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.

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.

A Requirement for K+-Channel Activity in Growth Factor–Mediated Extracellular Signal-Regulated Kinase Activation in Human Myeloblastic Leukemia ML-1 Cells

Blood ◽  
1999 ◽  
Vol 94 (1) ◽  
pp. 139-145 ◽  
Author(s):  
Dazhong Xu ◽  
Ling Wang ◽  
Wei Dai ◽  
Luo Lu
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Growth Factor ◽  
Protein Kinase ◽  
K Channel ◽  
Serum Starvation ◽  
Channel Activity ◽  
K Channels ◽  
Voltage Gated ◽  
Extracellular Signal

Voltage-gated K+ channels have been shown to be required for proliferation of various types of cells. Much evidence indicates that K+-channel activity is required for G1 progression of the cell cycle in different cell backgrounds, suggesting that K+-channel activity is required for early-stage cell proliferation in these cells. However, little is known about the molecular mechanisms that underlie this phenomenon. We have shown in human myeloblastic leukemia ML-1 cells that K+ channels are activated by epidermal growth factor (EGF), whereas serum starvation deprivation suppressed their activity. In addition, voltage-gated K+ channels are required for G1/S-phase transition of the cell cycle. We report here that suppression of K+ channels prevented the activation of extracellular signal-regulated protein kinase 2 (ERK-2) in response to EGF and serum. However, blockade of K+ channels did not prevent ERK-2 activation induced by 12-O-tetradecanoyl-phorbol 13-acetate (TPA). Elimination of extracellular Ca2+ did not alter either ERK-2 activation or the effect of K+-channel blockade on ERK-2 activation. Our data demonstrate that the K+ channel is a part of the EGF-mediated mitogenic signal-transduction process and is required for initiation of the EGF-mediated mitogen-activated protein kinase (MAPK) pathways. Our findings may thus explain why an increase in K+-channel activity is associated with cell proliferation in many types of cells, including ML-1 cells.

scholarly journals Cell membrane changes of structure and function in protein kinase inhibitor‐induced polyploid cells

2000 ◽  
Vol 33 (1) ◽  
pp. 29-38 ◽  
Author(s):  
Z. P. Zong ◽  
K. Fujikawa‐Yamamoto ◽  
A. L. Li ◽  
N. Yamaguchi ◽  
Y. G. Chang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cell Membrane ◽  
Kinase Inhibitor ◽  
Structure And Function ◽  
Protein Kinase Inhibitor ◽  
Polyploid Cells ◽  
Membrane Changes ◽  
And Function

Fatty acid modulation of K+ channels in taste receptor cells: gustatory cues for dietary fat

1997 ◽  
Vol 272 (4) ◽  
pp. C1203-C1210 ◽  
Author(s):  
T. A. Gilbertson ◽  
D. T. Fontenot ◽  
L. Liu ◽  
H. Zhang ◽  
W. T. Monroe
Keyword(s):  
Fatty Acids ◽  
Protein Kinase ◽  
Oral Cavity ◽  
Polyunsaturated Fatty Acids ◽  
Taste Receptor ◽  
K Channels ◽  
Receptor Cells ◽  
Associated Proteins ◽  
Taste Receptor Cells ◽  
K Currents

In an attempt to determine the chemosensory cues, if any, provided by fats in the oral cavity, we have performed patch-clamp recordings on isolated rat taste receptor cells during application of free fatty acids. Cis-polyunsaturated fatty acids, when applied extracellularly, inhibit delayed-rectifying K+ channels. In a subset of cells, these fatty acids also enhance inwardly rectifying K+ currents. Saturated, monounsaturated, and trans-polyunsaturated fatty acids have no significant effect on K+ currents. These effects do not involve activation of G protein-mediated pathways, including protein kinase C and protein kinase A, lipoxygenase pathways, cyclooxygenase pathways, or cytochrome P-450 pathways, consistent with direct effects on these ion channels or closely associated proteins. The net effect of fatty acids is to prolong stimulus-induced depolarizations of taste receptor cells, and we propose the effects on K+ channels represent the mechanism by which fats are detected by receptor cells in the oral cavity.

