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Robinson KS, Aw R. The Commonalities in Bacterial Effector Inhibition of Apoptosis. Trends Microbiol 2016; 24:665-680. [PMID: 27117049 DOI: 10.1016/j.tim.2016.04.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Revised: 03/13/2016] [Accepted: 04/01/2016] [Indexed: 02/09/2023]
Abstract
Antiapoptotic pathways of the host cell play integral roles in bacterial pathogenesis, with inhibition of those pathways resulting in halted disease pathology. Certain pathogens have developed elegant mechanisms to modulate the fate of the host cell, many of which target novel pathways that are poorly understood in the context of the cell biology. Bacterial pathogenesis research not only promotes the understanding of the role of antiapoptotic pathways in bacterial infection, but has a broader context in understanding the epitome of human disease, that is, developing the understanding of tumorigenic or inflammatory pathways. Here we review host antiapoptotic signalling pathways manipulated by translocated bacterial effectors that propagate the disease state, drawing common parallels and showing the novel differences.
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Affiliation(s)
- Keith S Robinson
- Department of Life Science, Imperial College London, London, UK.
| | - Rochelle Aw
- Department of Life Science, Imperial College London, London, UK
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Bruschi M, Santucci L, Ravera S, Candiano G, Bartolucci M, Calzia D, Lavarello C, Inglese E, Ramenghi LA, Petretto A, Ghiggeri GM, Panfoli I. Human urinary exosome proteome unveils its aerobic respiratory ability. J Proteomics 2016; 136:25-34. [PMID: 26850698 DOI: 10.1016/j.jprot.2016.02.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 01/28/2016] [Accepted: 02/01/2016] [Indexed: 12/13/2022]
Abstract
UNLABELLED Exosomes are 40-100-nm vesicles released by most cell types after fusion of multivesicular endosomes with the plasma membrane. Exosomes, ubiquitary in body fluids including urines, contain proteins and RNA species specific of the tissue of origin. Exosomes from urine have been extensively studied as a promising reservoir for disease biomarkers. Here, we report the proteome analysis of urinary exosomes compared to urinoma, studied by Orbitrap mass spectrometry. A discovery approach was utilized on the sample. 3429 proteins were present, with minimal overlapping among exosome and urinoma. 959 proteins (28%) in exosome and 1478 proteins (43%) in urinoma were exclusively present in only one group. By cytoscape analysis, the biological process gene ontology was correlated to their probability (P ≤ 0.05) to be functional. This was never studied before and showed a significant clustering around metabolic functions, in particular to aerobic ATP production. Urinary exosomes carry out oxidative phosphorylation, being able to synthesize ATP and consume oxygen. A previously unsuspected function emerges for human urinary exosomes as bioactive vesicles that consume oxygen to aerobically synthesize ATP. Determination of normal human urine proteome can help generate the healthy urinary protein database for comparison, useful for various renal diseases. BIOLOGICAL SIGNIFICANCE The findings reported represent a significant advance in the understanding of the healthy human urinary proteome. The methodology utilized to analyze the collection of proteomic data allowed the assessment of the unique composition of urinary exosomes with respect to urinoma and to elucidate the presence in the former of molecular pathways previously unknown. The paper has the potential to impact its field of research, due to the biological relevance of the metabolic capacity of urinary exosomes, which may represent their important general feature.
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Affiliation(s)
- Maurizio Bruschi
- Division of Nephrology, Dialysis, and Transplantation and Laboratory on Pathophysiology of Uremia, Istituto Giannina Gaslini, Genoa, Italy
| | - Laura Santucci
- Division of Nephrology, Dialysis, and Transplantation and Laboratory on Pathophysiology of Uremia, Istituto Giannina Gaslini, Genoa, Italy
| | - Silvia Ravera
- Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy
| | - Giovanni Candiano
- Division of Nephrology, Dialysis, and Transplantation and Laboratory on Pathophysiology of Uremia, Istituto Giannina Gaslini, Genoa, Italy
| | - Martina Bartolucci
- Laboratory of Mass Spectrometry - Core Facilities, Istituto Giannina Gaslini, Genova, Italy
| | - Daniela Calzia
- Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy
| | - Chiara Lavarello
- Laboratory of Mass Spectrometry - Core Facilities, Istituto Giannina Gaslini, Genova, Italy
| | - Elvira Inglese
- Laboratory of Mass Spectrometry - Core Facilities, Istituto Giannina Gaslini, Genova, Italy
| | - Luca A Ramenghi
- Neonatal Intensive Care Unit, Istituto Giannina Gaslini, Genoa, Italy
| | - Andrea Petretto
- Laboratory of Mass Spectrometry - Core Facilities, Istituto Giannina Gaslini, Genova, Italy
| | - Gian Marco Ghiggeri
- Division of Nephrology, Dialysis, and Transplantation and Laboratory on Pathophysiology of Uremia, Istituto Giannina Gaslini, Genoa, Italy
| | - Isabella Panfoli
- Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy.
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Panfoli I, Ravera S, Podestà M, Cossu C, Santucci L, Bartolucci M, Bruschi M, Calzia D, Sabatini F, Bruschettini M, Ramenghi LA, Romantsik O, Marimpietri D, Pistoia V, Ghiggeri G, Frassoni F, Candiano G. Exosomes from human mesenchymal stem cells conduct aerobic metabolism in term and preterm newborn infants. FASEB J 2015; 30:1416-24. [PMID: 26655706 DOI: 10.1096/fj.15-279679] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 11/23/2015] [Indexed: 01/13/2023]
Abstract
Exosomes are secreted nanovesicles that are able to transfer RNA and proteins to target cells. The emerging role of mesenchymal stem cell (MSC) exosomes as promoters of aerobic ATP synthesis restoration in damaged cells, prompted us to assess whether they contain an extramitochondrial aerobic respiration capacity. Exosomes were isolated from culture medium of human MSCs from umbilical cord of ≥37-wk-old newborns or between 28- to 30-wk-old newborns (i.e.,term or preterm infants). Characterization of samples was conducted by cytofluorometry. Oxidative phosphorylation capacity was assessed by Western blot analysis, oximetry, and luminometric and fluorometric analyses. MSC exosomes express functional respiratory complexes I, IV, and V, consuming oxygen. ATP synthesis was only detectable in exosomes from term newborns, suggestive of a specific mechanism that is not completed at an early gestational age. Activities are outward facing and comparable to those detected in mitochondria isolated from term MSCs. MSC exosomes display an unsuspected aerobic respiratory ability independent of whole mitochondria. This may be relevant for their ability to rescue cell bioenergetics. The differential oxidative metabolism of pretermvs.term exosomes sheds new light on the preterm newborn's clinical vulnerability. A reduced ability to repair damaged tissue and an increased capability to cope with anoxic environment for preterm infants can be envisaged.-Panfoli, I., Ravera, S., Podestà, M., Cossu, C., Santucci, L., Bartolucci, M., Bruschi, M., Calzia, D., Sabatini, F., Bruschettini, M., Ramenghi, L. A., Romantsik, O., Marimpietri, D., Pistoia, V., Ghiggeri, G., Frassoni, F., Candiano, G. Exosomes from human mesenchymal stem cells conduct aerobic metabolism in term and preterm newborn infants.
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Affiliation(s)
- Isabella Panfoli
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Silvia Ravera
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Marina Podestà
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Claudia Cossu
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Laura Santucci
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Martina Bartolucci
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Maurizio Bruschi
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Daniela Calzia
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Federica Sabatini
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Matteo Bruschettini
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Luca Antonio Ramenghi
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Olga Romantsik
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Danilo Marimpietri
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Vito Pistoia
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Gianmarco Ghiggeri
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Francesco Frassoni
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
| | - Giovanni Candiano
- *Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy; and Laboratorio Cellule Staminali Post-Natali e Terapie Cellulari, Laboratory of Pathophysiology of Uremia, Neonatal Intensive Care Unit, and Laboratorio Oncologia, Istituto Giannina Gaslini, Genoa, Italy
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Das A, Panitz F, Gregersen VR, Bendixen C, Holm LE. Deep sequencing of Danish Holstein dairy cattle for variant detection and insight into potential loss-of-function variants in protein coding genes. BMC Genomics 2015; 16:1043. [PMID: 26645365 PMCID: PMC4673847 DOI: 10.1186/s12864-015-2249-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 11/27/2015] [Indexed: 12/30/2022] Open
Abstract
Background Over the last few years, continuous development of high-throughput sequencing platforms and sequence analysis tools has facilitated reliable identification and characterization of genetic variants in many cattle breeds. Deep sequencing of entire genomes within a cattle breed that has not been thoroughly investigated would be imagined to discover functional variants that are underlying phenotypic differences. Here, we sequenced to a high coverage the Danish Holstein cattle breed to detect and characterize single nucleotide polymorphisms (SNPs), insertion/deletions (Indels), and loss-of-function (LoF) variants in protein-coding genes in order to provide a comprehensive resource for subsequent detection of causal variants for recessive traits. Results We sequenced four genetically unrelated Danish Holstein cows with a mean coverage of 27X using an Illumina Hiseq 2000. Multi-sample SNP calling identified 10,796,794 SNPs and 1,295,036 indels whereof 482,835 (4.5 %) SNPs and 231,359 (17.9 %) indels were novel. A comparison between sequencing-derived SNPs and genotyping from the BovineHD BeadChip revealed a concordance rate of 99.6–99.8 % for homozygous SNPs and 93.3–96.5 % for heterozygous SNPs. Annotation of the SNPs discovered 74,886 SNPs and 1937 indels affecting coding sequences with 2145 being LoF mutations. The frequency of LoF variants differed greatly across the genome, a hot spot with a strikingly high density was observed in a 6 Mb region on BTA18. LoF affected genes were enriched for functional categories related to olfactory reception and underrepresented for genes related to key cellular constituents and cellular and biological process regulation. Filtering using sequence derived genotype data for 288 Holstein animals from the 1000 bull genomes project removing variants containing homozygous individuals retained 345 of the LoF variants as putatively deleterious. A substantial number of the putative deleterious LoF variants had a minor allele frequency >0.05 in the 1000 bull genomes data set. Conclusions Deep sequencing of Danish Holstein genomes enabled us to identify 12.1 million variants. An investigation into LoF variants discovered a set of variants predicted to disrupt protein-coding genes. This catalog of variants will be a resource for future studies to understand variation underlying important phenotypes, particularly recessively inherited lethal phenotypes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2249-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ashutosh Das
- Department of Molecular Biology and Genetics, Aarhus University, DK-8830, Tjele, Denmark.
| | - Frank Panitz
- Department of Molecular Biology and Genetics, Aarhus University, DK-8830, Tjele, Denmark.
| | | | - Christian Bendixen
- Department of Molecular Biology and Genetics, Aarhus University, DK-8830, Tjele, Denmark.
| | - Lars-Erik Holm
- Department of Molecular Biology and Genetics, Aarhus University, DK-8830, Tjele, Denmark.
