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Colameo D, Rajman M, Soutschek M, Bicker S, von Ziegler L, Bohacek J, Winterer J, Germain PL, Dieterich C, Schratt G. Pervasive compartment-specific regulation of gene expression during homeostatic synaptic scaling. EMBO Rep 2021; 22:e52094. [PMID: 34396684 PMCID: PMC8490987 DOI: 10.15252/embr.202052094] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 07/12/2021] [Accepted: 07/20/2021] [Indexed: 12/13/2022] Open
Abstract
Synaptic scaling is a form of homeostatic plasticity which allows neurons to adjust their action potential firing rate in response to chronic alterations in neural activity. Synaptic scaling requires profound changes in gene expression, but the relative contribution of local and cell‐wide mechanisms is controversial. Here we perform a comprehensive multi‐omics characterization of the somatic and process compartments of primary rat hippocampal neurons during synaptic scaling. We uncover both highly compartment‐specific and correlating changes in the neuronal transcriptome and proteome. Whereas downregulation of crucial regulators of neuronal excitability occurs primarily in the somatic compartment, structural components of excitatory postsynapses are mostly downregulated in processes. Local inhibition of protein synthesis in processes during scaling is confirmed for candidate synaptic proteins. Motif analysis further suggests an important role for trans‐acting post‐transcriptional regulators, including RNA‐binding proteins and microRNAs, in the local regulation of the corresponding mRNAs. Altogether, our study indicates that, during synaptic scaling, compartmentalized gene expression changes might co‐exist with neuron‐wide mechanisms to allow synaptic computation and homeostasis.
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Affiliation(s)
- David Colameo
- Laboratory of Systems Neuroscience, Institute for Neuroscience, Department of Health Science and Technology, Swiss Federal Institute of Technology ETH, Zurich, Switzerland.,Neuroscience Center Zurich, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Marek Rajman
- Institute for Physiological Chemistry, Biochemical-Pharmacological Center Marburg, Philipps-University of Marburg, Marburg, Germany
| | - Michael Soutschek
- Laboratory of Systems Neuroscience, Institute for Neuroscience, Department of Health Science and Technology, Swiss Federal Institute of Technology ETH, Zurich, Switzerland.,Neuroscience Center Zurich, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Silvia Bicker
- Laboratory of Systems Neuroscience, Institute for Neuroscience, Department of Health Science and Technology, Swiss Federal Institute of Technology ETH, Zurich, Switzerland.,Neuroscience Center Zurich, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Lukas von Ziegler
- Neuroscience Center Zurich, ETH Zurich and University of Zurich, Zurich, Switzerland.,Laboratory of Behavioural and Molecular Neuroscience, Institute for Neuroscience, Department of Health Science and Technology, Swiss Federal Institute of Technology ETH, Zurich, Switzerland
| | - Johannes Bohacek
- Neuroscience Center Zurich, ETH Zurich and University of Zurich, Zurich, Switzerland.,Laboratory of Behavioural and Molecular Neuroscience, Institute for Neuroscience, Department of Health Science and Technology, Swiss Federal Institute of Technology ETH, Zurich, Switzerland
| | - Jochen Winterer
- Laboratory of Systems Neuroscience, Institute for Neuroscience, Department of Health Science and Technology, Swiss Federal Institute of Technology ETH, Zurich, Switzerland.,Neuroscience Center Zurich, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Pierre-Luc Germain
- Institute for Neuroscience, Department of Health Science and Technology, Swiss Federal Institute of Technology ETH, Zurich, Switzerland.,Laboratory of Statistical Bioinformatics, Department of Molecular Life Sciences, University of Zürich, Zurich, Switzerland
| | - Christoph Dieterich
- Section of Bioinformatics and Systems Cardiology, Department of Internal Medicine III and Klaus Tschira Institute for Integrative Computational Cardiology, University of Heidelberg, Heidelberg, Germany
| | - Gerhard Schratt
- Laboratory of Systems Neuroscience, Institute for Neuroscience, Department of Health Science and Technology, Swiss Federal Institute of Technology ETH, Zurich, Switzerland.,Neuroscience Center Zurich, ETH Zurich and University of Zurich, Zurich, Switzerland
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2
