Tyrosine-protein kinase Src regulates Kv1.5 channel activity and membrane expression through interaction with the N-terminus of the channel

2020 ◽  
Author(s):  
Taylore Dodd ◽  
Tingzhong Wang ◽  
Shetuan Zhang
Keyword(s):  
Protein Kinase ◽  
Cell Voltage ◽  
Underlying Mechanism ◽  
Delayed Rectifier ◽  
Binding Motif ◽  
Membrane Expression ◽  
Binding Motifs ◽  
Delayed Rectifier Potassium Current ◽  
N Terminus ◽  
Tyrosine Protein Kinase

Kv1.5 is a voltage-gated potassium channel that generates the ultra-rapid delayed rectifier potassium current (IKur) important in the repolarization of the atrial action potential. Malfunction of the Kv1.5 channel often results in atrial fibrillation (AFib). A reduction in Kv1.5 current (IKv1.5) occurs upon activation of the endogenous tyrosine-protein kinase Src. The Src SH3 domain binds to proline-rich motifs located within the N-terminus of Kv1.5. Disruption of these binding motifs has been involved in the development of familial AFib. The mechanism underlying the reduction of IKv1.5 upon Src activation has not yet been established and the relationship between Kv1.5 and Src is poorly understood. Therefore, the present study aims to further elucidate the mechanism behind IKv1.5  reduction. The hypothesis that Src regulates Kv1.5 activity by altering the density of mature membrane-localized channels was tested using whole-cell voltage clamp and Western blot analysis. We demonstrate that Src tonically inhibits Kv1.5 activity and decreases the density of mature membrane-localized channels. Kv1.5 channels possessing mutations within the Src binding motifs were also investigated and it was determined that each binding motif contributes to the Kv1.5-Src relationship, however, the binding of Src to an individual motif is sufficiently effective. Our findings indicate that Src regulates Kv1.5 through an interaction with the N-terminal binding motifs and suggests that the inhibition of forward trafficking may be involved in the underlying mechanism. (Supported by the Heart and Stroke foundation of Canada and The Canadian Institutes of Health Research).

scholarly journals P938Regulation of the delayed rectifier potassium current during the adrenergic adaptation of cardiomyocytes

EP Europace ◽  
2020 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
D Kiss ◽  
T Hezso ◽  
B Kurtan ◽  
R Veress ◽  
D Baranyai ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Potassium Current ◽  
Slow Component ◽  
Delayed Rectifier ◽  
Total Charge ◽  
Current Profile ◽  
Calcium Calmodulin Dependent ◽  
Delayed Rectifier Potassium Current ◽  
Innovation And Technology ◽  
Dependent Protein

Abstract Funding Acknowledgements Supported by the ÚNKP-19-3 New National Excellence program of the Ministry for Innovation and Technology Introduction and aims Adaptation of the human heart to physical activity is a complex mechanism that includes the change of heart rate, morphology of the action potential (AP) among others. Stimulation of β-adrenergic receptors (β-AR) causes the shortening of the AP duration of ventricular cardiomyocytes. This is caused by the regulation of the potassium currents by the β-adrenergic signaling pathway. Our aim was to investigate the role of protein kinase A (PKA) and calcium/calmodulin-dependent protein kinase II (CaMKII) in the regulation of the slow component (IKs) of the delayed rectifier potassium current under β-AR activation. Methods Our experiments were performed on isolated canine cardiomyocytes from the left ventricle. The IKs current profile was determined under a ventricular AP. We used "AP voltage clamp" conditions in six experimental groups: Control (CTRL), β-AR stimulation with isoproterenol (ISO), CaMKII inhibition with KN-93 (KN-93), PKA inhibition with H-89 (H-89) β-AR stimulation with inhibited CaMKII (KN-93 + ISO), β-AR stimulation with inhibited PKA (H-89 + ISO). β-AR stimulation with inhibited CaMKII and PKA (KN-93 + H-89 + ISO) Results The highest current density of IKs was approximately 6 times higher and the charge delivered by IKs was about 8 times larger in the ISO group than in CTRL or KN-93 conditions. In the KN-93 + ISO group, IKs amplitude was about 60% smaller and delivered about half the total charge compared to the ISO group. In the H‑89 + ISO group, IKs was about 30% smaller and delivered 40% less total charge than in the ISO group. In the KN-93 + H-89 + ISO group the IKs did not changed sicnificantly. Conclusion Based on our results, CaMKII plays an important role in regulating IKs by β-AR stimulation.

