Toward antiapoptosis as a new treatment modality

Overview of mechanism of electroacupuncture pretreatment for prevention and treatment of cardiovascular and cerebrovascular diseases

Cardio-cerebrovascular disease (CCVD) is a serious threat to huma strategy to prevent the occurrence and development of disease by giving electroacupuncture intervention before the disease occurs. EAP has been shown in many preclinical studies to relieve ischemic symptoms and improve damage from ischemia-reperfusion, with no comprehensive review of its mechanisms in cardiovascular disease yet. In this paper, we first systematically discussed the meridian and acupoint selection law of EAP for CCVD and focused on the progress of the mechanism of action of EAP for the prevention and treatment of CCVD. As a result, in preclinical studies, AMI and MCAO models are commonly used to simulate ischemic injury in CCVD, while MIRI and CI/RI models are used to simulate reperfusion injury caused by blood flow recovery after focal tissue ischemia. According to the meridian matching rules of EAP for CCVD, PC6 in the pericardial meridian is the most commonly used acupoint in cardiovascular diseases, while GV20 in the Du meridian is the most commonly used acupoint in cerebrovascular diseases. In terms of intervention parameters, EAP intervention generally lasts for 30 min, with acupuncture depths mostly between 1.5 and 5 mm, stimulation intensities mostly at 1 mA, and commonly used frequencies being low frequencies. In terms of molecular mechanisms, the key pathways of EAP in preventing and treating cardiovascular and cerebrovascular diseases are partially similar. EAP can play a protective role in cardiovascular and cerebrovascular diseases by promoting autophagy, regulating Ca2+ overload, and promoting vascular regeneration through anti-inflammatory reactions, antioxidant stress, and anti-apoptosis. Of course, both pathways involved have their corresponding specificities. When using EAP to prevent and treat cardiovascular diseases, it involves the metabolic pathway of glutamate, while when using EAP to prevent and treat cerebrovascular diseases, it involves the homeostasis of the blood-brain barrier and the release of neurotransmitters and nutritional factors. I hope these data can provide experimental basis and reference for the clinical promotion and application of EAP in CCVD treatment.

Cardioprotective Effect of Nec-1 in Rats Subjected to MI/R: Downregulation of Autophagy-Like Cell Death

OBJECTIVE

Necrostatin-1 (Nec-1), an inhibitor of necroptosis, has been reported to protect against myocardial ischemia-reperfusion (MI/R) injury. However, the contribution of the potential antinecroptotic effect of Nec-1 on its infarct limitation and cardiac function improvement effects after MI/R has not been investigated.

METHODS

The present study investigated the effect of Nec-1 on myocardial infarct size, necroptosis, and cardiac functional recovery in rats subjected to myocardial ischemia-reperfusion (MI/R 30 min/12, 24, 48, and 72 h).

RESULTS

The study showed that Nec-1 might reduce myocardial cell death and maintain myoarchitectonic integrity, consequently inhibiting the reactive fibrosis process in rats in myocardial ischemia/late reperfusion. Moreover, the administration of Nec-1 (0.6 mg/kg) at the onset of reperfusion significantly reduced the release of creatine kinase and downregulation of autophagy within 24 h after reperfusion, and there was a significantly positive correlation between them.

CONCLUSION

These results suggest that antinecroptosis treatment may improve the clinical outcomes of patients with ischemic heart disease.

Cardiomyocyte-Specific COMMD1 Deletion Suppresses Ischemia-Induced Myocardial Apoptosis

Copper metabolism MURR domain 1 (COMMD1) increases in ischemic myocardium along with suppressed contractility. Cardiomyocyte-specific deletion of COMMD1 preserved myocardial contractile function in response to the same ischemic insult. This study was undertaken to test the hypothesis that cardiomyocyte protection in COMMD1 myocardium is responsible for the functional preservation of the heart in response to ischemic insult. After ischemic insult, there were significantly more cardiomyocytes in the cardiomyocyte-specific COMMD1 deletion myocardium than that in WT controls. This preservation of cardiomyocytes was paralleled by a significant suppression of apoptosis in the COMMD1 deletion myocardium compared to controls. In searching for the mechanistic understanding of the anti-apoptotic effect of COMMD1 deletion, we found the anti-apoptotic Bcl-2 mRNA and protein expression were upregulated and the pro-apoptotic Bax mRNA and protein expression were downregulated. The critical transcription factor RelA, maintaining a high ratio between Bcl-2 and Bax for anti-apoptotic action, was suppressed by ischemia, but was rescued in the COMMD1 deletion myocardium. Because COMMD1 is critically involved in RelA ubiquitination and degradation, the data obtained here demonstrate that COMMD1 deletion leads to RelA preservation in ischemic myocardium, promoting the Bcl-2 anti-apoptotic pathway and suppressing the Bax pro-apoptotic pathway, and in combination, leading to protection of cardiomyocytes from ischemia-induced apoptosis.

Long noncoding RNA NEAT1 sponges miR‑125a‑5p to suppress cardiomyocyte apoptosis via BCL2L12

Increasing evidence has suggested that long non‑coding RNA nuclear paraspeckle assembly transcript 1 (NEAT1) has critical roles in multiple biological processes; however, few studies have reported on its function in heart disease. The present study indicated that NEAT1 expression is markedly downregulated in cardiomyocytes following ischemia/reperfusion injury in vivo and hydrogen peroxide treatment in vitro. Further experiments suggested that ectopic overexpression of NEAT1 suppresses cardiomyocyte apoptosis induced by hydrogen peroxide, as assessed by TUNEL assay and flow cytometry. In addition, using a dual‑luciferase reporter assay, NEAT1 was demonstrated to directly interact with microRNA (miR)‑125a‑5p and overexpression of miR‑125a‑5p efficiently reversed the stimulatory effect of NEAT1 on B‑cell lymphoma‑2‑like 12 (BCL2L12) expression. Furthermore, the results indicated that NEAT1 inhibits cardiomyocyte apoptosis via regulating the expression of BCL2L12, which appeared to be mediated via miR‑125a‑5p. In conclusion, the present study suggested that NEAT1 functions as a miR sponge to inhibit cardiomyocyte apoptosis and may be a novel therapeutic target for cardiomyocyte apoptosis‑associated heart diseases.

