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Carbone A, De Santis E, Cela O, Giambra V, Miele L, Marrone G, Grieco A, Buschbeck M, Capitanio N, Mazza T, Mazzoccoli G. The Histone Variant MacroH2A1 Impacts Circadian Gene Expression and Cell Phenotype in an In Vitro Model of Hepatocellular Carcinoma. Biomedicines 2021; 9:biomedicines9081057. [PMID: 34440260 PMCID: PMC8391426 DOI: 10.3390/biomedicines9081057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 08/18/2021] [Accepted: 08/19/2021] [Indexed: 12/21/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. A foremost risk factor for HCC is obesity/metabolic syndrome-related non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH), which is prompted by remarkable changes in transcription patterns of genes enriching metabolic, immune/inflammatory, and circadian pathways. Epigenetic mechanisms play a role in NAFLD-associated HCC, and macroH2A1, a variant of histone H2A, is involved in the pathogenesis modulating the expression of oncogenes and/or tumor suppressor genes and interacting with SIRT1, which crucially impacts the circadian clock circuitry. Hence, we aimed to appraise if and how macroH2A1 regulated the expression patterns of circadian genes in the setting of NAFLD-associated HCC. We took advantage of an in vitro model of liver cancer represented by HepG2 (human hepatocarcinoma) cells stably knocked down for macroH2A1 and conducted whole transcriptome profiling and deep phenotyping analysis. We found up-regulation of PER1 along with several deregulated circadian genes, enriching several important pathways and functions related to cancer onset and progression, such as epithelial-to-mesenchymal transition, cell cycle deregulation, and DNA damage. PER1 silencing partially mitigated the malignant phenotype induced by the loss of macroH2A1 in HCC cells. In conclusion, our findings suggest a modulatory role for the core circadian protein PER1 in liver carcinogenesis in the context of a lack of the macroH2A1 epigenetic and transcriptional landscape.
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Affiliation(s)
- Annalucia Carbone
- Department of Medical Sciences, Division of Internal Medicine and Chronobiology Laboratory, Fondazione IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy;
| | - Elisabetta De Santis
- Institute for Stem Cell Biology, Regenerative Medicine and Innovative Therapies (ISBReMIT), Fondazione IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; (E.D.S.); (V.G.)
| | - Olga Cela
- Department of Clinical and Experimental Medicine, University of Foggia, 71100 Foggia, Italy; (O.C.); (N.C.)
| | - Vincenzo Giambra
- Institute for Stem Cell Biology, Regenerative Medicine and Innovative Therapies (ISBReMIT), Fondazione IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; (E.D.S.); (V.G.)
| | - Luca Miele
- Fondazione Policlinico Universitario A. Gemelli-IRCCS, Catholic University of the Sacred Heart, 00168 Rome, Italy; (L.M.); (G.M.); (A.G.)
| | - Giuseppe Marrone
- Fondazione Policlinico Universitario A. Gemelli-IRCCS, Catholic University of the Sacred Heart, 00168 Rome, Italy; (L.M.); (G.M.); (A.G.)
| | - Antonio Grieco
- Fondazione Policlinico Universitario A. Gemelli-IRCCS, Catholic University of the Sacred Heart, 00168 Rome, Italy; (L.M.); (G.M.); (A.G.)
| | - Marcus Buschbeck
- Josep Carreras Leukaemia Research Institute, IJC Building, Can Ruti Campus Ctra de Can Ruti, Camí de les Escoles s/n, 08916 Badalona, Spain;
| | - Nazzareno Capitanio
- Department of Clinical and Experimental Medicine, University of Foggia, 71100 Foggia, Italy; (O.C.); (N.C.)
