Luteoloside attenuates anoxia/reoxygenation-induced cardiomyocytes injury via mitochondrial pathway mediated by 14-3-3η protein.

Ischemia/reperfusion (I/R) injury is the major cause of acute cardiovascular disease worldwide. 14-3-3η protein has been demonstrated to protect myocardium against I/R injury. Luteoloside (Lut), a flavonoid found in many Chinese herbs, exerts myocardial protection effects. However, the mechanism remains unclear. We hypothesize that the cardioprotective role of Lut is exerted by regulating the 14-3-3η signal pathway. To investigate our hypothesis, an in vitro I/R model was generated in H9C2 cardiomyocytes by anoxia/reoxygenation (A/R) treatment. The effects of Lut on cardiomyocytes with A/R injury were assessed by determining the cell viability, lactate dehydrogenase levels, intracellular reactive oxygen species levels, mitochondrial permeability transition pores (mPTP) openness, caspase-3 activity, and apoptosis rate. The effects on protein expression were tested using western blot analysis. Lut attenuated A/R-induced injury to cardiomyocytes by increasing the expression of 14-3-3η protein and cell viability; decreasing levels of lactate dehydrogenase, reactive oxygen species, mPTP openness, caspase-3 activity, and low apoptosis rate were observed. However, the cardioprotective effects of Lut were blocked by AD14-3-3ηRNAi, an adenovirus knocking down the intracellular 14-3-3η expression. In conclusion, to our knowledge, this is the first study to demonstrate that Lut protected cardiomyocytes from A/R-induced injury via the regulation of 14-3-3η signaling pathway.

Inhibitory interaction of the 14-3-3 proteins with ubiquitous (PMCA1) and tissue-specific (PMCA3) isoforms of the plasma membrane Ca2+ pump.

A previous study has demonstrated that the ubiquitous plasma membrane Ca(2+) pump PMCA4 interacted with isoform epsilon of the 14-3-3 protein, whereas the nervous tissue-specific PMCA2 did not. The 14-3-3 proteins are widely expressed small acidic proteins, which modulate cell signaling, intracellular trafficking, transcription and apoptosis. The investigation has been extended to the other tissue-restricted pump (PMCA3) and to the other ubiquitous pump (PMCA1). At variance with PMCA2, PMCA3 interacted with the 14-3-3epsilon protein in a two-hybrid system assay, which could not be used for PMCA1. The 14-3-3epsilon protein immunoprecipitated with both PMCA3 and PMCA1 when expressed in HeLa cells. Pull-down experiments using GST-PMCA1 and GST-PMCA3 fusion products confirmed the interaction of both pumps with the 14-3-3epsilon protein. The binding was phosphorylation-independent with both PMCA3 and PMCA1. The 14-3-3zeta isoform also interacted with PMCA3; however, it did not interact with PMCA1. The effect of the interaction on the activity of the two pumps, and thus on the homeostasis of Ca(2+), was investigated by co-expressing the 14-3-3epsilon protein and PMCA3 or PMCA1 in CHO cells together with the recombinant Ca(2+) indicator aequorin: the ability of cells to re-establish the basal Ca(2+) concentration following a Ca(2+) transient induced by an InsP(3)-producing agonist was substantially decreased with both pumps, indicating that the interaction with the 14-3-3 protein inhibited the activity of both PMCA3 and PMCA1.

The Attenuation of 14-3-3ζ is Involved in the Caffeic Acid-Blocked Lipopolysaccharide-Stimulated Inflammatory Response in RAW264.7 Macrophages.

Inflammation plays important roles in the initiation and progress of many diseases. Caffeic acid (CaA) is a naturally occurring hydroxycinnamic acid derivative, which shows hypotoxicity and diverse biological functions, including anti-inflammation. The molecular mechanisms involved in the CaA-inhibited inflammatory response are very complex; generally, the down-regulated phosphorylation of such important transcriptional factors, for example, nuclear factor κB (NF-κB) and signal transducers and activators of transcription-3 (STAT-3), plays an important role. Here, we found that in RAW264.7 macrophage cells, CaA blocked lipopolysaccharide (LPS)-stimulated inflammatory response by attenuating the expression of 14-3-3ζ (a phosphorylated protein regulator). Briefly, the increased expression of 14-3-3ζ was involved in the LPS-induced inflammatory response. CaA blocked the LPS-elevated 14-3-3ζ via attenuating the LPS-induced tumor necrosis factor-α (TNF-α) secretion and via enhancing the 14-3-3ζ ubiquitination. These processes inhibited the LPS-induced activation (phosphorylation) of NF-κB and STAT-3, in turn blocked the transcriptional activation of inducible NO synthase (iNOS), interleukin-6 (IL-6), and TNF-α, and finally attenuated the productions of nitric oxide (NO), IL-6, and TNF-α. By understanding a novel mechanism whereby CaA inhibited the 14-3-3ζ, our study expanded the understanding of the molecular mechanisms involved in the anti-inflammation potential induced by CaA.

Estradiol prevents the injury-induced decrease of Akt activation and Bad phosphorylation.