Leonurine protects cardiac function following acute myocardial infarction through anti‑apoptosis by the PI3K/AKT/GSK3β signaling pathway

Leonurine is a compound derived from Herba leonuri, which has been reported to protect cardiac tissue against ischemic injury via antioxidant and anti‑apoptosis effects. The present study investigated whether these effects may be applied to acute myocardial infarction (MI) and examined the underlying mechanisms of leonurine treatment. A rat model of MI was induced by coronary artery ligation. Leonurine was administered at 15 mg/kg/day by oral gavage following the onset of MI. Rats in the sham group and the saline group were administered with an equal volume of saline. Echocardiography, Masson's trichrome staining, and terminal‑deoxynucleotidyl transferase‑mediated dUTP nick end labeling assays were performed 28 days post MI. The expression of B‑cell lymphoma‑2 and Bax were assessed by western blot analysis and reverse transcription‑quantitative polymerase chain reaction. Phosphoinositide 3‑kinase (PI3K), protein kinase B and glycogen synthase kinase‑3β (GSK3β) protein expression were investigated by western blot analysis. Leonurine significantly alleviated collagen deposition and MI size, inhibited cell apoptosis and improved myocardial function. This was accompanied by significantly increased levels of phosphorylated (p)‑PI3K, p‑AKT, p‑GSK3β and Bcl‑2, as well as significantly decreased levels of caspase3, cleaved‑caspase3 and Bax following MI. The results demonstrated that leonurine exerts potent cardio‑protective effects in a rat model of MI by inducing anti‑apoptotic effects by activating the PI3K/AKT/GSK3β signaling pathway.

Necroptotic cell death in failing heart: relevance and proposed mechanisms

As cardiomyocytes have a limited capability for proliferation, renewal, and repair, the loss of heart cells followed by replacement with fibrous tissue is considered to result in the development of ventricular dysfunction and progression to heart failure (HF). The loss of cardiac myocytes in HF has been traditionally believed to occur mainly due to programmed apoptosis or unregulated necrosis. While extensive research work is being carried out to define the exact significance and contribution of both these cell death modalities in the development of HF, recent knowledge has indicated the existence and importance of a different form of cell death called necroptosis in the failing heart. This new cell damaging process, resembling some of the morphological features of passive necrosis as well as maladaptive autophagy, is a programmed process and is orchestrated by a complex set of proteins involving receptor-interacting protein kinase 1 and 3 (RIP1, RIP3) and mixed lineage kinase domain-like protein (MLKL). Activation of the RIP1-RIP3-MLKL signaling pathway leads to disruption of cation homeostasis, plasma membrane rupture, and finally cell death. It seems likely that inhibition of any site in this pathway may prove as an effective pharmacological intervention for preventing the necroptotic cell death in the failing heart. This review is intended to describe general aspects of the signaling pathway associated with necroptosis, to describe its relationship with cardiac dysfunction in some models of cardiac injury and discuss its potential relevance in various types of HF with respect to the underlying pathologic mechanisms.

TGF-β improves myocardial function and prevents apoptosis induced by anoxia-reoxygenation, through the reduction of endoplasmic reticulum stress

BACKGROUND

Transforming growth factor-β (TGF-β) is known for its role in ventricular remodeling, inflammatory response, cell survival, and apoptosis. However, its role in improving myocardial function in rat hearts subjected to ischemia-reperfusion (I/R) and protecting against apoptosis induced in cardiomyocytes by anoxia-reoxygenation (A/R) has not been elucidated. This study investigated the protective effects and molecular mechanisms of TGF-β on myocardial function and cardiomyocyte apoptosis.

METHODS AND RESULTS

We used TUNEL staining, we tested cell viability, and we measured mitochondrial membrane potential and levels of mitochondrial ROS after 6 h of simulated anoxia together with various durations of simulated reoxygenation in H9c2 cells. We further observed the contractile function in rat hearts after they were subjected to 30 min global ischemia and 180 min reperfusion. Pretreatment with TGF-β markedly inhibited apoptosis in H9c2 cells, as evidenced by increased cell viability and decreased numbers of TUNEL-positive cells, maintained mitochondrial membrane potential, and diminished mitochondrial production of reactive oxygen species (ROS). These changes were associated with the inhibition of endoplasmic reticulum (ER) stress-dependent markers of apoptosis (GRP78, CHOP, caspase-12, and JNK), and the modulation of the expression of Bcl2/Bax. Furthermore, TGF-β improved I/R-induced myocardial contractile dysfunction. All of these protective effects were concentration-dependent.

CONCLUSION

Our results show that TGF-β prevents A/R-induced apoptosis of cardiomyocytes and improves myocardial function in rat hearts injured by I/R.

Survivin gene therapy attenuates left ventricular systolic dysfunction in doxorubicin cardiomyopathy by reducing apoptosis and fibrosis

AIMS

The aim of this study was to investigate anti-apoptotic gene therapy using ultrasound-mediated plasmid delivery of survivin, an inhibitor of apoptosis protein, to prevent apoptosis and to attenuate left ventricular (LV) systolic dysfunction in a model of heart failure induced by doxorubicin.

