Effects of N-n-butyl haloperidol iodide on myocardial ischemia/reperfusion injury and Egr-1 expression in rat

N-n-Butyl Haloperidol Iodide, a Derivative of the Anti-psychotic Haloperidol, Antagonizes Hypoxia/Reoxygenation Injury by Inhibiting an Egr-1/ROS Positive Feedback Loop in H9c2 Cells

Early growth response-1 (Egr-1), a transcription factor which often underlies the molecular basis of myocardial ischemia/reperfusion (I/R) injury, and oxidative stress, is key to myocardial I/R injury. Silent information regulator of transcription 1(SIRT1) not only interacts with and is inhibited by Egr-1, but also downregulates reactive oxygen species (ROS) via the Forkhead box O1(FOXO1)/manganese superoxide dismutase (Mn-SOD) signaling pathway. N-n-butyl haloperidol iodide (F₂), a new patented compound, protects the myocardium against myocardial I/R injury in various animal I/R models in vivo and various heart-derived cell hypoxia/reoxygenation (H/R) models in vitro. In addition, F₂ can regulate the abnormal ROS/Egr-1 signaling pathway in cardiac microvascular endothelial cells (CMECs) and H9c2 cells after H/R. We studied whether there is an inverse Egr-1/ROS signaling pathway in H9c2 cells and whether the SIRT1/FOXO1/Mn-SOD signaling pathway mediates this. We verified a ROS/Egr-1 signaling loop in H9c2 cells during H/R and that F₂ protects against myocardial H/R injury by affecting SIRT1-related signaling pathways. Knockdown of Egr-1, by siRNA interference, reduced ROS generation, and alleviated oxidative stress injury induced by H/R, as shown by upregulated mitochondrial membrane potential, increased glutathione peroxidase (GSH-px) and total SOD anti-oxidative enzyme activity, and downregulated MDA. Decreases in FOXO1 protein expression and Mn-SOD activity occurred after H/R, but could be blocked by Egr-1 siRNA. F₂ treatment attenuated H/R-induced Egr-1 expression, ROS generation and other forms of oxidative stress injury such as MDA, and prevented H/R-induced decreases in FOXO1 and Mn-SOD activity_. Nuclear co-localization between Egr-1 and SIRT1 was increased by H/R and decreased by either Egr-1 siRNA or F₂. Therefore, our results suggest that Egr-1 inhibits the SIRT1/FOXO1/Mn-SOD antioxidant signaling pathway to increase ROS and perpetuate I/R injury. F₂ inhibits induction of Egr-1 by H/R, thereby activating SIRT1/FOXO1/Mn-SOD antioxidant signaling and decreasing H/R-induced ROS, demonstrating an important mechanism by which F₂ protects against myocardial H/R injury.

Effect of N-n-butyl haloperidol iodide on ROS/JNK/Egr-1 signaling in H9c2 cells after hypoxia/reoxygenation

Reactive oxygen species (ROS)-induced oxidative stress in cells is an important pathophysiological process during myocardial ischemia/reperfusion (I/R) injury, and the transcription factor Egr-1 is a master switch for various damage pathways during reperfusion injury. An in vitro model of myocardial I/R injury and H9c2 cardiomyoblast cells hypoxia/reoxygenation (H/R) was used to assess whether there is abnormal intracellular ROS/JNK/Egr-1 signaling. We also assessed whether N-n-butyl haloperidol (F2), which exerts protective effects during myocardial I/R injury, can modulate this pathway. H/R induced ROS generation, JNK activation, and increased the expression of Egr-1 protein in H9c2 cells. The ROS scavengers edaravone (EDA) and N-acetyl-L-cysteine (NAC) reduced ROS level, downregulated JNK activation, and Egr-1 expression in H9c2 cells after H/R. The JNK inhibitor SP600125 inhibited Egr-1 overexpression in H9c2 cells caused by H/R. F2 could downregulate H/R-induced ROS level, JNK activation, and Egr-1 expression in H9c2 cells in a dose-dependent manner. The ROS donor hypoxanthine-xanthine oxidase (XO/HX) and the JNK activator ANISO antagonized the effects of F2. Therefore, H/R activates ROS/Egr-1 signaling pathway in H9c2 cells, and JNK activation plays an important role in this pathway. F2 regulates H/R-induced ROS/JNK/Egr-1 signaling, which might be an important mechanism by which it antagonizes myocardial I/R injury.

