Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
PLoS One
2016 May 23;115:e0156181. doi: 10.1371/journal.pone.0156181.
Show Gene links
Show Anatomy links
Inhibition of Cardiac Kir Current (IK1) by Protein Kinase C Critically Depends on PKCβ and Kir2.2.
Scherer D
,
Seyler C
,
Xynogalos P
,
Scholz EP
,
Thomas D
,
Backs J
,
Andrassy M
,
Völkers M
,
Karle CA
,
Katus HA
,
Zitron E
.
???displayArticle.abstract???
Cardiac inwardly rectifying Kir current (IK1) mediates terminal repolarisation and is critical for the stabilization of the diastolic membrane potential. Its predominant molecular basis in mammalian ventricle is heterotetrameric assembly of Kir2.1 and Kir2.2 channel subunits. It has been shown that PKC inhibition of IK1 promotes focal ventricular ectopy. However, the underlying molecular mechanism has not been fully elucidated to date. In the Xenopus oocyte expression system, we observed a pronounced PKC-induced inhibition of Kir2.2 but not Kir2.1 currents. The PKC regulation of Kir2.2 could be reproduced by an activator of conventional PKC isoforms and antagonized by pharmacological inhibition of PKCβ. In isolated ventricular cardiomyocytes (rat, mouse), pharmacological activation of conventional PKC isoforms induced a pronounced inhibition of IK1. The PKC effect in rat ventricular cardiomyocytes was markedly attenuated following co-application of a small molecule inhibitor of PKCβ. Underlining the critical role of PKCβ, the PKC-induced inhibition of IK1 was absent in homozygous PKCβ knockout-mice. After heterologous expression of Kir2.1-Kir2.2 concatemers in Xenopus oocytes, heteromeric Kir2.1/Kir2.2 currents were also inhibited following activation of PKC. We conclude that inhibition of cardiac IK1 by PKC critically depends on the PKCβ isoform and Kir2.2 subunits. This regulation represents a potential novel target for the antiarrhythmic therapy of focal ventricular arrhythmias.
???displayArticle.pubmedLink???
27214373
???displayArticle.pmcLink???PMC4877014 ???displayArticle.link???PLoS One
Fig 1. Effects of different protein kinase C activators on Kir2.1 and Kir2.2 currents indicate a pronounced inhibitory regulation of Kir2.2 by conventional PKC isoforms with a predominant role of PKCβ.Representative recordings of Kir2.1 currents before and after superfusion with PMA (1 μmol/l) for 30 minutes (A-B). Corresponding IV-curves (C). Typical recording of Kir2.2 currents under control conditions (D), after superfusion with PMA (1 μmol/l) for 30 minutes (E) and corresponding IV-curves (F). (G) Summary data of the experiments with different PKC activators is shown for Kir2.1. (H) Summary data of the experiments with different PKC activators and co-applied PKCβ inhibitor is shown for Kir2.2. * indicates statistically significant difference to control experiments. These data point to a pronounced inhibitory regulation of Kir2.2 currents by PKC that predominantly depends on conventional PKC isoforms with a crucial role of PKCβ. In contrast, the moderate inhibition of Kir2.1 channels by PMA is likely to be independent of PKC signalling pathways. Protocol: holding potential -80 mV; test pulses from -120 mV to +40 mV in 10 mV-increments (400 ms).
Fig 2. Application of a small-molecule PKCβ inhibitor abolishes the inhibitory effect of thymeleatoxin on IK1 in rat ventricular cardiomyocytes.Whole-cell patch-clamp experiments with isolated rat ventricular cardiomyocytes were performed using thymeleatoxin (TMTX 100 nmol/l) as PKC activator. A typical experiment is displayed in panels (A–C). Panel (D) shows the time course of effect. BaCl2, applied at the end of the observation period induced only a slight further current inhibition, i.e. about 84% of barium-sensitive currents had been inhibited by TMTX before. Currents remained nearly unaltered when the PKCβ inhibitor (3 μmol/l) was co-applied with TMTX (E). Subsequent application of BaCl2 to the bath at the end of the observation period lead to a fast block of inward currents. (F) Summary data of all experiments in rat ventricular cardiomyocytes. Protocol: holding potential -80 mV; test pulses from -130 mV to -80 mV in 10 mV-increments (200 ms). * indicates statistical significance.
