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Scheufele F, Wolf B, Kruse M, Hartmann T, Lempart J, Mühlich S, Pfeiffer AFH, Field LJ, Charron MJ, Pan ZQ, Engelhardt S, Sarikas A. Evidence for a regulatory role of Cullin-RING E3 ubiquitin ligase 7 in insulin signaling. Cell Signal 2013; 26:233-239. [PMID: 24219910 DOI: 10.1016/j.cellsig.2013.11.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 11/01/2013] [Indexed: 01/05/2023]
Abstract
Dysfunctional regulation of signaling pathways downstream of the insulin receptor plays a pivotal role in the pathogenesis of insulin resistance and type 2 diabetes. In this study we report both in vitro and in vivo experimental evidence for a role of Cullin-RING E3 ubiquitin ligase 7 (CRL7) in the regulation of insulin signaling and glucose homeostasis. We show that Cul7(-/-) mouse embryonic fibroblasts displayed enhanced AKT and Erk MAP kinase phosphorylation upon insulin stimulation. Depletion of CUL7 by RNA interference in C2C12 myotubes led to increased activation of insulin signaling pathways and cellular glucose uptake, as well as a reduced capacity of these cells to execute insulin-induced degradation of insulin receptor substrate 1 (IRS1). In vivo, heterozygosity of either Cul7 or Fbxw8, both key components of CRL7, resulted in elevated PI3 kinase/AKT activation in skeletal muscle tissue upon insulin stimulation when compared to wild-type controls. Finally, Cul7(+/-) or Fbxw8(+/-) mice exhibited enhanced insulin sensitivity and plasma glucose clearance. Collectively, our findings point to a yet unrecognized role of CRL7 in insulin-mediated control of glucose homeostasis by restraining PI3 kinase/AKT activities in skeletal muscle cells.
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Affiliation(s)
- Florian Scheufele
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Benjamin Wolf
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Michael Kruse
- German Institute of Human Nutrition Potsdam-Rehbrücke, Department of Clinical Nutrition, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany.,Departments of Biochemistry, Medicine (Endocrinology) and Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Thomas Hartmann
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Justine Lempart
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Susanne Mühlich
- Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University, Goethestraße 33, 80336 Munich, Germany
| | - Andreas F H Pfeiffer
- German Institute of Human Nutrition Potsdam-Rehbrücke, Department of Clinical Nutrition, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany.,Department of Endocrinology, Diabetes and Nutrition, Charité University Medicine, 10117 Berlin, Germany
| | - Loren J Field
- Krannert Institute of Cardiology, University of Indiana, Indianapolis, IN 46202, USA
| | - Maureen J Charron
- Departments of Biochemistry, Medicine (Endocrinology) and Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Zhen-Qiang Pan
- Mount Sinai School of Medicine, Icahn Medical Institute, Dept. of Oncological Sciences, 1425 Madison Avenue, New York, NY 10029, USA
| | - Stefan Engelhardt
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany.,DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, 80802 Munich, Germany
| | - Antonio Sarikas
- Institute of Pharmacology and Toxicology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany.,DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, 80802 Munich, Germany
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Caldeira MV, Salazar IL, Curcio M, Canzoniero LMT, Duarte CB. Role of the ubiquitin-proteasome system in brain ischemia: friend or foe? Prog Neurobiol 2013; 112:50-69. [PMID: 24157661 DOI: 10.1016/j.pneurobio.2013.10.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 10/08/2013] [Accepted: 10/15/2013] [Indexed: 11/26/2022]
Abstract
The ubiquitin-proteasome system (UPS) is a catalytic machinery that targets numerous cellular proteins for degradation, thus being essential to control a wide range of basic cellular processes and cell survival. Degradation of intracellular proteins via the UPS is a tightly regulated process initiated by tagging a target protein with a specific ubiquitin chain. Neurons are particularly vulnerable to any change in protein composition, and therefore the UPS is a key regulator of neuronal physiology. Alterations in UPS activity may induce pathological responses, ultimately leading to neuronal cell death. Brain ischemia triggers a complex series of biochemical and molecular mechanisms, such as an inflammatory response, an exacerbated production of misfolded and oxidized proteins, due to oxidative stress, and the breakdown of cellular integrity mainly mediated by excitotoxic glutamatergic signaling. Brain ischemia also damages protein degradation pathways which, together with the overproduction of damaged proteins and consequent upregulation of ubiquitin-conjugated proteins, contribute to the accumulation of ubiquitin-containing proteinaceous deposits. Despite recent advances, the factors leading to deposition of such aggregates after cerebral ischemic injury remain poorly understood. This review discusses the current knowledge on the role of the UPS in brain function and the molecular mechanisms contributing to UPS dysfunction in brain ischemia with consequent accumulation of ubiquitin-containing proteins. Chemical inhibitors of the proteasome and small molecule inhibitors of deubiquitinating enzymes, which promote the degradation of proteins by the proteasome, were both shown to provide neuroprotection in brain ischemia, and this apparent contradiction is also discussed in this review.
