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Gooran N, Kopra K. Fluorescence-Based Protein Stability Monitoring-A Review. Int J Mol Sci 2024; 25:1764. [PMID: 38339045 PMCID: PMC10855643 DOI: 10.3390/ijms25031764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 01/26/2024] [Accepted: 01/29/2024] [Indexed: 02/12/2024] Open
Abstract
Proteins are large biomolecules with a specific structure that is composed of one or more long amino acid chains. Correct protein structures are directly linked to their correct function, and many environmental factors can have either positive or negative effects on this structure. Thus, there is a clear need for methods enabling the study of proteins, their correct folding, and components affecting protein stability. There is a significant number of label-free methods to study protein stability. In this review, we provide a general overview of these methods, but the main focus is on fluorescence-based low-instrument and -expertise-demand techniques. Different aspects related to thermal shift assays (TSAs), also called differential scanning fluorimetry (DSF) or ThermoFluor, are introduced and compared to isothermal chemical denaturation (ICD). Finally, we discuss the challenges and comparative aspects related to these methods, as well as future opportunities and assay development directions.
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Affiliation(s)
| | - Kari Kopra
- Department of Chemistry, University of Turku, Henrikinkatu 2, 20500 Turku, Finland;
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2
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Alam SR, Mahadevan MS, Periasamy A. Detecting RNA-Protein Interactions With EGFP-Cy3 FRET by Acceptor Photobleaching. Curr Protoc 2023; 3:e689. [PMID: 36821783 DOI: 10.1002/cpz1.689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Förster Resonance Energy Transfer (FRET) is a great tool for cell biologists to investigate molecular interactions in live specimens. FRET is a distance-dependent phenomenon which can detect molecular interactions at distances between 1-10 nm. Several FRET approaches are reported in the literature for live and fixed cells to study protein-protein interactions; this protocol provides details of acceptor photobleaching as a FRET method to study RNA-Protein interactions. Cy3-labeled RNA foci (FRET acceptors) are photobleached at the intra-cellular site of interest (the nuclei) and the intensity of the EGFP-tagged proteins (FRET donors) at that same site are measured pre- and post- photobleaching. In principle, FRET is detected if the intensity of EGFP increases after photobleaching of Cy3. This protocol describes necessary steps and appropriate controls to conduct FRET measurements by the acceptor photobleaching method. Successful applications of this protocol will provide data to support the conclusion that EGFP-labeled proteins directly interact with Cy3-labeled RNA at the site of photobleaching. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: FRET in fixed cells Alternate Protocol: FRET in live cells.
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Affiliation(s)
- Shagufta Rehman Alam
- W. M. Keck Center for Cellular Imaging, University of Virginia, Charlottesville, Virginia
| | - Mani S Mahadevan
- Department of Pathology, University of Virginia, Charlottesville, Virginia
| | - Ammasi Periasamy
- W. M. Keck Center for Cellular Imaging, University of Virginia, Charlottesville, Virginia.,Departments of Biology and Biomedical Engineering, University of Virginia, Charlottesville, Virginia
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3
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Clegg LAM, Sloth JK, Bæk R, Jørgensen MM. Photometric method for dual targeting of surface and surface-associated proteins on extracellular vesicles in the multiparametric test. Front Mol Biosci 2022; 9:917487. [DOI: 10.3389/fmolb.2022.917487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 10/03/2022] [Indexed: 11/13/2022] Open
Abstract
Extracellular vesicles (EVs) have become a topic of interest within the field of diagnostic biomarkers; however, recent developments in the study of EVs have increased the need for simpler but still comprehensive methods for characterization. Here, we describe how to simultaneously measure several surface or surface-associated proteins on EVs using a multiparametric microarray-based analysis termed Extracellular Vesicle Array (EV Array), which is developed to catch and phenotypically characterize small EVs. Previously, this analysis has been limited to measuring only one fluorescent signal per analysis. The analysis relies on antibodies printed onto a solid surface, for catching the EVs carrying the specific surface or surface-associated proteins, and on the subsequent fluorescent detection. For the optimization of detection, two antibodies with attached Cy3 or Cy5 were added to various combinations of the EV surface or surface-associated proteins: CD9, CD63, CD81, flotillin-1, and HSP90. In this study, the EV surface or surface-associated proteins were analyzed in human plasma from six healthy subjects. Changes observed in signal intensities from Cy3 and Cy5 related specifically to these combinations and allowed for a comparison of the two different fluorescent signals. When comparing the results, it was observed that it is possible to measure the EV surface or surface-associated proteins at both 532 nm (Cy3) and 635 nm (Cy5) simultaneously without a significant change in signals from the detection molecules. This allows us to measure multiple EV marker proteins in a single analysis, thereby more quickly finding complex biomarker patterns in a sample.