Fig 3. In homozygous PKCβ-knockout mice the ventricular IK1 is not inhibited after PKC activation with thymeleatoxin.Isolated ventricular cardiomyocytes from wild type (A-C) and PKCβ-knockout mice (D-F) were examined using the whole-cell patch-clamp configuration. Thymeleatoxin (TMTX; 100 nmol/l) was used for PKC activation. The same voltage protocol as in the experiments with rat ventricular cardiomyocytes was used. (G-H) Summary data from the experiments using cardiomyocytes from wild type and PKCβ-knockout mice. BaCl2 induced a rapid inhibition of inward currents in PKCβ-knockout mice but not in wild type mice, pointing to a nearly absent PKC regulation of IK1 in PKCβ-knockout mice. * indicates statistical significance.
Fig 4. Heteromeric Kir2.1/Kir2.2 channels are inhibited by protein kinase C.Heteromeric Kir2.1/Kir2.2 channels were expressed as concatemers according to Preisig-Müller et al. (2002) [3]. (A-C) A representative experiment and corresponding IV-curves. (D) Summary data of relative currents upon activation of PKC by thymeleatoxin (TMTX; 100 nmol/l) compared to measurements of Kir2.1/Kir2.2 heteromeric channels under control conditions. * indicates statistical significance.
Fig 5. The functional PKC consensus sites S64 and T353 are lacking in Kir2.1 channels.(A) Alignment of the amino acid sequence of Kir2.1 and Kir2.2. Interestingly, in Kir2.1 channels, the PKC consensus sites S64 and T353 which have been shown to be functionally relevant are lacking. (B) Schematic picture of a Kir2.2 channel subunit with the suggested locations of the PKC phosphorylation sites.
Adibhatla,
Tricyclodecan-9-yl-xanthogenate (D609) mechanism of actions: a mini-review of literature.
2012, Pubmed
Adibhatla,
Tricyclodecan-9-yl-xanthogenate (D609) mechanism of actions: a mini-review of literature.
2012,
Pubmed
Becker,
Ventricular arrhythmias induced by endothelin-1 or by acute ischemia: a comparative analysis using three-dimensional mapping.
2000,
Pubmed
Beuckelmann,
Alterations of K+ currents in isolated human ventricular myocytes from patients with terminal heart failure.
1993,
Pubmed
Bowman,
Expression of protein kinase C beta in the heart causes hypertrophy in adult mice and sudden death in neonates.
1997,
Pubmed
Dhamoon,
Unique Kir2.x properties determine regional and species differences in the cardiac inward rectifier K+ current.
2004,
Pubmed
Fakler,
Kir2.1 inward rectifier K+ channels are regulated independently by protein kinases and ATP hydrolysis.
1994,
Pubmed
,
Xenbase
Hardie,
In vivo light-induced and basal phospholipase C activity in Drosophila photoreceptors measured with genetically targeted phosphatidylinositol 4,5-bisphosphate-sensitive ion channels (Kir2.1).
2004,
Pubmed
Henry,
Protein kinase C inhibition of cloned inward rectifier (HRK1/KIR2.3) K+ channels expressed in Xenopus oocytes.
1996,
Pubmed
,
Xenbase
Janse,
Electrophysiological changes in heart failure and their relationship to arrhythmogenesis.
2004,
Pubmed
Karle,
Human cardiac inwardly-rectifying K+ channel Kir(2.1b) is inhibited by direct protein kinase C-dependent regulation in human isolated cardiomyocytes and in an expression system.
