Ca2+-dependence of the depolarization-inducible Na+ current ofXenopus oocytes

Bossi, Elena; Centinaio, E.; Moriondo, Andrea; Peres, Antonio

doi:10.1002/(sici)1097-4652(199802)174:2<154::aid-jcp2>3.0.co;2-n

Cited by 9 publications

(6 citation statements)

References 20 publications

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“…(v) One Na channel reported in X. laevis oocytes is the Na x channel, which is blocked by TTX at high concentrations. Na x is activated by a long depolarisation to positive voltages, with the activation facilitated by insulin and mobilisation of intracellular Ca 2+ (Baud et al, 1982;Bossi et al, 1998;Charpentier and Kado, 1999;Vasilyev et al, 2002). Na x is blocked by extracellular polyvalent cations, intracellular Mg 2+ and high concentrations of the local anaesthetics lidocaine (Charpentier, 2002;Quinteiro-Blondin and Charpentier, 2001;Vasilyev et al, 2002).…”

Section: 3mentioning

confidence: 99%

The role of ion channels and intracellular metal ions in apoptosis of Xenopus oocytes

Englund¹

2014

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Apoptosis is one type of programmed cell death, important during tissue development and to maintain the tissue homeostasis. Apoptosis comprises a complex network of internal signaling pathways, and an important part of this signaling network is the action of voltage‐gated ion channels. The aim of this thesis was to explore the role of ion channels and the role of intracellular metal ions during apoptosis in Xenopus laevis oocytes. The reasons for using these oocytes are that they are large, robust, easy to handle, and easy to study electrophysiologically. Apoptosis was induced either chemically by incubation of the oocytes in staurosporine (STS) or mechanically by centrifugation of the oocytes. Ion currents were measured by a two‐electrode voltage clamp technique, intracellular ion concentrations were measured either directly by in‐house developed K+‐selective microelectrodes or indirectly by the electrophysiological technique, and apoptosis was measured by caspase‐3 activation. Paper I describes that the intracellular K+ concentration was reduced by about 30 % during STS‐induced apoptosis. However, this reduction was prevented by excessive expression of exogenous ion channels. Despite the magnitude of the intracellular K+ concentration, either normal or reduced level, the oocytes displayed normal signs of apoptosis, suggesting that the intracellular K+ reduction was not required for the apoptotic process. Because the intracellular K+ concentration was not critical for apoptosis we searched for other ion fluxes by exploring the electrophysiological properties of X. laevis oocytes. Paper II, describes a non‐inactivating Na+ current activated at positive membrane voltages that was upregulated by a factor of five during STS‐induced apoptosis. By preventing influx of Na+, the apoptotic signaling network involving capsase‐3 was prevented. To molecularly identify this voltage‐gated Na channel, the X. tropicalis genome and conserved regions of the human SCNA genes were used as a map. Paper III, shows that the voltage‐gated Na channel corresponds to the SCN2A gene ortholog and that supression of this SCN2A ortholog using miRNA prevented cell death. In conclusion, this thesis work demonstrated that a voltage‐gated Na channel is critical for the apoptotic process in X. laevis oocytes by increasing the intracellular Na+ concentration

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Section: 3mentioning

confidence: 99%

The role of ion channels and intracellular metal ions in apoptosis of Xenopus oocytes

Englund¹

2014

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“…L'implication des enzymes PLC et PKC dans l'induc tion des canaux Na+ lents suggère que les ions C'a2' pour raient également jouer un rôle important puisque l'acti vité de ces enzymes est accrue par l'augmentation du calcium cytosolique (Kikkawa & Nishizuka, 1986). En effet, des injections intra-ovocytaires de chélateurs du calcium, tels que l'EGTA (Bossi et al, 1998) ou le BAPTA (Charpentier & Kado, 1999), réduisent ou même suppriment le courant Na+ . De plus, le taux d'induction des canaux et l'amplitude du courant sont augmentés lorsque la concentration de calcium cytosolique est accrue (Bossi et al, 1998).…”

Section: Mécanisme D'inductionunclassified

“…En effet, des injections intra-ovocytaires de chélateurs du calcium, tels que l'EGTA (Bossi et al, 1998) ou le BAPTA (Charpentier & Kado, 1999), réduisent ou même suppriment le courant Na+ . De plus, le taux d'induction des canaux et l'amplitude du courant sont augmentés lorsque la concentration de calcium cytosolique est accrue (Bossi et al, 1998). Le calcium nécessaire à l'induction ne provient pas de l'extérieur de la cellule puisque la suppression de ces ions dans le milieu de superfusion n'empêche pas ce processus de se dérouler normalement (Baud & Kado, 1984;Bossi et al , 1998;Charpentier & Kado, 1999).…”

Section: Mécanisme D'inductionunclassified

Induction de l’excitabilité membranaire dans les ovocytes de Xénope

Charpentier

1999

J. Soc. Biol.

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“…Consequently, the expression of heterologous proteins is usually very high with a very low background signal. A great number of endogenous electrogenic proteins and membrane conductance are characterized and known [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. The multimeric proteins are correctly assembled (more details are reported in these references [ 15 , 16 , 17 , 18 ]) , and the biophysical parameters are comparable to those collected with different approaches in the primary culture [ 19 ], cell line [ 20 , 21 ], and native membrane environment [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

The “www” of Xenopus laevis Oocytes: The Why, When, What of Xenopus laevis Oocytes in Membrane Transporters Research

et al. 2022

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After 50 years, the heterologous expression of proteins in Xenopus laevis oocytes is still essential in many research fields. New approaches and revised protocols, but also classical methods, such as the two-electrode voltage clamp, are applied in studying membrane transporters. New and old methods for investigating the activity and the expression of Solute Carriers (SLC) are reviewed, and the kinds of experiment that are still useful to perform with this kind of cell are reported. Xenopus laevis oocytes at the full-grown stage have a highly efficient biosynthetic apparatus that correctly targets functional proteins at the defined compartment. This small protein factory can produce, fold, and localize almost any kind of wild-type or recombinant protein; some tricks are required to obtain high expression and to verify the functionality. The methodologies examined here are mainly related to research in the field of membrane transporters. This work is certainly not exhaustive; it has been carried out to be helpful to researchers who want to quickly find suggestions and detailed indications when investigating the functionality and expression of the different members of the solute carrier families.

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Ca2+-dependence of the depolarization-inducible Na+ current ofXenopus oocytes

Cited by 9 publications

References 20 publications

The role of ion channels and intracellular metal ions in apoptosis of Xenopus oocytes

The role of ion channels and intracellular metal ions in apoptosis of Xenopus oocytes

Induction de l’excitabilité membranaire dans les ovocytes de Xénope

The “www” of Xenopus laevis Oocytes: The Why, When, What of Xenopus laevis Oocytes in Membrane Transporters Research

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