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Nayar S, Thangavel G. CsubMADS1, a lag phase transcription factor, controls development of polar eukaryotic microalga Coccomyxa subellipsoidea C-169. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 107:1228-1242. [PMID: 34160095 DOI: 10.1111/tpj.15380] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/30/2021] [Accepted: 06/19/2021] [Indexed: 06/13/2023]
Abstract
MADS-box transcription factors (TFs) have not been functionally delineated in microalgae. In this study, the role of CsubMADS1 from microalga Coccomyxa subellipsoidea C-169 has been explored. Unlike Type II MADS-box proteins of seed plants with MADS, Intervening, K-box, and C domains, CsubMADS1 only has MADS and Intervening domains. It forms a group with MADS TFs from algae in the phylogenetic tree within the Type II MIKCC clade. CsubMADS1 is expressed strongly in the lag phase of growth. The CsubMADS1 monomer does not have a specific localization in the nucleus, and it forms homodimers to localize exclusively in the nucleus. The monomer has two nuclear localization signals (NLSs): an N-terminal NLS and an internal NLS. The internal NLS is functional, and the homodimer requires two NLSs for specific nuclear localization. Overexpression (OX) of CsubMADS1 slows down the growth of the culture and leads to the creation of giant polyploid multinucleate cells, resembling autospore mother cells. This implies that the release of autospores from autospore mother cells may be delayed. Thus, in wild-type (WT) cells, CsubMADS1 may play a crucial role in slowing down growth during the lag phase. Due to starvation in 2-month-old colonies on solid media, the WT colonies produce mucilage, whereas OX colonies produce significantly less mucilage. Thus, CsubMADS1 also negatively regulates stress-induced mucilage production and probably plays a role in stress tolerance during the lag phase. Taken together, our results reveal that CsubMADS1 is a key TF involved in the development and stress tolerance of this polar microalga.
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Affiliation(s)
- Saraswati Nayar
- Division of Plant Molecular Biology, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, 695014, India
| | - Gokilavani Thangavel
- Division of Plant Molecular Biology, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, 695014, India
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5
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Dutta P, Zhang L, Zhang H, Peng Q, Montgrain PR, Wang Y, Song Y, Li J, Li WX. Unphosphorylated STAT3 in heterochromatin formation and tumor suppression in lung cancer. BMC Cancer 2020; 20:145. [PMID: 32087696 PMCID: PMC7036253 DOI: 10.1186/s12885-020-6649-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 02/17/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Aberrant JAK/STAT activation has been detected in many types of human cancers. The role of JAK/STAT activation in cancer has been mostly attributed to direct transcriptional regulation of target genes by phosphorylated STAT (pSTAT), while the unphosphorylated STAT (uSTAT) is believed to be dormant and reside in the cytoplasm. However, several studies have shown that uSTATs can be found in the nucleus. In addition, it has been shown that tissue-specific loss of STAT3 or STAT5 in mice promotes cancer growth in certain tissues, and thus these STAT proteins can act as tumor suppressors. However, no unifying mechanism has been shown for the tumor suppressor function of STATs to date. We have previously demonstrated a non-canonical mode of JAK/STAT signaling for Drosophila STAT and human STAT5A, where a fraction of uSTAT is in the nucleus and associated with Heterochromatin Protein 1 (HP1); STAT activation (by phosphorylation) causes its dispersal, leading to HP1 delocalization and heterochromatin loss. METHODS We used a combination of imaging, cell biological assays, and mouse xenografts to investigate the role of STAT3 in lung cancer development. RESULTS We found that uSTAT3 has a function in promoting heterochromatin formation in lung cancer cells, suppressing cell proliferation in vitro, and suppressing tumor growth in mouse xenografts. CONCLUSIONS Thus, uSTAT3 possesses noncanonical function in promoting heterochromatin formation, and the tumor suppressor function of STAT3 is likely attributable to the heterochromatin-promoting activity of uSTAT3 in the non-canonical JAK/STAT pathway.
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Affiliation(s)
- Pranabananda Dutta
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Lin Zhang
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Huijun Zhang
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Pulmonary Medicine, Shanghai Respiratory Research Institute, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Qin Peng
- Department of Bioengineering, Institute of Engineering in Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Phillippe R Montgrain
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
- Veterans Affairs San Diego Healthcare System, San Diego, CA, CA92037, USA
| | - Yingxiao Wang
- Department of Bioengineering, Institute of Engineering in Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Yuanlin Song
- Department of Pulmonary Medicine, Shanghai Respiratory Research Institute, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jinghong Li
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Willis X Li
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA.