Intracellular Ca2+ and protein kinase C modulate K+ current in guinea pig heart cells

1987 ◽  
Vol 253 (5) ◽  
pp. H1321-H1324 ◽  
Author(s):  
N. Tohse ◽  
M. Kameyama ◽  
H. Irisawa
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Guinea Pig ◽  
Cell Voltage ◽  
Delayed Rectifier ◽  
Heart Cells ◽  
Guinea Pig Heart ◽  
Kinase C ◽  
Ventricular Cells ◽  
K Current

Effects of protein kinase C (PKC) and intracellular calcium ion (Cai2+) on the delayed rectifier K+ current (IK) were investigated in the single ventricular cells of guinea pig by use of an internal-dialysis method and a whole cell voltage-clamp technique. 12-O-tetradecanoylphorbol-13-acetate (TPA, 10(-9) M), an activator of PKC, increased the amplitude of IK in the presence of Cai2+ higher than 10(-10) M. This effect of TPA was mimicked by a synthetic diacylglycerol, 1-oleoyl-2-acetylglycerol (OAG), 50 micrograms/ml, 125 microM, and was blocked by 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (10 microM). The above findings suggest that IK channels were phosphorylated by PKC and thereby the amplitude of IK was increased. IK was also increased by elevating the concentration of Cai2+ in the absence of TPA. It is thus indicated that IK channels are modulated by Cai2+ not only through activation of PKC but also directly. Our observation may provide a possible mechanism by which Cai2+ mediates the link between the Ca2+ transients during contraction and the action potential duration.

scholarly journals Nicotine inhibits potassium currents in Aplysia bag cell neurons

2016 ◽  
Vol 115 (5) ◽  
pp. 2635-2648 ◽  
Author(s):  
Sean H. White ◽  
Raymond M. Sturgeon ◽  
Neil S. Magoski
Keyword(s):  
Membrane Conductance ◽  
Cell Voltage ◽  
Underlying Mechanism ◽  
Resting Membrane Potential ◽  
Delayed Rectifier ◽  
Current Response ◽  
Induced Current ◽  
Ionotropic Receptors ◽  
Transient Activation ◽  
Bag Cell Neurons

Acetylcholine and the archetypal cholinergic agonist, nicotine, are typically associated with the opening of ionotropic receptors. In the bag cell neurons, which govern the reproductive behavior of the marine snail, Aplysia californica, there are two cholinergic responses: a relatively large acetylcholine-induced current and a relatively small nicotine-induced current. Both currents are readily apparent at resting membrane potential and result from the opening of distinct ionotropic receptors. We now report a separate current response elicited by applying nicotine to cultured bag cell neurons under whole cell voltage-clamp. This current was ostensibly inward, best resolved at depolarized voltages, presented a noncooperative dose-response with a half-maximal concentration near 1.5 mM, and associated with a decrease in membrane conductance. The unique nicotine-evoked response was not altered by intracellular perfusion with the G protein blocker GDPβS or exposure to classical nicotinic antagonists but was occluded by replacing intracellular K+ with Cs+. Consistent with an underlying mechanism of direct inhibition of one or more K+ channels, nicotine was found to rapidly reduce the fast-inactivating A-type K+ current as well as both components of the delayed-rectifier K+ current. Finally, nicotine increased bag cell neuron excitability, which manifested as reduction in spike threshold, greater action potential height and width, and markedly more spiking to continuous depolarizing current injection. In contrast to conventional transient activation of nicotinic ionotropic receptors, block of K+ channels could represent a nonstandard means for nicotine to profoundly alter the electrical properties of neurons over prolonged periods of time.

scholarly journals SNX27-FERM-SNX1 complex structure rationalizes divergent trafficking pathways by SNX17 and SNX27

2021 ◽  
Vol 118 (36) ◽  
pp. e2105510118
Author(s):  
Xin Yong ◽  
Lin Zhao ◽  
Wenfeng Hu ◽  
Qingxiang Sun ◽  
Hyoungjun Ham ◽  
...  
Keyword(s):  
Complex Structure ◽  
Pdz Domain ◽  
Underlying Mechanism ◽  
Endocytic Recycling ◽  
Ferm Domain ◽  
Binding Motifs ◽  
Molecular Events ◽  
N Terminus ◽  
Cargo Proteins ◽  
Positively Charged

The molecular events that determine the recycling versus degradation fates of internalized membrane proteins remain poorly understood. Two of the three members of the SNX-FERM family, SNX17 and SNX31, utilize their FERM domain to mediate endocytic trafficking of cargo proteins harboring the NPxY/NxxY motif. In contrast, SNX27 does not recycle NPxY/NxxY-containing cargo but instead recycles cargo containing PDZ-binding motifs via its PDZ domain. The underlying mechanism governing this divergence in FERM domain binding is poorly understood. Here, we report that the FERM domain of SNX27 is functionally distinct from SNX17 and interacts with a novel DLF motif localized within the N terminus of SNX1/2 instead of the NPxY/NxxY motif in cargo proteins. The SNX27-FERM-SNX1 complex structure reveals that the DLF motif of SNX1 binds to a hydrophobic cave surrounded by positively charged residues on the surface of SNX27. The interaction between SNX27 and SNX1/2 is critical for efficient SNX27 recruitment to endosomes and endocytic recycling of multiple cargoes. Finally, we show that the interaction between SNX27 and SNX1/2 is critical for brain development in zebrafish. Altogether, our study solves a long-standing puzzle in the field and suggests that SNX27 and SNX17 mediate endocytic recycling through fundamentally distinct mechanisms.

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