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Your search keyword '"Feltz, Anne"' showing total 169 results
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169 results on '"Feltz, Anne"'

2. Contribution of the kinetics of G protein dissociation to the characteristic modifications of N-type calcium channel activity

Author

Weiss, Norbert, Arnoult, Christophe, Feltz, Anne, and De Waard, Michel

Subjects
Quantitative Biology - Neurons and Cognition
Abstract

Direct G protein inhibition of N-type calcium channels is recognized by characteristic biophysical modifications. In this study, we quantify and simulate the importance of G protein dissociation on the phenotype of G protein-regulated whole-cell currents. Based on the observation that the voltage-dependence of the time constant of recovery from G protein inhibition is correlated with the voltage-dependence of channel opening, we depict all G protein effects by a simple kinetic scheme. All landmark modifications in calcium currents, except inhibition, can be successfully described using three simple biophysical parameters (extent of block, extent of recovery, and time constant of recovery). Modifications of these parameters by auxiliary beta subunits are at the origin of differences in N-type channel regulation by G proteins. The simulation data illustrate that channel reluctance can occur as the result of an experimental bias linked to the variable extent of G protein dissociation when peak currents are measured at various membrane potentials. To produce alterations in channel kinetics, the two most important parameters are the extents of initial block and recovery. These data emphasize the contribution of the degree and kinetics of G protein dissociation in the modification of N-type currents.

Published
2009
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20. How do G proteins directly control neuronal [Ca.sup.2+] channel function?

Author

De Waard, Michel, Hering, Julien, Weiss, Norbert, and Feltz, Anne

Subjects
Ion channels -- Research, G proteins -- Research, G proteins -- Physiological aspects, Pharmacology -- Research, Neurons -- Research, Biological sciences, Chemistry, Pharmaceuticals and cosmetics industries
Abstract

[Ca.sup.2+] entry into neuronal cells is modulated by the activation of numerous G-protein-coupled receptors (GPCRs). Much effort has been invested in studying direct G-protein-mediated inhibition of voltage-dependent [Ca.sub.v]2 [Ca.sup.2+]. channels. This inhibition occurs through a series of convergent modifications in the biophysical properties of the channels. An integrated view of the structural organization of the G[beta][gamma]-dimer binding-site pocket within the channel is emerging. In this review, we discuss how variable geometry of the G[beta][gamma] binding pocket can yield distinct sets of channel inhibition. In addition, we propose specific mechanisms for the regulation of the channel by G proteins that take into account the regulatory input of each G[beta][gamma] binding element.

Published
2005

24. Identifying neuronal non-L Ca(super 2+) channels - more than stamp collecting?

Author

Nooney, Janet M., Lambert, Regis C., and Feltz, Anne

Subjects
Calcium channels -- Research, Neuropharmacology -- Research, Biological sciences, Chemistry, Pharmaceuticals and cosmetics industries
Abstract

The pharmacology of the majority of [Ca.sup.2+] channels in the nervous system is very limited. Although attempts have been made to constrain native [Ca.sup.2+] channels into the framework provided by the six pore-forming molecules cloned to date, refined biophysical analysis of [Ca.sup.2+] currents, expression techniques and the use of selective toxins have helped to identify unambiguously only a limited number of [Ca.sup.2+] channels. In fact, many native [Ca.sup.2+] channel activities remain as 'orphans', waiting for their molecular counterparts to be defined. In this article, Janet Nooney, Regis Lambert and Anne Feltz systematically delineate the well characterized non-L [Ca.sup.2+] channel activities and the missing elements in our knowledge of the [Ca.sup.2+] channel family.

Published
1997

28. H-Rubies, a new family of red emitting fluorescent pH sensors for living cells† †Electronic supplementary information (ESI) available: Details of the organic synthesis, characterisations (HPLC, NMR, mass spectra) as well as measurements of their photophysical properties can be found in the supplementary information. See DOI: 10.1039/c5sc01113b

Author

Despras, Guillaume, Zamaleeva, Alsu I., Dardevet, Lucie, Tisseyre, Céline, Magalhaes, Joao Gamelas, Garner, Charlotte, De Waard, Michel, Amigorena, Sebastian, Feltz, Anne, Mallet, Jean-Maurice, and Collot, Mayeul

