scholarly journals Kv4 channels to kisspeptin neurons: ‘Let's (not) go steady’

2018 ◽  
Vol 596 (5) ◽  
pp. 757-758
Author(s):  
Richard Piet
Keyword(s):  
Kv4 Channels

scholarly journals A Dipeptidyl Aminopeptidase–like Protein Remodels Gating Charge Dynamics in Kv4.2 Channels

2006 ◽  
Vol 128 (6) ◽  
pp. 745-753 ◽  
Author(s):  
Kevin Dougherty ◽  
Manuel Covarrubias
Keyword(s):  
Membrane Potentials ◽  
Charge Movement ◽  
Transmembrane Segment ◽  
Gating Currents ◽  
Voltage Sensing ◽  
Charge Voltage ◽  
Charge Dynamics ◽  
Gating Charge ◽  
Kv4 Channels ◽  
Dipeptidyl Aminopeptidase

Dipeptidyl aminopeptidase–like proteins (DPLPs) interact with Kv4 channels and thereby induce a profound remodeling of activation and inactivation gating. DPLPs are constitutive components of the neuronal Kv4 channel complex, and recent observations have suggested the critical functional role of the single transmembrane segment of these proteins (Zagha, E., A. Ozaita, S.Y. Chang, M.S. Nadal, U. Lin, M.J. Saganich, T. McCormack, K.O. Akinsanya, S.Y. Qi, and B. Rudy. 2005. J. Biol. Chem. 280:18853–18861). However, the underlying mechanism of action is unknown. We hypothesized that a unique interaction between the Kv4.2 channel and a DPLP found in brain (DPPX-S) may remodel the channel's voltage-sensing domain. To test this hypothesis, we implemented a robust experimental system to measure Kv4.2 gating currents and study gating charge dynamics in the absence and presence of DPPX-S. The results demonstrated that coexpression of Kv4.2 and DPPX-S causes a −26 mV parallel shift in the gating charge-voltage (Q-V) relationship. This shift is associated with faster outward movements of the gating charge over a broad range of relevant membrane potentials and accelerated gating charge return upon repolarization. In sharp contrast, DPPX-S had no effect on gating charge movements of the Shaker B Kv channel. We propose that DPPX-S destabilizes resting and intermediate states in the voltage-dependent activation pathway, which promotes the outward gating charge movement. The remodeling of gating charge dynamics may involve specific protein–protein interactions of the DPPX-S's transmembrane segment with the voltage-sensing and pore domains of the Kv4.2 channel. This mechanism may determine the characteristic fast operation of neuronal Kv4 channels in the subthreshold range of membrane potentials.

Kv4 channels underlie A-currents with highly variable inactivation time courses but homogeneous other gating properties in the nucleus tractus solitarii

2014 ◽  
Vol 467 (4) ◽  
pp. 789-803 ◽  
Author(s):  
Caroline Strube ◽  
Layal Saliba ◽  
Estelle Moubarak ◽  
Virginie Penalba ◽  
Marie-France Martin-Eauclaire ◽  
...  
Keyword(s):  
Nucleus Tractus Solitarii ◽  
Kv4 Channels ◽  
Time Courses

Differential contribution of sialic acid to the function of repolarizing K+ currents in ventricular myocytes

2001 ◽  
Vol 281 (2) ◽  
pp. C464-C474 ◽  
Author(s):  
Carmen A. Ufret-Vincenty ◽  
Deborah J. Baro ◽  
L. F. Santana
Keyword(s):  
Sialic Acid ◽  
Voltage Dependence ◽  
Ventricular Myocytes ◽  
Chinese Hamster ◽  
Ovary Cell ◽  
Early Afterdepolarizations ◽  
Kv4 Channels ◽  
Ovary Cell Line ◽  
Differential Contribution ◽  
K Currents

We investigated the contribution of sialic acid residues to the K+ currents involved in the repolarization of mouse ventricular myocytes. Ventricular K+ currents had a rapidly inactivating component followed by slowly decaying and sustained components. This current was produced by the summation of three distinct currents: I to, which contributed to the transient component; I ss, which contributed to the sustained component; and I K,slow, which contributed to both components. Incubation of ventricular myocytes with the sialidase neuraminidase reduced the amplitude of I to without altering I K,slow and I ss. We found that the reduction in I to amplitude resulted from a depolarizing shift in the voltage of activation and a reduction in the conductance of I to. Expression of Kv4.3 channels, a major contributor to I to in the ventricle, in a sialylation-deficient Chinese hamster ovary cell line (lec2) mimicked the effects of neuraminidase on the ventricular I to. Furthermore, we showed that sialylated glycolipids have little effect on the voltage dependence of I to. Finally, consistent with its actions on I to, neuraminidase produced an increase in the duration of the action potential of ventricular myocytes and the frequency of early afterdepolarizations. We conclude that sialylation of the proteins forming Kv4 channels is important in determining the voltage dependence and conductance of I to and that incomplete glycosylation of these channels could lead to arrhythmias.

