scholarly journals Spatial distribution and functional significance of activated vinculin in living cells

2005 ◽  
Vol 169 (3) ◽  
pp. 459-470 ◽  
Author(s):  
Hui Chen ◽  
Daniel M. Cohen ◽  
Dilshad M. Choudhury ◽  
Noriyuki Kioka ◽  
Susan W. Craig
Keyword(s):  
Conformational Change ◽  
Direct Evidence ◽  
Resonance Energy Transfer ◽  
Focal Adhesions ◽  
Resonance Energy ◽  
Time Lapse ◽  
Living Cells ◽  
Actin Binding ◽  
Binding Conformation ◽  
Time Lapse Imaging

Conformational change is believed to be important to vinculin's function at sites of cell adhesion. However, nothing is known about vinculin's conformation in living cells. Using a Forster resonance energy transfer probe that reports on changes in vinculin's conformation, we find that vinculin is in the actin-binding conformation in a peripheral band of adhesive puncta in spreading cells. However, in fully spread cells with established polarity, vinculin's conformation is variable at focal adhesions. Time-lapse imaging reveals a gradient of conformational change that precedes loss of vinculin from focal adhesions in retracting regions. At stable or protruding regions, recruitment of vinculin is not necessarily coupled to the actin-binding conformation. However, a different measure of vinculin conformation, the recruitment of vinexin β by activated vinculin, shows that autoinhibition of endogenous vinculin is relaxed at focal adhesions. Beyond providing direct evidence that vinculin is activated at focal adhesions, this study shows that the specific functional conformation correlates with regional cellular dynamics.

scholarly journals Live imaging of apoptosis in a novel transgenic mouse highlights its role in neural tube closure

2011 ◽  
Vol 195 (6) ◽  
pp. 1047-1060 ◽  
Author(s):  
Yoshifumi Yamaguchi ◽  
Naomi Shinotsuka ◽  
Keiko Nonomura ◽  
Kiwamu Takemoto ◽  
Keisuke Kuida ◽  
...  
Keyword(s):  
Transgenic Mouse ◽  
Neural Tube ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Time Lapse ◽  
Neural Tube Closure ◽  
Caspase Activation ◽  
Fluorescent Reporter ◽  
Time Lapse Imaging ◽  
Tube Closure

Many cells die during development, tissue homeostasis, and disease. Dysregulation of apoptosis leads to cranial neural tube closure (NTC) defects like exencephaly, although the mechanism is unclear. Observing cells undergoing apoptosis in a living context could help elucidate their origin, behavior, and influence on surrounding tissues, but few tools are available for this purpose, especially in mammals. In this paper, we used insulator sequences to generate a transgenic mouse that stably expressed a genetically encoded fluorescence resonance energy transfer (FRET)–based fluorescent reporter for caspase activation and performed simultaneous time-lapse imaging of apoptosis and morphogenesis in living embryos. Live FRET imaging with a fast-scanning confocal microscope revealed that cells containing activated caspases showed typical and nontypical apoptotic behavior in a region-specific manner during NTC. Inhibiting caspase activation perturbed and delayed the smooth progression of cranial NTC, which might increase the risk of exencephaly. Our results suggest that caspase-mediated cell removal facilitates NTC completion within a limited developmental window.

scholarly journals Imaging kinase–AKAP79–phosphatase scaffold complexes at the plasma membrane in living cells using FRET microscopy

2002 ◽  
Vol 160 (1) ◽  
pp. 101-112 ◽  
Author(s):  
Seth F. Oliveria ◽  
Lisa L. Gomez ◽  
Mark L. Dell'Acqua
Keyword(s):  
Signal Transduction ◽  
Glutamate Receptors ◽  
Direct Evidence ◽  
Protein A ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Adaptor Proteins ◽  
Living Cells ◽  
Intact Cells ◽  
Anchoring Protein