| | - Tommaso Mazza
- Bioinformatics Unit, Fondazione IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy;
| | - Gianluigi Mazzoccoli
- Department of Medical Sciences, Division of Internal Medicine and Chronobiology Laboratory, Fondazione IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy;
- Correspondence: ; Tel./Fax: +39-(0882)-410-255
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Batt SM, Burke CE, Moorey AR, Besra GS. Antibiotics and resistance: the two-sided coin of the mycobacterial cell wall. Cell Surf 2020; 6:100044. [PMID: 32995684 PMCID: PMC7502851 DOI: 10.1016/j.tcsw.2020.100044] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/26/2020] [Accepted: 08/26/2020] [Indexed: 01/07/2023] Open
Abstract
Mycobacterium tuberculosis, the bacterium responsible for tuberculosis, is the global leading cause of mortality from an infectious agent. Part of this success relies on the unique cell wall, which consists of a thick waxy coat with tightly packed layers of complexed sugars, lipids and peptides. This coat provides a protective hydrophobic barrier to antibiotics and the host's defences, while enabling the bacterium to spread efficiently through sputum to infect and survive within the macrophages of new hosts. However, part of this success comes at a cost, with many of the current first- and second-line drugs targeting the enzymes involved in cell wall biosynthesis. The flip side of this coin is that resistance to these drugs develops either in the target enzymes or the activation pathways of the drugs, paving the way for new resistant clinical strains. This review provides a synopsis of the structure and synthesis of the cell wall and the major current drugs and targets, along with any mechanisms of resistance.
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Affiliation(s)
- Sarah M. Batt
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Christopher E. Burke
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Alice R. Moorey
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Gurdyal S. Besra
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Schrecker M, Korobenko J, Hite RK. Cryo-EM structure of the lysosomal chloride-proton exchanger CLC-7 in complex with OSTM1. eLife 2020; 9:e59555. [PMID: 32749217 PMCID: PMC7440919 DOI: 10.7554/elife.59555] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/29/2020] [Indexed: 01/21/2023] Open
Abstract
The chloride-proton exchanger CLC-7 plays critical roles in lysosomal homeostasis and bone regeneration and its mutation can lead to osteopetrosis, lysosomal storage disease and neurological disorders. In lysosomes and the ruffled border of osteoclasts, CLC-7 requires a β-subunit, OSTM1, for stability and activity. Here, we present electron cryomicroscopy structures of CLC-7 in occluded states by itself and in complex with OSTM1, determined at resolutions up to 2.8 Å. In the complex, the luminal surface of CLC-7 is entirely covered by a dimer of the heavily glycosylated and disulfide-bonded OSTM1, which serves to protect CLC-7 from the degradative environment of the lysosomal lumen. OSTM1 binding does not induce large-scale rearrangements of CLC-7, but does have minor effects on the conformation of the ion-conduction pathway, potentially contributing to its regulatory role. These studies provide insights into the role of OSTM1 and serve as a foundation for understanding the mechanisms of CLC-7 regulation.
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Affiliation(s)
- Marina Schrecker
- Structural Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
| | - Julia Korobenko
- Structural Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
| | - Richard K Hite
- Structural Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
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Papadopoulos T, Schemm R, Grubmüller H, Brose N. Lipid binding defects and perturbed synaptogenic activity of a Collybistin R290H mutant that causes epilepsy and intellectual disability. J Biol Chem 2015; 290:8256-70. [PMID: 25678704 DOI: 10.1074/jbc.m114.633024] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Signaling at nerve cell synapses is a key determinant of proper brain function, and synaptic defects--or synaptopathies--are at the basis of many neurological and psychiatric disorders. In key areas of the mammalian brain, such as the hippocampus or the basolateral amygdala, the clustering of the scaffolding protein Gephyrin and of γ-aminobutyric acid type A receptors at inhibitory neuronal synapses is critically dependent upon the brain-specific guanine nucleotide exchange factor Collybistin (Cb). Accordingly, it was discovered recently that an R290H missense mutation in the diffuse B-cell lymphoma homology domain of Cb, which carries the guanine nucleotide exchange factor activity, leads to epilepsy and intellectual disability in human patients. In the present study, we determined the mechanism by which the Cb(R290H) mutation perturbs inhibitory synapse formation and causes brain dysfunction. Based on a combination of biochemical, cell biological, and molecular dynamics simulation approaches, we demonstrate that the R290H mutation alters the strength of intramolecular interactions between the diffuse B-cell lymphoma homology domain and the pleckstrin homology domain of Cb. This defect reduces the phosphatidylinositol 3-phosphate binding affinity of Cb, which limits its normal synaptogenic activity. Our data indicate that impairment of the membrane lipid binding activity of Cb and a consequent defect in inhibitory synapse maturation represent a likely molecular pathomechanism of epilepsy and mental retardation in humans.