Estradiol prevents neuronal cell death through the inhibition of apoptotic signals and the activation of cell survival signals. This study investigated whether estradiol modulates the anti-apoptotic signal through the activation of Akt and its downstream targets, including Bad, Bcl-x(L), and 14-3-3. Adult female rats were ovariectomied and treated with estradiol prior to middle cerebral artery occlusion (MCAO). Brains were collected 24 h after MCAO and infarct volumes were analyzed. We confirmed that estradiol significantly reduces infarct volume and decreases the positive cells of TUNEL staining in the cerebral cortex. Potential activation was measured by phosphorylation of Akt at Ser473 and Bad at Ser136 using Western blot analysis. Estradiol prevents the injury-induced decrease of pAkt, pBad, and Bcl-x(L). Further, in the presence of estradiol, the interaction of pBad and 14-3-3 increased, compared to that of oil-treated animals. Our findings suggest that estradiol prevents cell death due to brain injury and that Akt activation and Bad phosphorylation by estradiol mediated these protective effects.

In-vivo administration of clozapine affects behaviour but does not reverse dendritic spine deficits in the 14-3-3ζ KO mouse model of schizophrenia-like disorders.

Clozapine is an atypical antipsychotic drug used in the treatment of schizophrenia, which has been shown to reverse behavioural and dendritic spine deficits in mice. It has recently been shown that deficiency of 14-3-3ζ has an association with schizophrenia, and that a mouse model lacking this protein displays several schizophrenia-like behavioural deficits. To test the effect of clozapine in this mouse model, 14-3-3ζ KO mice were administered clozapine (5mg/kg) for two weeks prior to being analysed in a test battery of cognition, anxiety, and despair (depression-like) behaviours. Following behavioural testing brain samples were collected for analysis of specific anatomical defects and dendritic spine formation. We found that clozapine reduced despair behaviour of 14-3-3ζ KO mice in the forced swim test (FST) and altered the behaviour of wild types and 14-3-3ζ KO mice in the Y-maze task. In contrast, clozapine had no effects on hippocampal laminar defects or decreased dendritic spine density observed in 14-3-3ζ KO mice. Our results suggest that clozapine may have beneficial effects on clinical behaviours associated with deficiencies in the 14-3-3ζ molecular pathway, despite having no effects on morphological defects. These findings may provide mechanistic insight to the action of this drug.

Curcumin suppresses PPARdelta expression and related genes in HT-29 cells.

AIM: To investigate the effects of curcumin on the expression of peroxisome proliferator-activated receptordelta (PPARdelta) and related genes in HT-29 cells. METHODS: HT-29 cells were treated with curcumin (0-80 micromol/L) for 24 h. The effects of curcumin on the morphology of HT-29 cells were studied by Hoechst 33342 staining. The activity of caspase-3 was determined using DEVD-pNA as substrate. The levels of peroxisome PPARdelta, 14-3-3epsilon and vascular endothelial growth factor (VEGF) in HT-29 cells were determined by Western blotting analysis and their mRNA expression was determined by real-time quantitative RT-PCR. RESULTS: Treatment with 10-80 micromol/L curcumin induced typical features of apoptosis and activated the caspase-3 in HT-29 cells. The expression of PPARdelta, 14-3-3epsilon and VEGF was reduced and the activity of beta-catenin/Tcf-4 signaling was inhibited by curcumin treatment. CONCLUSION: Curcumin can induce apoptosis of HT-29 cells and down-regulate the expression of PPARdelta, 14-3-3epsilon and VEGF in HT-29.

Dynamic 14-3-3/client protein interactions integrate survival and apoptotic pathways.

The serine/threonine binding protein, 14-3-3, possesses a diverse array of client proteins. It is involved in the regulation of apoptosis through multiple interactions with proteins of the core mitochondrial machinery, pro-apoptotic transcription factors, and their upstream signaling pathways. 14-3-3 coordinates with survival kinases to inhibit multiple pro-apoptotic molecules. One prominent mechanism for the suppression of apoptosis is through 14-3-3-mediated sequestration of pro-apoptotic client proteins. On the other hand, cellular stresses appear to signal through the inhibition of 14-3-3 function to exert their pro-apoptotic effect. Global inhibition of 14-3-3/client protein interaction induces apoptosis, and stands as an attractive intervention in diseases involving overactive survival signaling pathways. Because dysregulation of 14-3-3 has been associated with poor survival of cancer patients, targeting 14-3-3 may provide a novel therapeutic approach for the treatment of cancer.

Protective effect of D609 against amyloid-beta1-42-induced oxidative modification of neuronal proteins: redox proteomics study.

Oxidative stress has been implicated in the pathophysiology of a number of diseases, including neurodegenerative disorders such as Alzheimer's disease (AD), a neurodegenerative disorder associated with cognitive decline and enhanced oxidative stress. Amyloid-beta peptide(1-42) (Abeta(1-42)), one of the main component of senile plaques, can induce in vitro and in vivo oxidative damage to neuronal cells through its ability to produce free radicals. The aim of this study was to investigate the protective effect of the xanthate D609 on Abeta(1-42)-induced protein oxidation by using a redox proteomics approach. D609 was recently found to be a free radical scavenger and antioxidant. In the present study, rat primary neuronal cells were pretreated with 50 microM of D609, followed by incubation with 10 microM Abeta(1-42) for 24 hr. In the cells treated with Abeta(1-42) alone, four proteins that were significantly oxidized were identified: glyceraldehyde-3-phosphate dehydrogenase, pyruvate kinase, malate dehydrogenase, and 14-3-3 zeta. Pretreatment of neuronal cultures with D609 prior to Abeta(1-42) protected all the identified oxidized proteins in the present study against Abeta(1-42)-mediated protein oxidation. Therefore, D609 may ameliorate the Abeta(1-42)-induced oxidative modification. We discuss the implications of these Abeta(1-42)-mediated oxidatively modified proteins for AD pathology and for potential therapeutic intervention in this dementing disorder.