scholarly journals A novel epitope tagging system to visualize and monitor antigens in live cells with chromobodies

2020 ◽  
Author(s):  
Bjoern Traenkle ◽  
Sören Segan ◽  
Philipp D. Kaiser ◽  
Ulrich Rothbauer
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Drug Action ◽  
Live Cells ◽  
Antigen Concentration ◽  
Epitope Tagging ◽  
Dynamic Regulation ◽  
Short Peptide ◽  
Cellular Compartments ◽  
Tagging System

SummaryEpitope tagging is a versatile approach to study different proteins using a well-defined and established methodology. To date, most epitope tags such as myc, HA, V5 and FLAG tags are recognized by antibodies which limits their application to fixed cells, tissues or protein samples. Here we introduce a broadly applicable tagging strategy utilizing a short peptide tag/chromobody (PepTag/PepCB) system. The addition of the small PepTag does not interfere with the examined structures in different cellular compartments and its detection with the fluorescently labeled Pep-chromobody (PepCB) enables optical antigen tracing in real time. By employing the phenomenon of antigen-mediated chromobody stabilization (AMCBS) using a turnover-accelerated PepCB we demonstrated that the system is suitable to visualize and quantify changes in Pep-tagged antigen concentration by quantitative live-cell imaging. We expect that this novel tagging strategy offers new opportunities to study the dynamic regulation of proteins, e.g. during cellular signaling, cell differentiation, or upon drug action.

A single probe to sense Al(iii) colorimetrically and Cd(ii) by turn-on fluorescence in physiological conditions and live cells, corroborated by X-ray crystallographic and theoretical studies

2015 ◽  
Vol 44 (9) ◽  
pp. 4123-4132 ◽  
Author(s):  
Chirantan Kar ◽  
Soham Samanta ◽  
Sudeep Goswami ◽  
Aiyagari Ramesh ◽  
Gopal Das
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Selective Recognition ◽  
Live Cells ◽  
Paper Strip ◽  
Theoretical Studies ◽  
X Ray ◽  
Physiological Conditions ◽  
Turn On ◽  
Single Probe

Selective recognition of Al3+and Cd2+by UV-Vis and fluorescence based techniques using a cinnamaldehyde functionalized conjugated ligand, and its applications in paper strip and live cell imaging.

scholarly journals Live-Cell Imaging of Caspase Activation for High-Content Screening

2009 ◽  
Vol 14 (8) ◽  
pp. 956-969 ◽  
Author(s):  
Christophe Antczak ◽  
Toshimitsu Takagi ◽  
Christina N. Ramirez ◽  
Constantin Radu ◽  
Hakim Djaballah
Keyword(s):  
Cell Death ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Exposure Period ◽  
Live Cells ◽  
Assay Method ◽  
Caspase Activation ◽  
Fluorogenic Substrate ◽  
Automated Imaging ◽  
First Time

Caspases are central to the execution of programmed cell death, and their activation constitutes the biochemical hallmark of apoptosis. In this article, the authors report the successful adaptation of a high-content assay method using the DEVDNucView488™ fluorogenic substrate, and for the first time, they show caspase activation in live cells induced by either drugs or siRNA. The fluorogenic substrate was found to be nontoxic over an exposure period of several days, during which the authors demonstrate automated imaging and quantification of caspase activation of the same cell population as a function of time. Overexpression of the antiapoptotic protein Bcl-XL, alone or in combination with the inhibitor Z-VAD-FMK, attenuated caspase activation in HeLa cells exposed to doxorubicin, etoposide, or cell death siRNA. This method was further validated against 2 well-characterized NSCLC cell lines reported to be sensitive (H3255) or refractory (H2030) to erlotinib, where the authors show a differential time-dependent activation was observed for H3255 and no significant changes in H2030, consistent with their respective chemosensitivity profile. In summary, the results demonstrate the feasibility of using this newly adapted and validated high-content assay to screen chemical or RNAi libraries for the identification of previously uncovered enhancers and suppressors of the apoptotic machinery in live cells. ( Journal of Biomolecular Screening 2009:956-969)

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 CRISPR-mediated Multiplexed Live Cell Imaging of Nonrepetitive Genomic Loci

2020 ◽  
Author(s):  
Patricia A. Clow ◽  
Nathaniel Jillette ◽  
Jacqueline J. Zhu ◽  
Albert W. Cheng
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Repetitive Sequences ◽  
Binary Sequence ◽  
Three Dimensional ◽  
Live Cell ◽  
Live Cells ◽  
Imaging Method ◽  
Genomic Locus ◽  
Time Dynamics