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Affiliation(s)
- Theofilos Papadopoulos
- From the Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany, and
| | - Rudolf Schemm
- the Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Helmut Grubmüller
- the Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Nils Brose
- From the Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany, and
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Abstract
Phosphoinositides (PIs) are minor lipid components of cellular membranes that play critical roles in membrane dynamics, trafficking, and cellular signaling. Among the seven naturally occurring PIs, the monophosphate phosphatidylinositol 3-phosphate (PtdIns3P) and the bisphosphate phosphatidylinositol 3,5-bisphosphate [PtdIns(3,5)P2] have been mainly associated with endosomes and endosomal functions. Metabolic labeling and HPLC analysis revealed that a bulk of PtdIns3P is constitutively present in cells, making it the only detectable product of the enzymes phosphoinositide 3-kinases in unstimulated, normal cells. The use of specific tagged-PtdIns3P-binding domains later demonstrated that this constitutive PtdIns3P accumulates in endosomes where it critically regulates trafficking and membrane dynamics.
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Affiliation(s)
- Tania Maffucci
- Inositide Signalling Group, Centre for Diabetes, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Marco Falasca
- Inositide Signalling Group, Centre for Diabetes, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.
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Catimel B, Kapp E, Yin MX, Gregory M, Wong LSM, Condron M, Church N, Kershaw N, Holmes AB, Burgess AW. The PI(3)P interactome from a colon cancer cell. J Proteomics 2013; 82:35-51. [DOI: 10.1016/j.jprot.2013.01.031] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 12/21/2012] [Accepted: 01/24/2013] [Indexed: 02/07/2023]
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Cordeiro A, Souza LL, Einicker-Lamas M, Pazos-Moura CC. Non-classic thyroid hormone signalling involved in hepatic lipid metabolism. J Endocrinol 2013; 216:R47-57. [PMID: 23297113 DOI: 10.1530/joe-12-0542] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Thyroid hormones are important modulators of lipid metabolism because the liver is a primary hormonal target. The hypolipidaemic effects of thyroid hormones result from the balance between direct and indirect actions resulting in stimulation of lipid synthesis and lipid oxidation, which favours degradation pathways. Originally, it was believed that thyroid hormone activity was only transduced by alteration of gene transcription mediated by the nuclear receptor thyroid hormone receptors, comprising the classic action of thyroid hormone. However, the discovery of other effects independent of this classic mechanism characterised a new model of thyroid hormone action, the non-classic mechanism that involves other signalling pathways. To date, this mechanism and its relevance have been intensively described. Considering the increasing evidence for non-classic signalling of thyroid hormones and the major influence of these hormones in the regulation of lipid metabolism, we reviewed the role of thyroid hormone in cytosolic signalling cascades, focusing on the regulation of second messengers, and the activity of effector proteins and the implication of these mechanisms on the control of hepatic lipid metabolism.
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Affiliation(s)
- Aline Cordeiro
- Biophysics Institute Carlos Chagas Filho, Federal University of Rio de Janeiro, Centro de Ciências da Saúde, Avenida Carlos Chagas Filho, 373, Bloco G, Cidade Universitária - Ilha do Fundão, Rio de Janeiro - RJ 21941-902, Brazil.
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Abstract
PtdIns3P is recognized as an important player in the control of the endocytotic pathway and in autophagy. Recent data also suggest that PtdIns3P contributes to molecular mechanisms taking place at the plasma membrane and at the midbody during cytokinesis. This lipid is present in low amounts in mammalian cells and remains difficult to quantify either by traditional techniques based on radiolabelling followed by HPLC to separate the different phosphatidylinositol monophosphates, or by high-sensitive liquid chromatography coupled to MS, which is still under development. In the present study, we describe a mass assay to quantify this lipid from various biological samples using the recombinant PtdIns3P 5-kinase, PIKfyve. Using this assay, we show an increase in the mass level of PtdIns3P in mouse and human platelets following stimulation, loss of this lipid in Vps34-deficient yeasts and its relative enrichment in early endosomes isolated from BHK cells.
