scholarly journals Regulation of Voltage Gated K+ Channel KCNE1/KCNQ1 by the Janus Kinase JAK3

2015 ◽  
Vol 37 (6) ◽  
pp. 2476-2485
Author(s):  
Jamshed Warsi ◽  
Abeer Abousaab ◽  
Myriam Fezai ◽  
Bernat Elvira ◽  
Florian Lang
Keyword(s):  
Cell Membrane ◽  
Brefeldin A ◽  
Janus Kinase ◽  
K Channel ◽  
Wild Type ◽  
Protein Insertion ◽  
Voltage Gated ◽  
Electrode Voltage ◽  
Jak3 Inhibitor ◽  
The Difference

Background/Aims: Janus kinase 3 (JAK3), a kinase mainly expressed in hematopoietic cells, has been shown to down-regulate the Na+/K+ ATPase and participate in the regulation of several ion channels and carriers. Channels expressed in thymus and regulating the abundance of T lymphocytes include the voltage gated K+ channel KCNE1/KCNQ1. The present study explored whether JAK3 contributes to the regulation of KCNE1/KCNQ1. Methods: cRNA encoding KCNE1/KCNQ1 was injected into Xenopus oocytes with or without additional injection of cRNA encoding wild-type JAK3, constitutively active A568VJAK3, or inactive K851AJAK3. Voltage gated K+ channel activity was measured utilizing two electrode voltage clamp. Results: KCNE1/KCNQ1 activity was significantly increased by wild-type JAK3 and A568VJAK3, but not by K851AJAK3. The difference between oocytes expressing KCNE1/KCNQ1 alone and oocytes expressing KCNE1/KCNQ1 with A568VJAK3 was virtually abrogated by JAK3 inhibitor WHI-P154 (22 µM) but not by inhibition of transcription with actinomycin D (50 nM). Inhibition of KCNE1/KCNQ1 protein insertion into the cell membrane by brefeldin A (5 µM) resulted in a decline of the voltage gated current, which was similar in the absence and presence of A568VJAK3, suggesting that A568VJAK3 did not accelerate KCNE1/KCNQ1 protein retrieval from the cell membrane. Conclusion: JAK3 contributes to the regulation of membrane KCNE1/KCNQ1 activity, an effect sensitive to JAK3 inhibitor WHI-P154.

scholarly journals Regulation of Large Conductance Voltage-and Ca2+-Activated K+ Channels by the Janus Kinase JAK3

2015 ◽  
Vol 37 (1) ◽  
pp. 297-305 ◽  
Author(s):  
Jamshed Warsi ◽  
Yogesh Singh ◽  
Bernat Elvira ◽  
Zohreh Hosseinzadeh ◽  
Florian Lang
Keyword(s):  
Cell Proliferation ◽  
Cell Membrane ◽  
Bk Channel ◽  
Janus Kinase ◽  
Negative Regulator ◽  
K Channel ◽  
Protein Abundance ◽  
Wild Type ◽  
Protein Insertion ◽  
Channel Protein

Background/Aims: Janus kinase 3 (JAK3), a tyrosine kinase contributing to the regulation of cell proliferation and apoptosis of lymphocytes and tumour cells, has been shown to modify the expression and function of several ion channels and transport proteins. Channels involved in the regulation of cell proliferation include the large conductance voltage- and Ca2+-activated K+ channel BK. The present study explored whether JAK3 modifies BK channel protein abundance and current. Methods: cRNA encoding Ca2+-insensitive BK channel (BKM513I+Δ899-903) was injected into Xenopus oocytes with or without additional injection of cRNA encoding wild-type JAK3, constitutively active A568VJAK3, or inactive K851AJAK3. Voltage gated K+ channel activity was measured utilizing dual electrode voltage clamp. Moreover, BK channel protein abundance was determined utilizing flow cytometry in CD19+ B lymphocyte cell membranes from mice lacking functional JAK3 (jak3-/-) and corresponding wild-type mice (jak3+/+). Results: BK activity in BKM513I+Δ899-903 expressing oocytes was slightly but significantly decreased by coexpression of wild-type JAK3 and of A568VJAK3, but not by coexpression of K851AJAK3. The BK channel protein abundance in the cell membrane was significantly higher in jak3-/- than in jak3+/+ B lymphocytes. The decline of conductance in BK and JAK3 coexpressing oocytes following inhibition of channel protein insertion by brefeldin A (5 µM) was similar in oocytes expressing BK with JAK3 and oocytes expressing BK alone, indicating that JAK3 might slow channel protein insertion into rather than accelerating channel protein retrieval from the cell membrane. Conclusion: JAK3 is a weak negative regulator of membrane BK protein abundance and activity.