Scaffold, anchoring, and adaptor proteins coordinate the assembly and localization of signaling complexes providing efficiency and specificity in signal transduction. The PKA, PKC, and protein phosphatase-2B/calcineurin (CaN) scaffold protein A–kinase anchoring protein (AKAP) 79 is localized to excitatory neuronal synapses where it is recruited to glutamate receptors by interactions with membrane-associated guanylate kinase (MAGUK) scaffold proteins. Anchored PKA and CaN in these complexes could have important functions in regulating glutamate receptors in synaptic plasticity. However, direct evidence for the assembly of complexes containing PKA, CaN, AKAP79, and MAGUKs in intact cells has not been available. In this report, we use immunofluorescence and fluorescence resonance energy transfer (FRET) microscopy to demonstrate membrane cytoskeleton–localized assembly of this complex. Using FRET, we directly observed binding of CaN catalytic A subunit (CaNA) and PKA-RII subunits to membrane-targeted AKAP79. We also detected FRET between CaNA and PKA-RII bound simultaneously to AKAP79 within 50 Å of each other, thus providing the first direct evidence of a ternary kinase–scaffold–phosphatase complex in living cells. This finding of AKAP-mediated PKA and CaN colocalization on a nanometer scale gives new appreciation to the level of compartmentalized signal transduction possible within scaffolds. Finally, we demonstrated AKAP79-regulated membrane localization of the MAGUK synapse-associated protein 97 (SAP97), suggesting that AKAP79 functions to organize even larger signaling complexes.

scholarly journals Tracking the Interactions of rRNA Processing Proteins during Nucleolar Assembly in Living Cells

2005 ◽  
Vol 16 (6) ◽  
pp. 2862-2871 ◽  
Author(s):  
Nicole Angelier ◽  
Marc Tramier ◽  
Emilie Louvet ◽  
Maïté Coppey-Moisan ◽  
Tula M. Savino ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Time Lapse ◽  
Living Cells ◽  
Rrna Processing ◽  
Rdna Transcription ◽  
Pass Through ◽  
Protein Recruitment ◽  
First Time

Reorganization of the nuclear machinery after mitosis is a fundamental but poorly understood process. Here, we investigate the recruitment of the nucleolar processing proteins in the nucleolus of living cells at the time of nucleus formation. We question the role of the prenucleolar bodies (PNBs), during migration of the processing proteins from the chromosome periphery to sites of rDNA transcription. Surprisingly, early and late processing proteins pass through the same PNBs as demonstrated by rapid two-color four-dimensional imaging and quantification, whereas a different order of processing protein recruitment into nucleoli is supported by differential sorting. Protein interactions along the recruitment pathway were investigated using a promising time-lapse analysis of fluorescence resonance energy transfer. For the first time, it was possible to detect in living cells the interactions between proteins of the same rRNA processing machinery in nucleoli. Interestingly interactions between such proteins also occur in PNBs but not at the chromosome periphery. The dynamics of these interactions suggests that PNBs are preassembly platforms for rRNA processing complexes.

scholarly journals Spatial and Temporal Regulation of Focal Adhesion Kinase Activity in Living Cells

2007 ◽  
Vol 28 (1) ◽  
pp. 201-214 ◽  
Author(s):  
Xinming Cai ◽  
Daniel Lietha ◽  
Derek F. Ceccarelli ◽  
Andrei V. Karginov ◽  
Zenon Rajfur ◽  
...  
Keyword(s):  
Focal Adhesion Kinase ◽  
Conformational Change ◽  
Focal Adhesion ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Living Cells ◽  
Live Cells ◽  
Major Mechanism