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Shaashua L, Eckerling A, Israeli B, Yanovich G, Rosenne E, Fichman-Horn S, Ben Zvi I, Sorski L, Haldar R, Satchi-Fainaro R, Geiger T, Sloan EK, Ben-Eliyahu S. Spontaneous regression of micro-metastases following primary tumor excision: a critical role for primary tumor secretome. BMC Biol 2020; 18:163. [PMID: 33158447 PMCID: PMC7646068 DOI: 10.1186/s12915-020-00893-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 10/09/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Numerous case studies have reported spontaneous regression of recognized metastases following primary tumor excision, but underlying mechanisms are elusive. Here, we present a model of regression and latency of metastases following primary tumor excision and identify potential underlying mechanisms. RESULTS Using MDA-MB-231HM human breast cancer cells that express highly sensitive luciferase, we monitored early development stages of spontaneous metastases in BALB/c nu/nu mice. Removal of the primary tumor caused marked regression of micro-metastases, but not of larger metastases, and in vivo supplementation of tumor secretome diminished this regression, suggesting that primary tumor-secreted factors promote early metastatic growth. Correspondingly, MDA-MB-231HM-conditioned medium increased in vitro tumor proliferation and adhesion and reduced apoptosis. To identify specific mediating factors, cytokine array and proteomic analysis of MDA-MB-231HM secretome were conducted. The results identified significant enrichment of angiogenesis, growth factor binding and activity, focal adhesion, and metalloprotease and apoptosis regulation processes. Neutralization of MDA-MB-231HM-secreted key mediators of these processes, IL-8, PDGF-AA, Serpin E1 (PAI-1), and MIF, each antagonized secretome-induced proliferation. Moreover, their in vivo simultaneous blockade in the presence of the primary tumor arrested the development of micro-metastases. Interestingly, in the METABRIC cohort of breast cancer patients, elevated expression of Serpin E1, IL-8, or the four factors combined predicted poor survival. CONCLUSIONS These results demonstrate regression and latency of micro-metastases following primary tumor excision and a crucial role for primary tumor secretome in promoting early metastatic growth in MDA-MB-231HM xenografts. If generalized, such findings can suggest novel approaches to control micro-metastases and minimal residual disease.
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Affiliation(s)
- Lee Shaashua
- Sagol School of Neuroscience and School of Psychological Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Anabel Eckerling
- Sagol School of Neuroscience and School of Psychological Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Boaz Israeli
- Sagol School of Neuroscience and School of Psychological Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Gali Yanovich
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ella Rosenne
- Sagol School of Neuroscience and School of Psychological Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Suzana Fichman-Horn
- Pathology Institute, Rabin Medical Center, Tel Aviv University, Petach Tikva, Israel
| | - Ido Ben Zvi
- Neurosurgery Department, Rabin Medical Center, Tel Aviv University, Petach Tikva, Israel
| | - Liat Sorski
- Sagol School of Neuroscience and School of Psychological Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Rita Haldar
- Sagol School of Neuroscience and School of Psychological Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Ronit Satchi-Fainaro
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Tamar Geiger
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Erica K Sloan
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Shamgar Ben-Eliyahu
- Sagol School of Neuroscience and School of Psychological Sciences, Tel Aviv University, 69978, Tel Aviv, Israel.
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3
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Şengül B, Dursun E, Verkhratsky A, Gezen-Ak D. Overexpression of α-Synuclein Reorganises Growth Factor Profile of Human Astrocytes. Mol Neurobiol 2020; 58:184-203. [PMID: 32914394 DOI: 10.1007/s12035-020-02114-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 09/01/2020] [Indexed: 12/26/2022]
Abstract
Misfolding and accumulation of aberrant α-synuclein in the brain is associated with the distinct class of neurodegenerative diseases known as α-synucleinopathies, which include Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. Pathological changes in astrocytes contribute to all neurological disorders, and astrocytes are reported to possess α-synuclein inclusions in the context of α-synucleinopathies. Astrocytes are known to express and secrete numerous growth factors, which are fundamental for neuroprotection, synaptic connectivity and brain metabolism; changes in growth factor secretion may contribute to pathobiology of neurological disorders. Here we analysed the effect of α-synuclein overexpression in cultured human astrocytes on growth factor expression and release. For this purpose, the intracellular and secreted levels of 33 growth factors (GFs) and 8 growth factor receptors (GFRs) were analysed in cultured human astrocytes by chemiluminescence-based western/dot blot. Overexpression of human α-synuclein in cultured foetal human astrocytes significantly changes the profile of GF production and secretion. We found that human astrocytes express and secrete FGF2, FGF6, EGF, IGF1, AREG, IGFBP2, IGFBP4, VEGFD, PDGFs, KITLG, PGF, TGFB3 and NTF4. Overexpression of human α-synuclein significantly modified the profile of GF production and secretion, with particularly strong changes in EGF, PDGF, VEGF and their receptors as well as in IGF-related proteins. Bioinformatics analysis revealed possible interactions between α-synuclein and EGFR and GDNF, as well as with three GF receptors, EGFR, CSF1R and PDGFRB.
