the hydrolysis of triacylglycerol (TG) that is found in white adipocytes is known to be augmented via the activation of these lipolytic events, which is referred to as the "lipolytic cascade." Indeed, evidence has shown that the lipolytic responses in white adipocytes are upregulated by continuous exercise training (ET) through the adaptive changes in molecules that constitute the lipolytic cascade. During the past few decades, many lipolysis-related molecules have been identified. Of note, the discovery of a new lipase, known as adipose triglyceride lipase, has redefined the existing concepts of the hormone-sensitive lipase-dependent hydrolysis of TG in white adipocytes. This review outlines the alterations in the lipolytic molecules of white adipocytes that result from ET, which includes the molecular regulation of TG lipases through the lipolytic cascade.
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Affiliation(s)
- Junetsu Ogasawara
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
- *Junetsu Ogasawara:
| | - Tetsuya Izawa
- Graduate School of Health and Sports Science, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
| | - Tomonobu Sakurai
- Faculty of Culture and Sport Policy, Toin University of Yokohama, Yokohama, Kanagawa 225-8503, Japan
| | - Takuya Sakurai
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Ken Shirato
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Yoshinaga Ishibashi
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Hitoshi Ishida
- Department of Third Internal Medicine, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Hideki Ohno
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Takako Kizaki
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
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Chishiki K, Kamakura S, Yuzawa S, Hayase J, Sumimoto H. Ubiquitination of the heterotrimeric G protein α subunits Gαi2 and Gαq is prevented by the guanine nucleotide exchange factor Ric-8A. Biochem Biophys Res Commun 2013; 435:414-9. [DOI: 10.1016/j.bbrc.2013.04.103] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 04/30/2013] [Indexed: 01/01/2023]
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Chandrasekaran P, Buckley M, Moore V, Wang LQ, Kehrl JH, Venkatesan S. HIV-1 Nef impairs heterotrimeric G-protein signaling by targeting Gα(i2) for degradation through ubiquitination. J Biol Chem 2012; 287:41481-98. [PMID: 23071112 DOI: 10.1074/jbc.m112.361782] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The HIV Nef protein is an important pathogenic factor that modulates cell surface receptor trafficking and impairs cell motility, presumably by interfering at multiple steps with chemotactic receptor signaling. Here, we report that a dominant effect of Nef is to trigger AIP4 E3 ligase-mediated Gα(i2) ubiquitination, which leads to Gα(i2) endolysosomal sequestration and destruction. The loss of the Gα(i2) subunit was demonstrable in many cell types in the context of gene transfection, HIV infection, or Nef protein transduction. Nef directly interacts with Gα(i2) and ternary complexes containing AIP4, Nef, and Gα(i2) form. A substantial reversal of Gα(i2) loss and a partial recovery of impaired chemotaxis occurred following siRNA knockdown of AIP4 or NEDD4 or by inhibiting dynamin. The N-terminal myristoyl group, (62)EEEE(65) motif, and (72)PXXP(75) motif of Nef are critical for this effect to occur. Nef expression does not affect a Gq(i5) chimera where the five C-terminal residues of Gq are replaced with those of Gα(i2). Lysine at position 296 of Gα(i2) was identified as the critical determinant of Nef-induced degradation. By specifically degrading Gα(i2), Nef directly subverts leukocyte migration and homing. Impaired trafficking and homing of HIV Nef-expressing lymphocytes probably contributes to early immune dysfunction following HIV infection.
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Affiliation(s)
- Prabha Chandrasekaran
- Laboratory of Molecular Immunology, NIAID, National Institutes of Health, Bethesda, Maryland 20892, USA
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Ogasawara J, Sakurai T, Kizaki T, Ishibashi Y, Izawa T, Sumitani Y, Ishida H, Radak Z, Haga S, Ohno H. Higher levels of ATGL are associated with exercise-induced enhancement of lipolysis in rat epididymal adipocytes. PLoS One 2012; 7:e40876. [PMID: 22815850 PMCID: PMC3397928 DOI: 10.1371/journal.pone.0040876] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 06/18/2012] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND In adipose cells, adipose triglyceride lipase (ATGL) catalyzes the first step in adipocyte triacylglyceride hydrolysis, thereby regulating both basal and hormone-stimulated lipolysis. However, little is known about the molecular mechanism(s) underlying habitual exercise-induced adaptive modulation of ATGL in white adipocytes via alteration in transcription regulator and lipolytic cofactors. METHODOLOGY/PRINCIPAL RESULTS Male Wistar rats were randomly divided into 2 groups a sedentary control group (CG) and a habitual exercise group (EG). The EG was subjected to running on a treadmill set at 5 days per week for 9 weeks. The CG was not subjected to running on a treadmill. In the EG, levels of ATGL mRNA and protein were elevated with a significant increase in lipolysis compared with the CG, accompanied by a significant increase in associations of CGI-58 with ATGL protein. Under these conditions, an upregulation of peroxisome proliferation-activated receptorg-2 (PPARg-2) was observed. In the EG, the addition of rosiglitazone further significantly increased the levels of ATGL protein compared with the CG. However, attenuated levels of the ATGL protein in adipocytes were obtained by the addition of insulin, which is known to inhibit the expression of ATGL, in both types of groups. Actually, levels of plasma insulin were significantly reduced in the EG compared with the CG. CONCLUSIONS These data suggest that elevated levels of ATGL are involved in the exercise-induced enhancement of lipolysis in primary adipocytes. The exact mechanism(s) underlying this phenomenon is associated, at least in part, with upregulated transcriptional activation of PPARg-2. In addition, exercise-induced lower circulation levels of insulin also correlate with habitual exercise-induced higher levels of ATGL in primary adipocytes.