Molecular basis of organ fibrosis: potential therapeutic approaches

Fibrosis, a non-physiological wound healing in multiple organs, is associated with end-stage pathological symptoms of a wide variety of vascular injury and inflammation related diseases. In response to chemical, immunological and physical insults, the body's defense system and matrix synthetic machinery respond to healing the wound and maintain tissue homeostasis. However, uncontrolled wound healing leads to scarring or fibrosis, a pathological condition characterized by excessive synthesis and accumulation of extracellular matrix proteins, loss of tissue homeostasis and organ failure. Understanding the actual cause of pathological wound healing and identification of igniter(s) of fibrogenesis would be helpful to design novel therapeutic approaches to control pathological wound healing and to prevent fibrosis related morbidity and mortality. In this article, we review the significance of a few key cytokines (TGF-β, IFN-γ, IL-10) transcriptional activators (Sp1, Egr-1, Smad3), repressors (Smad7, Fli-1, PPAR-γ, p53, Klotho) and epigenetic modulators (acetyltransferase, methyltransferases, deacetylases, microRNAs) involved in major matrix protein collagen synthesis under pathological stage of wound healing, and the potentiality of these regulators as therapeutic targets for fibrosis treatment. The significance of endothelial to mesenchymal transition (EndMT) and senescence, two newly emerged fields in fibrosis research, has also been discussed.

N-n-butyl haloperidol iodide ameliorates cardiomyocytes hypoxia/reoxygenation injury by extracellular calcium-dependent and -independent mechanisms

N-n-butyl haloperidol iodide (F2) has been shown to antagonize myocardial ischemia/reperfusion injury by blocking calcium channels. This study explores the biological functions of ERK pathway in cardiomyocytes hypoxia/reoxygenation injury and clarifies the mechanisms by which F2 ameliorates cardiomyocytes hypoxia/reoxygenation injury through the extracellular-calcium-dependent and -independent ERK1/2-related pathways. In extracellularcalcium-containing hypoxia/reoxygenation cardiomyocytes, PKCα and ERK1/2 were activated, Egr-1 protein level and cTnI leakage increased, and cell viability decreased. The ERK1/2 inhibitors suppressed extracellular-calcium-containing-hypoxia/reoxygenation-induced Egr-1 overexpression and cardiomyocytes injury. PKCα inhibitor downregulated extracellularcalcium-containing-hypoxia/reoxygenation-induced increase in p-ERK1/2 and Egr-1 expression. F2 downregulated hypoxia/reoxygenation-induced elevation of p-PKCα, p-ERK1/2, and Egr-1 expression and inhibited cardiomyocytes damage. The ERK1/2 and PKCα activators antagonized F2's effects. In extracellular-calcium-free-hypoxia/reoxygenation cardiomyocytes, ERK1/2 was activated, LDH and cTnI leakage increased, and cell viability decreased. F2 and ERK1/2 inhibitors antagonized extracellular-calcium-free-hypoxia/reoxygenation-induced ERK1/2 activation and suppressed cardiomyocytes damage. The ERK1/2 activator antagonized F2's above effects. F2 had no effect on cardiomyocyte cAMP content or PKA and Egr-1 expression. Altogether, ERK activation in extracellular-calcium-containing and extracellular-calcium-free hypoxia/reoxygenation leads to cardiomyocytes damage. F2 may ameliorate cardiomyocytes hypoxia/reoxygenation injury by regulating the extracellular-calcium-dependent PKCα/ERK1/2/Egr-1 pathway and through the extracellular-calcium-independent ERK1/2 activation independently of the cAMP/PKA pathway or Egr-1 overexpression.