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Forteza R, Ahsan MK, Cartón-García F, Arango D, Ameen NA, Salas PJ. Glucocorticoids and myosin5b loss of function induce heightened PKA signaling in addition to membrane traffic defects. Mol Biol Cell 2019; 30:3076-3089. [PMID: 31664880 PMCID: PMC6938243 DOI: 10.1091/mbc.e18-07-0415] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Loss-of-function mutations in the nonconventional myosin Vb (Myo5b) result in microvillus inclusion disease (MVID) and massive secretory diarrhea that often begins at birth. Myo5b mutations disrupt the apical recycling endosome (ARE) and membrane traffic, resulting in reduced surface expression of apical membrane proteins. ARE disruption also results in constitutive phosphoinositide-dependent kinase 1 gain of function. In MVID, decreased surface expression of apical anion channels involved in Cl- extrusion, such as cystic fibrosis transmembrane conductance regulator (CFTR), should reduce fluid secretion into the intestinal lumen. But the opposite phenotype is observed. To explain this contradiction and the onset of diarrhea, we hypothesized that signaling effects downstream from Myo5b loss of function synergize with higher levels of glucocorticoids to activate PKA and CFTR. Data from intestinal cell lines, human MVID, and Myo5b KO mouse intestine revealed changes in the subcellular redistribution of PKA activity to the apical pole, increased CFTR phosphorylation, and establishment of apical cAMP gradients in Myo5b-defective cells exposed to physiological levels of glucocorticoids. These cells also displayed net secretory fluid fluxes and transepithelial currents mainly from PKA-dependent Cl- secretion. We conclude that Myo5b defects result in PKA stimulation that activates residual channels on the surface when intestinal epithelia are exposed to glucocorticoids at birth.
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Affiliation(s)
- Radia Forteza
- Department of Cell Biology, Miller School of Medicine, University of Miami, Miami, FL 33136
| | - M Kaimul Ahsan
- Department of Pediatrics, Yale School of Medicine, Yale University, New Haven, CT 06510
| | - Fernando Cartón-García
- Group of Biomedical Research in Digestive Tract Tumors, CIBBIM-Nanomedicine, Vall d'Hebron University Hospital Research Institute (VHIR), Universitat Autónoma de Barcelona, 08035 Barcelona, Spain
| | - Diego Arango
- Group of Biomedical Research in Digestive Tract Tumors, CIBBIM-Nanomedicine, Vall d'Hebron University Hospital Research Institute (VHIR), Universitat Autónoma de Barcelona, 08035 Barcelona, Spain
| | - Nadia A Ameen
- Department of Pediatrics, Yale School of Medicine, Yale University, New Haven, CT 06510
| | - Pedro J Salas
- Department of Cell Biology, Miller School of Medicine, University of Miami, Miami, FL 33136
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Bird MF, Guerrini R, Willets JM, Thompson JP, Caló G, Lambert DG. Nociceptin/Orphanin FQ (N/OFQ) conjugated to ATTO594: a novel fluorescent probe for the N/OFQ (NOP) receptor. Br J Pharmacol 2018; 175:4496-4506. [PMID: 30276802 PMCID: PMC6255954 DOI: 10.1111/bph.14504] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 08/31/2018] [Accepted: 09/04/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND AND PURPOSE The nociceptin/orphanin FQ (N/OFQ) receptor (NOP) is a member of the opioid receptor family and is involved in a number of physiological responses, pain and immune regulation as examples. In this study, we conjugated a red fluorophore-ATTO594 to the peptide ligand N/OFQ (N/OFQATTO594 ) for the NOP receptor and explored NOP receptor function at high (in recombinant systems) and low (on immune cells) expression. EXPERIMENTAL APPROACH We assessed N/OFQATTO594 receptor binding, selectivity and functional activity in recombinant (CHO) cell lines. Live cell N/OFQATTO594 binding was measured in (i) HEK cells expressing NOP and NOPGFP receptors, (ii) CHO cells expressing the hNOPGαqi5 chimera (to force coupling to measurable Ca2+ responses) and (iii) freshly isolated human polymorphonuclear cells (PMN). KEY RESULTS N/OFQATTO594 bound to NOP receptor with nM affinity and high selectivity. N/OFQATTO594 activated NOP receptor by reducing cAMP formation and increasing Ca2+ levels in CHOhNOPGαqi5 cells. N/OFQATTO594 was also able to visualize NOP receptors at low expression levels on PMN cells. In NOP-GFP-tagged receptors, N/OFQATTO594 was used in a FRET protocol where GFP emission activated ATTO, visualizing ligand-receptor interaction. When the NOPGFP receptor is activated by N/OFQATTO594 , movement of ligand and receptor from the cell surface to the cytosol can be measured. CONCLUSIONS AND IMPLICATIONS In the absence of validated NOP receptor antibodies and issues surrounding the use of radiolabels (especially in low expression systems), these data indicate the utility of N/OFQATTO594 to study a wide range of N/OFQ-driven cellular responses.