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Affiliation(s)
- Büşra Şengül
- Brain and Neurodegenerative Disorders Research Laboratories, Department of Medical Biology, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Erdinç Dursun
- Brain and Neurodegenerative Disorders Research Laboratories, Department of Medical Biology, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Istanbul, Turkey.,Department of Neuroscience, Institute of Neurological Sciences, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK. .,Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Duygu Gezen-Ak
- Brain and Neurodegenerative Disorders Research Laboratories, Department of Medical Biology, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Istanbul, Turkey.
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4
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Derler R, Gesslbauer B, Weber C, Strutzmann E, Miller I, Kungl A. Glycosaminoglycan-Mediated Downstream Signaling of CXCL8 Binding to Endothelial Cells. Int J Mol Sci 2017; 18:ijms18122605. [PMID: 29207576 PMCID: PMC5751208 DOI: 10.3390/ijms18122605] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 11/24/2017] [Accepted: 11/29/2017] [Indexed: 01/13/2023] Open
Abstract
The recruitment of leukocytes, mediated by endothelium bound chemokine gradients, is a vital process in inflammation. The highly negatively charged, unbranched polysaccharide family of glycosaminoglycans (GAGs), such as heparan sulfate and chondroitin sulfate mediate chemokine immobilization. Specifically the binding of CXCL8 (interleukin 8) to GAGs on endothelial cell surfaces is known to regulate neutrophil recruitment. Currently, it is not clear if binding of CXCL8 to GAGs leads to endothelial downstream signaling in addition to the typical CXCR1/CXCR2 (C-X-C motif chemokine receptor 1 and 2)-mediated signaling which activates neutrophils. Here we have investigated the changes in protein expression of human microvascular endothelial cells induced by CXCL8. Tumor necrosis factor alpha (TNFα) stimulation was used to mimic an inflammatory state which allowed us to identify syndecan-4 (SDC4) as the potential proteoglycan co-receptor of CXCL8 by gene array, real-time PCR and flow cytometry experiments. Enzymatic GAG depolymerization via heparinase III and chondroitinase ABC was used to emulate the effect of glycocalyx remodeling on CXCL8-induced endothelial downstream signaling. Proteomic analyses showed changes in the expression pattern of a number of endothelial proteins such as Zyxin and Caldesmon involved in cytoskeletal organization, cell adhesion and cell mobility. These results demonstrate for the first time a potential role of GAG-mediated endothelial downstream signaling in addition to the well-known CXCL8-CXCR1/CXCR2 signaling pathways in neutrophils.
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Affiliation(s)
- Rupert Derler
- Antagonis Biotherapeutics GmbH, Strasserhofweg 77a, 8045 Graz, Austria.
- Department of Pharmaceutical Chemistry, Institute of Pharmaceutical Sciences, University of Graz, Schubertstrasse 1, 8010 Graz, Austria.
| | - Bernd Gesslbauer
- Department of Pharmaceutical Chemistry, Institute of Pharmaceutical Sciences, University of Graz, Schubertstrasse 1, 8010 Graz, Austria.
| | - Corinna Weber
- Department of Pharmaceutical Chemistry, Institute of Pharmaceutical Sciences, University of Graz, Schubertstrasse 1, 8010 Graz, Austria.
| | - Elisabeth Strutzmann
- Department of Pharmaceutical Chemistry, Institute of Pharmaceutical Sciences, University of Graz, Schubertstrasse 1, 8010 Graz, Austria.
| | - Ingrid Miller
- Institute for Medical Biochemistry, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria.
| | - Andreas Kungl
- Antagonis Biotherapeutics GmbH, Strasserhofweg 77a, 8045 Graz, Austria.