ABSTRACT Focal adhesion kinase (FAK) is an essential kinase that regulates developmental processes and functions in the pathology of human disease. An intramolecular autoinhibitory interaction between the FERM and catalytic domains is a major mechanism of regulation. Based upon structural studies, a fluorescence resonance energy transfer (FRET)-based FAK biosensor that discriminates between autoinhibited and active conformations of the kinase was developed. This biosensor was used to probe FAK conformational change in live cells and the mechanism of regulation. The biosensor demonstrates directly that FAK undergoes conformational change in vivo in response to activating stimuli. A conserved FERM domain basic patch is required for this conformational change and for interaction with a novel ligand for FAK, acidic phospholipids. Binding to phosphatidylinositol 4,5-bisphosphate (PIP2)-containing phospholipid vesicles activated and induced conformational change in FAK in vitro, and alteration of PIP2 levels in vivo changed the level of activation of the conformational biosensor. These findings provide direct evidence of conformational regulation of FAK in living cells and novel insight into the mechanism regulating FAK conformation.

scholarly journals Multiplexed bioluminescence microscopy via phasor analysis

2021 ◽  
Author(s):  
Zi Yao ◽  
Caroline K. Brennan ◽  
Lorenzo Scipioni ◽  
Hongtao Chen ◽  
Kevin Ng ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Bioluminescence Imaging ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Time Lapse ◽  
Detection Methods ◽  
Transfer Processes ◽  
Time Lapse Imaging ◽  
Luciferase Reporters ◽  
Phasor Analysis

Microscopic bioluminescence imaging has been historically challenging due to a lack of detection methods and easily resolved probes. Here we combine bioluminescence with phasor analysis, an optical method commonly used to distinguish spectrally similar fluorophores. Bioluminescent phasor enabled rapid differentiation of multiple luciferase reporters and resonance energy transfer processes. The merger of bioluminescence and phasor analysis provides a platform for routine, time-lapse imaging of collections of cellular features.

Development and use of fluorescent nanosensors for metabolite imaging in living cells

2005 ◽  
Vol 33 (1) ◽  
pp. 287-290 ◽  
Author(s):  
M. Fehr ◽  
S. Okumoto ◽  
K. Deuschle ◽  
I. Lager ◽  
L.L. Looger ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Real Time ◽  
Conformational Change ◽  
Binding Proteins ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Living Cells ◽  
Periplasmic Binding Proteins ◽  
Living Organisms ◽  
Subcellular Resolution

To understand metabolic networks, fluxes and regulation, it is crucial to be able to determine the cellular and subcellular levels of metabolites. Methods such as PET and NMR imaging have provided us with the possibility of studying metabolic processes in living organisms. However, at present these technologies do not permit measuring at the subcellular level. The cameleon, a fluorescence resonance energy transfer (FRET)-based nanosensor uses the ability of the calcium-bound form of calmodulin to interact with calmodulin binding polypeptides to turn the corresponding dramatic conformational change into a change in resonance energy transfer between two fluorescent proteins attached to the fusion protein. The cameleon and its derivatives were successfully used to follow calcium changes in real time not only in isolated cells, but also in living organisms. To provide a set of tools for real-time measurements of metabolite levels with subcellular resolution, protein-based nanosensors for various metabolites were developed. The metabolite nanosensors consist of two variants of the green fluorescent protein fused to bacterial periplasmic binding proteins. Different from the cameleon, a conformational change in the binding protein is directly detected as a change in FRET efficiency. The prototypes are able to detect various carbohydrates such as ribose, glucose and maltose as purified proteins in vitro. The nanosensors can be expressed in yeast and in mammalian cell cultures and were used to determine carbohydrate homeostasis in living cells with subcellular resolution. One future goal is to expand the set of sensors to cover a wider spectrum of metabolites by using the natural spectrum of bacterial periplasmic binding proteins and by computational design of the binding pockets of the prototype sensors.

scholarly journals A Fluorescence Resonance Energy Transfer-Based Analytical Tool for Nitrate Quantification in Living Cells

ACS Omega ◽  
2020 ◽  
Vol 5 (46) ◽  
pp. 30306-30314
Author(s):  
Urooj Fatima ◽  
Fuad Ameen ◽  
Neha Soleja ◽  
Parvez Khan ◽  
Abobakr Almansob ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Fluorescence Resonance Energy Transfer ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Living Cells ◽  
Analytical Tool ◽  
Fluorescence Resonance
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