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Abstract
Phosphoinositides (PIs) are minor components of cellular membranes that play critical regulatory roles in several intracellular functions. This chapter describes the main enzymes regulating the turnover of each of the seven PIs in mammalian cells and introduces to some of their intracellular functions and to some evidences of their involvement in human diseases. Due to the complex interrelation between the distinct PIs and the plethora of functions that they can regulate inside a cell, this chapter is not meant to be a comprehensive coverage of all aspects of PI signalling but rather an introduction to this complex signalling field. For more details of their regulation/functions and extensive description of their intracellular roles, more detailed reviews are suggested on each single topic.
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Affiliation(s)
- Tania Maffucci
- Centre for Diabetes, Blizard Institute, Inositide Signalling Group, Queen Mary University of London, Barts and The London School of Medicine and Dentistry, UK.
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10
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Papadopoulos T, Soykan T. The role of collybistin in gephyrin clustering at inhibitory synapses: facts and open questions. Front Cell Neurosci 2011; 5:11. [PMID: 21738498 PMCID: PMC3125517 DOI: 10.3389/fncel.2011.00011] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 06/13/2011] [Indexed: 11/13/2022] Open
Abstract
Collybistin (Cb) is a brain-specific GDP/GTP-exchange factor, which interacts with the inhibitory receptor anchoring protein gephyrin. Data from mice carrying an inactivated Cb gene indicate that Cb is required for the formation and maintenance of gephyrin and gephyrin-dependent GABA(A) receptor (GABA(A)R) clusters at inhibitory postsynapses in selected regions of the mammalian forebrain. However, important aspects of how Cb's GDP/GTP-exchange activity, structure, and regulation contribute to gephyrin and GABA(A)R clustering, as well as its role in synaptic plasticity, remain poorly understood. Here we review the current state of knowledge about Cb's function and address open questions concerning its contribution to synapse formation, maintenance, plasticity, and adaptive changes in response to altered network activity.
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Affiliation(s)
- Theofilos Papadopoulos
- Department of Molecular Neurobiology, Max-Planck Institute of Experimental Medicine , Göttingen, Germany
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11
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Abstract
Phosphoinositide 3-kinases (PI3Ks) function early in intracellular signal transduction pathways and affect many biological functions. A further level of complexity derives from the existence of eight PI3K isoforms, which are divided into class I, class II and class III PI3Ks. PI3K signalling has been implicated in metabolic control, immunity, angiogenesis and cardiovascular homeostasis, and is one of the most frequently deregulated pathways in cancer. PI3K inhibitors have recently entered clinical trials in oncology. A better understanding of how the different PI3K isoforms are regulated and control signalling could uncover their roles in pathology and reveal in which disease contexts their blockade could be most beneficial.
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Morita YS, Yamaryo-Botte Y, Miyanagi K, Callaghan JM, Patterson JH, Crellin PK, Coppel RL, Billman-Jacobe H, Kinoshita T, McConville MJ. Stress-induced synthesis of phosphatidylinositol 3-phosphate in mycobacteria. J Biol Chem 2010; 285:16643-50. [PMID: 20364020 DOI: 10.1074/jbc.m110.119263] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Phosphoinositides play key roles in regulating membrane dynamics and intracellular signaling in eukaryotic cells. However, comparable lipid-based signaling pathways have not been identified in bacteria. Here we show that Mycobacterium smegmatis and other Actinomycetes bacteria can synthesize the phosphoinositide, phosphatidylinositol 3-phosphate (PI3P). This lipid was transiently labeled with [(3)H]inositol. Sensitivity of the purified lipid to alkaline phosphatase, headgroup analysis by high-pressure liquid chromatography, and mass spectrometry demonstrated that it had the structure 1,2-[tuberculostearoyl, octadecenoyl]-sn-glycero 3-phosphoinositol 3-phosphate. Synthesis of PI3P was elevated by salt stress but not by exposure to high concentrations of non-ionic solutes. Synthesis of PI3P in a cell-free system was stimulated by the synthesis of CDP-diacylglycerol, a lipid substrate for phosphatidylinositol (PI) biosynthesis, suggesting that efficient cell-free PI3P synthesis is dependent on de novo PI synthesis. In vitro experiments further indicated that the rapid turnover of this lipid was mediated, at least in part, by a vanadate-sensitive phosphatase. This is the first example of de novo synthesis of PI3P in bacteria, and the transient synthesis in response to environmental stimuli suggests that some bacteria may have evolved similar lipid-mediated signaling pathways to those observed in eukaryotic cells.