- Department of Pharmaceutical Chemistry, Institute of Pharmaceutical Sciences, University of Graz, Schubertstrasse 1, 8010 Graz, Austria.
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5
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Abstract
The myosin holoenzyme is a multimeric protein complex consisting of heavy chains and light chains. Myosin light chains are calmodulin family members which are crucially involved in the mechanoenzymatic function of the myosin holoenzyme. This review examines the diversity of light chains within the myosin superfamily, discusses interactions between the light chain and the myosin heavy chain as well as regulatory and structural functions of the light chain as a subunit of the myosin holoenzyme. It covers aspects of the myosin light chain in the localization of the myosin holoenzyme, protein-protein interactions and light chain binding to non-myosin binding partners. Finally, this review challenges the dogma that myosin regulatory and essential light chain exclusively associate with conventional myosin heavy chains while unconventional myosin heavy chains usually associate with calmodulin.
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Affiliation(s)
- Sarah M Heissler
- a Laboratory of Molecular Physiology; National Heart, Lung, and Blood Institute; National Institutes of Health ; Bethesda , MD USA
| | - James R Sellers
- a Laboratory of Molecular Physiology; National Heart, Lung, and Blood Institute; National Institutes of Health ; Bethesda , MD USA
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6
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Nagano K, Akpan A, Warnasuriya G, Corless S, Totty N, Yang A, Stein R, Zvelebil M, Stensballe A, Burlingame A, Waterfield M, Cramer R, Timms JF, Naaby-Hansen S. Functional proteomic analysis of long-term growth factor stimulation and receptor tyrosine kinase coactivation in Swiss 3T3 fibroblasts. Mol Cell Proteomics 2012; 11:1690-708. [PMID: 22956732 DOI: 10.1074/mcp.m112.019778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Swiss 3T3 fibroblasts, long-term stimulation with PDGF, but not insulin-like growth factor 1 (IGF-1) or EGF, results in the establishment of an elongated migratory phenotype, characterized by the formation of retractile dendritic protrusions and absence of actin stress fibers and focal adhesion complexes. To identify receptor tyrosine kinase-specific reorganization of the Swiss 3T3 proteome during phenotypic differentiation, we compared changes in the pattern of protein synthesis and phosphorylation during long-term exposure to PDGF, IGF-1, EGF, and their combinations using 2DE-based proteomics after (35)S- and (33)P-metabolic labeling. One hundred and five differentially regulated proteins were identified by mass spectrometry and some of these extensively validated. PDGF stimulation produced the highest overall rate of protein synthesis at any given time and induced the most sustained phospho-signaling. Simultaneous activation with two or three of the growth factors revealed both synergistic and antagonistic effects on protein synthesis and expression levels with PDGF showing dominance over both IGF-1 and EGF in generating distinct proteome compositions. Using signaling pathway inhibitors, PI3K was identified as an early site for signal diversification, with sustained activity of the PI3K/AKT pathway critical for regulating late protein synthesis and phosphorylation of target proteins and required for maintaining the PDGF-dependent motile phenotype. Several proteins were identified with novel PI3K/Akt-dependent synthesis and phosphorylations including eEF2, PRS7, RACK-1, acidic calponin, NAP1L1, Hsp73, and fascin. The data also reveal induction/suppression of key F-actin and actomyosin regulators and chaperonins that enable PDGFR to direct the assembly of a motile cytoskeleton, despite simultaneous antagonistic signaling activities. Together, the study demonstrates that long-term exposure to different growth factors results in receptor tyrosine kinase-specific regulation of relatively small subproteomes, and implies that the strength and longevity of receptor tyrosine kinase-specific signals are critical in defining the composition and functional activity of the resulting proteome.