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Affiliation(s)
- M F Bird
- Department of Cardiovascular Sciences, Anaesthesia, Critical Care and Pain Management, Leicester Royal InfirmaryUniversity of LeicesterLeicesterUK
| | - R Guerrini
- Department of Chemical and Pharmaceutical Sciences and LTTAUniversity of FerraraFerraraItaly
| | - J M Willets
- Department of Molecular and Cell BiologyUniversity of LeicesterLeicesterUK
| | - J P Thompson
- Department of Cardiovascular Sciences, Anaesthesia, Critical Care and Pain Management, Leicester Royal InfirmaryUniversity of LeicesterLeicesterUK
| | - G Caló
- Department of Medical Sciences, Section of Pharmacology and National Institute of NeuroscienceUniversity of FerraraFerraraItaly
| | - D G Lambert
- Department of Cardiovascular Sciences, Anaesthesia, Critical Care and Pain Management, Leicester Royal InfirmaryUniversity of LeicesterLeicesterUK
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Bae SJ, Shin MW, Kim RH, Shin D, Son T, Wee HJ, Kim KW. Ninjurin1 Assembles Into a Homomeric Protein Complex Maintained by N-linked Glycosylation. J Cell Biochem 2017; 118:2219-2230. [PMID: 28067406 DOI: 10.1002/jcb.25872] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 12/16/2016] [Indexed: 12/11/2022]
Abstract
Ninjurin1 (Ninj1) is a cell surface protein known as a homophilic adhesion molecule. Previous studies have shown a trans-interaction of Ninj1 between immune cells and endothelial cells; however, little is known about Ninj1 modification and structure in the cis-interaction. We showed that Ninj1 assembles into a homomeric complex via a cis-interaction mediated by the intracellular region and N-glycosylation at Asn60 . We identified cis-interaction between Ninj1 proteins using CFP- and YFP-tagged Ninj1 by Förster resonance energy transfer using a confocal microscope and fluorescence-activated cell sorter. We further observed the Ninj1 homomeric complexes composed of two to six monomeric Ninj1 molecules by a formaldehyde cross-linking assay. Co-immunoprecipitation assays with epitope-tagged truncated Ninj1 suggested that the intracellular region encompassing Leu101 -Ala110 participates in Ninj1 homomer assembly. Ninj1 N-glycosylation was characterized by treatment of tunicamycin and substitution of Asn to Gln or Ala. Fluorescence-activated cell sorting-based Förster resonance energy transfer assays further demonstrated that N-glycosylation is indispensable for the Ninj1 cis-interaction, and a formaldehyde cross-linking assay confirmed that interruption of N-glycosylation by Asn substitution disrupted Ninj1 homomeric complex formation. In silico analysis revealed that Ninj1 is highly conserved in vertebrates and that the conserved sequence contains an N-glycosylation motif and cis-interacting intracellular region, which participate in Ninj1 homomer assembly. Taken together, these data show that Ninj1 assembles into a homomeric protein complex and that N-glycosylation is a prerequisite for Ninj1 homomer assembly. J. Cell. Biochem. 118: 2219-2230, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Sung-Jin Bae
- SNU-Harvard NeuroVascular Protection Research Center, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, 08826, Korea
| | - Min Wook Shin
- SNU-Harvard NeuroVascular Protection Research Center, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, 08826, Korea
| | - Ran Hee Kim
- SNU-Harvard NeuroVascular Protection Research Center, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, 08826, Korea
| | - Dongyoon Shin
- SNU-Harvard NeuroVascular Protection Research Center, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, 08826, Korea
| | - Taekwon Son
- SNU-Harvard NeuroVascular Protection Research Center, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, 08826, Korea
| | - Hee-Jun Wee
- SNU-Harvard NeuroVascular Protection Research Center, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, 08826, Korea
| | - Kyu-Won Kim
- SNU-Harvard NeuroVascular Protection Research Center, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, 08826, Korea.,Crop Biotechnology Institute, GreenBio Science and Technology, Seoul National University, Pyeongchang, 25354, Korea
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Sklodowski K, Riedelsberger J, Raddatz N, Riadi G, Caballero J, Chérel I, Schulze W, Graf A, Dreyer I. The receptor-like pseudokinase MRH1 interacts with the voltage-gated potassium channel AKT2. Sci Rep 2017; 7:44611. [PMID: 28300158 PMCID: PMC5353636 DOI: 10.1038/srep44611] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 01/25/2017] [Indexed: 12/23/2022] Open
Abstract
The potassium channel AKT2 plays important roles in phloem loading and unloading. It can operate as inward-rectifying channel that allows H+-ATPase-energized K+ uptake. Moreover, through reversible post-translational modifications it can also function as an open, K+-selective channel, which taps a 'potassium battery', providing additional energy for transmembrane transport processes. Knowledge about proteins involved in the regulation of the operational mode of AKT2 is very limited. Here, we employed a large-scale yeast two-hybrid screen in combination with fluorescence tagging and null-allele mutant phenotype analysis and identified the plasma membrane localized receptor-like kinase MRH1/MDIS2 (AT4G18640) as interaction partner of AKT2. The phenotype of the mrh1-1 knockout plant mirrors that of akt2 knockout plants in energy limiting conditions. Electrophysiological analyses showed that MRH1/MDIS2 failed to exert any functional regulation on AKT2. Using structural protein modeling approaches, we instead gathered evidence that the putative kinase domain of MRH1/MDIS2 lacks essential sites that are indispensable for a functional kinase suggesting that MRH1/MDIS2 is a pseudokinase. We propose that MRH1/MDIS2 and AKT2 are likely parts of a bigger protein complex. MRH1 might help to recruit other, so far unknown partners, which post-translationally regulate AKT2. Additionally, MRH1 might be involved in the recognition of chemical signals.