Attenuation of endothelin-1-induced PKB and ERK1/2 signaling, as well as Egr-1 expression, by curcumin in A-10 vascular smooth muscle cells

Endothelin-1 (ET-1) is implicated in the pathogenesis of vascular abnormalities through the hyperactivation of growth promoting pathways, including protein kinase B (PKB) and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling. ET-1 has been shown to elicit its responses through the generation of reactive oxygen species (ROS). Curcumin, the main constituent of the spice turmeric, exhibits cardio-protective, anti-proliferative, and antioxidant properties; however, the precise molecular mechanism of its action is unclear. Therefore, in the present study, we investigated the effects of curcumin on ET-1-induced PKB and ERK1/2 signaling, as well as insulin-like growth factor type receptor (IGF-1R) phosphorylation. Curcumin dose-dependently inhibited ET-1-induced phosphorylation of PKB, ERK1/2, c-Raf, and insulin-like growth factor type 1 receptor (IGF-1R), in vascular smooth muscle cells (VSMC). Furthermore, curcumin also attenuated ET-1-induced expression of early growth response (Egr)-1, a transcription factor downstream of ERK1/2 that plays a regulatory role in several cardiovascular pathological processes. In conclusion, these data demonstrate that curcumin is a potent inhibitor of ET-1-induced mitogenic and proliferative signaling events in VSMC and suggest that the ability of curcumin to attenuate these events may contribute as a potential mechanism for its cardiovascular protective response.

Effects of N-n-butyl haloperidol iodide on the rat myocardial sarcoplasmic reticulum Ca(2+)-ATPase during ischemia/reperfusion

We have previously shown that N-n-butyl haloperidol iodide (F(2)), a newly synthesized compound, reduces ischemia/reperfusion (I/R) injury by preventing intracellular Ca(2+) overload through inhibiting L-type calcium channels and outward current of Na(+)/Ca(2+) exchanger. This study was to investigate the effects of F(2) on activity and protein expression of the rat myocardial sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) during I/R to discover other molecular mechanisms by which F(2) maintains intracellular Ca(2+) homeostasis. In an in vivo rat model of myocardial I/R achieved by occluding coronary artery for 30-60 min followed by 0-120 min reperfusion, treatment with F(2) (0.25, 0.5, 1, 2 and 4 mg/kg, respectively) dose-dependently inhibited the I/R-induced decrease in SERCA activity. However, neither different durations of I/R nor different doses of F(2) altered the expression levels of myocardial SERCA2a protein. These results indicate that F(2) exerts cardioprotective effects against I/R injury by inhibiting I/R-mediated decrease in SERCA activity by a mechanism independent of SERCA2a protein levels modulation.

The protective effects of Egr-1 antisense oligodeoxyribonucleotide on cardiac microvascular endothelial injury induced by hypoxia-reoxygenation

Early growth response 1 (Egr-1) over-expression has been demonstrated in myocardial ischemia-reperfusion injury, which is closely associated with endothelial dysfunction. In the present study we investigated the expression of Egr-1 on cultured cardiac microvascular endothelial cells (CMECs) to help define the mechanism of myocardial ischemia-reperfusion injury. A model of cultured CMECs exposed to hypoxia-reoxygenation was developed in which synthesized Egr-1 sense and antisense oligodeoxyribonucleotide were transfected into the cells. The expression of Egr-1 was examined by Western blot analysis. Lactate dehydrogenase, malondialdehyde, superoxide dismutase, tumor necrosis factor alpha, and intercellular adhesion molecule 1 were measured after hypoxia-reoxygenation to assess cell function and injury. Cell morphology, cell viability, and neutrophil adhesion to the CMECs were measured to assess the degree of injury and inflammation. Only cells transfected with Egr-1 antisense oligodeoxyribonucleotide showed a significant reduction in Egr-1 protein expression following hypoxia-reoxygenation. Consistent with the down-regulation of Egr-1 expression, other forms of cell injury were significantly reduced in this group of cells, as evidenced by less alteration in cell morphology, a decrease in expression of tumor necrosis factor alpha and intercellular adhesion molecule 1, improved cell survival, and reduced neutrophil adhesion.

