scholarly journals Human embryonic kidney (HEK293) cells express endogenous voltage-gated sodium currents and Nav1.7 sodium channels

2010 ◽  
Vol 469 (2) ◽  
pp. 268-272 ◽  
Author(s):  
Bingjun He ◽  
David M. Soderlund
Keyword(s):  
Sodium Channels ◽  
Hek293 Cells ◽  
Sodium Currents ◽  
Human Embryonic Kidney ◽  
Voltage Gated

scholarly journals Inter-Regulation of Kv4.3 and Voltage-Gated Sodium Channels Underlies Predisposition to Cardiac and Neuronal Channelopathies

2020 ◽  
Vol 21 (14) ◽  
pp. 5057
Author(s):  
Jérôme Clatot ◽  
Nathalie Neyroud ◽  
Robert Cox ◽  
Charlotte Souil ◽  
Jing Huang ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Outward Current ◽  
Surface Expression ◽  
Hek293 Cells ◽  
Cell Surface Expression ◽  
Transient Outward Current ◽  
Loss Of Function ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Intracellular Compartments

Background: Genetic variants in voltage-gated sodium channels (Nav) encoded by SCNXA genes, responsible for INa, and Kv4.3 channels encoded by KCND3, responsible for the transient outward current (Ito), contribute to the manifestation of both Brugada syndrome (BrS) and spinocerebellar ataxia (SCA19/22). We examined the hypothesis that Kv4.3 and Nav variants regulate each other’s function, thus modulating INa/Ito balance in cardiomyocytes and INa/I(A) balance in neurons. Methods: Bicistronic and other constructs were used to express WT or variant Nav1.5 and Kv4.3 channels in HEK293 cells. INa and Ito were recorded. Results: SCN5A variants associated with BrS reduced INa, but increased Ito. Moreover, BrS and SCA19/22 KCND3 variants associated with a gain of function of Ito, significantly reduced INa, whereas the SCA19/22 KCND3 variants associated with a loss of function (LOF) of Ito significantly increased INa. Auxiliary subunits Navβ1, MiRP3 and KChIP2 also modulated INa/Ito balance. Co-immunoprecipitation and Duolink studies suggested that the two channels interact within the intracellular compartments and biotinylation showed that LOF SCN5A variants can increase Kv4.3 cell-surface expression. Conclusion: Nav and Kv4.3 channels modulate each other’s function via trafficking and gating mechanisms, which have important implications for improved understanding of these allelic cardiac and neuronal syndromes.

scholarly journals Neurosteroids Allopregnanolone Sulfate and Pregnanolone Sulfate Have Diverse Effect on the α Subunit of the Neuronal Voltage-gated Sodium Channels Nav1.2, Nav1.6, Nav1.7, and Nav1.8 Expressed in Xenopus Oocytes

2014 ◽  
Vol 121 (3) ◽  
pp. 620-631 ◽  
Author(s):  
Takafumi Horishita ◽  
Nobuyuki Yanagihara ◽  
Susumu Ueno ◽  
Yuka Sudo ◽  
Yasuhito Uezono ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Xenopus Oocytes ◽  
Sodium Current ◽  
Dependent Manner ◽  
Sodium Currents ◽  
Concentration Dependent Manner ◽  
Α Subunit ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Α Subunits

Abstract Background: The neurosteroids allopregnanolone and pregnanolone are potent positive modulators of γ-aminobutyric acid type A receptors. Antinociceptive effects of allopregnanolone have attracted much attention because recent reports have indicated the potential of allopregnanolone as a therapeutic agent for refractory pain. However, the analgesic mechanisms of allopregnanolone are still unclear. Voltage-gated sodium channels (Nav) are thought to play important roles in inflammatory and neuropathic pain, but there have been few investigations on the effects of allopregnanolone on sodium channels. Methods: Using voltage-clamp techniques, the effects of allopregnanolone sulfate (APAS) and pregnanolone sulfate (PAS) on sodium current were examined in Xenopus oocytes expressing Nav1.2, Nav1.6, Nav1.7, and Nav1.8 α subunits. Results: APAS suppressed sodium currents of Nav1.2, Nav1.6, and Nav1.7 at a holding potential causing half-maximal current in a concentration-dependent manner, whereas it markedly enhanced sodium current of Nav1.8 at a holding potential causing maximal current. Half-maximal inhibitory concentration values for Nav1.2, Nav1.6, and Nav1.7 were 12 ± 4 (n = 6), 41 ± 2 (n = 7), and 131 ± 15 (n = 5) μmol/l (mean ± SEM), respectively. The effects of PAS were lower than those of APAS. From gating analysis, two compounds increased inactivation of all α subunits, while they showed different actions on activation of each α subunit. Moreover, two compounds showed a use-dependent block on Nav1.2, Nav1.6, and Nav1.7. Conclusion: APAS and PAS have diverse effects on sodium currents in oocytes expressing four α subunits. APAS inhibited the sodium currents of Nav1.2 most strongly.