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Affiliation(s)
- Kamil Sklodowski
- Heisenberg Group of Biophysics and Molecular Plant Biology, Institute of Biochemistry and Biology, Molecular Biology, University of Potsdam, D-14476 Potsdam-Golm, Germany
- Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany
- ETH Zürich, Department of Biology, CH-8092 Zürich, Switzerland
| | - Janin Riedelsberger
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Natalia Raddatz
- Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), E-28223 Pozuelo de Alarcón (Madrid), Spain
- Instituto de Biología Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas, E-41092 Sevilla, Spain
| | - Gonzalo Riadi
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Julio Caballero
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Isabelle Chérel
- Biochimie et Physiologie Moléculaire des Plantes, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5004, Institut National de la Recherche Agronomique U386, Montpellier SupAgro, Université Montpellier II, F-34060 Montpellier cedex 2, France
| | - Waltraud Schulze
- Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany
- Department of Plant Systems Biology, University of Hohenheim, D-70593 Stuttgart, Germany
| | - Alexander Graf
- Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany
| | - Ingo Dreyer
- Heisenberg Group of Biophysics and Molecular Plant Biology, Institute of Biochemistry and Biology, Molecular Biology, University of Potsdam, D-14476 Potsdam-Golm, Germany
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile
- Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), E-28223 Pozuelo de Alarcón (Madrid), Spain
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Ghosh P, Aznar N, Swanson L, Lo IC, Lopez-Sanchez I, Ear J, Rohena C, Kalogriopoulos N, Joosen L, Dunkel Y, Sun N, Nguyen P, Bhandari D. Biochemical, Biophysical and Cellular Techniques to Study the Guanine Nucleotide Exchange Factor, GIV/Girdin. CURRENT PROTOCOLS IN CHEMICAL BIOLOGY 2016; 8:265-298. [PMID: 27925669 PMCID: PMC5154557 DOI: 10.1002/cpch.13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Canonical signal transduction via heterotrimeric G proteins is spatiotemporally restricted, i.e., triggered exclusively at the plasma membrane, only by agonist activation of G protein-coupled receptors via a finite process that is terminated within a few hundred milliseconds. Recently, a rapidly emerging paradigm has revealed a noncanonical pathway for activation of heterotrimeric G proteins via the nonreceptor guanidine-nucleotide exchange factor, GIV/Girdin. Biochemical, biophysical, and functional studies evaluating this pathway have unraveled its unique properties and distinctive spatiotemporal features. As in the case of any new pathway/paradigm, these studies first required an in-depth optimization of tools/techniques and protocols, governed by rationale and fundamentals unique to the pathway, and more specifically to the large multimodular GIV protein. Here we provide the most up-to-date overview of protocols that have generated most of what we know today about noncanonical G protein activation by GIV and its relevance in health and disease. © 2016 by John Wiley & Sons, Inc.
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Affiliation(s)
- Pradipta Ghosh
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0651
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Nicolas Aznar
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Lee Swanson
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - I-Chung Lo
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | | | - Jason Ear
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Cristina Rohena
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | | | - Linda Joosen
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Ying Dunkel
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Nina Sun
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Peter Nguyen
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, CA 90840-9507
| | - Deepali Bhandari
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, CA 90840-9507
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11
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Butler B, Saha K, Rana T, Becker JP, Sambo D, Davari P, Goodwin JS, Khoshbouei H. Dopamine Transporter Activity Is Modulated by α-Synuclein. J Biol Chem 2015; 290:29542-54. [PMID: 26442590 DOI: 10.1074/jbc.m115.691592] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Indexed: 12/24/2022] Open
Abstract
The duration and strength of the dopaminergic signal are regulated by the dopamine transporter (DAT). Drug addiction and neurodegenerative and neuropsychiatric diseases have all been associated with altered DAT activity. The membrane localization and the activity of DAT are regulated by a number of intracellular proteins. α-Synuclein, a protein partner of DAT, is implicated in neurodegenerative disease and drug addiction. Little is known about the regulatory mechanisms of the interaction between DAT and α-synuclein, the cellular location of this interaction, and the functional consequences of this interaction on the basal, amphetamine-induced DAT-mediated dopamine efflux, and membrane microdomain distribution of the transporter. Here, we found that the majority of DAT·α-synuclein protein complexes are found at the plasma membrane of dopaminergic neurons or mammalian cells and that the amphetamine-mediated increase in DAT activity enhances the association of these proteins at the plasma membrane. Further examination of the interaction of DAT and α-synuclein revealed a transient interaction between these two proteins at the plasma membrane. Additionally, we found DAT-induced membrane depolarization enhances plasma membrane localization of α-synuclein, which in turn increases dopamine efflux and enhances DAT localization in cholesterol-rich membrane microdomains.