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55
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Xia Y, Li M, Charubin K, Liu Y, Heberle FA, Katsaras J, Jing B, Zhu Y, Nieh MP. Effects of Nanoparticle Morphology and Acyl Chain Length on Spontaneous Lipid Transfer Rates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12920-8. [PMID: 26540211 DOI: 10.1021/acs.langmuir.5b03291] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We report on studies of lipid transfer rates between different morphology nanoparticles and lipids with different length acyl chains. The lipid transfer rate of dimyristoylphosphatidylcholine (di-C14, DMPC) in discoidal "bicelles" (0.156 h(-1)) is 2 orders of magnitude greater than that of DMPC vesicles (ULVs) (1.1 × 10(-3) h(-1)). For both bicellar and ULV morphologies, increasing the acyl chain length by two carbons [going from di-C14 DMPC to di-C16, dipalmitoylphosphatidylcholine (DPPC)] causes lipid transfer rates to decrease by more than 2 orders of magnitude. Results from small angle neutron scattering (SANS), differential scanning calorimetry (DSC), and fluorescence correlation spectroscopy (FCS) are in good agreement. The present studies highlight the importance of lipid dynamic processes taking place in different morphology biomimetic membranes.
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Affiliation(s)
- Yan Xia
- Department of Chemical and Biomolecular Engineering, University of Connecticut , Storrs, Connecticut 06269, United States
| | - Ming Li
- Polymer Program, Institute of Materials Science, University of Connecticut , Storrs, Connecticut 06269, United States
| | - Kamil Charubin
- Department of Chemical and Biomolecular Engineering, University of Connecticut , Storrs, Connecticut 06269, United States
| | - Ying Liu
- Department of Chemical and Biomolecular Engineering, University of Connecticut , Storrs, Connecticut 06269, United States
| | - Frederick A Heberle
- Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831 United States
- Joint Institute for Neutron Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - John Katsaras
- Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831 United States
- Department of Physics and Astronomy, University of Tennessee , Knoxville, Tennessee 37996, United States
- Joint Institute for Neutron Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Benxin Jing
- Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Yingxi Zhu
- Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
- Department of Chemical Engineering and Materials Science, Wayne State University , Detroit, Michigan 48202 United States
| | - Mu-Ping Nieh
- Department of Chemical and Biomolecular Engineering, University of Connecticut , Storrs, Connecticut 06269, United States
- Polymer Program, Institute of Materials Science, University of Connecticut , Storrs, Connecticut 06269, United States
- Department of Biomedical Engineering, University of Connecticut , Storrs, Connecticut 06269, United States
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Fueller J, Egorov MV, Walther KA, Sabet O, Mallah J, Grabenbauer M, Kinkhabwala A. Subcellular Partitioning of Protein Tyrosine Phosphatase 1B to the Endoplasmic Reticulum and Mitochondria Depends Sensitively on the Composition of Its Tail Anchor. PLoS One 2015; 10:e0139429. [PMID: 26431424 PMCID: PMC4592070 DOI: 10.1371/journal.pone.0139429] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 09/14/2015] [Indexed: 01/15/2023] Open
Abstract
The canonical protein tyrosine phosphatase PTP1B is an important regulator of diverse cellular signaling networks. PTP1B has long been thought to exert its influence solely from its perch on the endoplasmic reticulum (ER); however, an additional subpopulation of PTP1B has recently been detected in mitochondria extracted from rat brain tissue. Here, we show that PTP1B’s mitochondrial localization is general (observed across diverse mammalian cell lines) and sensitively dependent on the transmembrane domain length, C-terminal charge and hydropathy of its short (≤35 amino acid) tail anchor. Our electron microscopy of specific DAB precipitation revealed that PTP1B localizes via its tail anchor to the outer mitochondrial membrane (OMM), with fluorescence lifetime imaging microscopy establishing that this OMM pool contributes to the previously reported cytoplasmic interaction of PTP1B with endocytosed epidermal growth factor receptor. We additionally examined the mechanism of PTP1B’s insertion into the ER membrane through heterologous expression of PTP1B’s tail anchor in wild-type yeast and yeast mutants of major conserved ER insertion pathways: In none of these yeast strains was ER targeting significantly impeded, providing in vivo support for the hypothesis of spontaneous membrane insertion (as previously demonstrated in vitro). Further functional elucidation of the newly recognized mitochondrial pool of PTP1B will likely be important for understanding its complex roles in cellular responses to external stimuli, cell proliferation and diseased states.
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Affiliation(s)
- Julia Fueller
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
- Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Mikhail V. Egorov
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
- Institute of Anatomy and Cell Biology, Heidelberg University, Im Neuenheimer Feld 307, 69120, Heidelberg, Germany
| | - Kirstin A. Walther
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
| | - Ola Sabet
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
| | - Jana Mallah
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
| | - Markus Grabenbauer
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
- Institute of Anatomy and Cell Biology, Heidelberg University, Im Neuenheimer Feld 307, 69120, Heidelberg, Germany
| | - Ali Kinkhabwala
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
- * E-mail:
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Bartolucci M, Ravera S, Garbarino G, Ramoino P, Ferrando S, Calzia D, Candiani S, Morelli A, Panfoli I. Functional Expression of Electron Transport Chain and FoF1-ATP Synthase in Optic Nerve Myelin Sheath. Neurochem Res 2015; 40:2230-41. [PMID: 26334391 DOI: 10.1007/s11064-015-1712-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 08/23/2015] [Accepted: 08/27/2015] [Indexed: 12/15/2022]
Abstract
Our previous studies reported evidence for aerobic ATP synthesis by myelin from both bovine brainstem and rat sciatic nerve. Considering that the optic nerve displays a high oxygen demand, here we evaluated the expression and activity of the five Respiratory Complexes in myelin purified from either bovine or murine optic nerves. Western blot analyses on isolated myelin confirmed the expression of ND4L (subunit of Complex I), COX IV (subunit of Complex IV) and β subunit of F1Fo-ATP synthase. Moreover, spectrophotometric and in-gel activity assays on isolated myelin, as well as histochemical activity assays on both bovine and murine transversal optic nerve sections showed that the respiratory Complexes are functional in myelin and are organized in a supercomplex. Expression of oxidative phosphorylation proteins was also evaluated on bovine optic nerve sections by confocal and transmission electron microscopy. Having excluded a mitochondrial contamination of isolated myelin and considering the results form in situ analyses, it is proposed that the oxidative phosphorylation machinery is truly resident in optic myelin sheath. Data may shed a new light on the unknown trophic role of myelin sheath. It may be energy supplier for the axon, explaining why in demyelinating diseases and neuropathies, myelin sheath loss is associated with axonal degeneration.
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Affiliation(s)
- Martina Bartolucci
- Biochemistry Laboratory, Department of Pharmacy (DIFAR), University of Genova, Viale Benedetto XV, 3, 16132, Genoa, Italy
| | - Silvia Ravera
- Biochemistry Laboratory, Department of Pharmacy (DIFAR), University of Genova, Viale Benedetto XV, 3, 16132, Genoa, Italy.
| | - Greta Garbarino
- Department of Earth, Environmental and Life Sciences, (DISTAV), University of Genova, C.so Europa 26, 16132, Genoa, Italy
| | - Paola Ramoino
- Department of Earth, Environmental and Life Sciences, (DISTAV), University of Genova, C.so Europa 26, 16132, Genoa, Italy
| | - Sara Ferrando
- Department of Earth, Environmental and Life Sciences, (DISTAV), University of Genova, C.so Europa 26, 16132, Genoa, Italy
| | - Daniela Calzia
- Biochemistry Laboratory, Department of Pharmacy (DIFAR), University of Genova, Viale Benedetto XV, 3, 16132, Genoa, Italy
| | - Simona Candiani
- Department of Earth, Environmental and Life Sciences, (DISTAV), University of Genova, C.so Europa 26, 16132, Genoa, Italy
| | - Alessandro Morelli
- Biochemistry Laboratory, Department of Pharmacy (DIFAR), University of Genova, Viale Benedetto XV, 3, 16132, Genoa, Italy
| | - Isabella Panfoli
- Biochemistry Laboratory, Department of Pharmacy (DIFAR), University of Genova, Viale Benedetto XV, 3, 16132, Genoa, Italy
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Mitochondrial proteomes of porcine kidney cortex and medulla: foundation for translational proteomics. Clin Exp Nephrol 2015; 20:39-49. [PMID: 26072732 DOI: 10.1007/s10157-015-1135-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 06/02/2015] [Indexed: 12/15/2022]
Abstract
BACKGROUND Emerging evidence has linked mitochondrial dysfunction to the pathogenesis of many renal disorders, including acute kidney injury, sepsis and even chronic kidney disease. Proteomics is a powerful tool in elucidating the role of mitochondria in renal pathologies. Since the pig is increasingly recognized as a major mammalian model for translational research, the lack of physiological proteome data of large mammals prompted us to examine renal mitochondrial proteome in porcine kidney cortex and medulla METHODS Kidneys were obtained from six healthy pigs. Mitochondria from cortex and medulla were isolated using differential centrifugation and proteome maps of cortical and medullar mitochondria were constructed using two-dimensional gel electrophoresis (2DE). Protein spots with significant difference between mitochondrial fraction of renal cortex and medulla were identified by mass spectrometry. RESULTS Proteomic analysis identified 81 protein spots. Of these spots, 41 mitochondrial proteins were statistically different between renal cortex and medulla (p < 0.05). Protein spots containing enzymes of beta oxidation, amino acid metabolism, and gluconeogenesis were predominant in kidney cortex mitochondria. Spots containing tricarboxylic acid cycle enzymes and electron transport system proteins, proteins maintaining metabolite transport and mitochondrial translation were more abundant in medullar mitochondria. CONCLUSION This study provides the first proteomic profile of porcine kidney cortex and medullar mitochondrial proteome. Different protein expression pattern reflects divergent functional metabolic role of mitochondria in various kidney compartments. Our study could serve as a useful reference for further porcine experiments investigating renal mitochondrial physiology under various pathological states.