scholarly journals SGK3 Sensitivity of Voltage Gated K+ Channel Kv1.5 (KCNA5)

2016 ◽  
Vol 38 (1) ◽  
pp. 359-367 ◽  
Author(s):  
Musaab Ahmed ◽  
Myriam Fezai ◽  
Nestor L. Uzcategui ◽  
Zohreh Hosseinzadeh ◽  
Florian Lang
Keyword(s):  
Ubiquitin Ligase ◽  
Xenopus Oocytes ◽  
Cardiac Action Potential ◽  
K Channel ◽  
Channel Activity ◽  
Wild Type ◽  
Voltage Gated ◽  
Cardiac Action ◽  
Electrode Voltage ◽  
Potential Activity

Background: The serum & glucocorticoid inducible kinase isoform SGK3 is a powerful regulator of several transporters, ion channels and the Na+/K+ ATPase. Targets of SGK3 include the ubiquitin ligase Nedd4-2, which is in turn a known regulator of the voltage gated K+ channel Kv1.5 (KCNA5). The present study thus explored whether SGK3 modifies the activity of the voltage gated K+ channel KCNA5, which participates in the regulation of diverse functions including atrial cardiac action potential, activity of vascular smooth muscle cells, insulin release and tumour cell proliferation. Methods: cRNA encoding KCNA5 was injected into Xenopus oocytes with and without additional injection of cRNA encoding wild-type SGK3, constitutively active S419DSGK3, inactive K191NSGK3 and/or wild type Nedd4-2. Voltage gated K+ channel activity was quantified utilizing dual electrode voltage clamp. Results: Voltage gated current in KCNA5 expressing Xenopus oocytes was significantly enhanced by wild-type SGK3 and S419DSGK3, but not by K191NSGK3. SGK3 was effective in the presence of ouabain (1 mM) and thus did not require Na+/K+ ATPase activity. Coexpression of Nedd4-2 decreased the voltage gated current in KCNA5 expressing Xenopus oocytes, an effect largely reversed by additional coexpression of SGK3. Conclusion: SGK3 is a positive regulator of KCNA5, which is at least partially effective by abrogating the effect of Nedd4-2.

scholarly journals Up-Regulation of Voltage Gated K+ Channels Kv1.3 and Kv1.5 by Protein Kinase PKB/Akt

2015 ◽  
Vol 37 (6) ◽  
pp. 2454-2463 ◽  
Author(s):  
Jamshed Warsi ◽  
Myriam Fezai ◽  
Mireia Fores ◽  
Bernat Elvira ◽  
Florian Lang
Keyword(s):  
Cell Proliferation ◽  
Protein Kinase ◽  
Cell Membrane ◽  
Brefeldin A ◽  
Xenopus Laevis Oocytes ◽  
K Channels ◽  
Voltage Gated ◽  
Electrode Voltage ◽  
And Function ◽  
K Currents

