scholarly journals The Central Role of Protein Kinase C Epsilon in Cyanide Cardiotoxicity and Its Treatment

2019 ◽  
Vol 171 (1) ◽  
pp. 247-257 ◽  
Author(s):  
Joseph Y Cheung ◽  
Salim Merali ◽  
JuFang Wang ◽  
Xue-Qian Zhang ◽  
Jianliang Song ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cardiac Contractility ◽  
Ionic Currents ◽  
Ion Fluxes ◽  
Consensus Sequences ◽  
Kinase C ◽  
Protein Kinase C Epsilon ◽  
Life Threatening

Abstract In adult mouse myocytes, brief exposure to sodium cyanide (CN) in the presence of glucose does not decrease ATP levels, yet produces profound reduction in contractility, intracellular Ca2+ concentration ([Ca2+]i) transient and L-type Ca2+ current (ICa) amplitudes. We analyzed proteomes from myocytes exposed to CN, focusing on ionic currents associated with excitation-contraction coupling. CN induced phosphorylation of α1c subunit of L-type Ca2+ channel and α2 subunit of Na+-K+-ATPase. Methylene blue (MB), a CN antidote that we previously reported to ameliorate CN-induced reduction in contraction, [Ca2+]i transient and ICa amplitudes, was able to reverse this phosphorylation. CN decreased Na+-K+-ATPase current contributed by α2 but not α1 subunit, an effect that was also counteracted by MB. Peptide consensus sequences suggested CN-induced phosphorylation was mediated by protein kinase C epsilon (PKCε). Indeed, CN stimulated PKC kinase activity and induced PKCε membrane translocation, effects that were prevented by MB. Pretreatment with myristoylated PKCε translocation activator or inhibitor peptides mimicked and inhibited the effects of CN on ICa and myocyte contraction, respectively. We conclude that CN activates PKCε, which phosphorylates L-type Ca2+ channel and Na+-K+-ATPase, resulting in depressed cardiac contractility. We hypothesize that this inhibition of ion fluxes represents a novel mechanism by which the cardiomyocyte reduces its ATP demand (decreased ion fluxes and contractility), diminishes ATP turnover and preserves cell viability. However, this cellular protective effect translates into life-threatening cardiogenic shock in vivo, thereby creating a profound disconnect between survival mechanisms at the cardiomyocyte level from those at the level of the whole organism.

Abstract TP267: Protein Kinase C Epsilon-activation Mediates Ischemic Neuroprotection by Activating an Activity-regulated Cytoskeleton-associated Protein-dependent Mechanism

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Charles H Cohan ◽  
Holly M Stradecki ◽  
Kahlilia C Morris-Blanco ◽  
Nathalie Khoury ◽  
Kevin B Koronowski ◽  
...  
Keyword(s):  
Cell Death ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Glucose Deprivation ◽  
T Test ◽  
Kinase C ◽  
Protein Kinase C Epsilon ◽  
Cultured Slices ◽  
Dependent Mechanism