METHODS AND RESULTS

Effect of survivin transduction was investigated in vitro in rat cardiomyoblasts. After survivin transduction, survivin protein was detected in cell culture supernate confirming secretion of extracellular survivin. Under doxorubicin stimulation, survivin-transduced cells had significantly reduced apoptosis; however, incubation with survivin-conditioned media also showed reduced apoptosis that was absent with null-conditioned media. Doxorubicin-induced cardiomyopathy was established in Fischer rats. Subsets of animals underwent ultrasound-mediated survivin gene delivery or empty vector gene delivery at Week 3. Control rats received doxorubicin alone. Animals were studied using PCR, immunohistochemistry, echocardiography, and invasive haemodynamic studies out to Week 6. By Week 6, LV % fractional shortening by echocardiography and systolic function by pressure-volume loops were greater in survivin treated when compared with control- and empty-treated animals. There was reduced apoptosis by TUNEL and caspase activity in survivin-treated animals compared with control and empty treated at Week 4, with reduced interstitial fibrosis at Week 6.

CONCLUSION

Survivin gene therapy can attenuate the progression of LV systolic dysfunction in doxorubicin cardiomyopathy. This effect can be attributed to decreased myocyte apoptosis and prevention of maladaptive LV remodelling, by both direct myocyte transfection and potentially by paracrine mechanisms.

Magnesium lithospermate B improves myocardial function and prevents simulated ischemia/reperfusion injury-induced H9c2 cardiomyocytes apoptosis through Akt-dependent pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Magnesium lithospermate B (MLB), an active polyphenol acid of Radix Salviae Miltiorrhizae (Danshen), showed a wide range of pharmacological activities in cardiovascular diseases. However, its role in protection against ischemia/reperfusion injury in H9c2 cardiomyocytes has not been elucidated. This study was aimed to investigate the protective effect and potential molecular mechanisms of MLB on apoptosis in H9c2 cardiomyocytes in vitro.

MATERIALS AND METHODS

We tested cell viability, shortening amplitude, necrosis, apoptosis, and the expression levels of Akt, phosphorylated Akt, Bcl-2 and Bax after 2-h simulated ischemia and 24-h simulated reperfusion in H9c2 cardiomyocytes. We further observed the contractile function in hearts after they were subjected to global 30-min ischemia and 180-min reperfusion.

RESULTS

Pretreatment with MLB markedly increased cell viability and while reducing evidence of necrosis and apoptosis in H9c2 cardiomyocytes. In addition, the expression of Bcl-2 and Bax protein was modulated. The results also showed that MLB significantly increased phosphorylation of Akt and that this phosphorylation can be partially inhibited by phosphoinositide 3-kinase/Akt inhibitor. Furthermore, MLB improved MI/R-induced myocardial contractile function.

CONCLUSION

Our results showed that MLB prevents I/R-induced myocardial damage by reducing necrosis and apoptosis in H9c2 cardiomyocytes and improving myocardial function in rat hearts.

In vivo gene delivery of XIAP protects against myocardial apoptosis and infarction following ischemia/reperfusion in conscious rabbits

AIMS

We tested the hypothesis that an in vivo gene delivery of the pro-survival protein XIAP (X-chromosome linked inhibitor of apoptosis protein) protects against myocardial apoptosis and infarction following ischemia/reperfusion.

MAIN METHODS

Nineteen rabbits were chronically instrumented with a hydraulic occluder placed around the circumflex coronary artery. Adenovirus harboring XIAP (Ad.XIAP; 1×10(10)pfu/ml) or β-galactosidase (5×10(9)pfu/ml), as a control, was constructed and transfected into the heart using a catheter placed into the left ventricle accompanied by cross-clamping. 1-2weeks after gene delivery, myocardial ischemia was induced by a 30-min occlusion followed by reperfusion for four days. Protein expression was determined by Western blot and apoptosis (% of myocytes) was quantified by TUNEL staining.

KEY FINDINGS

Myocardial infarct size, expressed as a fraction of the area at risk, was reduced in Ad.XIAP (n=5) compared to control (n=7) rabbits (21±3% vs. 30±2%, p<0.05). Apoptosis was reduced in Ad.XIAP rabbits compared to control rabbits (2.96±0.68% vs. 8.98±1.84%, p<0.01). This was associated with an approximate 60% decrease in the cleaved caspase-3 level in Ad.XIAP rabbits compared to control rabbits.

SIGNIFICANCE

The current findings demonstrate that overexpression of XIAP via in vivo delivery in an adenovirus can reduce both myocardial apoptosis and infarction following ischemia/reperfusion, at least in part, due to the ability of XIAP to inhibit caspase-3. These findings confirm previous work suggesting a link between myocardial apoptosis and infarction i.e., anti-apoptotic therapy was effective in reducing myocardial infarct size.

Activated protein C protects myocardium via activation of anti-apoptotic pathways of survival in ischemia-reperfused rat heart

Activated protein C (APC) is known to be beneficial on ischemia reperfusion injury in myocardium. However, the protection mechanism of APC is not fully understood. The purpose of this study was to investigate the effects and possible mechanisms of APC on myocardial ischemic damage. Artificially ventilated anaesthetized Sprague-Dawley rats were subjected to a 30 min of left anterior descending coronary artery occlusion followed by 2 hr of reperfusion. Rats were randomly divided into four groups; Sham, I/R, APC preconditioning and postconditioning group. Myocardial infarct size, apoptosis index, the phosphorylation of ERK1/2, Bcl-2, Bax and cytochrome c genes and proteins were assessed. In APC-administrated rat hearts, regardless of the timing of administration, infarct size was consistently reduced compared to ischemia/reperfusion (I/R) rats. APC improved the expression of ERK1/2 and anti-apoptotic protein Bcl-2 which were significantly reduced in the I/R rats. APC reduced the expression of pro-apoptotic genes, Bax and cytochrome c. These findings suggest that APC produces cardioprotective effect by preserving the expression of proteins and genes involved in anti-apoptotic pathways, regardless of the timing of administration.

