Inhibitory kappa B kinase-beta is a target for specific nuclear factor kappa B-mediated delayed cardioprotection.
ABSTRACT Myocardial ischemia/reperfusion injury remains a vexing problem. Translating experimental strategies that deliver protective agents before the ischemic insult limits clinical applicability. We targeted 2 proteins in the nuclear factor-kappaB pathway, inhibitory kappa B kinase-beta, and 26S cardiac proteasome to determine their cardioprotective effects when delivered during reperfusion.
C57BL/6 mice underwent left anterior descending artery occlusion for 30 minutes. An inhibitory kappa B kinase-beta inhibitor (Compound A), a proteasome inhibitor (PS-519), or vehicle was administered at left anterior descending artery release or 2 hours afterward. Infarct size was analyzed 24 hours later. Pressure-volume loops were performed at 72 hours. Serum and left ventricular tissue were collected 1 hour after injury to examine protein expression by enzyme-linked immunosorbent assay and Western blot.
Inhibitory kappa B kinase-beta and proteasome inhibition significantly attenuated infarct size and preserved ejection fraction compared with the vehicle groups. When delivered even 2 hours after reperfusion, Compound A, but not PS-519, still decreased infarct size in mice. Finally, when delivered at reperfusion, successful inhibition of phosphorylated-p65 and decreased interleukin-6 and tumor necrosis factor-alpha levels occurred in mice given the inhibitory kappa B kinase-beta inhibitor, but not in mice with proteasome inhibition.
Although inhibitory kappa B kinase-beta and proteasome inhibition at reperfusion attenuated infarct size after acute ischemia/reperfusion, only inhibitory kappa B kinase-beta inhibition provided cardioprotection through specific suppression of nuclear factor-kappaB signaling. This feature of highly targeted nuclear factor-kappaB inhibition might account for its delayed protective effects, providing a clinically relevant option for treating myocardial ischemia/reperfusion associated with unknown periods of ischemia and reperfusion as seen in cardiac surgery and acute coronary syndromes.
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ABSTRACT: The biological functions of NFκB1 (p50) have not been studied as often as other members of the NFκB family due to its lack of a transcriptional domain. Our recently studies demonstrate that p50 functions as an apoptotic mediator via its inhibition of GADD45α protein degradation and increase in p53 protein translation. Here, we reported a novel function of p50 in its regulation of SOD2 transcription via the NFκB-independent pathway. We found that the deletion of p50 in MEFs (p50-/-) upregulated SOD2 expression at both protein and mRNA levels. SOD2 promoter-driven luciferase was also upregulated in p50-/- cells compared with that in wide-type MEF (p50+/+) cells, suggesting p50 regulation of SOD2 at transcriptional level. Our results also showed that p50-deficiency specifically resulted in down-regulation of phosphorylation and an increase transactivation of FoxO3a compared with WT cells. Further studies indicated that p50-down-regulated FoxO3a phosphorylation was mediated by activated Akt via up-regulation of miR-190, in turn inhibiting PHLPP1 translation. Together, our studies identify a p50 novel function in the regulation of SOD2 transcription via modulating of the miR-190/PHLPP1/Akt-FoxO3a pathway, which provides significant insight into understanding of the p50 physiological function.Molecular biology of the cell 09/2013; · 5.98 Impact Factor
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ABSTRACT: Nuclear factor kappa B (NF-κB) is a well-known transcription factor that is intimately involved with inflammation and immunity. We have previously shown that NF-κB promotes inflammatory events and mediates adverse cardiac remodeling following ischemia reperfusion (IR). Conversely, others have pointed to the beneficial influence of NF-κB in IR injury related to its anti-apoptotic effects. Understanding the seemingly disparate influence of manipulating NF-κB is hindered, in part, by current approaches that only indirectly interfere with the function of its most transcriptionally active unit, p65 NF-κB. Mice were generated with cardiomyocyte-specific deletion of p65 NF-κB. Phenotypically, these mice and their hearts appeared normal. Basal and stimulated p65 expression were significantly reduced in whole hearts and completely ablated in isolated cardiomyocytes. Compared to wild type mice, transgenic animals were protected from both global IR by Langendorff as well as regional IR by coronary ligation and release. The protected, transgenic hearts had less cytokine activity and decreased apoptosis. Furthermore, p65 ablation was associated with enhanced calcium reuptake by the sarcoplasmic reticulum. This influence on calcium handling was related to increased expression of phosphorylated phospholamban in conditional p65 null mice. In conclusion, cardiomyocyte-specific deletion of the most active, canonical NF-κB subunit affords cardioprotection to both global and regional IR injury. The beneficial effects of NF-κB inhibition are related, in part, to modulation of intracellular calcium homeostasis.AJP Heart and Circulatory Physiology 08/2013; · 4.01 Impact Factor
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ABSTRACT: Introduction: The ubiquitin-proteasome system (UPS) is responsible for the degradation of misfolded or damaged proteins, regulating inflammatory processes and cell cycle progression. The aim of this article is to summarize the currently available data regarding the possible utility of proteasome inhibitors (PIs) in the treatment of ischemia-reperfusion injury (IRI). Areas covered: Data were reviewed from the published literature using the Medline database. The effect of PIs on IRI is dependent on the dosage, time of administration (prior to or post IRI induction), the affected organ, and the experimental model used. Undoubtedly, in most cases PIs' application resulted in attenuated IRI, although it was uniformly shown that inhibition of the UPS prior to ischemic preconditioning (IPC) abolished the protective effect of IPC in IRI. Mechanism of action involves several pathways, including nuclear factor kappa-B (NF-κB) inactivation, antineutrophil action, decreased intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression, and the cytoprotective proteins eNOS, heme oxigenase 1 and hsp70 up-regulation. Expert opinion: Current data are limited, but appear promising with regard to PI consideration as an effective future therapeutic strategy for IRI. Nevertheless, further investigation is required in terms of safety and validation of the appropriate for each agent dosage, in order to establish their possible contribution in human IRI.Expert Opinion on Investigational Drugs 10/2013; · 4.74 Impact Factor