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Affiliation(s)
- Kohji Nagano
- Discovery Research Department, Chugai Pharmaceutical Co. Ltd., Japan
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7
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Ball SG, Shuttleworth A, Kielty CM. Inhibition of platelet-derived growth factor receptor signaling regulates Oct4 and Nanog expression, cell shape, and mesenchymal stem cell potency. Stem Cells 2012; 30:548-60. [PMID: 22213560 PMCID: PMC3537888 DOI: 10.1002/stem.1015] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Defining the signaling mechanisms that regulate the fate of adult stem cells is an essential step toward their use in regenerative medicine. Platelet-derived growth factor receptor (PDGFR) signaling plays a crucial role in specifying mesenchymal stem cell (MSC) commitment to mesenchymal lineages. Based on the hypothesis that selective inhibition of signaling pathways involved in differentiation may increase stem cell potency, we examined the role of PDGFR signaling in controlling the fate of human MSCs. Using a small molecular PDGFR inhibitor that induced MSCs toward a more rounded shape, expression of Oct4 and Nanog were markedly upregulated. In these PDGFR inhibitor-treated MSCs, Oct4 and Nanog expression and cell shape were regulated by janus kinase (JAK), MAPK kinase (MEK), and epidermal growth factor receptor (EGFR) signaling. Under defined differentiation conditions, these PDGFR-inhibited MSCs expressed definitive endodermal, ectodermal, and mesodermal markers. We also confirmed that depletion of individual PDGF receptors upregulated expression of Oct4A and Nanog. This study identifies PDGFR signaling as a key regulator of Oct4 and Nanog expression and of MSC potency. Thus, inhibiting these specific receptor tyrosine kinases, which play essential roles in tissue formation, offers a novel approach to unlock the therapeutic capacity of MSCs. STEM CELLS 2012;30:548–560
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Affiliation(s)
- Stephen G Ball
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester, UK
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8
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Abstract
Post-translational modifications are used by cells to link additional information to proteins. Most modifications are subtle and concern small moieties such as a phosphate group or a lipid. In contrast, protein ubiquitylation entails the covalent attachment of a full-length protein such as ubiquitin. The protein ubiquitylation machinery is remarkably complex, comprising more than 15 Ubls (ubiquitin-like proteins) and several hundreds of ubiquitin-conjugating enzymes. Ubiquitin is best known for its role as a tag that induces protein destruction either by the proteasome or through targeting to lysosomes. However, addition of one or more Ubls also affects vesicular traffic, protein-protein interactions and signal transduction. It is by now well established that ubiquitylation is a component of most, if not all, cellular signalling pathways. Owing to its abundance in controlling cellular functions, ubiquitylation is also of key relevance to human pathologies, including cancer and inflammation. In the present review, we focus on its role in the control of cell adhesion, polarity and directional migration. It will become clear that protein modification by Ubls occurs at every level from the receptors at the plasma membrane down to cytoskeletal components such as actin, with differential consequences for the pathway's final output. Since ubiquitylation is fast as well as reversible, it represents a bona fide signalling event, which is used to fine-tune a cell's responses to receptor agonists.
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9
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Do HT, Tselykh TV, Mäkelä J, Ho TH, Olkkonen VM, Bornhauser BC, Korhonen L, Zelcer N, Lindholm D. Fibroblast growth factor-21 (FGF21) regulates low-density lipoprotein receptor (LDLR) levels in cells via the E3-ubiquitin ligase Mylip/Idol and the Canopy2 (Cnpy2)/Mylip-interacting saposin-like protein (Msap). J Biol Chem 2012; 287:12602-11. [PMID: 22378787 DOI: 10.1074/jbc.m112.341248] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The LDLR is a critical factor in the regulation of blood cholesterol levels that are altered in different human diseases. The level of LDLR in the cell is regulated by both transcriptional and post-transcriptional events. The E3 ubiquitin ligase, myosin regulatory light chain-interacting protein (Mylip)/inducible degrader of the LDL-R (Idol) was shown to induce degradation of LDLR via protein ubiquitination. We have here studied novel factors and mechanisms that may regulate Mylip/Idol in human hepatocyte cells and in mouse macrophages. We observed that FGF21 that is present in serum in different conditions reduced Mylip/Idol at the RNA and protein level, and increased LDLR levels and stability in the cells. FGF21 also enhanced expression of Canopy2 (Cnpy2)/MIR-interacting Saposin-like protein (Msap) that is known to interact with Mylip/Idol. Overexpression of Cnpy2/Msap increased LDLRs, and knockdown experiments showed that Cnpy2/Msap is crucial for the FGF21 effect on LDLRs. Experiments using DiI-labeled LDL particles showed that FGF21 increased lipoprotein uptake and the effect of FGF21 was additive to that of statins. Our results are consistent with an important role of FGF21 and Cnpy2/Msap in the regulation of LDLRs in cultured cells, which warrants further studies using human samples.