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Affiliation(s)
- Brittany Butler
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Kaustuv Saha
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Tanu Rana
- the Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, Tennessee 37208
| | - Jonas P Becker
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Danielle Sambo
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Paran Davari
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - J Shawn Goodwin
- the Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, Tennessee 37208
| | - Habibeh Khoshbouei
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
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12
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Ng KK, Zheng G. Molecular Interactions in Organic Nanoparticles for Phototheranostic Applications. Chem Rev 2015; 115:11012-42. [PMID: 26244706 DOI: 10.1021/acs.chemrev.5b00140] [Citation(s) in RCA: 353] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Kenneth K Ng
- Princess Margaret Cancer Centre and Techna Institute, University Health Network , Toronto, Ontario M5G 2C4, Canada
| | - Gang Zheng
- Princess Margaret Cancer Centre and Techna Institute, University Health Network , Toronto, Ontario M5G 2C4, Canada
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13
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Janzen WP. Screening technologies for small molecule discovery: the state of the art. ACTA ACUST UNITED AC 2015; 21:1162-70. [PMID: 25237860 DOI: 10.1016/j.chembiol.2014.07.015] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 07/14/2014] [Accepted: 07/16/2014] [Indexed: 01/24/2023]
Abstract
Screening, high-throughput screening, and ultra-high-throughput screening are all really just points on a spectrum that represent differing applications of the same process: the creation of biologically relevant assays that are relevant, reproducible, reliable, and robust. Whether the discovery program is developing a pharmaceutical, an academic probe, cosmetics, pesticides, or a toxicity monitoring assay, the development of a screen focuses on generating a method that will reliably deliver reproducible results over a period of weeks, months, or years and that will generate consistent results for every test along the way. This review provides both historical perspective on how this unique scientific discipline evolved and commentary on the current state of the art technologies and techniques.
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Affiliation(s)
- William P Janzen
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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14
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Hoffmann B, Klöcker N, Benndorf K, Biskup C. Visualization of the dynamics of PSD-95 and Kir2.1 interaction by fluorescence lifetime-based resonance energy transfer imaging. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.medpho.2014.11.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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15
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Parkin maintains mitochondrial levels of the protective Parkinson's disease-related enzyme 17-β hydroxysteroid dehydrogenase type 10. Cell Death Differ 2015; 22:1563-76. [PMID: 25591737 DOI: 10.1038/cdd.2014.224] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 10/08/2014] [Accepted: 11/25/2014] [Indexed: 11/08/2022] Open
Abstract
Mutations of the PARK2 and PINK1 genes, encoding the cytosolic E3 ubiquitin-protein ligase Parkin and the mitochondrial serine/threonine kinase PINK1, respectively, cause autosomal recessive early-onset Parkinson's disease (PD). Parkin and PINK1 cooperate in a biochemical mitochondrial quality control pathway regulating mitochondrial morphology, dynamics and clearance. This study identifies the multifunctional PD-related mitochondrial matrix enzyme 17-β hydroxysteroid dehydrogenase type 10 (HSD17B10) as a new Parkin substrate. Parkin overproduction in cells increased mitochondrial HSD17B10 abundance by a mechanism involving ubiquitin chain extension, whereas PARK2 downregulation or deficiency caused mitochondrial HSD17B10 depletion in cells and mice. HSD17B10 levels were also found to be low in the brains of PD patients with PARK2 mutations. Confocal and Förster resonance energy transfer (FRET) microscopy revealed that HSD17B10 recruited Parkin to the translocase of the outer membrane (TOM), close to PINK1, both in functional mitochondria and after the collapse of mitochondrial membrane potential (ΔΨm). PD-causing PARK2 mutations impaired interaction with HSD17B10 and the HSD17B10-dependent mitochondrial translocation of Parkin. HSD17B10 overproduction promoted mitochondrial elongation and mitigated CCCP-induced mitochondrial degradation independently of enzymatic activity. These effects were abolished by overproduction of the fission-promiting dynamin-related protein 1 (Drp1). By contrast, siRNA-mediated HSD17B10 silencing enhanced mitochondrial fission and mitophagy. These findings suggest that the maintenance of appropriate mitochondrial HSD17B10 levels is one of the mechanisms by which Parkin preserves mitochondrial quality. The loss of this protective mechanism may contribute to mitochondrial dysfunction and neuronal degeneration in autosomal recessive PD.