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Derré I. Chlamydiae interaction with the endoplasmic reticulum: contact, function and consequences. Cell Microbiol 2015; 17:959-66. [PMID: 25930206 DOI: 10.1111/cmi.12455] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 04/13/2015] [Accepted: 04/27/2015] [Indexed: 01/30/2023]
Abstract
Chlamydiae and chlamydiae-related organisms are obligate intracellular bacterial pathogens. They reside in a membrane-bound compartment termed the inclusion and have evolved sophisticated mechanisms to interact with cellular organelles. This review focuses on the nature, the function(s) and the consequences of chlamydiae-inclusion interaction with the endoplasmic reticulum (ER). The inclusion membrane establishes very close contact with the ER at specific sites termed ER-inclusion membrane contact sites (MCSs). These MCSs are constituted of a specific set of factors, including the C. trachomatis effector protein IncD and the host cell proteins CERT and VAPA/B. Because CERT and VAPA/B have a demonstrated role in the non-vesicular trafficking of lipids between the ER and the Golgi, it was proposed that Chlamydia establish MCSs with the ER to acquire host lipids. However, the recruitment of additional factors to ER-inclusion MCSs, such as the ER calcium sensor STIM1, may suggest additional functions unrelated to lipid acquisition. Finally, chlamydiae interaction with the ER appears to induce the ER stress response, but this response is quickly dampened by chlamydiae to promote host cell survival.
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Affiliation(s)
- Isabelle Derré
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA, USA
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60
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Giorgi C, Missiroli S, Patergnani S, Duszynski J, Wieckowski MR, Pinton P. Mitochondria-associated membranes: composition, molecular mechanisms, and physiopathological implications. Antioxid Redox Signal 2015; 22:995-1019. [PMID: 25557408 DOI: 10.1089/ars.2014.6223] [Citation(s) in RCA: 229] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
SIGNIFICANCE In all cells, the endoplasmic reticulum (ER) and mitochondria are physically connected to form junctions termed mitochondria-associated membranes (MAMs). This subcellular compartment is under intense investigation because it represents a "hot spot" for the intracellular signaling of important pathways, including the synthesis of cholesterol and phospholipids, calcium homeostasis, and reactive oxygen species (ROS) generation and activity. RECENT ADVANCES The advanced methods currently used to study this fascinating intracellular microdomain in detail have enabled the identification of the molecular composition of MAMs and their involvement within different physiopathological contexts. CRITICAL ISSUES Here, we review the knowledge regarding (i) MAMs composition in terms of protein composition, (ii) the relationship between MAMs and ROS, (iii) the involvement of MAMs in cell death programs with particular emphasis within the tumor context, (iv) the emerging role of MAMs during inflammation, and (v) the key role of MAMs alterations in selected neurological disorders. FUTURE DIRECTIONS Whether alterations in MAMs represent a response to the disease pathogenesis or directly contribute to the disease has not yet been unequivocally established. In any case, the signaling at the MAMs represents a promising pharmacological target for several important human diseases.
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Affiliation(s)
- Carlotta Giorgi
- 1 Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), Department of Morphology, Surgery and Experimental Medicine, University of Ferrara , Ferrara, Italy
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61
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Carrillo L, Cucu B, Bandmann V, Homann U, Hertel B, Hillmer S, Thiel G, Bertl A. High-Resolution Membrane Capacitance Measurements for Studying Endocytosis and Exocytosis in Yeast. Traffic 2015; 16:760-72. [DOI: 10.1111/tra.12275] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 02/23/2015] [Accepted: 02/23/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Lucia Carrillo
- Technische Universität Darmstadt; Fachbereich Biologie; Schnittspahnstrasse 10 64287 Darmstadt Germany
| | - Bayram Cucu
- Technische Universität Darmstadt; Fachbereich Biologie; Schnittspahnstrasse 10 64287 Darmstadt Germany
| | - Vera Bandmann
- Technische Universität Darmstadt; Fachbereich Biologie; Schnittspahnstrasse 10 64287 Darmstadt Germany
- Present address: INM-Leibniz-Institute for New Materials; Biomineralization, Campus D2 2; 66123 Saarbrücken Germany
| | - Ulrike Homann
- Technische Universität Darmstadt; Fachbereich Biologie; Schnittspahnstrasse 10 64287 Darmstadt Germany
| | - Brigitte Hertel
- Technische Universität Darmstadt; Fachbereich Biologie; Schnittspahnstrasse 10 64287 Darmstadt Germany
| | - Stefan Hillmer
- Electron Microscopy Core Facility (EMCF), COS; Universität Heidelberg; Im Neuenheimer Feld 230 69120 Heidelberg Germany
| | - Gerhard Thiel
- Technische Universität Darmstadt; Fachbereich Biologie; Schnittspahnstrasse 10 64287 Darmstadt Germany
| | - Adam Bertl
- Technische Universität Darmstadt; Fachbereich Biologie; Schnittspahnstrasse 10 64287 Darmstadt Germany
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Reali V, Mehdawy B, Nardacci R, Filomeni G, Risuglia A, Rossin F, Antonioli M, Marsella C, Fimia GM, Piacentini M, Di Sano F. Reticulon protein-1C is a key component of MAMs. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:733-45. [PMID: 25573430 DOI: 10.1016/j.bbamcr.2014.12.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 12/17/2014] [Accepted: 12/27/2014] [Indexed: 12/01/2022]
Abstract
The endoplasmic reticulum (ER) is a key organelle fundamental for the maintenance of cellular homeostasis and the determination of cell fate under stress conditions. Reticulon-1C (RTN-1C) is a member of the reticulon family proteins localized primarily on the ER membrane and known to regulate ER structure and function. Several cellular processes depend on the structural and functional crosstalk between different organelles, particularly on the endoplasmic reticulum and mitochondria. These dynamic contacts, called mitochondria-associated ER membranes (MAMs), are essential for the maintenance of mitochondrial structure and participate in lipid and calcium exchanges between the two organelles. In this study we investigated the impact of RTN-1C modulation on mitochondrial dynamics. We demonstrate that RTN-1C controls mitochondrial structure and function affecting intracellular Ca2+ homeostasis and lipid exchange between ER and mitochondria. We propose that these events depend on RTN-1C involvement in the regulation of ER-mitochondria cross-talk and define a role for RTN-1C in maintaining the function of contacts between the two organelles.
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Affiliation(s)
- Valentina Reali
- Department of Biology, University of Rome 'Tor Vergata', Via della Ricerca Scientifica, 00133 Rome, Italy
| | - Bisan Mehdawy
- European Centre for Brain Research, IRCSS Santa Lucia Foundation, Via del Fosso di Fiorano 64, 00143 Rome, Italy
| | - Roberta Nardacci
- National Institute for Infectious Diseases, IRCCS 'L. Spallanzani', Via Portuense, 00149 Rome, Italy
| | - Giuseppe Filomeni
- Cell Stress and Survival Unit, Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen, Denmark
| | - Anna Risuglia
- Department of Biology, University of Rome 'Tor Vergata', Via della Ricerca Scientifica, 00133 Rome, Italy
| | - Federica Rossin
- Department of Biology, University of Rome 'Tor Vergata', Via della Ricerca Scientifica, 00133 Rome, Italy
| | - Manuela Antonioli
- Department of Biology, University of Rome 'Tor Vergata', Via della Ricerca Scientifica, 00133 Rome, Italy; National Institute for Infectious Diseases, IRCCS 'L. Spallanzani', Via Portuense, 00149 Rome, Italy
| | - Claudia Marsella
- Department of Biology, University of Rome 'Tor Vergata', Via della Ricerca Scientifica, 00133 Rome, Italy; National Institute for Infectious Diseases, IRCCS 'L. Spallanzani', Via Portuense, 00149 Rome, Italy
| | - Gian Maria Fimia
- National Institute for Infectious Diseases, IRCCS 'L. Spallanzani', Via Portuense, 00149 Rome, Italy; Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Lecce, Italy
| | - Mauro Piacentini
- Department of Biology, University of Rome 'Tor Vergata', Via della Ricerca Scientifica, 00133 Rome, Italy; National Institute for Infectious Diseases, IRCCS 'L. Spallanzani', Via Portuense, 00149 Rome, Italy
| | - Federica Di Sano
- Department of Biology, University of Rome 'Tor Vergata', Via della Ricerca Scientifica, 00133 Rome, Italy.
