scholarly journals The Molecular Chaperone DNAJB6, but Not DNAJB1, Suppresses the Seeded Aggregation of Alpha-Synuclein in Cells

2019 ◽  
Vol 20 (18) ◽  
pp. 4495 ◽  
Author(s):  
Natasja Deshayes ◽  
Sertan Arkan ◽  
Christian Hansen
Keyword(s):  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Resonance Energy Transfer ◽  
Lewy Bodies ◽  
Resonance Energy ◽  
Alpha Synuclein ◽  
Hek293 Cells ◽  
Induced Aggregation ◽  
In Cells

Alpha-synuclein (α-Syn) can misfold and aggregate, causing the degeneration of dopaminergic neurons, as seen in Parkinson’s disease (PD). We recently demonstrated that DNAJB6, a co-chaperone found in Lewy bodies (LB), suppresses the aggregation of α-Syn in cells and in vitro. In this study, we compared the capacities of DNAJB1 and DNAJB6 to suppress the seeded α-Syn aggregation in HEK293 cells expressing α-Syn tagged with cyan fluorescent protein (CFP) or yellow fluorescent protein (YFP). The aggregation of α-Syn was seeded by the transfection of the cells with recombinant α-Syn pre-formed fibrils (PFFs), following the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9-mediated knockout (KO) of these two genes, respectively. We quantified the α-Syn aggregation by fluorescence microscopy and fluorescence resonance energy transfer (FRET) analysis. We detected significantly more aggregates in the DNAJB6 KO cells compared with the parental cells, whereas the DNAJB1 KO had no effect on the α-Syn aggregation. This is the first evidence that DNAJB6 can suppress α-Syn aggregation, induced by exogenous α-Syn seeds, in cells. Next, we explored whether this mechanism could be dependent on protein degradation pathways. We observed that the increase in the α-Syn PFF-induced aggregation in the DNAJB6 KO cells compared with the parental cells was strongly diminished upon the incubation of the cells with the proteasomal inhibitor MG132. These results consolidate that DNAJB6 is a suppressor of α-Syn aggregation, and suggest that DNAJB6 may target misfolded and/or aggregated α-Syn for proteasomal degradation.

scholarly journals Multiple system atrophy-associated oligodendroglial protein p25α stimulates formation of novel α-synuclein strain with enhanced neurodegenerative potential

2021 ◽  
Author(s):  
Nelson Ferreira ◽  
Hjalte Gram ◽  
Zachary A. Sorrentino ◽  
Emil Gregersen ◽  
Sissel Ida Schmidt ◽  
...  
Keyword(s):  
Multiple System Atrophy ◽  
Protein Misfolding ◽  
Resonance Energy Transfer ◽  
Lewy Bodies ◽  
Resonance Energy ◽  
Alpha Synuclein ◽  
Striatal Neurons ◽  
End Stage ◽  
Intracellular Aggregates

AbstractPathology consisting of intracellular aggregates of alpha-Synuclein (α-Syn) spread through the nervous system in a variety of neurodegenerative disorders including Parkinson’s disease, dementia with Lewy bodies, and multiple system atrophy. The discovery of structurally distinct α-Syn polymorphs, so-called strains, supports a hypothesis where strain-specific structures are templated into aggregates formed by native α-Syn. These distinct strains are hypothesised to dictate the spreading of pathology in the tissue and the cellular impact of the aggregates, thereby contributing to the variety of clinical phenotypes. Here, we present evidence of a novel α-Syn strain induced by the multiple system atrophy-associated oligodendroglial protein p25α. Using an array of biophysical, biochemical, cellular, and in vivo analyses, we demonstrate that compared to α-Syn alone, a substoichiometric concentration of p25α redirects α-Syn aggregation into a unique α-Syn/p25α strain with a different structure and enhanced in vivo prodegenerative properties. The α-Syn/p25α strain induced larger inclusions in human dopaminergic neurons. In vivo, intramuscular injection of preformed fibrils (PFF) of the α-Syn/p25α strain compared to α-Syn PFF resulted in a shortened life span and a distinct anatomical distribution of inclusion pathology in the brain of a human A53T transgenic (line M83) mouse. Investigation of α-Syn aggregates in brain stem extracts of end-stage mice demonstrated that the more aggressive phenotype of the α-Syn/p25α strain was associated with an increased load of α-Syn aggregates based on a Förster resonance energy transfer immunoassay and a reduced α-Syn aggregate seeding activity based on a protein misfolding cyclic amplification assay. When injected unilaterally into the striata of wild-type mice, the α-Syn/p25α strain resulted in a more-pronounced motoric phenotype than α-Syn PFF and exhibited a “tropism” for nigro-striatal neurons compared to α-Syn PFF. Overall, our data support a hypothesis whereby oligodendroglial p25α is responsible for generating a highly prodegenerative α-Syn strain in multiple system atrophy.