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Affiliation(s)
- Yasu S Morita
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, Parkville, Victoria 3010, Australia.
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Falasca M, Maffucci T. Rethinking phosphatidylinositol 3-monophosphate. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:1795-803. [PMID: 19852987 DOI: 10.1016/j.bbamcr.2009.10.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/13/2009] [Revised: 10/06/2009] [Accepted: 10/13/2009] [Indexed: 11/27/2022]
Abstract
A generally accepted view considers phosphatidylinositol 3-monophosphate (PtdIns3P) as a lipid confined to the endosomal compartment where it regulates trafficking pathways and is produced constitutively and exclusively by class III phosphoinositide 3-kinase (PI3K). Recent evidence suggests that this phosphoinositide has a more complex role as a second messenger involved in different physiological and pathological events and that specific intracellular localization of kinases and/or phosphatases is critical for PtdIns3P synthesis and PtdIns3P-dependent intracellular functions. Here, we review the current knowledge of the regulation and function of PtdIns3P and discuss how the view of PtdIns3P changed in the last few years.
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Affiliation(s)
- Marco Falasca
- Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Blizard Institute of Cell and Molecular Science, Centre for Diabetes, Inositide Signalling Group, 4 Newark Street, London E1 2AT, UK.
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Phosphoinositides and the endocytic pathway. Exp Cell Res 2009; 315:1627-31. [DOI: 10.1016/j.yexcr.2008.10.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 10/05/2008] [Accepted: 10/07/2008] [Indexed: 11/21/2022]
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15
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Kalscheuer VM, Musante L, Fang C, Hoffmann K, Fuchs C, Carta E, Deas E, Venkateswarlu K, Menzel C, Ullmann R, Tommerup N, Dalprà L, Tzschach A, Selicorni A, Lüscher B, Ropers HH, Harvey K, Harvey RJ. A balanced chromosomal translocation disrupting ARHGEF9 is associated with epilepsy, anxiety, aggression, and mental retardation. Hum Mutat 2009; 30:61-8. [PMID: 18615734 DOI: 10.1002/humu.20814] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Clustering of inhibitory gamma-aminobutyric acid(A) (GABA(A)) and glycine receptors at synapses is thought to involve key interactions between the receptors, a "scaffolding" protein known as gephyrin and the RhoGEF collybistin. We report the identification of a balanced chromosomal translocation in a female patient presenting with a disturbed sleep-wake cycle, late-onset epileptic seizures, increased anxiety, aggressive behavior, and mental retardation, but not hyperekplexia. Fine mapping of the breakpoint indicates disruption of the collybistin gene (ARHGEF9) on chromosome Xq11, while the other breakpoint lies in a region of 18q11 that lacks any known or predicted genes. We show that defective collybistin transcripts are synthesized and exons 7-10 are replaced by cryptic exons from chromosomes X and 18. These mRNAs no longer encode the pleckstrin homology (PH) domain of collybistin, which we now show binds phosphatidylinositol-3-phosphate (PI3P/PtdIns-3-P), a phosphoinositide with an emerging role in membrane trafficking and signal transduction, rather than phosphatidylinositol 3,4,5-trisphosphate (PIP3/PtdIns-3,4,5-P) as previously suggested in the "membrane activation model" of gephyrin clustering. Consistent with this finding, expression of truncated collybistin proteins in cultured neurons interferes with synaptic localization of endogenous gephyrin and GABA(A) receptors. These results suggest that collybistin has a key role in membrane trafficking of gephyrin and selected GABA(A) receptor subtypes involved in epilepsy, anxiety, aggression, insomnia, and learning and memory.