Bacopa monniera protects rat heart against ischaemia–reperfusion injury: role of key apoptotic regulatory proteins and enzymes

Objectives

Rat isolated hearts were perfused in a Langendorff model to study the cardioprotective effects of Bacopa monniera, a medicinal herb used in the Indian system of medicine, on cardiomyocyte apoptosis and antioxidant status following ischaemia–reperfusion (I-R) injury.

Methods

Forty-eight rats were randomly divided into four groups (12 in each group): sham group (no ischaemia–reperfusion injury), B. monniera control group (orally fed B. monniera at a dose of 75 mg/kg, for three weeks); ischaemia–reperfusion control group(subjected to ischaemia–reperfusion-induced myocardial injury) and B. monniera-treated group (same protocol as ischaemia–reperfusion control group except that rats also fed B. monniera).

Key findings

Post-ischaemic reperfusion injury resulted in significant cardiac necrosis, apoptosis, depression of heart rate, decline in antioxidant status and elevation in lipid peroxidation. Oral administration of B. monniera per se for three weeks to healthy rats caused augmentation of myocardial antioxidants, superoxide dismutase, catalase and glutathione, along with induction of heat shock protein 72 (HSP72). Ischaemia–reperfusion-induced biochemical and histopathological perturbations were significantly prevented by B. monniera (75 mg/kg) pre-treatment. Interestingly, B. monniera also restored the antioxidant network of the myocardium and reduced myocardial apoptosis, caspase 3 and Bax protein expression.

Conclusions

Histopathological studies and myocardial creatine phosphokinase content further confirmed the cardioprotective effects of B. monniera (75 mg/kg) in the experimental model of ischaemia–reperfusion injury. The study provides scientific basis for the putative therapeutic effect of B. monniera in ischaemic heart disease.

Blockade of spinal nerves attenuates myocardial apoptosis in acute myocardial ischaemia/infarction in rats

BACKGROUND AND OBJECTIVES

Evidence showed involvement of neural activity in acute myocardial ischaemia but the knowledge about the role in the pathology is still limited. The objective of this study was to examine whether low cervical and upper thoracic epidural anaesthesia could reduce apoptosis of the myocardium induced by 3-h and 6-h permanent coronary artery occlusion (CAO) in rats.

METHODS

The left anterior descending branch of coronary artery was ligated in anaesthetized Sprague-Dawley rats with and without precondition of epidural anaesthesia at the level of upper thoracic segments. Apoptosis of the myocardium insulted by acute myocardial ischaemia and infarction was assessed using terminal deoxynucleotidyl transferase-mediated dUTP nick endlabelling and caspase assay.

RESULTS

The apoptotic rates of the myocytes were 16.90 +/- 1.38 and 19.75 +/- 1.47% in the groups of CAO 3 h and CAO 6 h, respectively, whereas in the epidural groups, 10.25 +/- 1.07 and 13.05 +/- 1.19% of the apoptotic rates were detected at 3 and 6 h of CAO, significantly lower than that in the time-matched CAO animals without epidural anaesthesia (P < 0.01). Lower caspase-3 activity was observed in epidural anaesthesia group, 1.41 +/- 0.11 folds of the sham (versus 1.86 +/- 0.14 folds in CAO-3 h group) and 2.0 +/- 0.18 folds (versus 2.87 +/- 0.20 folds in CAO-6 h group) at 3 and 6 h of CAO, respectively, which were statistically significant (P < 0.05).

CONCLUSION

The findings may indicate blockade of spinal nerves could reduce apoptosis of myocardium in acute myocardial ischaemia and infarction.

Myocardial remodelling induced by repeated low doses of isoproterenol

In the present work, the effect of isoproterenol on the electrical properties of the rat heart and on the cytoarchitecture of the surviving cardiomyocytes was studied. Myocardial remodelling was induced by the daily administration of 5 mg/kg isoproterenol (Iso) for 7 days. Administration resulted in a significant increase (52%) in the ratio of left ventricular weight to body weight. ECG voltage criteria confirmed the presence of left ventricular hypertrophy. QT interval prolongation by 23% and 58% was found in Iso rats and in the corresponding isolated hearts, respectively. Spontaneously beating Iso hearts had a higher incidence of dysrhythmias. The surviving cardiomyocytes showed an irregular shape with cytoplasmic processes rich in ribosomes and rough endoplasmic reticulum. In these regions, myofibril disorganization and mitochondrial fission were observed. A greatly increased incidence of caveolae was seen in the plasma membrane and in the mouth of t-tubules. The membranes of t-tubules showed vesiculation, especially near the dyads. Repeated administration of isoproterenol led to hypertrophy, characterized by the existence of myocytes with simultaneous signs of both mature and postnatally developing cardiomyocytes. Structural microheterogeneities at the level of individual cells may represent one of the factors leading to electrical imbalance in the myocardial tissue remodelled by isoproterenol.