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16
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Buhlman L, Damiano M, Bertolin G, Ferrando-Miguel R, Lombès A, Brice A, Corti O. Functional interplay between Parkin and Drp1 in mitochondrial fission and clearance. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2012-26. [PMID: 24878071 DOI: 10.1016/j.bbamcr.2014.05.012] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 05/16/2014] [Accepted: 05/19/2014] [Indexed: 12/25/2022]
Abstract
Autosomal recessive early-onset Parkinson's disease is most often caused by mutations in the genes encoding the cytosolic E3 ubiquitin ligase Parkin and the mitochondrial serine/threonine kinase PINK1. Studies in Drosophila models and mammalian cells have demonstrated that these proteins regulate various aspects of mitochondrial physiology, including organelle transport, dynamics and turnover. How PINK1 and Parkin orchestrate these processes, and whether they always do so within a common pathway remain to be clarified. We have revisited the role of PINK1 and Parkin in mitochondrial dynamics, and explored its relation to the mitochondrial clearance program controlled by these proteins. We show that PINK1 and Parkin promote Drp1-dependent mitochondrial fission by mechanisms that are at least in part independent. Parkin-mediated mitochondrial fragmentation was abolished by treatments interfering with the calcium/calmodulin/calcineurin signaling pathway, suggesting that it requires dephosphorylation of serine 637 of Drp1. Parkinson's disease-causing mutations with differential impact on mitochondrial morphology and organelle degradation demonstrated that the pro-fission effect of Parkin is not required for efficient mitochondrial clearance. In contrast, the use of Förster energy transfer imaging microscopy revealed that Drp1 and Parkin are co-recruited to mitochondria in proximity of PINK1 following mitochondrial depolarization, indicating spatial coordination between these events in mitochondrial degradation. Our results also hint at a major role of the outer mitochondrial adaptor MiD51 in Drp1 recruitment and Parkin-dependent mitophagy. Altogether, our observations provide new insight into the mechanisms underlying the regulation of mitochondrial dynamics by Parkin and its relation to the mitochondrial clearance program mediated by the PINK1/Parkin pathway.
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Affiliation(s)
- Lori Buhlman
- Inserm, U 1127, F-75013 Paris, France; CNRS, UMR 7225, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France; Department of Biomedical Sciences, Midwestern University, 19555N 59th Avenue, Glendale, Arizona 85308, United States
| | - Maria Damiano
- Inserm, U 1127, F-75013 Paris, France; CNRS, UMR 7225, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
| | - Giulia Bertolin
- Inserm, U 1127, F-75013 Paris, France; CNRS, UMR 7225, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
| | - Rosa Ferrando-Miguel
- Inserm, U 1127, F-75013 Paris, France; CNRS, UMR 7225, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
| | - Anne Lombès
- Inserm U 1016, Institut Cochin, F-75014, Paris, France; CNRS UMR 8104, F-75014 Paris, France; Université Paris 05, UMR_S1016 F-75014, Paris, France
| | - Alexis Brice
- Inserm, U 1127, F-75013 Paris, France; CNRS, UMR 7225, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
| | - Olga Corti
- Inserm, U 1127, F-75013 Paris, France; CNRS, UMR 7225, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France.
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17
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Stewart RS, Kiss IM, Wilkinson RS. Visualization of endosome dynamics in living nerve terminals with four-dimensional fluorescence imaging. J Vis Exp 2014. [PMID: 24799002 DOI: 10.3791/51477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Four-dimensional (4D) light imaging has been used to study behavior of small structures within motor nerve terminals of the thin transversus abdominis muscle of the garter snake. Raw data comprises time-lapse sequences of 3D z-stacks. Each stack contains 4-20 images acquired with epifluorescence optics at focal planes separated by 400-1,500 nm. Steps in the acquisition of image stacks, such as adjustment of focus, switching of excitation wavelengths, and operation of the digital camera, are automated as much as possible to maximize image rate and minimize tissue damage from light exposure. After acquisition, a set of image stacks is deconvolved to improve spatial resolution, converted to the desired 3D format, and used to create a 4D "movie" that is suitable for variety of computer-based analyses, depending upon the experimental data sought. One application is study of the dynamic behavior of two classes of endosomes found in nerve terminals-macroendosomes (MEs) and acidic endosomes (AEs)-whose sizes (200-800 nm for both types) are at or near the diffraction limit. Access to 3D information at each time point provides several advantages over conventional time-lapse imaging. In particular, size and velocity of movement of structures can be quantified over time without loss of sharp focus. Examples of data from 4D imaging reveal that MEs approach the plasma membrane and disappear, suggesting that they are exocytosed rather than simply moving vertically away from a single plane of focus. Also revealed is putative fusion of MEs and AEs, by visualization of overlap between the two dye-containing structures as viewed in each three orthogonal projections.
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Affiliation(s)
- Richard S Stewart
- Department of Cell Biology and Physiology, Washington University School of Medicine
| | - Ilona M Kiss
- Department of Cell Biology and Physiology, Washington University School of Medicine
| | - Robert S Wilkinson
- Department of Cell Biology and Physiology, Washington University School of Medicine;
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18
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Bertolin G, Ferrando-Miguel R, Jacoupy M, Traver S, Grenier K, Greene AW, Dauphin A, Waharte F, Bayot A, Salamero J, Lombès A, Bulteau AL, Fon EA, Brice A, Corti O. The TOMM machinery is a molecular switch in PINK1 and PARK2/PARKIN-dependent mitochondrial clearance. Autophagy 2013; 9:1801-17. [PMID: 24149440 DOI: 10.4161/auto.25884] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Loss-of-function mutations in PARK2/PARKIN and PINK1 cause early-onset autosomal recessive Parkinson disease (PD). The cytosolic E3 ubiquitin-protein ligase PARK2 cooperates with the mitochondrial kinase PINK1 to maintain mitochondrial quality. A loss of mitochondrial transmembrane potential (ΔΨ) leads to the PINK1-dependent recruitment of PARK2 to the outer mitochondrial membrane (OMM), followed by the ubiquitination and proteasome-dependent degradation of OMM proteins, and by the autophagy-dependent clearance of mitochondrial remnants. We showed here that blockade of mitochondrial protein import triggers the recruitment of PARK2, by PINK1, to the TOMM machinery. PD-causing PARK2 mutations weakened or disrupted the molecular interaction between PARK2 and specific TOMM subunits: the surface receptor, TOMM70A, and the channel protein, TOMM40. The downregulation of TOMM40 or its associated core subunit, TOMM22, was sufficient to trigger OMM protein clearance in the absence of PINK1 or PARK2. However, PARK2 was required to promote the degradation of whole organelles by autophagy. Furthermore, the overproduction of TOMM22 or TOMM40 reversed mitochondrial clearance promoted by PINK1 and PARK2 after ΔΨ loss. These results indicated that the TOMM machinery is a key molecular switch in the mitochondrial clearance program controlled by the PINK1-PARK2 pathway. Loss of functional coupling between mitochondrial protein import and the neuroprotective degradation of dysfunctional mitochondria may therefore be a primary pathogenic mechanism in autosomal recessive PD.