Background: The voltage gated K+ channels Kv1.3 and Kv1.5 contribute to the orchestration of cell proliferation. Kinases participating in the regulation of cell proliferation include protein kinase B (PKB/Akt). The present study thus explored whether PKB/Akt modifies the abundance and function of Kv1.3 and Kv1.5. Methods: Kv1.3 or Kv1.5 was expressed in Xenopus laevis oocytes with or without wild-type PKB/Akt, constitutively active T308D/S473DPKB/Akt or inactive T308A/S473APKB/Akt. The channel activity was quantified utilizing dual electrode voltage clamp. Moreover, HA-tagged Kv1.5 protein was determined utilizing chemiluminescence. Results: Voltage gated K+ currents were observed in Kv1.3 or Kv1.5 expressing oocytes but not in water-injected oocytes or in oocytes expressing PKB/Akt alone. Co-expression of PKB/Akt or T308D/S473DPKB/Akt, but not co-expression of T308A/S473APKB/Akt significantly increased the voltage gated current in both Kv1.3 and Kv1.5 expressing oocytes. As shown for Kv1.5, co-expression of PKB/Akt enhanced the channel protein abundance in the cell membrane. In Kv1.5 expressing oocytes voltage gated current decreased following inhibition of carrier insertion by brefeldin A (5 µM) to similarly low values in the absence and presence of PKB/Akt, suggesting that PKB/Akt stimulated carrier insertion into rather than inhibiting carrier retrieval from the cell membrane. Conclusion: PKB/Akt up-regulates both, Kv1.3 and Kv1.5 K+ channels.

Upregulation of the large conductance voltage- and Ca2+-activated K+ channels by Janus kinase 2

2014 ◽  
Vol 306 (11) ◽  
pp. C1041-C1049 ◽  
Author(s):  
Zohreh Hosseinzadeh ◽  
Ahmad Almilaji ◽  
Sabina Honisch ◽  
Tatsiana Pakladok ◽  
GuoXing Liu ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Brefeldin A ◽  
Bk Channels ◽  
Bk Channel ◽  
Janus Kinase ◽  
Protein Abundance ◽  
Janus Kinase 2 ◽  
Channel Protein ◽  
Jak2 Inhibitor ◽  
Whole Cell Patch Clamp

The iberiotoxin-sensitive large conductance voltage- and Ca2+-activated potassium (BK) channels (maxi-K+-channels) hyperpolarize the cell membrane thus supporting Ca2+ entry through Ca2+-release activated Ca2+ channels. Janus kinase-2 (JAK2) has been identified as novel regulator of ion transport. To explore whether JAK2 participates in the regulation of BK channels, cRNA encoding Ca2+-insensitive BK channels (BKM513I+Δ899–903) was injected into Xenopus oocytes with or without cRNA encoding wild-type JAK2, gain-of-function V617FJAK2, or inactive K882EJAK2. K+ conductance was determined by dual electrode voltage clamp and BK-channel protein abundance by confocal microscopy. In A204 alveolar rhabdomyosarcoma cells, iberiotoxin-sensitive K+ current was determined utilizing whole cell patch clamp. A204 cells were further transfected with JAK2 and BK-channel transcript, and protein abundance was quantified by RT-PCR and Western blotting, respectively. As a result, the K+ current in BKM513I+Δ899–903-expressing oocytes was significantly increased following coexpression of JAK2 or V617FJAK2 but not K882EJAK2. Coexpression of the BK channel with V617FJAK2 but not K882EJAK2 enhanced BK-channel protein abundance in the oocyte cell membrane. Exposure of BK-channel and V617FJAK2-expressing oocytes to the JAK2 inhibitor AG490 (40 μM) significantly decreased K+ current. Inhibition of channel insertion by brefeldin A (5 μM) decreased the K+ current to a similar extent in oocytes expressing the BK channel alone and in oocytes expressing the BK channel and V617FJAK2. The iberiotoxin (50 nM)-sensitive K+ current in rhabdomyosarcoma cells was significantly decreased by AG490 pretreatment (40 μM, 12 h). Moreover, overexpression of JAK2 in A204 cells significantly enhanced BK channel mRNA and protein abundance. In conclusion, JAK2 upregulates BK channels by increasing channel protein abundance in the cell membrane.

