Endogenous transport systems in the Xenopus laevis oocyte plasma membrane

“…If the intracellular concentrations of ions during apoptosis are not tightly regulated, apoptosis can easily turn over to necrosis (Barros et al, 2001;Koike et al, 2000;Maeno et al, 2012;Okada et al, 2004). X. laevis oocytes with their endogenous expression of ion transducting transmembrane proteins and ability to sustain intracellular manipulation can be used as a model system to study the role of ions and ionic signaling during apoptosis (Goldin, 1992;Sobczak et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

“…laevis oocytes express three different types of K channels. These channels are thoroughly discussed in a number of review articles (Sobczak et al, 2010;Weber, 1999 -inactivated Cl channels. These Cl channels are important to create a functional polarity of the oocyte, prevent polyspermy and to further maturation of the fertilised oocyte (Sobczak et al, 2010;Weber, 1999).…”

Section: 3mentioning

confidence: 99%

“…Several voltage-gated Ca channels belonging to the L, N and T-type, have been reported in X. laevis oocyte, as well as store-operated Ca channels that activates in response to elevated intracellular Ca 2+ (Sobczak et al, 2010;Weber, 1999). The increase in intracellular Ca 2+ through Ca channels and transporters (through the plasma membrane and from internal stores) is reported to be important during fertilisation (Busa and Nuccitelli, 1985;Sobczak et al, 2010;Weber, 1999).…”

Section: 3mentioning

confidence: 99%

“…The increase in intracellular Ca 2+ through Ca channels and transporters (through the plasma membrane and from internal stores) is reported to be important during fertilisation (Busa and Nuccitelli, 1985;Sobczak et al, 2010;Weber, 1999).…”

Section: 3mentioning

confidence: 99%

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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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The Medicago truncatula NIP/LATD Transporter Is Essential for Nodulation and Appropriate Root Architecture

Salehin

Bagchi

Huang³

et al. 2015

Biological Nitrogen Fixation

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Endogenous transport systems in the Xenopus laevis oocyte plasma membrane

Cited by 54 publications

References 170 publications

Single cell wound generates electric current circuit and cell membrane potential variations that requires calcium influx

Single cell wound generates electric current circuit and cell membrane potential variations that requires calcium influx

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

The Medicago truncatula NIP/LATD Transporter Is Essential for Nodulation and Appropriate Root Architecture

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