scholarly journals Enhanced brightness of bacterial luciferase by bioluminescence resonance energy transfer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tomomi Kaku ◽  
Kazunori Sugiura ◽  
Tetsuyuki Entani ◽  
Kenji Osabe ◽  
Takeharu Nagai
Keyword(s):  
Energy Transfer ◽  
Mammalian Cells ◽  
Fluorescent Protein ◽  
Color Change ◽  
Yellow Fluorescent Protein ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Bioluminescence Resonance Energy Transfer ◽  
Bacterial Luciferase ◽  
Bacterial Bioluminescence

AbstractUsing the lux operon (luxCDABE) of bacterial bioluminescence system as an autonomous luminous reporter has been demonstrated in bacteria, plant and mammalian cells. However, applications of bacterial bioluminescence-based imaging have been limited because of its low brightness. Here, we engineered the bacterial luciferase (heterodimer of luxA and luxB) by fusion with Venus, a bright variant of yellow fluorescent protein, to induce bioluminescence resonance energy transfer (BRET). By using decanal as an externally added substrate, color change and ten-times enhancement of brightness was achieved in Escherichia coli when circularly permuted Venus was fused to the C-terminus of luxB. Expression of the Venus-fused luciferase in human embryonic kidney cell lines (HEK293T) or in Nicotiana benthamiana leaves together with the substrate biosynthesis-related genes (luxC, luxD and luxE) enhanced the autonomous bioluminescence. We believe the improved luciferase will forge the way towards the potential development of autobioluminescent reporter system allowing spatiotemporal imaging in live cells.

scholarly journals tdLanYFP, a yellow, bright, photostable and pH insensitive fluorescent protein for live cell imaging and FRET-based sensing strategies

2021 ◽  
Author(s):  
Y. Bousmah ◽  
H. Valenta ◽  
G. Bertolin ◽  
U. Singh ◽  
V. Nicolas ◽  
...  
Keyword(s):  
Single Molecule ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Yellow Fluorescent Protein ◽  
Resonance Energy ◽  
Live Cell ◽  
Live Cells

AbstractYellow fluorescent proteins (YFP) are widely used as optical reporters in Förster Resonance Energy Transfer (FRET) based biosensors. Although great improvements have been done, the sensitivity of the biosensors is still limited by the low photostability and the poor fluorescence performances of YFPs at acidic pHs. In fact, today, there is no yellow variant derived from the EYFP with a pK1/2 below ∼5.5. Here, we characterize a new yellow fluorescent protein, tdLanYFP, derived from the tetrameric protein from the cephalochordate B. lanceolatum, LanYFP. With a quantum yield of 0.92 and an extinction coefficient of 133 000 mol−1.L.cm−1, it is, to our knowledge, the brightest dimeric fluorescent protein available, and brighter than most of the monomeric YFPs. Contrasting with EYFP and its derivatives, tdLanYFP has a very high photostability in vitro and preserves this property in live cells. As a consequence, tdLanYFP allows the imaging of cellular structures with sub-diffraction resolution with STED nanoscopy. We also demonstrate that the combination of high brightness and strong photostability is compatible with the use of spectro-microscopies in single molecule regimes. Its very low pK1/2 of 3.9 makes tdLanYFP an excellent tag even at acidic pHs. Finally, we show that tdLanYFP can be a FRET partner either as donor or acceptor in different biosensing modalities. Altogether, these assets make tdLanYFPa very attractive yellow fluorescent protein for long-term or single-molecule live-cell imaging that is also suitable for FRET experiment including at acidic pH.