Subjects
Chemistry
Abstract

H-Rubies is a family of pH probes that display a bright red fluorescence upon acidification. They have been used as molecular form to monitor mitochondrial acidification and as functionalised forms to provide ratiometric systems to measure phagosomal and endosomal pH in macrophages., Monitoring intracellular pH has drawn much attention due to its undeniably important function in cells. The widespread development of fluorescent imaging techniques makes pH sensitive fluorescent dyes valuable tools, especially red-emitting dyes which help to avoid the overcrowded green end of the spectral band. Herein, we present H-Rubies, a family of pH sensors based on a phenol moiety and a X-rhodamine fluorophore that display a bright red fluorescence upon acidification with pKa values spanning from 4 to 9. Slight structural modifications led to dramatic changes in their physicochemical properties and a relationship between their structures, their ability to form H-aggregates, and their apparent pKa was established. While molecular form H-Rubies can be used to monitor mitochondrial acidification of glioma cells, their functionalised forms were linked via click chemistry to dextrans or microbeads containing a near infrared Cy5 (Alexa-647) in order to provide ratiometric systems that were used to measure respectively the phagosomal and endosomal pH in macrophages (RAW 264.7 cells) using flow cytometry.

Published
2015

31. Getting across the plasma membrane and beyond: intracellular uses of colloidal semiconductor nanocrystals

Author

Luccardini, Camilla, Yakovlev, Aleksey, Gaillard, Stephane, van 't Hoff, Marcel, Alberola, Alicia Piera, Mallet, Jean-Maurice, Parak, Wolfgang J., Feltz, Anne, and Oheim, Martin

Subjects
Technology application, Usage, Nanotechnology -- Usage -- Technology application, Cytological research -- Technology application -- Usage, Semiconductors (Materials) -- Usage, Semiconductors -- Usage, Cell research -- Technology application -- Usage
Abstract

Semiconductor nanocrystals (NCs) are increasingly being used as photoluminescen markers in biological imaging. Their brightness, large Stokes shift, and high photostability compared to organic fluorophores permit the exploration of biological [...]

Published
2007

35. Calcium Rubies: A Family of Red-Emitting Functionalizable Indicators Suitable for Two-Photon Ca2+ Imaging

Author

Collot, Mayeul, primary, Loukou, Christina, additional, Yakovlev, Aleksey V., additional, Wilms, Christian D., additional, Li, Dongdong, additional, Evrard, Alexis, additional, Zamaleeva, Alsu, additional, Bourdieu, Laurent, additional, Léger, Jean-François, additional, Ropert, Nicole, additional, Eilers, Jens, additional, Oheim, Martin, additional, Feltz, Anne, additional, and Mallet, Jean-Maurice, additional

Published
2012
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36. Quantum Dot Peptide Biosensors for Monitoring Caspase 3 Proteolysis and Calcium Ions

Author

Prasuhn, Duane E., primary, Feltz, Anne, additional, Blanco-Canosa, Juan B., additional, Susumu, Kimihiro, additional, Stewart, Michael H., additional, Mei, Bing C., additional, Yakovlev, Aleksey V., additional, Loukou, Christina, additional, Mallet, Jean-Maurice, additional, Oheim, Martin, additional, Dawson, Philip E., additional, and Medintz, Igor L., additional

Published
2010
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38. Corrigendum to “Measuring mitochondrial and cytoplasmic Ca2+ in EGFP expressing cells with a low-affinity Calcium Ruby and its dextran conjugate” [Cell Calcium 45 (3) (2008)]

Author

Luccardini, Camilla, primary, Yakovlev, Aleksey V., additional, Pasche, Mathias, additional, Gaillard, Stéphane, additional, Li, Dongdong, additional, Rousseau, France, additional, Ly, Romain, additional, Becherer, Ute, additional, Mallet, Jean-Maurice, additional, Feltz, Anne, additional, and Oheim, Martin, additional

Published
2009
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39. Functional Coupling between mGluR1 and Cav3.1 T-Type Calcium Channels Contributes to Parallel Fiber-Induced Fast Calcium Signaling within Purkinje Cell Dendritic Spines

Author

Hildebrand, Michael E., primary, Isope, Philippe, additional, Miyazaki, Taisuke, additional, Nakaya, Toshitaka, additional, Garcia, Esperanza, additional, Feltz, Anne, additional, Schneider, Toni, additional, Hescheler, Jürgen, additional, Kano, Masanobu, additional, Sakimura, Kenji, additional, Watanabe, Masahiko, additional, Dieudonné, Stéphane, additional, and Snutch, Terrance P., additional

Published
2009
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40. Measuring mitochondrial and cytoplasmic Ca2+ in EGFP expressing cells with a low-affinity Calcium Ruby and its dextran conjugate

Author

Luccardini, Camilla, primary, Yakovlev, Aleksey V., additional, Pasche, Mathias, additional, Gaillard, Stéphane, additional, Li, Dongdong, additional, Rousseau, France, additional, Ly, Romain, additional, Becherer, Ute, additional, Mallet, Jean-Maurice, additional, Feltz, Anne, additional, and Oheim, Martin, additional