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63
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Prasad M, Kaur J, Pawlak KJ, Bose M, Whittal RM, Bose HS. Mitochondria-associated endoplasmic reticulum membrane (MAM) regulates steroidogenic activity via steroidogenic acute regulatory protein (StAR)-voltage-dependent anion channel 2 (VDAC2) interaction. J Biol Chem 2014; 290:2604-16. [PMID: 25505173 DOI: 10.1074/jbc.m114.605808] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Steroid hormones are essential for carbohydrate metabolism, stress management, and reproduction and are synthesized from cholesterol in mitochondria of adrenal glands and gonads/ovaries. In acute stress or hormonal stimulation, steroidogenic acute regulatory protein (StAR) transports substrate cholesterol into the mitochondria for steroidogenesis by an unknown mechanism. Here, we report for the first time that StAR interacts with voltage-dependent anion channel 2 (VDAC2) at the mitochondria-associated endoplasmic reticulum membrane (MAM) prior to its translocation to the mitochondrial matrix. In the MAM, StAR interacts with mitochondrial proteins Tom22 and VDAC2. However, Tom22 knockdown by siRNA had no effect on pregnenolone synthesis. In the absence of VDAC2, StAR was expressed but not processed into the mitochondria as a mature 30-kDa protein. VDAC2 interacted with StAR via its C-terminal 20 amino acids and N-terminal amino acids 221-229, regulating the mitochondrial processing of StAR into the mature protein. In the absence of VDAC2, StAR could not enter the mitochondria or interact with MAM-associated proteins, and therefore steroidogenesis was inhibited. Furthermore, the N terminus was not essential for StAR activity, and the N-terminal deletion mutant continued to interact with VDAC2. The endoplasmic reticulum-targeting prolactin signal sequence did not affect StAR association with the MAM and thus its mitochondrial targeting. Therefore, VDAC2 controls StAR processing and activity, and MAM is thus a central location for initiating mitochondrial steroidogenesis.
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Affiliation(s)
- Manoj Prasad
- From the Mercer University School of Medicine, Savannah, Georgia 31404
| | - Jasmeet Kaur
- From the Mercer University School of Medicine, Savannah, Georgia 31404
| | - Kevin J Pawlak
- From the Mercer University School of Medicine, Savannah, Georgia 31404
| | - Mahuya Bose
- Center of Excellence for Health Regeneration Biotechnology, Florida Biologix, University of Florida, Alachua, Florida 32615, Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida 32610
| | - Randy M Whittal
- Department of Chemistry, University of Alberta, Alberta T6G2G2, Canada, and
| | - Himangshu S Bose
- From the Mercer University School of Medicine, Savannah, Georgia 31404, Anderson Cancer Institute, Memorial University Medical Center, Savannah, Georgia 31404
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64
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Identification of tetrahydrocarbazoles as novel multifactorial drug candidates for treatment of Alzheimer's disease. Transl Psychiatry 2014; 4:e489. [PMID: 25514752 PMCID: PMC4270312 DOI: 10.1038/tp.2014.132] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 10/12/2014] [Accepted: 11/17/2014] [Indexed: 01/08/2023] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative brain disorder and the most frequent cause of dementia. To date, there are only a few approved drugs for AD, which show little or no effect on disease progression. Impaired intracellular calcium homeostasis is believed to occur early in the cascade of events leading to AD. Here, we examined the possibility of normalizing the disrupted calcium homeostasis in the endoplasmic reticulum (ER) store as an innovative approach for AD drug discovery. High-throughput screening of a small-molecule compound library led to the identification of tetrahydrocarbazoles, a novel multifactorial class of compounds that can normalize the impaired ER calcium homeostasis. We found that the tetrahydrocarbazole lead structure, first, dampens the enhanced calcium release from ER in HEK293 cells expressing familial Alzheimer's disease (FAD)-linked presenilin 1 mutations. Second, the lead structure also improves mitochondrial function, measured by increased mitochondrial membrane potential. Third, the same lead structure also attenuates the production of amyloid-beta (Aβ) peptides by decreasing the cleavage of amyloid precursor protein (APP) by β-secretase, without notably affecting α- and γ-secretase cleavage activities. Considering the beneficial effects of tetrahydrocarbazoles addressing three key pathological aspects of AD, these compounds hold promise for the development of potentially effective AD drug candidates.
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65
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Abstract
Acute kidney injury (AKI) is a serious clinical condition with no effective treatment. Tubular cells are key targets in AKI. Tubular cells and, specifically, proximal tubular cells are extremely rich in mitochondria and mitochondrial changes had long been known to be a feature of AKI. However, only recent advances in understanding the molecules involved in mitochondria biogenesis and dynamics and the availability of mitochondria-targeted drugs has allowed the exploration of the specific role of mitochondria in AKI. We now review the morphological and functional mitochondrial changes during AKI, as well as changes in the expression of mitochondrial genes and proteins. Finally, we summarise the current status of novel therapeutic strategies specifically targeting mitochondria such as mitochondrial permeability transition pore (MPTP) opening inhibitors (cyclosporine A (CsA)), quinone analogues (MitoQ, SkQ1 and SkQR1), superoxide dismutase (SOD) mimetics (Mito-CP), Szeto-Schiller (SS) peptides (Bendavia) and mitochondrial division inhibitors (mdivi-1). MitoQ, SkQ1, SkQR1, Mito-CP, Bendavia and mdivi-1 have improved the course of diverse experimental models of AKI. Evidence for a beneficial effect of CsA on human cardiac ischaemia-reperfusion injury derives from a clinical trial; however, CsA is nephrotoxic. MitoQ and Bendavia have been shown to be safe for humans. Ongoing clinical trials are testing the efficacy of Bendavia in AKI prevention following renal artery percutaneous transluminal angioplasty.
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66
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Dotti CG, Esteban JA, Ledesma MD. Lipid dynamics at dendritic spines. Front Neuroanat 2014; 8:76. [PMID: 25152717 PMCID: PMC4126552 DOI: 10.3389/fnana.2014.00076] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 07/21/2014] [Indexed: 11/13/2022] Open
Abstract
Dynamic changes in the structure and composition of the membrane protrusions forming dendritic spines underlie memory and learning processes. In recent years a great effort has been made to characterize in detail the protein machinery that controls spine plasticity. However, we know much less about the involvement of lipids, despite being major membrane components and structure determinants. Moreover, protein complexes that regulate spine plasticity depend on specific interactions with membrane lipids for proper function and accurate intracellular signaling. In this review we gather information available on the lipid composition at dendritic spine membranes and on its dynamics. We pay particular attention to the influence that spine lipid dynamism has on glutamate receptors, which are key regulators of synaptic plasticity.
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67
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Blacque OE, Sanders AAWM. Compartments within a compartment: what C. elegans can tell us about ciliary subdomain composition, biogenesis, function, and disease. Organogenesis 2014; 10:126-37. [PMID: 24732235 DOI: 10.4161/org.28830] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The primary cilium has emerged as a hotbed of sensory and developmental signaling, serving as a privileged domain to concentrate the functions of a wide number of channels, receptors and downstream signal transducers. This realization has provided important insight into the pathophysiological mechanisms underlying the ciliopathies, an ever expanding spectrum of multi-symptomatic disorders affecting the development and maintenance of multiple tissues and organs. One emerging research focus is the subcompartmentalised nature of the organelle, consisting of discrete structural and functional subdomains such as the periciliary membrane/basal body compartment, the transition zone, the Inv compartment and the distal segment/ciliary tip region. Numerous ciliopathy, transport-related and signaling molecules localize at these compartments, indicating specific roles at these subciliary sites. Here, by focusing predominantly on research from the genetically tractable nematode C. elegans, we review ciliary subcompartments in terms of their structure, function, composition, biogenesis and relationship to human disease.
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Affiliation(s)
- Oliver E Blacque
- School of Biomolecular and Biomedical Science; University College Dublin; Dublin, Ireland
| | - Anna A W M Sanders
- School of Biomolecular and Biomedical Science; University College Dublin; Dublin, Ireland
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68
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Expression of the effector protein IncD in Chlamydia trachomatis mediates recruitment of the lipid transfer protein CERT and the endoplasmic reticulum-resident protein VAPB to the inclusion membrane. Infect Immun 2014; 82:2037-47. [PMID: 24595143 DOI: 10.1128/iai.01530-14] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chlamydia trachomatis is an obligate intracellular human pathogen responsible for ocular and genital infections. To establish its membrane-bound intracellular niche, the inclusion, C. trachomatis relies on a set of effector proteins that are injected into the host cells or inserted into the inclusion membrane. We previously proposed that insertion of the C. trachomatis effector protein IncD into the inclusion membrane contributes to the recruitment of the lipid transfer protein CERT to the inclusion. Due to the genetically intractable status of C. trachomatis at that time, this model of IncD-CERT interaction was inferred from ectopic expression of IncD and CERT in the host cell. In the present study, we investigated the impact of conditionally expressing a FLAG-tagged version of IncD in C. trachomatis. This genetic approach allowed us to establish that IncD-3×FLAG localized to the inclusion membrane and caused a massive recruitment of the lipid transfer protein CERT that relied on the PH domain of CERT. In addition, we showed that the massive IncD-dependent association of CERT with the inclusion led to an increased recruitment of the endoplasmic reticulum (ER)-resident protein VAPB, and we determined that, at the inclusion, CERT-VAPB interaction relied on the FFAT domain of CERT. Altogether, the data presented here show that expression of the C. trachomatis effector protein IncD mediates the recruitment of the lipid transfer protein CERT and the ER-resident protein VAPB to the inclusion.
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69
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Endoplasmic reticulum stress in cerebral ischemia. Neurochem Int 2014; 68:18-27. [DOI: 10.1016/j.neuint.2014.02.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 12/27/2013] [Accepted: 02/03/2014] [Indexed: 12/20/2022]
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70
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Abstract
Target of rapamycin (TOR) forms two conserved, structurally distinct kinase complexes termed TOR complex 1 (TORC1) and TORC2. Each complex phosphorylates a different set of substrates to regulate cell growth. In mammals, mTOR is stimulated by nutrients and growth factors and inhibited by stress to ensure that cells grow only during favorable conditions. Studies in different organisms have reported localization of TOR to several distinct subcellular compartments. Notably, the finding that mTORC1 is localized to the lysosome has significantly enhanced our understanding of mTORC1 regulation. Subcellular localization may be a general principle used by TOR to enact precise spatial and temporal control of cell growth.