scholarly journals Analysis of IFITM-IFITM Interactions by a Flow Cytometry-Based FRET Assay

2019 ◽  
Vol 20 (16) ◽  
pp. 3859 ◽  
Author(s):  
Michael Winkler ◽  
Florian Wrensch ◽  
Pascale Bosch ◽  
Maike Knoth ◽  
Michael Schindler ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Protein Interactions ◽  
Viral Entry ◽  
Cellular Localization ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Yellow Fluorescent Protein ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Protein Protein Interactions

The interferon-induced transmembrane proteins 1–3 (IFITM1–3) inhibit host cell entry of several viruses. However, it is incompletely understood how IFITM1–3 exert antiviral activity. Two phenylalanine residues, F75 and F78, within the intramembrane domain 1 (IM1) were previously shown to be required for IFITM3/IFITM3 interactions and for inhibition of viral entry, suggesting that IFITM/IFITM interactions might be pivotal to antiviral activity. Here, we employed a fluorescence resonance energy transfer (FRET) assay to analyze IFITM/IFITM interactions. For assay calibration, we equipped two cytosolic, non-interacting proteins, super yellow fluorescent protein (SYFP) and super cyan fluorescent protein (SCFP), with signals that target proteins to membrane rafts and also analyzed a SCFP-SYFP fusion protein. This strategy allowed us to discriminate background signals resulting from colocalization of proteins at membrane subdomains from signals elicited by protein–protein interactions. Coexpression of IFITM1–3 and IFITM5 fused to fluorescent proteins elicited strong FRET signals, and mutation of F75 and F78 in IFITM3 (mutant IFITM3-FF) abrogated antiviral activity, as expected, but did not alter cellular localization and FRET signals. Moreover, IFITM3-FF co-immunoprecipitated efficiently with wild type (wt) IFITM3, lending further support to the finding that lack of antiviral activity of IFITM3-FF was not due to altered membrane targeting or abrogated IFITM3-IFITM3 interactions. Collectively, we report an assay that allows quantifying IFITM/IFITM interactions. Moreover, we confirm residues F75 and F78 as critical for antiviral activity but also show that these residues are dispensable for IFITM3 membrane localization and IFITM3/IFITM3 interactions.

scholarly journals The Receptor for Parathyroid Hormone and Parathyroid Hormone-Related Peptide Is Hydrolyzed and Its Signaling Properties Are Altered by Directly Binding the Calpain Small Subunit

Endocrinology ◽  
2005 ◽  
Vol 146 (5) ◽  
pp. 2336-2344 ◽  
Author(s):  
Masako Shimada ◽  
Matthew J. Mahon ◽  
Peter A. Greer ◽  
Gino V. Segre
Keyword(s):  
Parathyroid Hormone ◽  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Small Subunit ◽  
Hek293 Cells ◽  
Calpain Inhibitor ◽  
Dependent Manner ◽  
Intact Cells ◽  
Calcium Dependent

Abstract We show calcium-dependent, direct binding between the N-terminal portion of the PTH/PTHrP receptor (PTH1R) C-terminal intracellular tail and the calpain small subunit. Binding requires, but may not be limited to, amino acids W474, S475, and W477. The wild-type, full-length rat (r) PTH1R, but not rPTH1R with W474A/W477A substitutions, copurifies with the endogenous calpain small subunit in HEK293 cells. Calpain hydrolyzes ΔNt-rPTH1R, a receptor with a 156-amino acid N-terminal deletion, in a calcium-dependent manner in vitro and in intact cells. Most importantly, PTH stimulation increases the cleavage of ΔNt-rPTH1R and rPTH1R-yellow fluorescent protein in HEK293 cells, and of talin in HEK293 cells expressing rPTH1R-yellow fluorescent protein and in ROS17/2.8 osteoblast-like cells that express rPTH1R endogenously. The absence of calpain in Capn4-null embryonic fibroblasts and the lowered calpain activity in MC3T3-E1 osteoblastic cells due to stable expression of the calpain inhibitor, calpastatin, reduce PTH-stimulated cAMP accumulation. The calpain small subunit is the second protein, in addition to the sodium-hydrogen exchanger regulatory factor, and the first enzyme that binds the PTH1R; PTH1R bound to both of these proteins results in altered PTH signaling.