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Affiliation(s)
- Vera M Kalscheuer
- Department of Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany.
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Alterations of insulin signaling in type 2 diabetes: A review of the current evidence from humans. Biochim Biophys Acta Mol Basis Dis 2009; 1792:83-92. [DOI: 10.1016/j.bbadis.2008.10.019] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 10/21/2008] [Accepted: 10/21/2008] [Indexed: 01/03/2023]
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17
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Blagoveshchenskaya A, Mayinger P. SAC1 lipid phosphatase and growth control of the secretory pathway. MOLECULAR BIOSYSTEMS 2008; 5:36-42. [PMID: 19081929 DOI: 10.1039/b810979f] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Phosphoinositide lipids play a dual role in cell physiology. Specific sets of these molecules are short-lived downstream mediators of growth signals, regulating cell survival and differentiation. In addition, distinct classes of phosphoinositide lipids function as constitutive mediators of membrane traffic and organelle identity. Recent work has provided the first direct evidence that phosphoinositides also play a direct role in linking protein secretion with cell growth and proliferation. This review focuses on SAC1 lipid phosphatase and how this enzyme operates in an evolutionary conserved mechanism to coordinate the secretory capacity of ER and Golgi during cell growth.
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Affiliation(s)
- Anastasia Blagoveshchenskaya
- Division of Nephrology & Hypertension and Department of Cell & Developmental Biology, Oregon Health & Science University, Portland, Oregon, USA
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Falasca M, Maffucci T. Role of class II phosphoinositide 3-kinase in cell signalling. Biochem Soc Trans 2007; 35:211-4. [PMID: 17371240 DOI: 10.1042/bst0350211] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although it is now well established that PI3K (phosphoinositide 3-kinase) is a key enzyme in several intracellular processes, there are still relatively few reports that precisely identify the specific isoforms of PI3K actually involved in such events. The lack of specific inhibitors has made it particularly difficult to address the physiological roles of some isoforms, such as the members of class II. As a consequence, there is still relatively little understanding of the role of these enzymes and the question about the intracellular role of these isoforms still waits for more answers.
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Affiliation(s)
- M Falasca
- Centre for Cardiovascular Biology and Medicine, Division of Medicine, University College London, Rayne Building, London, UK.
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Falasca M, Hughes WE, Dominguez V, Sala G, Fostira F, Fang MQ, Cazzolli R, Shepherd PR, James DE, Maffucci T. The role of phosphoinositide 3-kinase C2alpha in insulin signaling. J Biol Chem 2007; 282:28226-36. [PMID: 17644513 DOI: 10.1074/jbc.m704357200] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The members of the class II phosphoinositide 3-kinase (PI3K) family can be activated by several stimuli, indicating that these enzymes can regulate many intracellular processes. Nevertheless, to date, there has been no definitive identification of their in vivo product, their mechanism(s) of activation, or their precise intracellular roles. By metabolic labeling, we here identify phosphatidylinositol 3-phosphate as the sole in vivo product of the insulin-dependent activation of PI3K-C2alpha, confirming the emerging role of such a phosphoinositide in signaling. We demonstrate that activation of PI3K-C2alpha involves its recruitment to the plasma membrane and that activation is mediated by the GTPase TC10. This is the first report showing a membrane targeting-mediated mechanism of activation for PI3K-C2alpha and that a small GTP-binding protein can activate a class II PI3K isoform. We also demonstrate that PI3K-C2alpha contributes to maximal insulin-induced translocation of the glucose transporter GLUT4 to the plasma membrane and subsequent glucose uptake, definitely assessing the role of this enzyme in insulin signaling.
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Affiliation(s)
- Marco Falasca
- Inositide Signalling Group, Centre for Diabetes and Metabolic Medicine, Institute of Cell and Molecular Science, Barts and The London, Queen Mary's School of Medicine and Dentistry, University of London, London E1 2AT, United Kingdom.
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