N-n-Butyl haloperidol iodide protects against hypoxia/reoxygenation-induced cardiomyocyte injury by modulating protein kinase C activity

N-n-Butyl haloperidol iodide (F2), a novel compound derived from haloperidol, protects against the damaging effects of ischemia/reperfusion (I/R) injury in vitro and in vivo. We tested whether the myocardial protection of F2 on cardiomyocyte hypoxia/reoxygenation (H/R) injury is mediated by modulating protein kinase C (PKC) activity in primary cultured cardiomyocytes. Primary cultures of ventricular cardiomyocytes underwent 2-h hypoxia and 30-min reoxygenation. Total PKC activity was measured, and the translocation pattern of PKCalpha, betaII, delta and epsilon isoforms was assessed by fractionated western blot analysis. We investigated the association of PKC isoform translocation and H/R-induced injury in the presence and absence of the specific inhibitors and activator. Measurements included cell damage evaluated by creatine kinase (CK) release, and apoptosis measured by annexin V-FITC assay. In primary cultured cardiomyocytes exposed to H/R, PKCalpha, delta and epsilon were translocated, with no change in PKCbetaII activity. Total PKC activity, CK release and apoptosis were increased after H/R. Treatment with the conventional PKC inhibitor Go6976 reduced early growth response-1 (Egr-1) protein expression and attenuated apoptosis. The PKCepsilon inhibitor peptide epsilonV1-2 increased H/R injury without influencing Egr-1 expression. Pretreatment with F2 inhibited translocation of PKCalpha, increased translocation of PKCepsilon, and relieved the CK release and apoptosis. The protection of F2 was blocked in part by the conventional PKC activator thymeleatoxin (TXA) and epsilonV1-2 peptide. F2 significantly alleviated H/R-induced injury, which might be attributed to the combined benefits of inhibiting PKCalpha and activating PKCepsilon.

Positive regulation of the Egr-1/osteopontin positive feedback loop in rat vascular smooth muscle cells by TGF-beta, ERK, JNK, and p38 MAPK signaling

Previous studies identified a positive feedback loop in rat vascular smooth muscle cells (VSMCs) in which early growth response factor-1 (Egr-1) binds to the osteopontin (OPN) promoter and upregulates OPN expression, and OPN upregulates Egr-1 expression via the extracellular signal-regulated protein kinase (ERK) signaling pathway. The current study examined whether transforming growth factor-beta (TGF-beta) activity contributes to Egr-1 binding to the OPN promoter, and whether other signaling pathways act downstream of OPN to regulate Egr-1 expression. ChIP assays using an anti-Egr-1 antibody showed that amplification of the OPN promoter sequence decreased in TGF-beta DNA enzyme-transfected VSMCs relative to control VSMCs. Treatment of VSMCs with PD98059 (ERK inhibitor), SP600125 (JNK inhibitor), or SB203580 (p38 MAPK inhibitor) significantly inhibited OPN-induced Egr-1 expression, and PD98059 treatment was associated with the most significant decrease in Egr-1 expression. OPN-stimulated VSMC cell migration was inhibited by SP600125 or SB203580, but not by PD98059. Furthermore, MTT assays showed that OPN-mediated cell proliferation was inhibited by PD98059, but not by SP600125 or SB203580. Taken together, the results of the current study show that Egr-1 binding to the OPN promoter is positively regulated by TGF-beta, and that the p38 MAPK, JNK, and ERK pathways are involved in OPN-mediated Egr-1 upregulation.