scholarly journals G-protein-coupled receptor 30 interacts with receptor activity-modifying protein 3 and confers sex-dependent cardioprotection

2013 ◽  
Vol 51 (1) ◽  
pp. 191-202 ◽  
Author(s):  
Patricia M Lenhart ◽  
Stefan Broselid ◽  
Cordelia J Barrick ◽  
L M Fredrik Leeb-Lundberg ◽  
Kathleen M Caron
Keyword(s):  
G Protein ◽  
Transmembrane Protein ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Cardiac Cells ◽  
Receptor Activity ◽  
Hek293 Cells ◽  
G Protein Coupled

Receptor activity-modifying protein 3 (RAMP3) is a single-pass transmembrane protein known to interact with and affect the trafficking of several G-protein-coupled receptors (GPCRs). We sought to determine whether RAMP3 interacts with GPR30, also known as G-protein-coupled estrogen receptor 1. GPR30 is a GPCR that binds estradiol and has important roles in cardiovascular and endocrine physiology. Using bioluminescence resonance energy transfer titration studies, co-immunoprecipitation, and confocal microscopy, we show that GPR30 and RAMP3 interact. Furthermore, the presence of GPR30 leads to increased expression of RAMP3 at the plasma membrane in HEK293 cells. In vivo, there are marked sex differences in the subcellular localization of GPR30 in cardiac cells, and the hearts of Ramp3−/− mice also show signs of GPR30 mislocalization. To determine whether this interaction might play a role in cardiovascular disease, we treated Ramp3+/+ and Ramp3−/− mice on a heart disease-prone genetic background with G-1, a specific agonist for GPR30. Importantly, this in vivo activation of GPR30 resulted in a significant reduction in cardiac hypertrophy and perivascular fibrosis that is both RAMP3 and sex dependent. Our results demonstrate that GPR30–RAMP3 interaction has functional consequences on the localization of these proteins both in vitro and in vivo and that RAMP3 is required for GPR30-mediated cardioprotection.

scholarly journals Ultra-Sensitive Hydrogen Peroxide Sensor Based on Peroxiredoxin and Fluorescence Resonance Energy Transfer

2020 ◽  
Vol 10 (10) ◽  
pp. 3508
Author(s):  
Haijun Yu ◽  
Haoxiang Li ◽  
Yao Zhou ◽  
Shengmin Zhou ◽  
Ping Wang
Keyword(s):  
Energy Transfer ◽  
Fluorescence Resonance Energy Transfer ◽  
Disulfide Bonds ◽  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Mixed Disulfide ◽  
Fluorescence Resonance ◽  
Protein Sensor

In this paper, a fluorescence resonance energy transfer (FRET)-based sensor for ultra-sensitive detection of H2O2 was developed by utilizing the unique enzymatic properties of peroxiredoxin (Prx) to H2O2. Cyan and yellow fluorescent protein (CFP and YFP) were fused to Prx and mutant thioredoxin (mTrx), respectively. In the presence of H2O2, Prx was oxidized into covalent homodimer through disulfide bonds, which were further reduced by mTrx to form a stable mixed disulfide bond intermediate between CFP-Prx and mTrx-YFP, inducing FRET. A linear quantification range of 10–320 nM was obtained according to the applied protein concentrations and the detection limit (LOD) was determined to be as low as 4 nM. By the assistance of glucose oxidase to transform glucose into H2O2, the CFP-Prx/mTrx-YFP system (CPmTY) was further exploited for the detection of glucose in real sample with good performance, suggesting this CPmTY protein sensor is highly practical.

Sustained Ca2+ signaling and delayed internalization associated with endothelin receptor heterodimers linked through a PDZ fingerThis article is one of a selection of papers published in the special issue (part 2 of 2) on Forefronts in Endothelin.