2002,
Pubmed
,
Xenbase
Kiesecker,
Regulation of cardiac inwardly rectifying potassium current IK1 and Kir2.x channels by endothelin-1.
2006,
Pubmed
,
Xenbase
Kong,
PKCbeta modulates ischemia-reperfusion injury in the heart.
2008,
Pubmed
Kääb,
Ionic mechanism of action potential prolongation in ventricular myocytes from dogs with pacing-induced heart failure.
1996,
Pubmed
Litosch,
Phosphatidic acid potentiates G(alpha)q stimulation of phospholipase C-beta1 signaling.
2009,
Pubmed
Lopatin,
Inward rectifiers in the heart: an update on I(K1).
2001,
Pubmed
Maeno-Hikichi,
A PKC epsilon-ENH-channel complex specifically modulates N-type Ca2+ channels.
2003,
Pubmed
,
Xenbase
Nattel,
Arrhythmogenic ion-channel remodeling in the heart: heart failure, myocardial infarction, and atrial fibrillation.
2007,
Pubmed
O'Connell,
Isolation and culture of adult mouse cardiac myocytes.
2007,
Pubmed
Ohoka,
Regulation of thymocyte lineage commitment by the level of classical protein kinase C activity.
1997,
Pubmed
Pogwizd,
Cellular basis of triggered arrhythmias in heart failure.
2004,
Pubmed
Preisig-Müller,
Heteromerization of Kir2.x potassium channels contributes to the phenotype of Andersen's syndrome.
2002,
Pubmed
,
Xenbase
Priori,
Inherited dysfunction of sarcoplasmic reticulum Ca2+ handling and arrhythmogenesis.
2011,
Pubmed
Rajagopal,
Protein kinase C isozyme-specific potentiation of expressed Ca v 2.3 currents by acetyl-beta-methylcholine and phorbol-12-myristate, 13-acetate.
2008,
Pubmed
,
Xenbase
Rohács,
Specificity of activation by phosphoinositides determines lipid regulation of Kir channels.
2003,
Pubmed
,
Xenbase
Ryves,
Activation of the PKC-isotypes alpha, beta 1, gamma, delta and epsilon by phorbol esters of different biological activities.
1991,
Pubmed
Sato,
Modulation of the inwardly rectifying K+ channel in isolated human atrial myocytes by alpha 1-adrenergic stimulation.
1995,
Pubmed
Schram,
Barium block of Kir2 and human cardiac inward rectifier currents: evidence for subunit-heteromeric contribution to native currents.
2003,
Pubmed
,
Xenbase
Sosunov,
Mechanisms of alpha-adrenergic potentiation of ventricular arrhythmias in dogs with inherited arrhythmic sudden death.
2004,
Pubmed
Tristani-Firouzi,
Functional and clinical characterization of KCNJ2 mutations associated with LQT7 (Andersen syndrome).
2002,
Pubmed
,
Xenbase
Zaritsky,
The consequences of disrupting cardiac inwardly rectifying K(+) current (I(K1)) as revealed by the targeted deletion of the murine Kir2.1 and Kir2.2 genes.
2001,
Pubmed
Zhu,
Suppression of Kir2.3 activity by protein kinase C phosphorylation of the channel protein at threonine 53.
1999,
Pubmed
,
Xenbase
Zitron,
Kir2.x inward rectifier potassium channels are differentially regulated by adrenergic alpha1A receptors.
2008,
Pubmed
,
Xenbase
Zitron,
Human cardiac inwardly rectifying current IKir2.2 is upregulated by activation of protein kinase A.
2004,
Pubmed
,
Xenbase
Zobel,
Molecular dissection of the inward rectifier potassium current (IK1) in rabbit cardiomyocytes: evidence for heteromeric co-assembly of Kir2.1 and Kir2.2.
2003,
Pubmed