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Affiliation(s)
- Charles Betz
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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71
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No evidence for a local renin-angiotensin system in liver mitochondria. Sci Rep 2014; 3:2467. [PMID: 23959064 PMCID: PMC3747509 DOI: 10.1038/srep02467] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 07/22/2013] [Indexed: 01/01/2023] Open
Abstract
The circulating, endocrine renin-angiotensin system (RAS) is important to circulatory homeostasis, while ubiquitous tissue and cellular RAS play diverse roles, including metabolic regulation. Indeed, inhibition of RAS is associated with improved cellular oxidative capacity. Recently it has been suggested that an intra-mitochondrial RAS directly impacts on metabolism. Here we sought to rigorously explore this hypothesis. Radiolabelled ligand-binding and unbiased proteomic approaches were applied to purified mitochondrial sub-fractions from rat liver, and the impact of AngII on mitochondrial function assessed. Whilst high-affinity AngII binding sites were found in the mitochondria-associated membrane (MAM) fraction, no RAS components could be detected in purified mitochondria. Moreover, AngII had no effect on the function of isolated mitochondria at physiologically relevant concentrations. We thus found no evidence of endogenous mitochondrial AngII production, and conclude that the effects of AngII on cellular energy metabolism are not mediated through its direct binding to mitochondrial targets.
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72
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Abstract
Key Points
Using state-of-the-art three-dimensional electron microscopy approaches, we show that the onset of the DMS formation is at the megakaryocyte plasma membrane. A pre-DMS structure is formed in the perinuclear region, through a PM invagination process that resembles cleavage furrow formation.
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73
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Suski JM, Lebiedzinska M, Wojtala A, Duszynski J, Giorgi C, Pinton P, Wieckowski MR. Isolation of plasma membrane-associated membranes from rat liver. Nat Protoc 2014; 9:312-22. [PMID: 24434800 DOI: 10.1038/nprot.2014.016] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Dynamic interplay between intracellular organelles requires a particular functional apposition of membrane structures. The organelles involved come into close contact, but do not fuse, thereby giving rise to notable microdomains; these microdomains allow rapid communication between the organelles. Plasma membrane-associated membranes (PAMs), which are microdomains of the plasma membrane (PM) interacting with the endoplasmic reticulum (ER) and mitochondria, are dynamic structures that mediate transport of proteins, lipids, ions and metabolites. These structures have gained much interest lately owing to their roles in many crucial cellular processes. Here we provide an optimized protocol for the isolation of PAM, PM and ER fractions from rat liver that is based on a series of differential centrifugations, followed by the fractionation of crude PM on a discontinuous sucrose gradient. The procedure requires ∼8-10 h, and it can be easily modified and adapted to other tissues and cell types.
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Affiliation(s)
- Jan M Suski
- 1] Nencki Institute of Experimental Biology, Department of Biochemistry, Warsaw, Poland. [2] Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Interdisciplinary Center for the Study of Inflammation (ICSI) and Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Magdalena Lebiedzinska
- 1] Nencki Institute of Experimental Biology, Department of Biochemistry, Warsaw, Poland. [2] Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Interdisciplinary Center for the Study of Inflammation (ICSI) and Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Aleksandra Wojtala
- Nencki Institute of Experimental Biology, Department of Biochemistry, Warsaw, Poland
| | - Jerzy Duszynski
- Nencki Institute of Experimental Biology, Department of Biochemistry, Warsaw, Poland
| | - Carlotta Giorgi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Interdisciplinary Center for the Study of Inflammation (ICSI) and Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Paolo Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Interdisciplinary Center for the Study of Inflammation (ICSI) and Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Mariusz R Wieckowski
- Nencki Institute of Experimental Biology, Department of Biochemistry, Warsaw, Poland
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74
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Bereiter-Hahn J. Mitochondrial dynamics in aging and disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 127:93-131. [PMID: 25149215 DOI: 10.1016/b978-0-12-394625-6.00004-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mitochondria are self-replicating organelles but nevertheless strongly depend on supply coded in nuclear genes. They serve many physiological demands in living cells. Supply of the cytoplasm with ATP and engagement in Ca(2+) regulation belong to the main functions of mitochondria. In large eukaryotic cells, in particular in neurons, with their long dendrites and axons, mitochondria have to move to the sites of their action. This trafficking involves several motor molecules and mechanisms to sense the sites of requirements of mitochondria. With aging and as a consequence of some diseases, mitochondrial components may be rendered dysfunctional, and mtDNA mutations arise during the course of replication and by the action of reactive oxygen species. Mutants in motor molecules engaged in trafficking and in the machinery of fusion and fission are causing severe deficiencies on the cellular level; they support neurodegeneration and, thus, cause many diseases. Frequent fusion and fission events mediate the elimination of impaired parts from mitochondria which finally will be degraded by autophagosomes. Extensive fusion provides a basis for functional complementation. Mobility of proteins and small molecules within the mitochondria is necessary to reach the functional goals of fusion and fission, although cristae and a large fraction of proteins of the respiratory complexes proved to be stable for hours after fusion and perform slow exchange of material.
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Affiliation(s)
- Jürgen Bereiter-Hahn
- Institute for Cell Biology and Neurosciences, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
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75
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Hypothesis of lipid-phase-continuity proton transfer for aerobic ATP synthesis. J Cereb Blood Flow Metab 2013; 33:1838-42. [PMID: 24084698 PMCID: PMC3851912 DOI: 10.1038/jcbfm.2013.175] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 09/09/2013] [Accepted: 09/12/2013] [Indexed: 12/12/2022]
Abstract
The basic processes harvesting chemical energy for life are driven by proton (H(+)) movements. These are accomplished by the mitochondrial redox complex V, integral membrane supramolecular aggregates, whose structure has recently been described by advanced studies. These did not identify classical aqueous pores. It was proposed that H(+) transfer for oxidative phosphorylation (OXPHOS) does not occur between aqueous sources and sinks, where an energy barrier would be insurmountable. This suggests a novel hypothesis for the proton transfer. A lipid-phase-continuity H(+) transfer is proposed in which H(+) are always bound to phospholipid heads and cardiolipin, according to Mitchell's hypothesis of asymmetric vectorial H(+) diffusion. A phase separation is proposed among the proton flow, following an intramembrane pathway, and the ATP synthesis, occurring in the aqueous phase. This view reminiscent of Grotthus mechanism would better account for the distance among the Fo and F1 moieties of FoF1-ATP synthase, for its mechanical coupling, as well as the necessity of a lipid membrane. A unique active role for lipids in the evolution of life can be envisaged. Interestingly, this view would also be consistent with the evidence of an OXPHOS outside mitochondria also found in non-vesicular membranes, housing the redox complexes.
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76
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Fredericks WJ, McGarvey T, Wang H, Zheng Y, Fredericks NJ, Yin H, Wang LP, Hsiao W, Lee R, Weiss JS, Nickerson ML, Kruth HS, Rauscher FJ, Malkowicz SB. The TERE1 protein interacts with mitochondrial TBL2: regulation of trans-membrane potential, ROS/RNS and SXR target genes. J Cell Biochem 2013; 114:2170-87. [PMID: 23564352 DOI: 10.1002/jcb.24567] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Accepted: 04/02/2013] [Indexed: 12/12/2022]
Abstract
We originally discovered TERE1 as a potential tumor suppressor protein based upon reduced expression in bladder and prostate cancer specimens and growth inhibition of tumor cell lines/xenografts upon ectopic expression. Analysis of TERE1 (aka UBIAD1) has shown it is a prenyltransferase enzyme in the natural bio-synthetic pathways for both vitamin K-2 and COQ10 production and exhibits multiple subcellular localizations including mitochondria, endoplasmic reticulum, and golgi. Vitamin K-2 is involved in mitochondrial electron transport, SXR nuclear hormone receptor signaling and redox cycling: together these functions may form the basis for tumor suppressor function. To gain further insight into mechanisms of growth suppression and enzymatic regulation of TERE1 we isolated TERE1 associated proteins and identified the WD40 repeat, mitochondrial protein TBL2. We examined whether disease specific mutations in TERE1 affected interactions with TBL2 and the role of each protein in altering mitochondrial function, ROS/RNS production and SXR target gene regulation. Biochemical binding assays demonstrated a direct, high affinity interaction between TERE1 and TBL2 proteins; TERE1 was localized to both mitochondrial and non-mitochondrial membranes whereas TBL2 was predominantly mitochondrial; multiple independent single amino acid substitutions in TERE1 which cause a human hereditary corneal disease reduced binding to TBL2 strongly suggesting the relevance of this interaction. Ectopic TERE1 expression elevated mitochondrial trans-membrane potential, oxidative stress, NO production, and activated SXR targets. A TERE1-TBL2 complex likely functions in oxidative/nitrosative stress, lipid metabolism, and SXR signaling pathways in its role as a tumor suppressor.
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Affiliation(s)
- William J Fredericks
- Division of Urology, Department of Surgery, University of Pennsylvania and Veterans Affairs Medical Center Philadelphia, Philadelphia, Pennsylvania 19104, USA.
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77
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Macromitophagy is a longevity assurance process that in chronologically aging yeast limited in calorie supply sustains functional mitochondria and maintains cellular lipid homeostasis. Aging (Albany NY) 2013; 5:234-69. [PMID: 23553280 PMCID: PMC3651518 DOI: 10.18632/aging.100547] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Macromitophagy controls mitochondrial quality and quantity. It involves the sequestration of dysfunctional or excessive mitochondria within double-membrane autophagosomes, which then fuse with the vacuole/lysosome to deliver these mitochondria for degradation. To investigate a physiological role of macromitophagy in yeast, we examined how theatg32Δ-dependent mutational block of this process influences the chronological lifespan of cells grown in a nutrient-rich medium containing low (0.2%) concentration of glucose. Under these longevity-extending conditions of caloric restriction (CR) yeast cells are not starving. We also assessed a role of macromitophagy in lifespan extension by lithocholic acid (LCA), a bile acid that prolongs yeast longevity under CR conditions. Our findings imply that macromitophagy is a longevity assurance process underlying the synergistic beneficial effects of CR and LCA on yeast lifespan. Our analysis of how the atg32Δ mutation influences mitochondrial morphology, composition and function revealed that macromitophagy is required to maintain a network of healthy mitochondria. Our comparative analysis of the membrane lipidomes of organelles purified from wild-type and atg32Δ cells revealed that macromitophagy is required for maintaining cellular lipid homeostasis. We concluded that macromitophagy defines yeast longevity by modulating vital cellular processes inside and outside of mitochondria.