Introduction: Cerebral ischemia can trigger cell death in the CA1 region of the hippocampus, an area important for memory. Protein kinase C epsilon (PKCε) activation prior to ischemia protects the CA1 from injury by modulating neurotransmission. The underlying mechanism needs further study. Hypothesis: PKCε-induced neuroprotection increases latency until anoxic depolarization (AD) through an activity-regulated cytoskeleton-associated protein (arc)-dependent mechanism of regulating AMPAR currents. Results: In vivo activation of PKCε by the PKCε-activator ψε-Receptor of Activated C Kinase (ψεRACK) increased BDNF 5.99 +/- 0.11 fold and TrkB phosphorylation levels 2.94 +/- 0.32 fold (enhancers of arc protein levels) (n = 4, p < 0.005, t-test). Arc mRNA and protein was increased 143.97 +/-7.68 % and 1.91 +/- 0.22 fold (n = 9, p < 0.005, t-test). Inhibition of arc using antisense oligodeoxynucleotides (arc AS ODNs) in cultured slices blocked PKCε-mediated neuroprotection against lethal oxygen and glucose deprivation (OGD) from 35.91 +/- 5.97 to 74.93 +/- 4.24 % cell death (n = 6, p < 0.005, ANOVA, Bonferroni). ΨεRACK decreased AMPAR-mediated mEPSC amplitude to 12.75 +/- 0.35 pA from 14.80 +/- 0.39 pA (n = 20, p < 0.01, ANOVA, Bonferroni). This effect was arc-dependent. Additionally, ψεRACK treatment increased latency until AD from 29.27 +/- 3.6 min 50.77 +/- 5.08 min (n = 13, p < 0.01, ANOVA, Bonferroni). This increase was arc-dependent, and required AMPAR internalization. Inhibiting internalization reduced AD latency from 54.5 +/- 8.40 min to 22.3 + 5.17 min (n = 6, p <0.005, t-test). Conclusion: Arc expression is necessary for neuroprotection afforded by PKCε-activation, modulates excitatory synaptic strength, and increases latency until AD. Methods: Western blot: Proteins (40 μg) were separated on a 12% SDS-PAGE gel. Immunofluorescence : 30 μm sections were incubated with 1:500 NeuN and 1:50 arc in PBS with 0.8% triton. Cultured slices preparation : sections from P9-11 rats were plated on inserts and cultured for 14 days. PI measurements of cell death : Slices were incubated in medium with 2 μg/mL PI. mEPSC measurements : Whole-cell voltage clamp was performed. AD: OGD, perfusate was switched to glucose free media, and bubbled with a 95% N 2 and 5% CO 2 gas.

scholarly journals Protein kinase C epsilon delays latency until anoxic depolarization through arc expression and GluR2 internalization

2017 ◽  
Vol 37 (12) ◽  
pp. 3774-3788 ◽  
Author(s):  
Charles H Cohan ◽  
Holly M Stradecki-Cohan ◽  
Kahlilia C Morris-Blanco ◽  
Nathalie Khoury ◽  
Kevin B Koronowski ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Learning And Memory ◽  
Global Cerebral Ischemia ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Kinase C ◽  
Anoxic Depolarization ◽  
Protein Kinase C Epsilon

Global cerebral ischemia is a debilitating injury that damages the CA1 region of the hippocampus, an area important for learning and memory. Protein kinase C epsilon (PKCɛ) activation is a critical component of many neuroprotective treatments. The ability of PKCɛ activation to regulate AMPA receptors (AMPARs) remains unexplored despite the role of AMPARs in excitotoxicity after brain ischemia. We determined that PKCɛ activation increased expression of a protein linked to learning and memory, activity-regulated cytoskeleton-associated protein (arc). Also, arc is necessary for neuroprotection and confers protection through decreasing AMPAR currents via GluR2 internalization. In vivo, activation of PKCɛ increased arc expression through a BDNF/TrkB pathway, and decreased GluR2 mRNA levels. In hippocampal cultured slices, PKCɛ activation decreased AMPAR current amplitudes in an arc- and GluR2-dependent manner. Additionally, PKCɛ activation triggered an arc- and GluR2 internalization-dependent delay in latency until anoxic depolarization. Inhibiting arc also blocked PKCɛ-mediated neuroprotection against lethal oxygen and glucose deprivation. These data characterize a novel PKCɛ-dependent mechanism that for the first time defines a role for arc and AMPAR internalization in conferring neuroprotection.