scholarly journals α- And β-subunit composition of voltage-gated sodium channels investigated with μ-conotoxins and the recently discovered μO§-conotoxin GVIIJ

2015 ◽  
Vol 113 (7) ◽  
pp. 2289-2301 ◽  
Author(s):  
Michael J. Wilson ◽  
Min-Min Zhang ◽  
Joanna Gajewiak ◽  
Layla Azam ◽  
Jean E. Rivier ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Sodium Channels ◽  
Action Potentials ◽  
Xenopus Laevis Oocytes ◽  
Sodium Currents ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Compound Action Potentials ◽  
Sciatic Nerves ◽  
Synthetic Derivatives

We investigated the identities of the isoforms of the α (NaV1)- and β (NaVβ)-subunits of voltage-gated sodium channels, including those responsible for action potentials in rodent sciatic nerves. To examine α-subunits, we used seven μ-conotoxins, which target site 1 of the channel. With the use of exogenously expressed channels, we show that two of the μ-conotoxins, μ-BuIIIB and μ-SxIIIA, are 50-fold more potent in blocking NaV1.6 from mouse than that from rat. Furthermore, we observed that μ-BuIIIB and μ-SxIIIA are potent blockers of large, myelinated A-fiber compound action potentials (A-CAPs) [but not small, unmyelinated C-fiber CAPs (C-CAPs)] in the sciatic nerve of the mouse (unlike A-CAPs of the rat, previously shown to be insensitive to these toxins). To investigate β-subunits, we used two synthetic derivatives of the recently discovered μO§-conotoxin GVIIJ that define site 8 of the channel, as previously characterized with cloned rat NaV1- and NaVβ-subunits expressed in Xenopus laevis oocytes, where it was shown that μO§-GVIIJ is a potent inhibitor of several NaV1-isoforms and that coexpression of NaVβ2 or -β4 (but not NaVβ1 or -β3) totally protects against block by μO§-GVIIJ. We report here the effects of μO§-GVIIJ on 1) sodium currents of mouse NaV1.6 coexpressed with various combinations of NaVβ-subunits in oocytes; 2) A- and C-CAPs of mouse and rat sciatic nerves; and 3) sodium currents of small and large neurons dissociated from rat dorsal root ganglia. Our overall results lead us to conclude that action potentials in A-fibers of the rodent sciatic nerve are mediated primarily by NaV1.6 associated with NaVβ2 or NaVβ4.

Cloning of a putative voltage-gated sodium channel from the turbellarian flatworm Bdelloura candida

Parasitology ◽  
1997 ◽  
Vol 115 (3) ◽  
pp. 289-296 ◽  
Author(s):  
M. C. JEZIORSKI ◽  
R. M. GREENBERG ◽  
P. A. V. ANDERSON
Keyword(s):  
Sodium Channels ◽  
Northern Blot Analysis ◽  
Amino Acid Identity ◽  
Structure Characteristic ◽  
Sodium Currents ◽  
Voltage Gated ◽  
Transmembrane Segments ◽  
Voltage Gated Sodium Channels ◽  
Multidomain Structure ◽  
Insight Into

The neuromuscular sodium currents of early invertebrates such as platyhelminths display distinctive kinetic and pharmacological properties. We have cloned a cDNA from the horseshoe crab flatworm Bdelloura candida that encodes a protein homologous to the primary subunit of voltage-gated sodium channels. The B. candida protein, named BdNa1, exhibits amino acid identity of 40–47% to sodium channels of vertebrates and higher invertebrates. BdNa1 has the multidomain structure characteristic of sodium channels, and is most highly conserved in the hydrophobic transmembrane segments and the regions that form the pore of the channel. Northern blot analysis confirms the presence of a 5·4 kb BdNa1 transcript in B. candida tissue. The information provided by analysis of the BdNa1 sequence offers insight into the physiology of platyhelminth sodium currents.

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