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Affiliation(s)
- Junetsu Ogasawara
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Tokyo, Japan.
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Ogasawara J, Nomura S, Rahman N, Sakurai T, Kizaki T, Izawa T, Ishida H, Haga S, Ohno H. Hormone-sensitive lipase is critical mediators of acute exercise-induced regulation of lipolysis in rat adipocytes. Biochem Biophys Res Commun 2010; 400:134-9. [PMID: 20708600 DOI: 10.1016/j.bbrc.2010.08.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Accepted: 08/09/2010] [Indexed: 11/30/2022]
Abstract
The purpose of the present study was to investigate the effect of acute exercise on lipolysis via coordination of hormone-sensitive lipase (HSL) and scaffold proteins, i.e., perilipin A and comparative gene identification-58 (CGI-58), in rat primary adipocytes. Glycerol release was significantly elevated immediately (0h) and three hours (3h) after exercise. Both activity and localization to the pellet of HSL were significantly greater in the pellet fraction, which is included in lipid droplet associated-proteins, than in the supernatant fraction. In the pellet fraction, although neither perilipin A nor CGI-58 protein level changed, level of perilipin A/CGI-58 complex was significantly reduced, accompanied by up-regulated association of perilipin A/HSL at 0h and 3h after exercise. On the other hand, there were no changes in these molecules at 24h after exercise, despite a significant decrease in lipolysis that was observed in response to isoproterenol. These findings suggest that acute exercise enhances lipolysis up to at least 3h after exercise in a manner dependent on modification of HSL and its association with and alteration in scaffold protein.
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Affiliation(s)
- Junetsu Ogasawara
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan.
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Wang Y, Dohlman HG. Regulation of G protein and mitogen-activated protein kinase signaling by ubiquitination: insights from model organisms. Circ Res 2007; 99:1305-14. [PMID: 17158346 DOI: 10.1161/01.res.0000251641.57410.81] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Guanine nucleotide binding proteins (G proteins) and mitogen-activated protein kinases are highly conserved signaling molecules engaged in a wide variety of cellular processes. The strength and duration of signaling mediated by G proteins and mitogen-activated protein kinases are well known to be regulated via phosphorylation of pathway components. Over the past few years, it has become evident that many of the same signaling proteins also undergo ubiquitination, a posttranslational modification that typically leads to protein degradation. Consequently the strength and duration of signaling can also be modulated by regulating the abundance of signaling proteins. This article describes G protein- and mitogen-activated protein kinase-mediated signaling pathways that are known to be regulated by ubiquitination. The focus is on studies performed in the budding yeast Saccharomyces cerevisiae, as many principles governing this new regulatory mechanism were initially discovered in this model organism. Similar mechanisms uncovered in other model systems are also briefly discussed to illustrate the importance and universality of signaling regulation by ubiquitination.
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Affiliation(s)
- Yuqi Wang
- Department of Biology, Saint Louis University, 128 Macelwane Hall, 3507 Laclede Ave, St Louis, MO 63103, USA.
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Ogasawara J, Sanpei M, Rahman N, Sakurai T, Kizaki T, Hitomi Y, Ohno H, Izawa T. Beta-adrenergic receptor trafficking by exercise in rat adipocytes: roles of G-protein-coupled receptor kinase-2, beta-arrestin-2, and the ubiquitin-proteasome pathway. FASEB J 2005; 20:350-2. [PMID: 16368719 DOI: 10.1096/fj.05-4688fje] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The effect of exercise on beta-adrenergic receptor (beta-AR) trafficking was investigated in rat adipocytes. The binding sites of a hydrophilic ligand, [(3)H]CGP12177, increased immediately (0 h) and at 3 h after exercise (3 h) but decreased at 24 h after exercise (24 h). The data of immunoblotting revealed that the alterations in the binding sites mainly paralleled the alterations in the beta2-AR proteins in membrane fractions. The protein expressions of both G-protein-coupled receptor kinase (GRK)-2 and beta-arrestin-2 were reduced, with a decline in beta2-AR ubiquitination at 0 h and 3 h. The protein expressions of beta2-AR, GRK-2, beta-arrestin-2, the beta2-AR/beta-arrestin-2 complex, and beta2-AR ubiquitination returned to their respective control levels at 24 h, whereas the beta2-AR mRNA level was reduced. Administration of either lactacystin or propranolol did not alter GRK-2 and beta2-AR protein expressions after exercise. Thus, the mechanism underlying the increased density of beta2-AR up to at least 3 h may involve alterations in a multistep event involving the coordinate interaction among proteins mediating beta2-AR trafficking, in which both the receptor-agonist interactions and ubiquitin-proteasome pathway have a key role. However, the decreased protein expression of beta2-AR at 24 h might be due to some change occurring at the translational levels.
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Affiliation(s)
- Junetsu Ogasawara
- Department of Kinesiology, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo, Japan
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