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Affiliation(s)
- Margarida V Caldeira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Ivan L Salazar
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Doctoral Programme in Experimental Biology and Biomedicine, Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra (IIIUC), Portugal
| | - Michele Curcio
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Science and Technology, University of Sannio, Benevento, Italy
| | | | - Carlos B Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal.
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Guerra DD, Pratelli R, Kraft E, Callis J, Pilot G. Functional conservation between mammalian MGRN1 and plant LOG2 ubiquitin ligases. FEBS Lett 2013; 587:3400-5. [PMID: 24036454 DOI: 10.1016/j.febslet.2013.08.045] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 08/23/2013] [Accepted: 08/27/2013] [Indexed: 10/26/2022]
Abstract
Plant LOSS OF GDU 2 (LOG2) and Mammalian Mahogunin Ring Finger 1 (MGRN1) proteins are RING-type E3 ligases sharing similarity N-terminal to the RING domain. Deletion of this region disrupts the interaction of LOG2 with the plant membrane protein GLUTAMINE DUMPER1 (GDU1). Phylogenetic analysis identified two clades of LOG2/MGRN1-like proteins in vertebrates and plants. The ability of MGRN1 to functionally replace LOG2 was tested. MGRN1 ubiquitylates GDU1 in vitro and can partially substitute for LOG2 in the plant, partially restoring amino acid resistance to a GDU1-myc over-expression, log2-2 background. Altogether, these results suggest a conserved function for the N-terminal domain in evolution.
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Affiliation(s)
- Damian D Guerra
- Department of Molecular and Cellular Biology, UC Davis, Davis, CA 95616, United States; UC Davis Biochemistry, Molecular, Cellular, Developmental Biology Graduate Group, United States
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Ryšlavá H, Doubnerová V, Kavan D, Vaněk O. Effect of posttranslational modifications on enzyme function and assembly. J Proteomics 2013; 92:80-109. [PMID: 23603109 DOI: 10.1016/j.jprot.2013.03.025] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 03/01/2013] [Accepted: 03/11/2013] [Indexed: 12/22/2022]
Abstract
The detailed examination of enzyme molecules by mass spectrometry and other techniques continues to identify hundreds of distinct PTMs. Recently, global analyses of enzymes using methods of contemporary proteomics revealed widespread distribution of PTMs on many key enzymes distributed in all cellular compartments. Critically, patterns of multiple enzymatic and nonenzymatic PTMs within a single enzyme are now functionally evaluated providing a holistic picture of a macromolecule interacting with low molecular mass compounds, some of them being substrates, enzyme regulators, or activated precursors for enzymatic and nonenzymatic PTMs. Multiple PTMs within a single enzyme molecule and their mutual interplays are critical for the regulation of catalytic activity. Full understanding of this regulation will require detailed structural investigation of enzymes, their structural analogs, and their complexes. Further, proteomics is now integrated with molecular genetics, transcriptomics, and other areas leading to systems biology strategies. These allow the functional interrogation of complex enzymatic networks in their natural environment. In the future, one might envisage the use of robust high throughput analytical techniques that will be able to detect multiple PTMs on a global scale of individual proteomes from a number of carefully selected cells and cellular compartments. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.
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Affiliation(s)
- Helena Ryšlavá
- Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, CZ-12840 Prague 2, Czech Republic.
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