AbstractThree-dimensional (3D) structures of the genome are dynamic, heterogeneous and functionally important. Live cell imaging has become the leading method for chromatin dynamics tracking. However, existing CRISPR- and TALE-based genomic labeling techniques have been hampered by laborious protocols and low signal-to-noise ratios (SNRs), and are thus mostly applicable to repetitive sequences. Here, we report a versatile CRISPR/Casilio-based imaging method, with an enhanced SNR, that allows for one nonrepetitive genomic locus to be labeled using a single sgRNA. We constructed Casilio dual-color probes to visualize the dynamic interactions of cohesin-bound elements in single live cells. By forming a binary sequence of multiple Casilio probes (PISCES) across a continuous stretch of DNA, we track the dynamic 3D folding of a 74kb genomic region over time. This method offers unprecedented resolution and scalability for delineating the dynamic 4D nucleome.One Sentence SummaryCasilio enables multiplexed live cell imaging of nonrepetitive DNA loci for illuminating the real-time dynamics of genome structures.

scholarly journals Live Cell Imaging: 3-Dimensional Tracking of Non-blinking ‘Giant’ Quantum Dots in Live Cells (Adv. Funct. Mater. 30/2014)

2014 ◽  
Vol 24 (30) ◽  
pp. 4795-4795 ◽  
Author(s):  
Aaron M. Keller ◽  
Yagnaseni Ghosh ◽  
Matthew S. DeVore ◽  
Mary E. Phipps ◽  
Michael H. Stewart ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell ◽  
Live Cells ◽  
3 Dimensional

scholarly journals Comparative assessment of fluorescent transgene methods for quantitative imaging in human cells

2014 ◽  
Vol 25 (22) ◽  
pp. 3610-3618 ◽  
Author(s):  
Robert Mahen ◽  
Birgit Koch ◽  
Malte Wachsmuth ◽  
Antonio Z. Politi ◽  
Alexis Perez-Gonzalez ◽  
...  
Keyword(s):  
Single Molecule ◽  
Protein Function ◽  
Mammalian Cells ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Quantitative Imaging ◽  
Live Cells ◽  
Single Molecule Spectroscopy ◽  
Mitotic Kinase ◽  
Endogenous Proteins

Fluorescence tagging of proteins is a widely used tool to study protein function and dynamics in live cells. However, the extent to which different mammalian transgene methods faithfully report on the properties of endogenous proteins has not been studied comparatively. Here we use quantitative live-cell imaging and single-molecule spectroscopy to analyze how different transgene systems affect imaging of the functional properties of the mitotic kinase Aurora B. We show that the transgene method fundamentally influences level and variability of expression and can severely compromise the ability to report on endogenous binding and localization parameters, providing a guide for quantitative imaging studies in mammalian cells.

scholarly journals Label-free and live cell imaging by interferometric scattering microscopy

2018 ◽  
Vol 9 (10) ◽  
pp. 2690-2697 ◽  
Author(s):  
Jin-Sung Park ◽  
Il-Buem Lee ◽  
Hyeon-Min Moon ◽  
Jong-Hyeon Joo ◽  
Kyoung-Hoon Kim ◽  
...  
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Complex Structure ◽  
Live Cell ◽  
Fluorescent Label ◽  
Live Cells ◽  
Label Free ◽  
Cytoplasmic Organelles ◽  
Microscopic Techniques

Despite recent remarkable advances in microscopic techniques, it still remains very challenging to directly observe the complex structure of cytoplasmic organelles in live cells without a fluorescent label.

scholarly journals A drug-compatible and temperature-controlled microfluidic device for live-cell imaging

Open Biology ◽  
2016 ◽  
Vol 6 (8) ◽  
pp. 160156 ◽  
Author(s):  
Tong Chen ◽  
Blanca Gomez-Escoda ◽  
Javier Munoz-Garcia ◽  
Julien Babic ◽  
Laurent Griscom ◽  
...  
Keyword(s):  
Cell Biology ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Critical Issue ◽  
Growth Conditions ◽  
Medium Composition ◽  
Live Cell ◽  
Model Systems ◽  
Dynamic Regulation ◽  
Cellular Environment