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78
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McInnes J. Mitochondrial-associated metabolic disorders: foundations, pathologies and recent progress. Nutr Metab (Lond) 2013; 10:63. [PMID: 24499129 PMCID: PMC3853754 DOI: 10.1186/1743-7075-10-63] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 10/08/2013] [Indexed: 01/06/2023] Open
Abstract
Research in the last decade has revolutionized the way in which we view mitochondria. Mitochondria are no longer viewed solely as cellular powerhouses; rather, mitochondria are now understood to be vibrant, mobile structures, constantly undergoing fusion and fission, and engaging in intimate interactions with other cellular compartments and structures. Findings have implicated mitochondria in a wide variety of cellular processes and molecular interactions, such as calcium buffering, lipid flux, and intracellular signaling. As such, it does not come as a surprise that an increasing number of human pathologies have been associated with functional defects in mitochondria. The difficulty in understanding and treating human pathologies caused by mitochondrial dysfunction arises from the complex relationships between mitochondria and other cellular processes, as well as the genetic background of such diseases. This review attempts to provide a summary of the background knowledge and recent developments in mitochondrial processes relating to mitochondrial-associated metabolic diseases arising from defects or deficiencies in mitochondrial function, as well as insights into current and future avenues for investigation.
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Affiliation(s)
- Joseph McInnes
- School of Engineering and Science, Research Center MOLIFE - Molecular Life Science, Jacobs University Bremen, Campus Ring 1, Research II, Room 120, Bremen D-28759, Germany.
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79
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Yang JS, Kim J, Park S, Jeon J, Shin YE, Kim S. Spatial and functional organization of mitochondrial protein network. Sci Rep 2013; 3:1403. [PMID: 23466738 PMCID: PMC3590558 DOI: 10.1038/srep01403] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Accepted: 02/21/2013] [Indexed: 12/24/2022] Open
Abstract
Characterizing the spatial organization of the human mitochondrial proteome will enhance our understanding of mitochondrial functions at the molecular level and provide key insight into protein-disease associations. However, the sub-organellar location and possible association with mitochondrial diseases are not annotated for most mitochondrial proteins. Here, we characterized the functional and spatial organization of mitochondrial proteins by assessing their position in the Mitochondrial Protein Functional (MPF) network. Network position was assigned to the MPF network and facilitated the determination of sub-organellar location and functional organization of mitochondrial proteins. Moreover, network position successfully identified candidate disease genes of several mitochondrial disorders. Thus, our data support the use of network position as a novel method to explore the molecular function and pathogenesis of mitochondrial proteins.
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Affiliation(s)
- Jae-Seong Yang
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Nam-gu, Pohang, Gyeongbuk, Korea, 790-784
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80
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Betz C, Stracka D, Prescianotto-Baschong C, Frieden M, Demaurex N, Hall MN. Feature Article: mTOR complex 2-Akt signaling at mitochondria-associated endoplasmic reticulum membranes (MAM) regulates mitochondrial physiology. Proc Natl Acad Sci U S A 2013; 110:12526-34. [PMID: 23852728 PMCID: PMC3732980 DOI: 10.1073/pnas.1302455110] [Citation(s) in RCA: 415] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The target of rapamycin (TOR) is a highly conserved protein kinase and a central controller of growth. Mammalian TOR complex 2 (mTORC2) regulates AGC kinase family members and is implicated in various disorders, including cancer and diabetes. Here we report that mTORC2 is localized to the endoplasmic reticulum (ER) subcompartment termed mitochondria-associated ER membrane (MAM). mTORC2 localization to MAM was growth factor-stimulated, and mTORC2 at MAM interacted with the IP3 receptor (IP3R)-Grp75-voltage-dependent anion-selective channel 1 ER-mitochondrial tethering complex. mTORC2 deficiency disrupted MAM, causing mitochondrial defects including increases in mitochondrial membrane potential, ATP production, and calcium uptake. mTORC2 controlled MAM integrity and mitochondrial function via Akt mediated phosphorylation of the MAM associated proteins IP3R, Hexokinase 2, and phosphofurin acidic cluster sorting protein 2. Thus, mTORC2 is at the core of a MAM signaling hub that controls growth and metabolism.
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Affiliation(s)
- Charles Betz
- Growth and Development, Biozentrum, University of Basel, CH-4056 Basel, Switzerland; and
| | - Daniele Stracka
- Growth and Development, Biozentrum, University of Basel, CH-4056 Basel, Switzerland; and
| | | | - Maud Frieden
- Department of Cell Physiology and Metabolism, University of Geneva, 1211 Geneva 4, Switzerland
| | - Nicolas Demaurex
- Department of Cell Physiology and Metabolism, University of Geneva, 1211 Geneva 4, Switzerland
| | - Michael N. Hall
- Growth and Development, Biozentrum, University of Basel, CH-4056 Basel, Switzerland; and
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81
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Interaction of membrane/lipid rafts with the cytoskeleton: impact on signaling and function: membrane/lipid rafts, mediators of cytoskeletal arrangement and cell signaling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:532-45. [PMID: 23899502 DOI: 10.1016/j.bbamem.2013.07.018] [Citation(s) in RCA: 382] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 05/14/2013] [Accepted: 07/16/2013] [Indexed: 12/14/2022]
Abstract
The plasma membrane in eukaryotic cells contains microdomains that are enriched in certain glycosphingolipids, gangliosides, and sterols (such as cholesterol) to form membrane/lipid rafts (MLR). These regions exist as caveolae, morphologically observable flask-like invaginations, or as a less easily detectable planar form. MLR are scaffolds for many molecular entities, including signaling receptors and ion channels that communicate extracellular stimuli to the intracellular milieu. Much evidence indicates that this organization and/or the clustering of MLR into more active signaling platforms depends upon interactions with and dynamic rearrangement of the cytoskeleton. Several cytoskeletal components and binding partners, as well as enzymes that regulate the cytoskeleton, localize to MLR and help regulate lateral diffusion of membrane proteins and lipids in response to extracellular events (e.g., receptor activation, shear stress, electrical conductance, and nutrient demand). MLR regulate cellular polarity, adherence to the extracellular matrix, signaling events (including ones that affect growth and migration), and are sites of cellular entry of certain pathogens, toxins and nanoparticles. The dynamic interaction between MLR and the underlying cytoskeleton thus regulates many facets of the function of eukaryotic cells and their adaptation to changing environments. Here, we review general features of MLR and caveolae and their role in several aspects of cellular function, including polarity of endothelial and epithelial cells, cell migration, mechanotransduction, lymphocyte activation, neuronal growth and signaling, and a variety of disease settings. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.
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82
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Goswami R, Majumdar T, Dhar J, Chattopadhyay S, Bandyopadhyay SK, Verbovetskaya V, Sen GC, Barik S. Viral degradasome hijacks mitochondria to suppress innate immunity. Cell Res 2013; 23:1025-42. [PMID: 23877405 DOI: 10.1038/cr.2013.98] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 04/02/2013] [Accepted: 04/27/2013] [Indexed: 12/14/2022] Open
Abstract
The balance between the innate immunity of the host and the ability of a pathogen to evade it strongly influences pathogenesis and virulence. The two nonstructural (NS) proteins, NS1 and NS2, of respiratory syncytial virus (RSV) are critically required for RSV virulence. Together, they strongly suppress the type I interferon (IFN)-mediated innate immunity of the host cells by degrading or inhibiting multiple cellular factors required for either IFN induction or response pathways, including RIG-I, IRF3, IRF7, TBK1 and STAT2. Here, we provide evidence for the existence of a large and heterogeneous degradative complex assembled by the NS proteins, which we named "NS-degradasome" (NSD). The NSD is roughly ∼300-750 kD in size, and its degradative activity was enhanced by the addition of purified mitochondria in vitro. Inside the cell, the majority of the NS proteins and the substrates of the NSD translocated to the mitochondria upon RSV infection. Genetic and pharmacological evidence shows that optimal suppression of innate immunity requires mitochondrial MAVS and mitochondrial motility. Together, we propose a novel paradigm in which the mitochondria, known to be important for the innate immune activation of the host, are also important for viral suppression of the innate immunity.
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Affiliation(s)
- Ramansu Goswami
- Center for Gene Regulation in Health and Disease, and Department of Biological, Geological and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
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83
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Romano JD, Coppens I. Host Organelle Hijackers: a similar modus operandi for Toxoplasma gondii and Chlamydia trachomatis: co-infection model as a tool to investigate pathogenesis. Pathog Dis 2013; 69:72-86. [PMID: 23821471 DOI: 10.1111/2049-632x.12057] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 06/11/2013] [Accepted: 06/11/2013] [Indexed: 12/27/2022] Open
Abstract
The bacterium Chlamydia trachomatis and the protozoan parasite Toxoplasma gondii are the causative agents of chlamydiosis and toxoplasmosis in humans, respectively. Both microorganisms are obligate intracellular pathogens and notorious for extensively modifying the cytoskeletal architecture and the endomembrane system of their host cells to establish productive infections. This review highlights the similar tactics developed by these two pathogens to manipulate their host cell despite their genetic unrelatedness. Using an in vitro cell culture model whereby single fibroblasts are infected by C. trachomatis and T. gondii simultaneously, thus setting up an intracellular competition, we demonstrate that the solutions to the problem of intracellular survival deployed by the parasite and the bacterium may represent an example of convergent evolution, driven by the necessity to acquire nutrients in a hostile environment.