Published
2009
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41. Wrapping Nanocrystals with an Amphiphilic Polymer Preloaded with Fixed Amounts of Fluorophore Generates FRET-Based Nanoprobes with a Controlled Donor/Acceptor Ratio

Author

Yakovlev, Aleksey V., primary, Zhang, Feng, additional, Zulqurnain, Ali, additional, Azhar-Zahoor, Abbasi, additional, Luccardini, Camilla, additional, Gaillard, Stéphane, additional, Mallet, Jean-Maurice, additional, Tauc, Patrick, additional, Brochon, Jean-Claude, additional, Parak, Wolfgang J., additional, Feltz, Anne, additional, and Oheim, Martin, additional

Published
2009
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43. Synthesis and Characterization of Polymer-Coated Quantum Dots with Integrated Acceptor Dyes as FRET-Based Nanoprobes

Author

Fernández-Argüelles, María Teresa, primary, Yakovlev, Aleksey, additional, Sperling, Ralph A., additional, Luccardini, Camilla, additional, Gaillard, Stéphane, additional, Sanz Medel, Alfredo, additional, Mallet, Jean-Maurice, additional, Brochon, Jean-Claude, additional, Feltz, Anne, additional, Oheim, Martin, additional, and Parak, Wolfgang J., additional

Published
2007
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44. FRET-Based Nanobiosensors for Imaging Intracellular Ca2+ and H+ Microdomains.

Author

Zamaleeva, Alsu I., Despras, Guillaume, Luccardini, Camilla, Collot, Mayeul, de Waard, Michel, Oheim, Martin, Mallet, Jean-Maurice, and Feltz, Anne

Subjects
BIOSENSORS, RHODAMINES, FLUOROPHORES, PHENOL, SEMICONDUCTOR nanocrystals, QUANTUM dots
Abstract

Semiconductor nanocrystals (NCs) or quantum dots (QDs) are luminous point emitters increasingly being used to tag and track biomolecules in biological/biomedical imaging. However, their intracellular use as highlighters of single-molecule localization and nanobiosensors reporting ion microdomains changes has remained a major challenge. Here, we report the design, generation and validation of FRET-based nanobiosensors for detection of intracellular Ca2+ and H+ transients. Our sensors combine a commercially available CANdot®565QD as an energy donor with, as an acceptor, our custom-synthesized red-emitting Ca2+ or H+ probes. These 'Rubies' are based on an extended rhodamine as a fluorophore and a phenol or BAPTA (1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid) for H+ or Ca2+ sensing, respectively, and additionally bear a linker arm for conjugation. QDs were stably functionalized using the same SH/maleimide crosslink chemistry for all desired reactants. Mixing ion sensor and cell-penetrating peptides (that facilitate cytoplasmic delivery) at the desired stoichiometric ratio produced controlled multi-conjugated assemblies. Multiple acceptors on the same central donor allow up-concentrating the ion sensor on the QD surface to concentrations higher than those that could be achieved in free solution, increasing FRET efficiency and improving the signal. We validate these nanosensors for the detection of intracellular Ca2+ and pH transients using live-cell fluorescence imaging. [ABSTRACT FROM AUTHOR]

Published
2015
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47. Post-Genomic Insights into T-Type Calcium Channel Functions in Neurons.

Author

Zamponi, Gerald W., Bourinet, Emmanuel, Lory, Philippe, Chemin, Jean, Dubel, Steve, Lambert, Régis, Poirot, Olivier, Monteil, Arnaud, Feltz, Anne, and Nargeot, Joël

Abstract

Genomic mining, the process of sifting through billions of genomic and EST sequences of several different species has led to the molecular identification of a family of low voltage activating channels, more commonly referred to as T-type channels. Historically, these channels were initially identified through the use of the patch-damp technique on various neuronal preparations. They were characterized by their small conductance, rapid voltage-dependent inactivation, a small window current and slow deactivation kinetics and their remarkable property of being able to open at membrane potentials just above the resting membrane potential of neurons. This property would allow for the entry of Ca2+ without the initiation of an action potential triggered by the opening of sodium channels. Thus the activity of these channels would contribute to modifying membrane excitability, allowing Ca2+ signaling events to occur at subthreshold potentials, and potentially modulate waveform patterns. Now, with the clones in hand, we have entered an exciting time where the molecular machinery can be dissected, modified and manipulated not only to investigate their biophysical properties, but to appreciate their role in a diverse range of cellular processes, find novel and useful therapeutic and pharmacological reagents, hunt down subunits and modifying proteins, study their localization and trafficking and incorporate these findings into the emerging field of systems biology where their roles can be placed in the context from a single neuron, to the organ, to the organism. [ABSTRACT FROM AUTHOR]

Published
2005
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