FAK regulates cardiomyocyte survival following ischemia/reperfusion

Myocyte apoptosis is central to myocardial dysfunction following ischemia/reperfusion (I/R) and during the transition from hypertrophy to heart failure. Focal adhesion kinase (FAK), a non-receptor tyrosine kinase regulates adhesion-dependent survival signals and unopposed FAK activation has been linked to tumor development. We previously showed that conditional myocyte-specific deletion of FAK (MFKO) in the adult heart did not affect basal cardiomyocyte survival or cardiac function but led to dilated cardiomyopathy and heart failure following pressure overload. In the present study, we sought to determine if FAK functions to limit stress-induced cardiomyocyte apoptosis. We reasoned that (I/R), which stimulates robust apoptotic cell death, might uncover an important cardioprotective function for FAK. We found that depletion of FAK markedly exacerbates hypoxia/re-oxygenation-induced cardiomyocyte cell death in vitro. Moreover, deletion of FAK in the adult myocardium resulted in significant increases in I/R-induced infarct size and cardiomyocyte apoptosis with a concomitant reduction in left ventricular function. Finally, our results suggest that NF-kappaB signaling may play a key role in modulating FAK-dependent cardioprotection, since FAK inactivation blunted activation of the NF-kappaB survival signaling pathway and reduced levels of the NF-kappaB target genes, Bcl2 and Bcl-xl. Since the toggling between pro-survival and pro-apoptotic signals remains central to preventing irreversible damage to the heart, we conclude that targeted FAK activation may be beneficial for protecting stress-dependent cardiac remodeling.

Anti-Apoptotic Effect of Magnolol in Myocardial Ischemia and Reperfusion Injury Requires Extracellular Signal-Regulated Kinase1/2 Pathways in RatIn Vivo

Magnolol, an active component extracted from Magnolia officinalis, has been reported to have protective effect on ischemia and reperfusion (I/R)-induced injury in experimental animals. The aim of the present investigation was to further evaluate the mechanism(s) by which magnolol reduces I/R-induced myocardial injury in rats in vivo. Under anesthesia, left anterior descending (LAD) coronary artery was occluded for 30 min followed by reperfusion for 24 h (for infarct size and cardiac function analysis). In some experiments, reperfusion was limited to 1 h or 6 h for analysis of biochemical and molecular events. Magnolol and DMSO solution (vehicle) were injected intra-peritoneally 1 h prior to I/R insult. The infarct size was measured by TTC technique and heart function was monitored by Millar Catheter. Apoptosis related events such as p-ERK, p-Bad, Bcl-xl and cytochrome c expression were evaluated by Western blot analysis and myocardial caspase-3 activity was also measured. Magnolol (10 mg/kg) reduced infarct size by 50% ( P < 0.01 versus vehicle), and also improved I/R-induced myocardial dysfunction. Left ventricular systolic pressure and positive and negative maximal values of the first derivative of left ventricular pressure (dP/dt) were significantly improved in magnolol-treated rats. Magnolol increased the expression of phosphor ERK and Bad which resulted in inhibition of myocardial apoptosis as evidenced by TUNEL analysis and DNA laddering experiments. Application of PD 98059, a selective MEK1/2 inhibitor, strongly antagonized the effect of magnolol. Taken together, we concluded that magnolol inhibits apoptosis through enhancing the activation of ERK1/2 and modulation of the Bcl-xl proteins which brings about reduction of infarct size and improvement of cardiac function in I/R-induced injury.

Pathogenesis of chronic heart failure: change of dominating paradigm

The review considers literature data reflecting the evolution of views on pathogenesis of chronic heart failure. Connection of revision of a dominating paradigm of pathogenesis at every stage of development of cardiology with changes in approaches to therapy of chronic heart failure is analyzed.

Caspases in myocardial infarction

The discovery of apoptosis sheds a new light on the role of cell death in myocardial infarction and other cardiovascular diseases. There is mounting evidence that apoptosis plays an important role at multiple points in the evolution of myocardial infarction, and comprises not only cardiomyocytes but also inflammatory cells, as well as cells of granulation tissue and fibrous tissue. It appears that apoptosis contributes to cardiomyocyte loss in the border zone and in remote myocardium in the early phase, as well as months after myocardial infarction, thus playing a role in remodeling and development of heart failure after myocardial infarction. Apoptosis, being a highly regulated process, is a potential target for therapeutic intervention. Caspases are the key effector molecules in apoptosis, and are therefore a particularly attractive target for pharmacological modulation of apoptosis. Although several potential therapeutic agents have been tested in animal models of ischemia/reperfusion heart injury with some success, nearly none of the specific antiapoptotic agents have reached the stage of clinical research.

Effect of pioglitazone, a peroxisome proliferator-activated receptor gamma agonist, on ischemia-reperfusion injury in rats

Two groups of rats were used to examine the effect of pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, on rat hearts using an in vivo model of ischemia-reperfusion (I/R) to elucidate potential mechanisms. One group was the 30-min reperfusion group, which was further subdivided into sham (n=5), vehicle (n=6) and pioglitazone (3 mg x kg(-1), n=7) treatment groups with 30 min ischemia followed by 30 min reperfusion to detect data related to cardiac function and the area of myocardial infarction. The other group was the 120-min reperfusion group, subdivided into sham (n=5), vehicle (n=6), and pioglitazone 0.3 mg x kg(-1) (n=6), 1 mg x kg(-1) (n=7) and 3 mg x kg(-1) (n=6) treatment groups. Immunohistochemistry, in situ hybridization, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) and DNA agarose gel electrophoresis were performed to detect apoptosis and expressions of Bax, Bcl-2, caspase 3, MMP-2 and PPARgamma protein, and MMP-2 and PPARgamma mRNA. We found that, after acute treatment with pioglitazone, the ratio of necrosis to area at risk decreased by 28% (p<0.01) and that of necrosis to left ventricle was reduced by 32% (p<0.01), compared with the vehicle group. Heart rate and +dp/dt(max), representing the cardiac systolic function, as well as -dp/dt(max), the indicator of cardiac diastolic function, improved significantly at 1 and 30 min after reperfusion (p<0.05-0.01). Furthermore, myocardial apoptosis was significantly suppressed by acute treatment with pioglitazone as evidenced by the decreased number of TUNEL-positive myocytes and DNA ladder, enhanced Bcl-2 protein expression, reduced Bax and caspase 3 protein expression in a dose-dependent manner compared with vehicle-treated rats. In addition, acute treatment with pioglitazone dose-dependently increased PPARgamma expression and decreased MMP-2 expression at protein and mRNA levels. Our findings demonstrate that a PPARgamma agonist may protect the heart from I/R injury. The protective effect is likely to occur by reducing cardiomyocyte apoptosis and inhibiting MMP-2.