2008 ◽  
Vol 86 (8) ◽  
pp. 526-535 ◽  
Author(s):  
Nathan J. Evans ◽  
Jeffery W. Walker
Keyword(s):  
Fluorescent Protein ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Hek293 Cells ◽  
Endothelin Receptor ◽  
Similar Time ◽  
Receptor Dimerization ◽  
C Terminus ◽  
Interaction Interface ◽  
Intracellular Ca

G protein-coupled receptors (GPCRs), including endothelin receptor A (ETA) and B (ETB), may form dimers or higher-order oligomers that profoundly influence signaling. Here we examined a PDZ finger motif within the C-terminus of ETA and its role in heterodimerization with ETB, and in homodimerization with itself, when expressed in HEK293 cells. Receptor dimerization was monitored by (i) fluorescence resonance energy transfer (FRET) between cyan fluorescent protein (CFP) (FRET donor) and tetracysteine/FlAsH (FRET acceptor) fused to the C-termini of ET receptors, and (ii) coimmunoprecipitation of ET receptors after mild detergent solubilization. Mutations in a PDZ finger motif at threonine403/serine404 eliminated FRET and reduced coimmunoprecipitation of heterodimers and homodimers. Functional consequences were evaluated by measuring mobilization of intracellular Ca2+ and internalization of receptors in response to a 10 nmol/L ET-1 challenge. PDZ mutations converted a sustained Ca2+ signal mediated by ETA:ETB heterodimers into a transient response, similar to that observed for homodimers or monomers. Heterodimers containing PDZ mutations were seen to internalize in a similar time domain (approximately 5 min) to the transient Ca2+ elevation and with similar kinetics to internalization of ETA homodimers or monomers. Without the PDZ mutations, heterodimers did not internalize over 15 min, suggesting the intriguing possibility that sustained Ca2+ signaling was a consequence (at least in part) of delayed internalization. The results are consistent with structural models of ETA-receptor dimerization that place threonine403/serine404 of the PDZ finger motif at the interaction interface between heterodimers and homodimers. Sustained Ca2+ signaling and delayed endocytosis of ETA:ETB heterodimers argues strongly for a unique dimer interface that impacts transmembrane signaling and internalization.

scholarly journals Activation Function 1 of Glucocorticoid Receptor Binds TATA-Binding Protein in Vitro and in Vivo

2006 ◽  
Vol 20 (6) ◽  
pp. 1218-1230 ◽  
Author(s):  
Alicja J. Copik ◽  
M. Scott Webb ◽  
Aaron L. Miller ◽  
Yongxin Wang ◽  
Raj Kumar ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Glucocorticoid Receptor ◽  
Fluorescent Protein ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Activation Function ◽  
Tata Binding Protein

Abstract The mechanism through which the glucocorticoid receptor (GR) stimulates transcription is still unclear, although it is clear that the GR affects assembly of the transcriptional machinery. The binding of the TATA-binding protein (TBP) to the TATA-box is accepted as essential in this process. It is known that the GR can interact in vitro with TBP, but the direct interaction of TBP with GR has not been previously characterized quantitatively and has not been appreciated as an important step in assembling the transcriptional complex. Herein, we demonstrate that the TBP-GR interaction is functionally significant by characterizing the association of TBP and GR in vitro by a combination of techniques and confirming the role of this interaction in vivo. Combined analysis, using native gel electrophoresis, sedimentation equilibrium, and isothermal microcalorimetry titrations, characterize the stoichiometry, affinity, and thermodynamics of the TBP-GR interaction. TBP binds recombinant GR activation function 1 (AF1) with a 1:2 stoichiometry and a dissociation constant in the nanomolar range. In vivo fluorescence resonance energy transfer experiments, using fluorescently labeled TBP and various GR constructs, transiently transfected into CV-1 cells, show GR-TBP interactions, dependent on AF1. AF1-deletion variants showed fluorescence resonance energy transfer efficiencies on the level of coexpressed cyan fluorescent protein and yellow fluorescent protein, indicating that the interaction is dependent on AF1 domain. To demonstrate the functional role of the in vivo GR-TBP interaction, increased amounts of TBP expressed in vivo stimulated expression of GR-driven reporters and endogenous genes, and the effect was also specifically dependent on AF1.

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