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Affiliation(s)
- Giulia Bertolin
- Inserm; U 975; CRICM; Hôpital de la Pitié-Salpêtrière; Paris, France; UPMC; Université Paris 06; UMR_S975; Paris, France; CNRS; UMR 7225; Paris, France
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19
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Maszczak-Seneczko D, Sosicka P, Majkowski M, Olczak T, Olczak M. UDP-N-acetylglucosamine transporter and UDP-galactose transporter form heterologous complexes in the Golgi membrane. FEBS Lett 2012; 586:4082-7. [PMID: 23089177 DOI: 10.1016/j.febslet.2012.10.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/02/2012] [Accepted: 10/08/2012] [Indexed: 10/27/2022]
Abstract
UDP-galactose transporter (UGT; SLC35A2) and UDP-N-acetylglucosamine transporter (NGT; SLC35A3) are evolutionarily related. We hypothesize that their role in glycosylation may be coupled through heterologous complex formation. Coimmunoprecipitation analysis and FLIM-FRET measurements performed on living cells showed that NGT and UGT form complexes when overexpressed in MDCK-RCA(r) cells. We also postulate that the interaction of NGT and UGT may explain the dual localization of UGT2. For the first time we demonstrated in vivo homodimerization of the NGT nucleotide sugar transporter. In conclusion, we suggest that NGT and UGT function in glycosylation is combined via their mutual interaction.
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20
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Aronson DE, Costantini LM, Snapp EL. Superfolder GFP is fluorescent in oxidizing environments when targeted via the Sec translocon. Traffic 2011; 12:543-8. [PMID: 21255213 DOI: 10.1111/j.1600-0854.2011.01168.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The ability to study proteins in live cells using genetically encoded fluorescent proteins (FPs) has revolutionized cell biology (1-3). Researchers have created numerous FP biosensors and optimized FPs for specific organisms and subcellular environments in a rainbow of colors (4,5). However, expressing FPs in oxidizing environments such as the eukaryotic endoplasmic reticulum (ER) or the bacterial periplasm can impair folding, thereby preventing fluorescence (6,7). A substantial fraction of enhanced green fluorescent protein (EGFP) oligomerizes to form non-fluorescent mixed disulfides in the ER (6) and EGFP does not fluoresce in the periplasm when targeted via the SecYEG translocon (7). To overcome these obstacles, we exploited the highly efficient folding capability of superfolder GFP (sfGFP) (8). Here, we report sfGFP does not form disulfide-linked oligomers in the ER and maltose-binding protein (MBP) signal sequence (peri)-sfGFP (9) is brightly fluorescent in the periplasm of Escherichia coli. Thus, sfGFP represents an important research tool for studying resident proteins of oxidizing environments.
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Affiliation(s)
- Deborah E Aronson
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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21
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Optical reporters for the conformation of alpha-synuclein reveal a specific interaction with mitochondria. J Neurosci 2009; 28:12305-17. [PMID: 19020024 DOI: 10.1523/jneurosci.3088-08.2008] [Citation(s) in RCA: 158] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The aggregation of abnormally folded proteins is a defining feature of neurodegenerative disease, but it has not previously been possible to assess the conformation of these proteins in a physiologically relevant context, before they form morphologically recognizable aggregates. We now describe FRET-based reporters for the conformation of alpha-synuclein, a protein central to the pathogenesis of Parkinson's disease (PD). Characterization in vitro shows that alpha-synuclein adopts a relatively "closed" conformation in solution that converts to "open" on membrane binding. In living cells, the closed conformation predominates. In neurons, however, cell bodies contain a much larger proportion of the open conformation than synaptic boutons. To account for these differences, we also used the reporters to characterize the interaction with native membranes. We find that the conformation of alpha-synuclein responds selectively to mitochondria, indicating a direct link between alpha-synuclein and an organelle strongly implicated in the pathogenesis of PD.
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