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Affiliation(s)
- Hai Thi Do
- Institute of Biomedicine/Biochemistry and Developmental Biology, University of Helsinki, Haartmaninkatu 8, FIN-00290 Helsinki, Finland
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10
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Farooqi AA, Waseem S, Riaz AM, Dilawar BA, Mukhtar S, Minhaj S, Waseem MS, Daniel S, Malik BA, Nawaz A, Bhatti S. PDGF: the nuts and bolts of signalling toolbox. Tumour Biol 2011; 32:1057-70. [PMID: 21769672 DOI: 10.1007/s13277-011-0212-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2011] [Accepted: 07/07/2011] [Indexed: 12/16/2022] Open
Abstract
PDGF is a growth factor and is extensively involved in multi-dimensional cellular dynamics. It switches on a plethora of molecules other than its classical pathway. It is engaged in various transitions of development; however, if the unleashed potentials lead astray, it brings forth tumourigenesis. Conventionally, it has been assumed that the components of this signalling pathway show fidelity and act with a high degree of autonomy. However, as illustrated by the PDGF signal transduction, reinterpretation of recent data suggests that machinery is often shared between multiple pathways, and other components crosstalk to each other through multiple mechanisms. It is important to note that metastatic cascade is an intricate process that we have only begun to understand in recent years. Many of the early steps of this PDGF cascade are not readily targetable in the clinic. In this review, we will unravel the paradoxes with reference to mitrons and cellular plasticity and discuss how disruption of signalling cascade triggers cellular proliferation phase transition and metastasis. We will also focus on the therapeutic interventions to counteract resultant molecular disorders.
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Affiliation(s)
- Ammad Ahmad Farooqi
- Institute of Molecular Biology and Biotechnology (IMBB), The University of Lahore, 1 km defence road, Lahore, Pakistan.
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11
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Lindholm D, Bornhauser BC, Korhonen L. Mylip makes an Idol turn into regulation of LDL receptor. Cell Mol Life Sci 2009; 66:3399-402. [PMID: 19688294 PMCID: PMC11115883 DOI: 10.1007/s00018-009-0127-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 07/30/2009] [Accepted: 08/04/2009] [Indexed: 01/29/2023]
Abstract
High blood low-density-lipoprotein (LDL) cholesterol is a serious health problem among an increased number of patients in the Western world. Statins and other cholesterol lowering drugs have proven to be beneficial as therapy but are not optimal and show adverse effects in some patients. The LDL receptor is a crucial determinant of cholesterol metabolism in the body and amenable for drug interventions. Novel insights into the physiology of this receptor come from studies on the ubiquitination and degradation of LDL receptor by the ubiquitin ligase Mylip/Idol that is induced in cells by the nuclear receptor, LXR. This may open up new possibilities in the future to influence LDL receptor levels and cholesterol metabolism pharmacologically in various diseases.
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Affiliation(s)
- Dan Lindholm
- Minerva Medical Research Institute, Biomedicum-2, Helsinki University, Stockholmsgatan 8, 00290 Helsinki, Finland.
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12
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Meima ME, Webb BA, Witkowska HE, Barber DL. The sodium-hydrogen exchanger NHE1 is an Akt substrate necessary for actin filament reorganization by growth factors. J Biol Chem 2009; 284:26666-75. [PMID: 19622752 DOI: 10.1074/jbc.m109.019448] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The kinase Akt mediates signals from growth factor receptors for increased cell proliferation, survival, and migration, which contribute to the positive effects of Akt in cancer progression. Substrates are generally inhibited when phosphorylated by Akt; however, we show phosphorylation of the plasma membrane sodium-hydrogen exchanger NHE1 by Akt increases exchanger activity (H(+) efflux). Our data fulfill criteria for NHE1 being a bona fide Akt substrate, including direct phosphorylation in vitro, using mass spectrometry and Akt phospho-substrate antibodies to identify Ser(648) as the Akt phosphorylation site and loss of increased exchanger phosphorylation and activity by insulin and platelet-derived growth factor in fibroblasts expressing a mutant NHE1-S648A. How Akt induces actin cytoskeleton remodeling to promote cell migration and tumor cell metastasis is unclear, but disassembly of actin stress fibers by platelet-derived growth factor and insulin and increased proliferation in growth medium are inhibited in fibroblasts expressing NHE1-S648A. We predict that other functions shared by Akt and NHE1, including cell growth and survival, might be regulated by increased H(+) efflux.