Monitoring cellular responses to changes in growth conditions and perturbation of targeted pathways is integral to the investigation of biological processes. However, manipulating cells and their environment during live-cell-imaging experiments still represents a major challenge. While the coupling of microfluidics with microscopy has emerged as a powerful solution to this problem, this approach remains severely underexploited. Indeed, most microdevices rely on the polymer polydimethylsiloxane (PDMS), which strongly absorbs a variety of molecules commonly used in cell biology. This effect of the microsystems on the cellular environment hampers our capacity to accurately modulate the composition of the medium and the concentration of specific compounds within the microchips, with implications for the reliability of these experiments. To overcome this critical issue, we developed new PDMS-free microdevices dedicated to live-cell imaging that show no interference with small molecules. They also integrate a module for maintaining precise sample temperature both above and below ambient as well as for rapid temperature shifts. Importantly, changes in medium composition and temperature can be efficiently achieved within the chips while recording cell behaviour by microscopy. Compatible with different model systems, our platforms provide a versatile solution for the dynamic regulation of the cellular environment during live-cell imaging.

scholarly journals PinMol: Python application for designing molecular beacons for live cell imaging of endogenous mRNAs

2018 ◽  
Author(s):  
Livia V. Bayer ◽  
Omar S. Omar ◽  
Diana P. Bratu ◽  
Irina E. Catrina
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Molecular Beacon ◽  
Structural Information ◽  
Live Cell ◽  
Molecular Beacons ◽  
Intramolecular Interactions ◽  
Live Cells ◽  
Target Rna

ABSTRACTMolecular beacons are nucleic acid oligomers labeled with a fluorophore and a quencher that fold in a hairpin-shaped structure, which fluoresce only when bound to their target RNA. They are used for the visualization of endogenous mRNAs in live cells. Here, we report a Python program (PinMol) that designs molecular beacons best suited for live cell imaging by using structural information from secondary structures of the target RNA, predicted via energy minimization approaches. PinMol takes into account the accessibility of the targeted regions, as well as the inter- and intramolecular interactions of each selected probe. To demonstrate its applicability, we synthesized an oskar mRNA-specific molecular beacon (osk1236), which is selected by PinMol to target a more accessible region than a manually designed oskar-specific molecular beacon (osk2216). We previously demonstrated osk2216 to be efficient in detecting oskar mRNA in in vivo experiments. Here, we show that osk1236 outperformed osk2216 in live cell imaging experiments.

scholarly journals PGE2 upregulates the Na+/K+ ATPase in HepG2 cells via EP4 receptors and intracellular calcium

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245400
Author(s):  
Rawad Hodeify ◽  
Mohamed Chakkour ◽  
Reem Rida ◽  
Sawsan Kreydiyyeh
Keyword(s):  
Intracellular Calcium ◽  
Hepg2 Cells ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Time Lapse ◽  
Live Cells ◽  
Ionic Homeostasis ◽  
Significant Stimulation ◽  
Time Lapse Imaging ◽  
Stimulation Of

The Na+/K+ ATPase is a key regulator of the hepatocytes ionic homeostasis, which when altered may lead to many liver disorders. We demonstrated recently, a significant stimulation of the Na+/K+ ATPase in HepG2 cells treated with the S1P analogue FTY 720P, that was mediated through PGE2. The mechanism by which the prostaglandin exerts its effect was not investigated, and is the focus of this work. The type of receptors involved was determined using pharmacological inhibitors, while western blot analysis, fluorescence imaging of GFP-tagged Na+/K+ ATPase, and time-lapse imaging on live cells were used to detect changes in membrane abundance of the Na+/K+ ATPase. The activity of the ATPase was assayed by measuring the amount of inorganic phosphate liberated in the presence and absence of ouabain. The enhanced activity of the ATPase was not observed when EP4 receptors were blocked but still appeared in presence inhibitors of EP1, EP2 and EP3 receptors. The involvement of EP4 was confirmed by the stimulation observed with EP4 agonist. The stimulatory effect of PGE2 did not appear in presence of Rp-cAMP, an inhibitor of PKA, and was imitated by db-cAMP, a PKA activator. Chelating intracellular calcium with BAPTA-AM abrogated the effect of db-cAMP as well as that of PGE2, but PGE2 treatment in a calcium-free PBS medium did not, suggesting an involvement of intracellular calcium, that was confirmed by the results obtained with 2-APB treatment. Live cell imaging showed movement of GFP–Na+/K+ ATPase-positive vesicles to the membrane and increased abundance of the ATPase at the membrane after PGE2 treatment. It was concluded that PGE2 acts via EP4, PKA, and intracellular calcium.

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