scholarly journals Shal/Kv4 Channels Are Required for Maintaining Excitability during Repetitive Firing and Normal Locomotion in Drosophila

PLoS ONE ◽  
2011 ◽  
Vol 6 (1) ◽  
pp. e16043 ◽  
Author(s):  
Yong Ping ◽  
Girma Waro ◽  
Ashley Licursi ◽  
Sarah Smith ◽  
Dai-An Vo-Ba ◽  
...  
Keyword(s):  
Repetitive Firing ◽  
Kv4 Channels

scholarly journals The Cytoplasmic N-Terminal Domain of DPP6K Disrupts KChiP Modulation of Kv4 Channels

2011 ◽  
Vol 100 (3) ◽  
pp. 98a ◽  
Author(s):  
Henry H. Jerng ◽  
Paul J. Pfaffinger
Keyword(s):  
Terminal Domain ◽  
Kv4 Channels

Role of S4 positively charged residues in the regulation of Kv4.3 inactivation and recovery

2007 ◽  
Vol 293 (3) ◽  
pp. C906-C914 ◽  
Author(s):  
Matthew R. Skerritt ◽  
Donald L. Campbell
Keyword(s):  
Positive Charge ◽  
Voltage Sensitivity ◽  
Shaker Channels ◽  
Recovery From Inactivation ◽  
Kv4 Channels ◽  
Charged Residues ◽  
Arginine Residues ◽  
Voltage Sensing Domain ◽  
Positively Charged

The molecular and biophysical mechanisms by which voltage-sensitive K+ (Kv)4 channels inactivate and recover from inactivation are presently unresolved. There is a general consensus, however, that Shaker-like N- and P/C-type mechanisms are likely not involved. Kv4 channels also display prominent inactivation from preactivated closed states [closed-state inactivation (CSI)], a process that appears to be absent in Shaker channels. As in Shaker channels, voltage sensitivity in Kv4 channels is thought to be conferred by positively charged residues localized to the fourth transmembrane segment (S4) of the voltage-sensing domain. To investigate the role of S4 positive charge in Kv4.3 gating transitions, we analyzed the effects of charge elimination at each positively charged arginine (R) residue by mutation to the uncharged residue alanine (A). We first demonstrated that R290A, R293A, R296A, and R302A mutants each alter basic activation characteristics consistent with positive charge removal. We then found strong evidence that recovery from inactivation is coupled to deactivation, showed that the precise location of the arginine residues within S4 plays an important role in the degree of development of CSI and recovery from CSI, and demonstrated that the development of CSI can be sequentially uncoupled from activation by R296A, specifically. Taken together, these results extend our current understanding of Kv4.3 gating transitions.

Modulation of Kv4 channels, key components of rat ventricular transient outward K+ current, by PKC

1997 ◽  
Vol 273 (4) ◽  
pp. H1775-H1786 ◽  
Author(s):  
Tomoe Y. Nakamura ◽  
William A. Coetzee ◽  
Eleazar Vega-Saenz De Miera ◽  
Michael Artman ◽  
Bernardo Rudy
Keyword(s):  
Outward Current ◽  
Current Evidence ◽  
Inactivation Kinetics ◽  
Transient Outward Current ◽  
Recovery From Inactivation ◽  
Kv4 Channels ◽  
K Current ◽  
Molecular Components ◽  
Kinetics Of ◽  
Pkc Activation

Current evidence suggests that members of the Kv4 subfamily may encode native cardiac transient outward current ( I to). Antisense hybrid-arrest with oligonucleotides targeted to Kv4 mRNAs specifically inhibited rat ventricular I to, supporting this hypothesis. To determine whether protein kinase C (PKC) affects I to by an action on these molecular components, we compared the effects of PKC activation on Kv4.2 and Kv4.3 currents expressed in Xenopus oocytes and rat ventricular I to. Phorbol 12-myristate 13-acetate (PMA) suppressed both Kv4.2 and Kv4.3 currents as well as native I to, but not after preincubation with PKC inhibitors (e.g., chelerythrine). An inactive stereoisomer of PMA had no effect. Phenylephrine or carbachol inhibited Kv4 currents only when coexpressed, respectively, with α1C-adrenergic or M1 muscarinic receptors (this inhibition was also prevented by chelerythrine). The voltage dependence and inactivation kinetics of Kv4.2 were unchanged by PKC, but small effects on the rates of inactivation and recovery from inactivation of native I to were observed. Thus Kv4.2 and Kv4.3 proteins are important subunits of native rat ventricular I to, and PKC appears to reduce this current by affecting the molecular components of the channels mediating I to.

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