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Affiliation(s)
- Marcel E Meima
- Department of Cell and Tissue Biology, University of California, San Francisco, California 94143, USA
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13
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Identification of c-Src tyrosine kinase substrates in platelet-derived growth factor receptor signaling. Mol Oncol 2009; 3:439-50. [PMID: 19632164 DOI: 10.1016/j.molonc.2009.07.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2009] [Revised: 06/17/2009] [Accepted: 07/04/2009] [Indexed: 11/20/2022] Open
Abstract
c-Src non-receptor tyrosine kinase is an important component of the platelet-derived growth factor (PDGF) receptor signaling pathway. c-Src has been shown to mediate the mitogenic response to PDGF in fibroblasts. However, the exact components of PDGF receptor signaling pathway mediated by c-Src remain unclear. Here, we used stable isotope labeling with amino acids in cell culture (SILAC) coupled with mass spectrometry to identify Src-family kinase substrates involved in PDGF signaling. Using SILAC, we were able to detect changes in tyrosine phosphorylation patterns of 43 potential c-Src kinase substrates in PDGF receptor signaling. This included 23 known c-Src kinase substrates, of which 16 proteins have known roles in PDGF signaling while the remaining 7 proteins have not previously been implicated in PDGF receptor signaling. Importantly, our analysis also led to identification of 20 novel Src-family kinase substrates, of which 5 proteins were previously reported as PDGF receptor signaling pathway intermediates while the remaining 15 proteins represent novel signaling intermediates in PDGF receptor signaling. In validation experiments, we demonstrated that PDGF indeed induced the phosphorylation of a subset of candidate Src-family kinase substrates - Calpain 2, Eps15 and Trim28 - in a c-Src-dependent fashion.
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14
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Bajaj G, Zhang Y, Schimerlik MI, Hau AM, Yang J, Filtz TM, Kioussi C, Ishmael JE. N-methyl-D-aspartate receptor subunits are non-myosin targets of myosin regulatory light chain. J Biol Chem 2009; 284:1252-66. [PMID: 18945678 PMCID: PMC2613636 DOI: 10.1074/jbc.m801861200] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 10/07/2008] [Indexed: 12/29/2022] Open
Abstract
Excitatory synapses contain multiple members of the myosin superfamily of molecular motors for which functions have not been assigned. In this study we characterized the molecular determinants of myosin regulatory light chain (RLC) binding to two major subunits of the N-methyl-d-aspartate receptor (NR). Myosin RLC bound to NR subunits in a manner that could be distinguished from the interaction of RLC with the neck region of non-muscle myosin II-B (NMII-B) heavy chain; NR-RLC interactions did not require the addition of magnesium, were maintained in the absence of the fourth EF-hand domain of the light chain, and were sensitive to RLC phosphorylation. Equilibrium fluorescence spectroscopy experiments indicate that the affinity of myosin RLC for NR1 is high (30 nm) in the context of the isolated light chain. Binding was not favored in the context of a recombinant NMII-B subfragment one, indicating that if the RLC is already bound to NMII-B it is unlikely to form a bridge between two binding partners. We report that sequence similarity in the "GXXXR" portion of the incomplete IQ2 motif found in NMII heavy chain isoforms likely contributes to recognition of NR2A as a non-myosin target of the RLC. Using site-directed mutagenesis to disrupt NR2A-RLC binding in intact cells, we find that RLC interactions facilitate trafficking of NR1/NR2A receptors to the cell membrane. We suggest that myosin RLC can adopt target-dependent conformations and that a role for this light chain in protein trafficking may be independent of the myosin II complex.