scholarly journals Coating nanofiber scaffolds with beta cell membrane to promote cell proliferation and function

Nanoscale ◽  
2016 ◽  
Vol 8 (19) ◽  
pp. 10364-10370 ◽  
Author(s):  
Wansong Chen ◽  
Qiangzhe Zhang ◽  
Brian T. Luk ◽  
Ronnie H. Fang ◽  
Younian Liu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Membrane ◽  
Beta Cell ◽  
Promote Cell Proliferation ◽  
Nanofiber Scaffolds ◽  
And Function

scholarly journals Reduction in Voltage-Gated K+ Currents in Primary Cultured Rat Pancreatic β-Cells by Linoleic Acids

Endocrinology ◽  
2006 ◽  
Vol 147 (2) ◽  
pp. 674-682 ◽  
Author(s):  
Dan Dan Feng ◽  
Ziqiang Luo ◽  
Sang-gun Roh ◽  
Maria Hernandez ◽  
Neveen Tawadros ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Linoleic Acid ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Voltage Gated ◽  
K Current ◽  
K Currents ◽  
Kinase A

Free fatty acids (FFAs), in addition to glucose, have been shown to stimulate insulin release through the G protein-coupled receptor (GPCR)40 receptor in pancreatic β-cells. Intracellular free calcium concentration ([Ca2+]i) in β-cells is elevated by FFAs, although the mechanism underlying the [Ca2+]i increase is still unknown. In this study, we investigated the action of linoleic acid on voltage-gated K+ currents. Nystatin-perforated recordings were performed on identified rat β-cells. In the presence of nifedipine, tetrodotoxin, and tolbutamide, voltage-gated K+ currents were observed. The transient current represents less than 5%, whereas the delayed rectifier current comprises more than 95%, of the total K+ currents. A long-chain unsaturated FFA, linoleic acid (10 μm), reversibly decreased the amplitude of K+ currents (to less than 10%). This reduction was abolished by the cAMP/protein kinase A system inhibitors H89 (1 μm) and Rp-cAMP (10 μm) but was not affected by protein kinase C inhibitor. In addition, forskolin and 8′-bromo-cAMP induced a similar reduction in the K+ current as that evoked by linoleic acid. Insulin secretion and cAMP accumulation in β-cells were also increased by linoleic acid. Methyl linoleate, which has a similar structure to linoleic acid but no binding affinity to GPR40, did not change K+ currents. Treatment of cultured cells with GPR40-specific small interfering RNA significantly reduced the decrease in K+ current induced by linoleic acid, whereas the cAMP-induced reduction of K+ current was not affected. We conclude that linoleic acid reduces the voltage-gated K+ current in rat β-cells through GPR40 and the cAMP-protein kinase A system, leading to an increase in [Ca2+]i and insulin secretion.

scholarly journals Expression and function of potassium channels in the human placental vasculature

2006 ◽  
Vol 291 (2) ◽  
pp. R437-R446 ◽  
Author(s):  
Mark Wareing ◽  
Xilian Bai ◽  
Fella Seghier ◽  
Claire M. Turner ◽  
Susan L. Greenwood ◽  
...  
Keyword(s):  
Vascular Function ◽  
Vascular Reactivity ◽  
Muscle Tone ◽  
K Channel ◽  
K Channels ◽  
Voltage Gated ◽  
Chorionic Plate ◽  
And Function ◽  
Vascular Smooth Muscle Tone ◽  
Arteries And Veins