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Affiliation(s)
- Julia D Romano
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
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84
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Schon EA, Area-Gomez E. Mitochondria-associated ER membranes in Alzheimer disease. Mol Cell Neurosci 2013; 55:26-36. [DOI: 10.1016/j.mcn.2012.07.011] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 07/26/2012] [Accepted: 07/27/2012] [Indexed: 01/03/2023] Open
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85
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Li J, Dong Y, Lü X, Wang L, Peng W, Zhang XC, Rao Z. Crystal structures and biochemical studies of human lysophosphatidic acid phosphatase type 6. Protein Cell 2013; 4:548-61. [PMID: 23807634 DOI: 10.1007/s13238-013-3031-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 05/28/2013] [Indexed: 10/26/2022] Open
Abstract
Lysophosphatidic acid (LPA) is an important bioactive phospholipid involved in cell signaling through Gprotein-coupled receptors pathways. It is also involved in balancing the lipid composition inside the cell, and modulates the function of lipid rafts as an intermediate in phospholipid metabolism. Because of its involvement in these important processes, LPA degradation needs to be regulated as precisely as its production. Lysophosphatidic acid phosphatase type 6 (ACP6) is an LPA-specific acid phosphatase that hydrolyzes LPA to monoacylglycerol (MAG) and phosphate. Here, we report three crystal structures of human ACP6 in complex with malonate, L-(+)-tartrate and tris, respectively. Our analyses revealed that ACP6 possesses a highly conserved Rossmann-foldlike body domain as well as a less conserved cap domain. The vast hydrophobic substrate-binding pocket, which is located between those two domains, is suitable for accommodating LPA, and its shape is different from that of other histidine acid phosphatases, a fact that is consistent with the observed difference in substrate preferences. Our analysis of the binding of three molecules in the active site reveals the involvement of six conserved and crucial residues in binding of the LPA phosphate group and its catalysis. The structure also indicates a water-supplying channel for substrate hydrolysis. Our structural data are consistent with the fact that the enzyme is active as a monomer. In combination with additional mutagenesis and enzyme activity studies, our structural data provide important insights into substrate recognition and the mechanism for catalytic activity of ACP6.
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Affiliation(s)
- Jun Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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86
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Fowler S, Akins M, Zhou H, Figeys D, Bennett SA. The liver connexin32 interactome is a novel plasma membrane-mitochondrial signaling nexus. J Proteome Res 2013; 12:2597-610. [PMID: 23590695 PMCID: PMC3714164 DOI: 10.1021/pr301166p] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Indexed: 02/07/2023]
Abstract
Connexins are the structural subunits of gap junctions and act as protein platforms for signaling complexes. Little is known about tissue-specific connexin signaling nexuses, given significant challenges associated with affinity-purifying endogenous channel complexes to the level required for interaction analyses. Here, we used multiple subcellular fractionation techniques to isolate connexin32-enriched membrane microdomains from murine liver. We show, for the first time, that connexin32 localizes to both the plasma membrane and inner mitochondrial membrane of hepatocytes. Using a combination of immunoprecipitation-high throughput mass spectrometry, reciprocal co-IP, and subcellular fractionation methodologies, we report a novel interactome validated using null mutant controls. Eighteen connexin32 interacting proteins were identified. The majority represent resident mitochondrial proteins, a minority represent plasma membrane, endoplasmic reticulum, or cytoplasmic partners. In particular, connexin32 interacts with connexin26 and the mitochondrial protein, sideroflexin-1, at the plasma membrane. Connexin32 interaction enhances connexin26 stability. Converging bioinformatic, biochemical, and confocal analyses support a role for connexin32 in transiently tethering mitochondria to connexin32-enriched plasma membrane microdomains through interaction with proteins in the outer mitochondrial membrane, including sideroflexin-1. Complex formation increases the pool of sideroflexin-1 that is present at the plasma membrane. Together, these data identify a novel plasma membrane/mitochondrial signaling nexus in the connexin32 interactome.
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Affiliation(s)
- Stephanie
L. Fowler
- Neural
Regeneration Laboratory, Ottawa Institute of Systems Biology, Department of
Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Mark Akins
- Neural
Regeneration Laboratory, Ottawa Institute of Systems Biology, Department of
Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Hu Zhou
- Neural
Regeneration Laboratory, Ottawa Institute of Systems Biology, Department of
Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- Shanghai Institute of Materia
Medica, Chinese Academy of Sciences, Shanghai,
China
| | - Daniel Figeys
- Neural
Regeneration Laboratory, Ottawa Institute of Systems Biology, Department of
Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Steffany A.L. Bennett
- Neural
Regeneration Laboratory, Ottawa Institute of Systems Biology, Department of
Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
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87
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Abstract
Mitochondria not only govern energy production, but are also involved in crucial cellular signalling processes. They are one of the most important organelles determining the Ca(2+) regulatory pathway in the cell. Several mathematical models explaining these mechanisms were constructed, but only few of them describe interplay between calcium concentrations in endoplasmic reticulum (ER), cytoplasm and mitochondria. Experiments measuring calcium concentrations in mitochondria and ER suggested the existence of cytosolic microdomains with locally elevated calcium concentration in the nearest vicinity of the outer mitochondrial membrane. These intermediate physical connections between ER and mitochondria are called MAM (mitochondria-associated ER membrane) complexes. We propose a model with a direct calcium flow from ER to mitochondria, which may be justified by the existence of MAMs, and perform detailed numerical analysis of the effect of this flow on the type and shape of calcium oscillations. The model is partially based on the Marhl et al model. We have numerically found that the stable oscillations exist for a considerable set of parameter values. However, for some parameter sets the oscillations disappear and the trajectories of the model tend to a steady state with very high calcium level in mitochondria. This can be interpreted as an early step in an apoptotic pathway.
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Affiliation(s)
- Piotr Szopa
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
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88
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Flis VV, Daum G. Lipid transport between the endoplasmic reticulum and mitochondria. Cold Spring Harb Perspect Biol 2013; 5:5/6/a013235. [PMID: 23732475 DOI: 10.1101/cshperspect.a013235] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Mitochondria are partially autonomous organelles that depend on the import of certain proteins and lipids to maintain cell survival and membrane formation. Although phosphatidylglycerol, cardiolipin, and phosphatidylethanolamine are synthesized by mitochondrial enzymes, phosphatidylcholine, phosphatidylinositol, phosphatidylserine, and sterols need to be imported from other organelles. The origin of most lipids imported into mitochondria is the endoplasmic reticulum, which requires interaction of these two subcellular compartments. Recently, protein complexes that are involved in membrane contact between endoplasmic reticulum and mitochondria were identified, but their role in lipid transport is still unclear. In the present review, we describe components involved in lipid translocation between the endoplasmic reticulum and mitochondria and discuss functional as well as regulatory aspects that are important for lipid homeostasis.
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Affiliation(s)
- Vid V Flis
- Institute of Biochemistry, Graz University of Technology, A-8010 Graz, Austria
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89
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McInnes J. Insights on altered mitochondrial function and dynamics in the pathogenesis of neurodegeneration. Transl Neurodegener 2013; 2:12. [PMID: 23711354 PMCID: PMC3669018 DOI: 10.1186/2047-9158-2-12] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 05/25/2013] [Indexed: 11/27/2022] Open
Abstract
In neurons, mitochondria are enriched to provide energy and calcium buffering required for synaptic transmission. Additionally, mitochondria localize to the synapse, where they are critical for the mobilization of reserve pool vesicles and for neurotransmitter release. Previously, functional defects in mitochondria were considered to be downstream effects of neurodegenerative diseases. However, more recent findings suggest mitochondria may serve as key mediators in the onset and progression of some types of neurodegeneration. In this review, we explore the possible roles of altered mitochondrial function and dynamics in the pathogenesis of neurodegenerative disorders, with a particular focus on Alzheimer’s disease (AD) and Parkinson’s disease (PD), which have highlighted the important role of mitochondria in neurodegeneration. While inheritable diseases like Charcot-Marie-Tooth disease type 2A are concretely linked to gene mutations affecting mitochondrial function, the cause of mitochondrial dysfunction in primarily sporadic diseases such as AD and PD is less clear. Neuronal death in PD is associated with defects in mitochondrial function and dynamics arising from mutations in proteins affecting these processes, including α-synuclein, DJ-1, LRRK2, Parkin and Pink1. In the case of AD, however, the connection between mitochondria and the onset of neurodegeneration has been less clear. Recent findings, however, have implicated altered function of ER-mitochondria contact sites and amyloid beta- and/or tau-induced defects in mitochondrial function and dynamics in the pathogenesis of AD, suggesting that mitochondrial defects may act as key mediators in the pathogenesis of AD as well. With recent findings at hand, it may be postulated that defects in mitochondrial processes comprise key events in the onset of neurodegeneration.
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Affiliation(s)
- Joseph McInnes
- School of Engineering and Science, Research Center MOLIFE-Molecular Life Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
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90
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Arismendi-Morillo G, Hoa NT, Ge L, Jadus MR. Mitochondrial network in glioma's invadopodia displays an activated state both in situ and in vitro: potential functional implications. Ultrastruct Pathol 2013; 36:409-14. [PMID: 23216239 DOI: 10.3109/01913123.2012.694582] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Gliomas are typically characterized by their infiltrative nature, and the prognosis can be linked to the invasive nature of the tumoral cells. Glioblastoma multiforme are very invasive cancers and this contributes to their lethality. The invadopodia are considered essential for their motility. Human glioma cell invadopodia were examined with transmission electron and immunofluorescent microscopy. By electron microscopy, in situ gliomas (fibrillary astrocytoma, anaplastic astrocytoma, glioblastoma multiforme, pilocytic astrocytoma) show mitochondria with a dense matrix condensed configuration, indicating an active state. The mitochondria were frequently in close contact with an extended smooth endoplasmic reticulum displaying an endoplasmic reticulum subfraction associated with mitochondria. Mitochondria were seen within the filopodia that were penetrating into the extracellular matrix. The activated mitochondria and smooth endoplasmic reticulum were also detected within the invadopdia, which was associated microblood vessels. Fluorescent microscopy confirmed that D54 and U251 glioma cells growing in vitro also contained filopodia with mitochondria. The U251 glioma cells' filopodia that penetrated through 1.2-μm pores of transwell chambers also contained mitocondria, suggesting that the mitochondria are actively involved in the invasion process. Migration and invasion of tumor cells requires an increase in cellular motility and involves formation of lamellipodia, protrusions of the plasma membrane, and individual filopodia [ 1 ]. Gliomas are typically characterized by their infiltrative nature, resulting in a poorly demarcated interface between tumor and normal brain tissue. Their poor prognosis can be linked to the invasive nature of these cells. The motility of these tumor cells is correlated with the presence of invadopodia [ 2 ], and, consequently, more insight is necessary into their structural and molecular aspects. Evidence of robust invadopodia activity in glioblastoma multiforme cells has been reported [ 3 , 4 ]. Because of the significant impact of invadopodia in oncological events such as cell invasion and matrix degradation, more insight into structural and molecular aspects is needed [ 2 ]. The dynamic assembly of invadopodia is still not well understood [ 2 ], and little is known of the alterations in mitochondrial structure and function that contribute to cell mobility [ 5 ]. This paper describes two prominent structural features of the mitochondrial network present within the glioma´s invadopodia that we have recently observed. We believe these two features (activated mitochondria and smooth ER, along with mitochondria contained within the filopodia) might provide researchers with possible targets for future therapies that can control glioma invasiveness.