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Affiliation(s)
- Gaurav Bajaj
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331, USA
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15
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Komatsu S, Ikebe M. The phosphorylation of myosin II at the Ser1 and Ser2 is critical for normal platelet-derived growth factor induced reorganization of myosin filaments. Mol Biol Cell 2007; 18:5081-90. [PMID: 17928407 DOI: 10.1091/mbc.e06-12-1076] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phosphorylation of the regulatory light chain of myosin II (MLC(20)) at the activation sites promotes both the motor activity and the filament formation of myosin II, thus playing an important role in various cell motile processes. In contrast, the physiological function of phosphorylation of MLC(20) at the inhibitory sites is unknown. Here we report for the first time the function of the inhibitory site phosphorylation in the cells. We successfully produced the antibodies specifically recognizing the phosphorylation sites of MLC(20) at Ser1, and the platelet-derived growth factor (PDGF)-induced change in the phosphorylation at the Ser1 was monitored. The phosphorylation of MLC(20) at the Ser1 significantly increased during the PDGF-induced actin cytoskeletal reorganization. PDGF disassembled the stress fibers, and this was attenuated with the expression of unphosphorylatable MLC(20) at the Ser1/Ser2 phosphorylation sites. The present results suggest that the down-regulation of myosin II activity achieved by the phosphorylation at the Ser1/Ser2 sites plays an important role in the normal reorganization of actomyosin filaments triggered by PDGF receptor stimulation.
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Affiliation(s)
- Satoshi Komatsu
- Department of Physiology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
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16
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Schebesta A, McManus S, Salvagiotto G, Delogu A, Busslinger GA, Busslinger M. Transcription factor Pax5 activates the chromatin of key genes involved in B cell signaling, adhesion, migration, and immune function. Immunity 2007; 27:49-63. [PMID: 17658281 DOI: 10.1016/j.immuni.2007.05.019] [Citation(s) in RCA: 201] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 05/21/2007] [Accepted: 05/24/2007] [Indexed: 01/03/2023]
Abstract
The transcription factor Pax5 represses B lineage-inappropriate genes and activates B cell-specific genes in B lymphocytes. Here we have identified 170 Pax5-activated genes. Conditional mutagenesis demonstrated that the Pax5-regulated genes require continuous Pax5 activity for normal expression in pro-B and mature B cells. Expression of half of the Pax5-activated genes is either absent or substantially reduced upon Pax5 loss in plasma cells. Direct Pax5 target genes were identified based on their protein synthesis-independent activation by a Pax5-estrogen receptor fusion protein. Chromatin immunoprecipitation (ChIP) of Pax5 together with chromatin profiling by ChIP-on-chip analysis demonstrated that Pax5 directly activates the chromatin at promoters or putative enhancers of Pax5 target genes. The Pax5-activated genes code for key regulatory and structural proteins involved in B cell signaling, adhesion, migration, antigen presentation, and germinal-center B cell formation, thus revealing a complex regulatory network that is activated by Pax5 to control B cell development and function.
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Affiliation(s)
- Alexandra Schebesta
- Research Institute of Molecular Pathology, Vienna Biocenter, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria
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17
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Inoue A, Sawata SY, Taira K, Wadhwa R. Loss-of-function screening by randomized intracellular antibodies: identification of hnRNP-K as a potential target for metastasis. Proc Natl Acad Sci U S A 2007; 104:8983-8. [PMID: 17483488 PMCID: PMC1885614 DOI: 10.1073/pnas.0607595104] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have developed a loss-of-function screening system on the basis of intracellular expression of single domain antibodies. We demonstrate its use in identification of potential targets of metastasis of human cancerous cells. Randomized intracellular antibodies were expressed in highly metastatic cells, and a derivative pool of cells with loss of migration phenotype in chemotaxis assay was isolated. Isolation of antibodies from cells with loss of migration phenotype and identification of their target proteins revealed the involvement of the heterogeneous nuclear ribonucleoprotein K (hnRNP-K), a multifunctional signaling protein, in metastasis. Furthermore, we found that the cytoplasmic accumulation of hnRNP-K is crucial for its role in metastasis. The results demonstrate (i) the advantages of our functional interference screening over the gene-knockouts and gene-silencing, (ii) hnRNP-K as a potential target of metastasis, and (iii) a potential anti-metastasis peptide validated in in vitro cell migration assays.
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Affiliation(s)
- Atsushi Inoue
- National Institute of Advanced Industrial Science and Technology (AIST), Central 4, 1-1-1 Higashi, Tsukuba Science City 305-8562, Japan.
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