Influence of cloned voltage-gated K+ channel expression on alanine transport, Rb+ uptake, and cell volume

1993 ◽  
Vol 265 (5) ◽  
pp. C1230-C1238 ◽  
Author(s):  
A. Felipe ◽  
D. J. Snyders ◽  
K. K. Deal ◽  
M. M. Tamkun
Keyword(s):  
Membrane Potential ◽  
Atpase Activity ◽  
Cell Volume ◽  
K Channel ◽  
Resting Membrane Potential ◽  
Wild Type ◽  
Transfected Cells ◽  
Voltage Gated ◽  
Alanine Transport ◽  
Channel Expression

Voltage-gated K+ channels are involved in regulation of action potential duration and in setting the resting membrane potential in nerve and muscle. To determine the effects of voltage-gated K+ channel expression on processes not associated with electrically excitable cells, we studied cell volume, membrane potential, Na(+)-K(+)-ATPase activity, and alanine transport after the stable expression of the Kv1.4 and Kv1.5 human K+ channels in Ltk- mouse fibroblasts (L-cells). The fast-activating noninactivating Kv1.5 channel, but not the rapidly inactivating Kv1.4 channel, prevented dexamethasone-induced increases in intracellular volume and inhibited Na(+)-K(+)-ATPase activity by 25%, as measured by 86Rb+ uptake. Alanine transport, measured separately by systems A and ASC, was lower in Kv1.5-expressing cells, indicating that the expression of this channel modified the Na(+)-dependent amino acid transport of both systems. Expression of the Kv1.4 channel did not alter alanine transport relative to wild-type or sham-transfected cells. The changes specific to Kv1.5 expression may be related to the resting membrane potential induced by this channel (-30 mV) in contrast to that measured in wild-type sham-transfected, or Kv1.4-transfected cells (-2 to 0 mV). Blocking of the Kv1.5 channel by 60 microM quinidine negated the effects of Kv1.5 expression on intracellular volume, Na(+)-K(+)-ATPase, and Na(+)-dependent alanine transport. These results indicate that delayed rectifier channels such as Kv1.5 can play a key role in the control of cell membrane potential, cell volume, Na(+)-K(+)-ATPase activity, and electrogenic alanine transport across the plasma membrane of electrically unexcitable cells.

Regulation of Voltage-Gated K+ Channel Kv1.5 by the Janus Kinase JAK3

2015 ◽  
Vol 248 (6) ◽  
pp. 1061-1070 ◽  
Author(s):  
Jamshed Warsi ◽  
Bernat Elvira ◽  
Rosi Bissinger ◽  
Zohreh Hosseinzadeh ◽  
Florian Lang
Keyword(s):  
Janus Kinase ◽  
K Channel ◽  
Voltage Gated

scholarly journals SPAK and OSR1 Sensitive Cell Membrane Protein Abundance and Activity of KCNQ1/E1 K+ Channels

2015 ◽  
Vol 37 (5) ◽  
pp. 2032-2042 ◽  
Author(s):  
Bernat Elvira ◽  
Jamshed Warsi ◽  
Myriam Fezai ◽  
Carlos Munoz ◽  
Florian Lang
Keyword(s):  
Cell Membrane ◽  
Cell Volume ◽  
Epithelial Transport ◽  
Cell Volume Regulation ◽  
K Channel ◽  
Protein Abundance ◽  
Wild Type ◽  
E1 Protein ◽  
Cell Membrane Protein ◽  
Constitutively Active