Bax deficiency reduces infarct size and improves long-term function after myocardial infarction

We have previously found that, following myocardial ischemia/reperfusion injury, isolated hearts from bax gene knockout mice [Bax(-/-)] exhibited higher cardioprotection than the wild-type. We here explore the effect of Bax(-/-), following myocardial infarction (MI) in vivo. Homozygotic Bax(-/-) and matched wild-type were studied. Mice underwent surgical ligation of the left anterior descending coronary artery (LAD). The progressive increase in left-ventricular end diastolic diameter, end systolic diameter, in Bax(-/-) was significantly smaller than in Bax(+/+) at 28 d following MI (p < 0.03) as seen by echocardiography. Concomitantly, fractional shortening was higher (35 +/- 4.1% and 27 +/- 2.5%, p < 0.001) and infarct size was smaller in Bax(-/-) compared to the wild-type at 28 days following MI (24 +/- 3.7 % and 37 +/- 3.3%, p < 0.001). Creatine kinase and lactate dehydrogenase release in serum were lower in Bax(-/-) than in Bax(+/+) 24 h following MI. Caspase 3 activity was elevated at 2 h after MI only in the wild-type, but reduced to baseline values at 1 and 28 d post-MI. Bax knockout mice hearts demonstrated reduced infarct size and improved myocardial function following permanent coronary artery occlusion. The Bax gene appears to play a significant role in the post-MI response that should be further investigated.

Corydalis yanhusuo rhizoma extract reduces infarct size and improves heart function during myocardial ischemia/reperfusion by inhibiting apoptosis in rats

The aim of the present investigation was to evaluate the effect of an extract from Corydalis yanhusuo W.T., a Chinese herbal medicine, on ischemia/reperfusion (I/R) injury and to determine the mechanism(s) involved. In rats, the left anterior descending (LAD) coronary artery was occluded for 30 min and then reperfused for 6 h. 0.5% carboxymethyl cellulose sodium was used as a vehicle (I/R control group) and Corydalis yanhusuo rhizoma extract (I/R + CY 200, 100 mg/kg groups) were given. Infarct size and hemodynamic parameters were measured. Apoptosis was detected quantitatively by the terminal transferase dUTP nick end-labeling (TUNEL) method and confirmed by DNA laddering on agarose gel. The expression of anti-apoptotic Bcl-2 and pro-apoptotic Bax proteins was visualized by western blot analysis. In contrast to the I/R control group, administration with CY 200 mg/kg resulted in a significant reduction in the infarct size and an improvement in heart function as evidenced by higher LVSP and +/-dp/dtmax. TUNEL-positive cells in the ischemic myocardium were also significantly reduced in the I/R + CY 200, 100 mg/kg groups, consistent with little DNA laddering in these two groups. Furthermore, greater Bcl-2 and attenuated Bax expression was found in the CY treated rats. These results suggest that the protective effect of Corydalis yanhusuo on myocardial I/R injury is closely associated with the inhibition of myocardial apoptosis through modulation of the Bcl-2 family.

The E23K polymorphism in Kir6.2 gene and coronary heart disease

BACKGROUND

The G to A mutation in the Kir 6.2, the ATP-sensitive potassium channel subunit, resulted a glutamate (E) to lysine (K) substitution at codon 23, and the A allele was shown to have a relationship with high risk to type 2 diabetes in previous study. Their role in coronary heart disease (CHD) has not been evaluated. We hypothesized that the polymorphism would be associated with increased susceptibility to CHD.

METHODS

The E23K gene polymorphism of Kir6.2 gene was analyzed by PCR-restriction site polymorphism (PCR-RSP) methods in 101 controls and 119 CHD patients. Serum lipids and C reactive protein concentrations were measured in all subjects.

RESULTS

Among the CHD patients, the frequency of the G allele was higher (63.4% vs. 56.9%, P>0.05) and the frequency of the A allele was lower (36.6% vs. 43.1%, P>0.05) than among controls. No significant differences were found in allele frequencies between CHD and controls (P>0.05), but there were significant differences in GG and combined (GA+AA) genotypes frequencies (42.0% vs. 28.7%, and 58.0% vs. 71.3%, P<0.050).

CONCLUSIONS

The E23K gene polymorphism in Kir6.2 gene appeared to be related to high susceptibility to CHD.

Studies on the Apoptotic Activity of Natural and Synthetic Retinoids: Discovery of a New Class of Synthetic Terphenyls That Potently Support Cell Growth and Inhibit Apoptosis in Neuronal and HL-60 Cells

New terphenyl derivatives have been synthesized and tested for their effect on cell survival in serum-free cultures. These compounds protected HL60 cells from death and supported their growth with an activity higher than that of the natural 14-hydroxy-retro-retinol. Terphenyls 26 and 28 also possess antiapoptotic activity on neuronal cells, proving them as possible candidates for the treatment of neurodegenerative and ischemic diseases.

Ischemia/reperfusion injury: a review in relation to free tissue transfers

Events during ischemia/reperfusion (I/R) injury include: neutrophil-mediated endothelial cytotoxicity and activation, generation of free radicals, triggering of cytokines and chemokines, and activation of adhesion molecules and complement system. This article briefly reviews events occurring during tissue ischemia and reperfusion in relation to free tissue transfers. The consequences of tissue damage at the microcirculatory level are presented. Preventive measures of I/R injury are outlined.