In the placental vasculature, where oxygenation may be an important regulator of vascular reactivity, there is a paucity of data on the expression of potassium (K) channels, which are important mediators of vascular smooth muscle tone. We therefore addressed the expression and function of several K channel subtypes in human placentas. The expression of voltage-gated (Kv)2.1, KV9.3, large-conductance Ca2+-activated K channel (BKCa), inward-rectified K+ channel (KIR)6.1, and two-pore domain inwardly rectifying potassium channel-related acid-sensitive K channels (TASK)1 in chorionic plate arteries, veins, and placental homogenate was assessed by RT-PCR and Western blot analysis. Functional activity of K channels was assessed pharmacologically in small chorionic plate arteries and veins by wire myography using 4-aminopyridine, iberiotoxin, pinacidil, and anandamide. Experiments were performed at 20, 7, and 2% oxygen to assess the effect of oxygenation on the efficacy of K channel modulators. KV2.1, KV9.3, BKCa, KIR6.1, and TASK1 channels were all demonstrated to be expressed at the message level. KV2.1, BKCa, KIR6.1, and TASK1 were all demonstrated at the protein level. Pharmacological manipulation of voltage-gated and ATP-sensitive channels produced the most marked modifications in vascular tone, in both arteries and veins. We conclude that K channels play an important role in controlling placental vascular function.

Impaired Function and Expression of Endothelial Small Ca 2+ -Activated K Channels (SK3) in Reendothelialized Carotid Arteries After Balloon Catheter Injury (BCI)

Hypertension ◽  
2000 ◽  
Vol 36 (suppl_1) ◽  
pp. 707-707
Author(s):  
Ralf Koehler ◽  
Robert Real ◽  
Christiane Degenhardt ◽  
Meike Kuehn ◽  
Hans-Dieter Orzechowski ◽  
...  
Keyword(s):  
Endothelial Function ◽  
Balloon Catheter ◽  
Sprague Dawley ◽  
Subsequent Formation ◽  
K Channels ◽  
Vasoactive Factors ◽  
The Right ◽  
And Function ◽  
Balloon Catheter Injury ◽  
K Currents

P80 Ca 2+ -activated K channels (K Ca ) play an important role in endothelial function by controlling the electrochemical driving force for Ca 2+ influx and subsequent formation of vasoactive factors like NO and EDHF. An altered endothelial function have been suggested to be present in reendothelialized arteries after balloon catheter injury (BCI). We compared expression and function of endothelial rSK3 in reendothelialized carotid artery (CA) after BCI and not injured contralateral CA (CON) by using single-cell RT-PCR and patch-clamp (PC) techniques. Male Sprague-Dawley rats underwent BCI of the right CA. After 6 weeks, neointima formation and reendothelialization were confirmed by morphological analysis. Single endothelial cells (EC) were directly harvested from the luminal wall with the patch pipette. cDNA of rSK3 was amplified along with cDNA of endothelial nitric oxide synthase (rNOSIII), an EC marker. The percentage of rNOSIII + -samples was not different between CON (84% ± 10) and injured CA (84% ± 6). Expression of rSK3 was detected in 50% ± 10 of rNOSIII + -EC from CON. From injured CA, expression of rSK3 was detected in only 3% ± 3 of NOSIII + -EC (P<0.05). In whole-cell PC experiments in EC from CON, cell dialysis with Ca 2+ induced K currents, which were sensitive to apamin, a blocker of SK3. In contrast, in EC from injured CA, cell dialysis with Ca 2+ did not activate K currents. In current-clamp PC measurements of EC membrane potential (Vm) of CON, acetylcholine (ACh) induced a sustained and apamin-sensitive hyperpolarization from a resting Vm of -19 ± 5 mV to 40 ± 13 mV (ΔVm -19 ± 7 mV). In injured CA, an ACh-induced hyperpolarization was not observed (-22 ± 7 mV, ΔVm 0 ± 1 mV). Resting Vm (22 ± 6 mV) was not different. In conclusion, the deficient expression of K Ca in reendothelialized injured CA abolishes endothelial hyperpolarization in response to humoral stimulation. The defective hyperpolarization presumably leads to a decreased Ca 2+ influx and subsequent synthesis of vasoactive factors. This might indicate a diminished function of the newly formed endothelium in CA after BCI.

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