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91
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Clayton EL, Minogue S, Waugh MG. Mammalian phosphatidylinositol 4-kinases as modulators of membrane trafficking and lipid signaling networks. Prog Lipid Res 2013; 52:294-304. [PMID: 23608234 PMCID: PMC3989048 DOI: 10.1016/j.plipres.2013.04.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 04/08/2013] [Indexed: 12/19/2022]
Abstract
The four mammalian phosphatidylinositol 4-kinases modulate inter-organelle lipid trafficking, phosphoinositide signalling and intracellular vesicle trafficking. In addition to catalytic domains required for the synthesis of PI4P, the phosphatidylinositol 4-kinases also contain isoform-specific structural motifs that mediate interactions with proteins such as AP-3 and the E3 ubiquitin ligase Itch, and such structural differences determine isoform-specific roles in membrane trafficking. Moreover, different permutations of phosphatidylinositol 4-kinase isozymes may be required for a single cellular function such as occurs during distinct stages of GPCR signalling and in Golgi to lysosome trafficking. Phosphatidylinositol 4-kinases have recently been implicated in human disease. Emerging paradigms include increased phosphatidylinositol 4-kinase expression in some cancers, impaired functioning associated with neurological pathologies, the subversion of PI4P trafficking functions in bacterial infection and the activation of lipid kinase activity in viral disease. We discuss how the diverse and sometimes overlapping functions of the phosphatidylinositol 4-kinases present challenges for the design of isoform-specific inhibitors in a therapeutic context.
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Affiliation(s)
- Emma L Clayton
- UCL Institute for Liver & Digestive Health, UCL Royal Free Campus, Rowland Hill Street, London NW3 2PF, United Kingdom
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92
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English AR, Voeltz GK. Endoplasmic reticulum structure and interconnections with other organelles. Cold Spring Harb Perspect Biol 2013; 5:a013227. [PMID: 23545422 DOI: 10.1101/cshperspect.a013227] [Citation(s) in RCA: 226] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The endoplasmic reticulum (ER) is a large, continuous membrane-bound organelle comprised of functionally and structurally distinct domains including the nuclear envelope, peripheral tubular ER, peripheral cisternae, and numerous membrane contact sites at the plasma membrane, mitochondria, Golgi, endosomes, and peroxisomes. These domains are required for multiple cellular processes, including synthesis of proteins and lipids, calcium level regulation, and exchange of macromolecules with various organelles at ER-membrane contact sites. The ER maintains its unique overall structure regardless of dynamics or transfer at ER-organelle contacts. In this review, we describe the numerous factors that contribute to the structure of the ER.
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Affiliation(s)
- Amber R English
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
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93
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Yamashita A, Taniwaki T, Kaikoi Y, Yamazaki T. Protective role of the endoplasmic reticulum protein mitsugumin23 against ultraviolet C-induced cell death. FEBS Lett 2013; 587:1299-303. [DOI: 10.1016/j.febslet.2013.03.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 12/27/2012] [Accepted: 03/14/2013] [Indexed: 12/15/2022]
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94
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Poston CN, Krishnan SC, Bazemore-Walker CR. In-depth proteomic analysis of mammalian mitochondria-associated membranes (MAM). J Proteomics 2013; 79:219-30. [DOI: 10.1016/j.jprot.2012.12.018] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 12/12/2012] [Accepted: 12/26/2012] [Indexed: 12/25/2022]
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95
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Transport and distribution of 45Ca2+ in the perfused rat liver and the influence of adjuvant-induced arthritis. Biochim Biophys Acta Mol Basis Dis 2013; 1832:249-62. [DOI: 10.1016/j.bbadis.2012.10.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 09/30/2012] [Accepted: 10/06/2012] [Indexed: 12/22/2022]
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96
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Fujioka H, Tandler B, Haldar SM, Jain MK, Hoppel CL. String mitochondria in mouse soleus muscle. Microsc Res Tech 2012; 76:237-41. [PMID: 23174930 DOI: 10.1002/jemt.22158] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 11/02/2012] [Indexed: 11/06/2022]
Abstract
Red myofibers in mouse soleus muscle have two spatially distinct populations of mitochondria: one where these organelles are disposed in large clusters just inside the sarcolemma and the other situated between the myofibrils. In most cases, the interfibrillar mitochondria (IFM), which are much smaller than the subsarcolemmal ones (SSM), are arranged as pairs, with each member on opposite sides of the Z-line. In some myofibers, the IFM have fused end-to-end to form greatly elongated organelles, which we call "string mitochondria." Although narrow, these can be many sarcomeres in length. The SSM do not form string mitochondria. Most of the string mitochondria exhibit many instances of "pinching," a process involved in mitochondrial division. Elements of sarcoplasmic reticulum are intimately involved with each mitochondrial membrane invagination. It appears as if the fusion:fission balance of IFM in the soleus muscle is slightly out of kilter, with end-to-end fusion predominating over fission.
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Affiliation(s)
- Hisashi Fujioka
- Electron Microscopy Facility, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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97
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Abstract
The transport of lipids from their synthesis site at the endoplasmic reticulum (ER) to different target membranes could be mediated by both vesicular and nonvesicular transport mechanisms. Nonvesicular lipid transport appears to be the major transport route of certain lipid species, and could be mediated by either spontaneous lipid transport or by lipid-transfer proteins (LTPs). Although nonvesicular lipid transport has been extensively studied for more than four decades, its underlying mechanism, advantage and regulation, have not been fully explored. In particular, the function of LTPs and their involvement in intracellular lipid movement remain largely controversial. In this article, we describe the pathways by which lipids are synthesized at the ER and delivered to different cellular membranes, and discuss the role of LTPs in lipid transport both in vitro and in intact cells.
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Affiliation(s)
- Sima Lev
- Molecular Cell Biology Department, Weizmann Institute of Science, Rehovot 76100, Israel.
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98
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Cosson P, Marchetti A, Ravazzola M, Orci L. Mitofusin-2 independent juxtaposition of endoplasmic reticulum and mitochondria: an ultrastructural study. PLoS One 2012; 7:e46293. [PMID: 23029466 PMCID: PMC3460865 DOI: 10.1371/journal.pone.0046293] [Citation(s) in RCA: 181] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 08/29/2012] [Indexed: 11/19/2022] Open
Abstract
Besides its role in controlling the morphology of mitochondria, mitofusin-2 has been proposed to tether mitochondria to the endoplasmic reticulum (ER), based largely on light microscopic analysis. In this study we have examined by electron microscopy the organization of ER and mitochondria in cells expressing or not mitofusin-2. Contrary to previous studies, we observed that loss of mitofusin-2 increased ER-mitochondria juxtaposition. These results suggest that mitofusin-2 does not play a critical role in the juxtapostion of ER and mitochondria, and highlight the essential role of ultrastructural analysis to visualize and measure contact between two intracellular compartments.
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Affiliation(s)
- Pierre Cosson
- Department for Cell Physiology and Metabolism, Centre Médical Universitaire, Geneva Faculty of Medicine, Geneva, Switzerland.
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99
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Abstract
During the past two decades calcium (Ca(2+)) accumulation in energized mitochondria has emerged as a biological process of utmost physiological relevance. Mitochondrial Ca(2+) uptake was shown to control intracellular Ca(2+) signalling, cell metabolism, cell survival and other cell-type specific functions by buffering cytosolic Ca(2+) levels and regulating mitochondrial effectors. Recently, the identity of mitochondrial Ca(2+) transporters has been revealed, opening new perspectives for investigation and molecular intervention.
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100
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Minogue S, Waugh MG. Lipid rafts, microdomain heterogeneity and inter-organelle contacts: impacts on membrane preparation for proteomic studies. Biol Cell 2012; 104:618-27. [PMID: 22694059 DOI: 10.1111/boc.201200020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 06/08/2012] [Indexed: 12/20/2022]
Abstract
In recent years, there has been considerable interest in mapping the protein content of isolated organelles using mass spectrometry. However, many subcellular compartments are highly dynamic with diverse and intricate architectures that are not always preserved during membrane isolation procedures. Furthermore, lateral heterogeneities in intra-membrane lipid and protein concentrations underlie the formation of membrane microdomains, trafficking vesicles and inter-membrane contacts. These complexities in membrane organisation have important consequences for the design of membrane preparation strategies and test the very concept of organelle purity. We illustrate how some of these biological considerations are relevant to membrane preparation and assess the numerous potential pitfalls in attempting to purify organelles from mammalian cells.
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Affiliation(s)
- Shane Minogue
- Centre for Molecular Cell Biology, UCL, Institute of Liver and Digestive Health, Royal Free Campus, UCL, London NW3 2PF, United Kingdom
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