Caspase inhibition attenuates contractile dysfunction following cardioplegic arrest and rewarming in the setting of left ventricular failure

Hyperkalemic cardioplegic arrest (HCA) and rewarming evokes postoperative myocyte contractile dysfunction, a phenomenon of particular importance in settings of preexisting left ventricular (LV) failure. Caspases are intracellular proteolytic enzymes recently demonstrated to degrade myocardial contractile proteins. This study tested the hypothesis that myocyte contractile dysfunction induced by HCA could be ameliorated with caspase inhibition in the setting of compromised myocardial function. LV myocytes were isolated from control pigs (n = 9, 30 kg) or pigs with LV failure induced by rapid pacing (n = 6, 240 bpm for 21 days) and were randomized to the following: (1) normothermia (2003 myocytes), incubation in cell culture medium for 2 hours at 37 degrees C; (2) HCA only (506 myocytes), incubation for 2 hours in hypothermic HCA solution (4 degrees C, 24 mEq K); or (3) HCA + z-VAD, incubation in hypothermic HCA solution supplemented with 10 microM of the caspase inhibitor z-VAD (z-Val-Ala-Asp-fluoromethyl-ketone, 415 myocytes). Inotropic responsiveness was examined using beta-adrenergic stimulation (25 nM isoproterenol). Ambient normothermic myocyte shortening velocity (microm/s) was reduced with LV failure compared with control values (54 +/- 2 versus 75 +/- 2, respectively, P < 0.05). Following HCA, shortening velocity decreased in the LV failure and control groups (27 +/- 5 and 45 +/- 3, P < 0.05). Institution of z-VAD increased myocyte shortening velocity following HCA in both the LV failure and control groups (49 +/- 5 and 65 +/- 5, P < 0.05). Moreover, HCA supplementation with z-VAD increased beta-adrenergic responsiveness in both groups compared with HCA-only values. This study provides proof of concept that caspase activity contributes to myocyte contractile dysfunction following simulated HCA. Pharmacologic caspase inhibition may hold particular relevance in the execution of cardiac surgical procedures requiring HCA in the context of preexisting LV failure.

Leptin does not induce hypertrophy, cell cycle alterations, or production of MCP-1 in cultured rat and mouse cardiomyocytes

BACKGROUND

Leptin has been proposed as an important mediator in cardiovascular pathophysiology. Patients with congestive heart failure (CHF) present high plasma leptin levels. CHF is generally preceded by myocardial remodeling involving hypertrophy, necrosis, and apoptosis.

AIM

To investigate whether leptin causes hypertrophy or cell cycle alterations, or induces MCP-1 synthesis in cardiomyocytes.

METHODS

Primary cultures of neonatal rat cardiomyocytes (PC) and murine cell line HL-1 were used. RT-PCR was used to identify Ob-Rb gene expression. Metabolic activity and proliferation of cardiomyocytes was studied using MTT and BrdU uptake, while apoptosis was assayed with Hoechst dye vital staining and flow cytometry. Measurement of the cell surface area was used to determine hypertrophy. MCP-1 levels were measured by ELISA.

RESULTS

RT-PCR showed Ob-Rb mRNA expression in HL-1 cells. Exposure to leptin induced no changes in metabolic activity, proliferation, and apoptotic rates, and did not alter cell cycle in cardiomyocytes. Leptin did not increase cell size of cardiomyocytes, and MCP-1 synthesis was not detected in PC and HL-1 cells treated with leptin.

CONCLUSION

This work shows that leptin does not induce changes in viability, proliferation, size or apoptosis of rat neonatal and HL-1 cardiomyocytes, and it does not induce MCP-1 secretion in these cells.

Gene therapy for chronic myocardial ischemia using platelet-derived endothelial cell growth factor in dogs

Platelet-derived endothelial cell growth factor (PD-ECGF), also known as thymidine phosphorylase (TP), has been reported to possess angiogenic activity and to inhibit apoptosis. This study was performed to determine whether PD-ECGF/TP can be used to ameliorate chronic myocardial ischemia. Myocardial ischemia was created in 40 mongrel dogs by placement of an ameroid constrictor on the proximal left anterior descending coronary artery (LAD). Plasmid vector encoding human PD-ECGF/TP cDNA (pCIhTP group; n = 12), empty vector pCI (pCI group; n = 12), or saline (Saline group; n = 12) was directly injected into the LAD territory 3 wk after ameroid constrictor implantation. Myocardial blood flow was detected using PET at baseline, 3 wk after ameroid constrictor implantation, and 2 wk after therapeutic treatment. At the end of the experiment, the hearts were isolated for biological and histological analysis. In the pCIhTP group, the transfected heart strongly expressed PD-ECGF/TP. The size of the infarct was smaller in the pCIhTP group than in the pCI or Saline group. The number of apoptotic myocardial cells was decreased in the pCIhTP group compared with the control groups based on triple immunohistochemical staining for von Willebrand factor, alpha-actin smooth muscle cells, and single-strand DNA. The level of proapoptotic protein Bax markedly decreased in the pCIhTP group compared with the other groups. Double immunohistochemical staining for von Willebrand factor and alpha-actin smooth muscle cells demonstrated that angiogenesis and arteriogenesis occurred, and paralleled the changes in myocardial blood flow and myocardial function in the pCIhTP group. We conclude that genetic approaches using PD-ECGF/TP to target the myocardium are effective for alleviating chronic myocardial ischemia.