N-n-butyl haloperidol iodide protects cardiac microvascular endothelial cells from hypoxia/reoxygenation injury by down-regulating Egr-1 expression

AIMS

Our previous studies have shown that N-n-butyl haloperidol iodide (F2) can antagonize myocardial ischemia/reperfusion (I/R) injury by down-regulating the early growth response (Egr)-1 expression, but the molecular mechanisms are not well understood. Because there is evidence implicating myocardial I/R injury is closely associated with endothelial dysfunction. The present study is to test the hypothesis that the protective effects of F2 on myocardial I/R injury is related closely with down-regulating Egr-1 expression on cardiac microvascular endothelial cells (CMECs).

METHODS

A model of cultured CMECs exposed to hypoxia/reoxygenation (H/R) was developed. With antisense Egr-1 oligodeoxyribonucleotide (ODN), the relationship between Egr-1 expression and endothelial H/R injury was investigated. Egr-1 mRNA and protein expression were examined by real-time fluorescent quantitative PCR, immunocytochemical staining and Western-blot analysis. Lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), intercellular adhesion molecule-1 (ICAM-1), adherence of neutrophil and platelets, and cell viability were measured after H/R to evaluate the degree of endothelial injury.

RESULTS

Pretreatment with antisense Egr-1 ODN significantly reduced Egr-1 protein expression and attenuated injury of CMECs. Consistent with down-regulation of Egr-1 expression by F2, inflammation and other damage were significantly reduced as evidenced by a decrease of ICAM-1 expression, reduction of neutrophil and platelets adherence, increase in SOD, and decreases in MDA and LDH levels, resulting in the rise of cell viability.

CONCLUSIONS

We demonstrate a protective effect of F2 in CMECs against H/R injury by down-regulating Egr-1 expression, which might be play a vital role in the pathogenesis of myocardial I/R injury.

The protective effects of N-n-butyl haloperidol iodide on myocardial ischemia-reperfusion injury in rats by inhibiting Egr-1 overexpression

AIMS

Our previous studies have shown that N-n-butyl haloperidol iodide (F(2)) can antagonize myocardial ischemia/reperfusion (I/R) injury by blocking intracellular Ca(2+) overload. The present study is to test the hypothesis that the protective effects of F(2) on myocardial I/R injury is mediated by downregulating Egr-1 expression.

METHODS

The Sprague-Dawley rat myocardial I/R model and cardiomyocyte hypoxia/reoxygenation (H/R) model were established. With antisense Egr-1 oligodeoxyribonucleotide (ODN), the relationship between Egr-1 expression and myocardial I/R injury was investigated. Hemodynamic parameters, myeloperoxidase (MPO), cardiac troponin I (cTnI) and tumor necrosis factor-alpha (TNF-alpha) were measured to assess the degree of injury and inflammation of myocardial tissues and cells. Egr-1 mRNA and protein expressions were examined by Northern-blot and Western-blot analyses.

RESULTS

Treatment with antisense Egr-1 ODN significantly reduced Egr-1 protein expression and attenuated injury of myocardial tissues and cells. Meanwhile, treatment with F(2) significantly inhibited the overexpression of Egr-1 mRNA and protein in myocardial tissues and cells. Consistent with downregulation of Egr-1 expression by F(2), inflammation and other damages were significantly relieved evidenced by the amelioration of hemodynamics, the reduction in myocardial MPO activity as well as the decrease in leakage of cTnI and release of TNF-alpha from cardiomyocyte.

CONCLUSIONS

These results suggested that the overexpression of Egr-1 was causative in myocardial I/R or H/R injury, and F(2) could protect myocardial tissues and cells from I/R or H/R injury, which was largely due to the inhibition of Egr-1 overexpression.