Background/Aims: KCNQ1/E1 channels are expressed in diverse tissues and serve a variety of functions including endolymph secretion in the inner ear, cardiac repolarization, epithelial transport and cell volume regulation. Kinases involved in regulation of epithelial transport and cell volume include SPAK (SPS1-related proline/alanine-rich kinase) and OSR1 (oxidative stress-responsive kinase 1), which are under control of WNK (with-no-K[Lys]) kinases. The present study explored whether KCNQ1/E1 channels are regulated by SPAK and/or OSR1. Methods: cRNA encoding KCNQ1/E1 was injected into Xenopus oocytes with or without additional injection of cRNA encoding wild-type SPAK, constitutively active T233ESPAK, WNK insensitive T233ASPAK, catalytically inactive D212ASPAK, wild-type OSR1, constitutively active T185EOSR1, WNK insensitive T185AOSR1 and catalytically inactive D164AOSR1. Voltage gated K+ channel activity was quantified utilizing dual electrode voltage clamp and KCNQ1/E1 channel protein abundance in the cell membrane utilizing chemiluminescence of KCNQ1/E1 containing an extracellular Flag tag epitope (KCNQ1-Flag/E1). Results: KCNQ1/E1 activity and KCNQ1-Flag/E1 protein abundance were significantly enhanced by wild-type SPAK and T233ESPAK, but not by T233ASPAK and D212ASPAK. Similarly, KCNQ1/E1 activity and KCNQ1-Flag/E1 protein abundance were significantly increased by wild-type OSR1 and T185EOSR1, but not by T185AOSR1 and D164AOSR1. Conclusions: SPAK and OSR1 participate in the regulation of KCNQ1/E1 protein abundance and activity.

Structural Influence of Hanatoxin Binding on the Carboxyl Terminus of S3 Segment in Voltage-Gated K + -Channel Kv2.1

2002 ◽  
Vol 8 (2) ◽  
pp. 79-85 ◽  
Author(s):  
P. T. Huang ◽  
T. Y. Chen ◽  
L. J. Tseng ◽  
K. L. Lou ◽  
H. H. Liou ◽  
...  
Keyword(s):  
Carboxyl Terminus ◽  
K Channel ◽  
Voltage Gated ◽  
S3 Segment ◽  
Structural Influence

scholarly journals Distribution and Severity of Placental Lesions Caused by the Chlamydia abortus 1B Vaccine Strain in Vaccinated Ewes

Pathogens ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 543
Author(s):  
Sergio Gastón Caspe ◽  
Javier Palarea-Albaladejo ◽  
Clare Underwood ◽  
Morag Livingstone ◽  
Sean Ranjan Wattegedera ◽  
...  
Keyword(s):  
Disease Outbreaks ◽  
Principal Component ◽  
Placental Pathology ◽  
Wild Type ◽  
Cell Infiltrate ◽  
Chlamydia Abortus ◽  
Vaccine Type ◽  
The Difference ◽  
Enzootic Abortion Of Ewes

Chlamydia abortus infects livestock species worldwide and is the cause of enzootic abortion of ewes (EAE). In Europe, control of the disease is achieved using a live vaccine based on C. abortus 1B strain. Although the vaccine has been useful for controlling disease outbreaks, abortion events due to the vaccine have been reported. Recently, placental pathology resulting from a vaccine type strain (vt) infection has been reported and shown to be similar to that resulting from a natural wild-type (wt) infection. The aim of this study was to extend these observations by comparing the distribution and severity of the lesions, the composition of the predominating cell infiltrate, the amount of bacteria present and the role of the blood supply in infection. A novel system for grading the histological and pathological features present was developed and the resulting multi-parameter data were statistically transformed for exploration and visualisation through a tailored principal component analysis (PCA) to evaluate the difference between them. The analysis provided no evidence of meaningful differences between vt and wt strains in terms of the measured pathological parameters. The study also contributes a novel methodology for analysing the progression of infection in the placenta for other abortifacient pathogens.

TNF-α inhibits the CD3-mediated upregulation of voltage-gated K+ channel (Kv1.3) in human T cells

2010 ◽  
Vol 391 (1) ◽  
pp. 909-914 ◽  
Author(s):  
Bo Pang ◽  
Haifeng Zheng ◽  
Dong Hoon Shin ◽  
Kyeong Cheon Jung ◽  
Jae Hong Ko ◽  
...  
Keyword(s):  
T Cells ◽  
K Channel ◽  
Voltage Gated ◽  
Human T Cells ◽  
Tnf Α
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