2008 Thomas W. Smith Memorial Lecture—Protein Kinase C α as a Novel Therapeutic Target for Treating Heart Failure

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Jeffrey Molkentin
Keyword(s):  
Heart Failure ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Sarcoplasmic Reticulum ◽  
Cardiac Contractility ◽  
Dominant Negative ◽  
Kinase C ◽  
Novel Therapeutic

We have shown that protein kinase C (PKC) α functions as a proximal regulator of Ca 2+ handling in cardiac myocytes (Braz et al, Nat. Med. 10:248, 2004). Deletion of PKC α in the mouse resulted in augmented sarcoplasmic reticulum Ca 2+ loading, enhanced Ca 2+ transients, and augmented contractility, whereas overexpression of PKCα in the heart blunted contractility. Mechanistically, PKCα regulates Ca 2+ handling by altering inhibitor-1 phosphorylation, which suppresses protein phosphatase-1 activity, thus modulating phospholamban activity and sarcoplasmic reticulum Ca 2+ AT-Pase 2 (SERCA2). Acute inhibition of PKCα with the pharmacologic agents Ro-32-0432 or Ro-31-8220 significantly augmented cardiac contractility in vivo or in an isolated work performing heart preparation in wild-type mice, but not in PKC α-deficient mice. Ro-32-0432 also acutely increased cardiac contractility in two different models of heart failure in vivo. Moreover, acute or chronic treatment with Ro-32-8220 in a mouse model of heart failure, due to deletion of the muscle lim protein (MLP) gene, significantly augmented cardiac contractility and restored normal pump function. Adenoviral-mediated gene therapy with a dominant negative PKCα cDNA rescued heart failure in a chronic rat model of postinfarction cardiomyopathy. Moreover, expression of dominant-negative PKCα in cardiac myocytes using a cardiac-specific transgenic system (tetracycline-regulated) also enhanced cardiac contractility and antagonized heart failure due to myocardial infarction injury. Finally, another PKCα/β inhibitor, ruboxistaurin (LY333531), antagonized heart failure after long-term pressure overload in mice. PKCα is the dominant conventional PKC isoform expressed in the adult human heart, providing potential relevance of these findings to human pathophysiology. Indeed, pharmacological inhibition of PKCα may serve as a novel therapeutic strategy for either enhancing cardiac contractility in the setting of severe functional deterioration or as a long-term treatment option to prevent worsening of heart failure in earlier stages.

Chronic treatment by the calcium channel blocker ± PN 200-110 in the rat counteracts the stimulations of pituitary weight, prolactin release and pituitary C-kinase activity induced by a chronic estradiol treatment, in vivo

1990 ◽  
Vol 122 (3) ◽  
pp. 403-408
Author(s):  
Ph. Touraine ◽  
P. Birman ◽  
F. Bai-Grenier ◽  
C. Dubray ◽  
F. Peillon ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Calcium Channel ◽  
Calcium Channel Blocker ◽  
Channel Blocker ◽  
Plasma Prolactin ◽  
Estradiol Treatment ◽  
Kinase C ◽  
Protein Kinase C Activity

Abstract In order to investigate whether a calcium channel blocker could modulate the protein kinase C activity in normal and estradiol pretreated rat pituitary, female Wistar rats were treated or not (controls) with ± PN 200-110 (3 mg · kg−1 · day−1, sc) for 8 days or with estradiol cervical implants for 8 or 15 days, alone or in combination with PN 200-110 the last 8 days. Estradiol treatment induced a significant increase in plasma prolactin levels and pituitary weight. PN 200-110 administered to normal rats did not modify these parameters, whereas it reduced the effects of the 15 days estradiol treatment on prolactin levels (53.1 ± 4.9 vs 95.0 ±9.1 μg/l, p<0.0001) and pituitary weight (19.9 ± 0.4 vs 23.0 ± 0.6 mg, p <0.001), to values statistically comparable to those measured after 8 days of estradiol treatment. PN 200-110 alone did not induce any change in protein kinase C activity as compared with controls. In contrast, PN 200-110 treatment significantly counteracted the large increase in soluble activity and the decrease in the particulate one induced by estradiol between day 8 and day 15. We conclude that PN 200-110 opposed the stimulatory effects of chronic in vivo estradiol treatment on plasma prolactin levels and pituitary weight and that this regulation was related to a concomitant modulation of the protein kinase C activity.

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