Apoptosis and oxidants in the heart

Cardiomyocyte (CM) apoptosis has been reported in a variety of cardiovascular diseases, including myocardial infarction, ischemia/reperfusion, end-stage heart failure, arrhythmogenic right ventricular dysplasia, and adriamycin-induced cardiomyopathy. The role of CM apoptosis in the development and progression of cardiac diseases merits further investigation. Cumulative evidence suggests that reactive oxygen species (ROS), which have been implicated in cardiac pathophysiology, can trigger myocyte apoptosis by up-regulating proapoptotic proteins, such as Bax and caspases, and the mitochondria-dependent pathway. These apoptotic proteins and pathways are inhibited by various antioxidants, as well as by overexpression of the antiapoptotic protein Bcl-2 by way of the antioxidant pathway. Detection of CM apoptosis with the terminal transferase-mediated DNA nick-end labeling assay alone has recently been questioned because of technical concerns regarding its sensitivity and specificity. Because CMs are mononuclear or binuclear, if only one nucleus or a certain percentage of fragmented nuclei is stained with TUNEL assay at the early stage of apoptotic cell death, it remains unknown whether this particular early apoptotic CM is still functionally active. The issue of TUNEL specificity further questions reports of high percentages of apoptotic CM nuclei (0.02%-35%) in the heart. Nevertheless, oxidative stress is a major apoptotic stimulus in many cardiovascular diseases and the process can be inhibited by antioxidants both in vitro and in vivo.

Bax ablation protects against myocardial ischemia-reperfusion injury in transgenic mice

The role of the proapototic Bax gene in ischemia-reperfusion (I/R) injury was studied in three groups of mice: homozygotic knockout mice lacking the Bax gene (Bax(-/-)), heterozygotic mice (Bax(+/-)), and wild-type mice (Bax(+/+)). Isolated hearts were subjected to ischemia (30 min, 37 degrees C) and then to 120 min of reperfusion. The left ventricular developed force of Bax-deficient vs. Bax(+/+) hearts at stabilization and at 120 min of reperfusion was 1,411 +/- 177 vs. 1,161 +/- 137 mg and 485 +/- 69 vs. 306 +/- 68 mg, respectively. Superior cardiac function of Bax(-/-) hearts after I/R was accompanied by a decrease in creatine kinase release, caspase 3 activity, irreversible ischemic injury, and the number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cardiomyocytes. Electron microscopic evaluation revealed reduced damage to mitochondria and the nuclear chromatin structure in Bax-deficient mice. In the Bax(+/-) hearts, the damage markers were moderate. The superior tolerance of Bax knockout hearts to I/R injury recommends this gene as a potential target for therapeutic intervention in patients with severe and intractable myocardial ischemia.

Apoptosis in heart: basic mechanisms and implications in cardiovascular diseases

Apoptosis has been implicated in both acute and chronic heart diseases. The loss of myocardium is an important pathogenic process in heart and, hence, the inhibition of apoptosis is a promising therapeutic option. Significant progress has been made in demonstrating the role of apoptosis in various heart diseases, and in elucidating the molecular mechanisms of cardiac apoptosis. In addition, the effects of various hypertrophic signaling molecules on apoptosis have been characterized. However, the significance of apoptosis to the overall pathogenesis of heart failure, and the relationship between cardiac hypertrophic signaling and apoptosis still needs further investigation.

Cell death induced by acute renal injury: a perspective on the contributions of apoptosis and necrosis

In humans and experimental models of renal ischemia, tubular cells in various nephron segments undergo necrotic and/or apoptotic cell death. Various factors, including nucleotide depletion, electrolyte imbalance, reactive oxygen species, endonucleases, disruption of mitochondrial integrity, and activation of various components of the apoptotic machinery, have been implicated in renal cell vulnerability. Several approaches to limit the injury and augment the regeneration process, including nucleotide repletion, administration of growth factors, reactive oxygen species scavengers, and inhibition of inducers and executioners of cell death, proved to be effective in animal models. Nevertheless, an effective approach to limit or prevent ischemic renal injury in humans remains elusive, primarily because of an incomplete understanding of the mechanisms of cellular injury. Elucidation of cell death pathways in animal models in the setting of renal injury and extrapolation of the findings to humans will aid in the design of potential therapeutic strategies. This review evaluates our understanding of the molecular signaling events in apoptotic and necrotic cell death and the contribution of various molecular components of these pathways to renal injury.

Tumor necrosis factor alpha induces a caspase-independent death pathway in human neutrophils

Tumor necrosis factor alpha (TNF-alpha) is a cytokine with multiple roles in the immune system, including the induction and potentiation of cellular functions in neutrophils (PMNs). TNF-alpha also induces apoptotic signals leading to the activation of several caspases, which are involved in different steps of the process of cell death. Inhibition of caspases usually increases cell survival. Here, we found that inhibition of caspases by the general caspase inhibitor zVAD-fmk did not prevent TNF-alpha-induced PMN death. After 6 hours of incubation, TNF-alpha alone caused PMN death with characteristic apoptotic features (typical morphologic changes, DNA laddering, external phosphatidyl serine [PS] exposure in the plasma membrane, Bax clustering and translocation to the mitochondria, and degradation of mitochondria), which coincided with activation of caspase-8 and caspase-3. However, in the presence of TNF-alpha, PMNs died even when caspases were completely inhibited. This type of cell death lacked nuclear features of apoptosis (ie, no DNA laddering but aberrant hyperlobulated nuclei without typical chromatin condensation) and demonstrated no Bax redistribution, but it did show mitochondria clustering and plasma membrane PS exposure. In contrast, Fas-triggered PMN apoptosis was completely blocked by zVAD-fmk. Experiments with scavengers of reactive oxygen species (ROS) and with inhibitors of mitochondrial respiration, with PMN-derived cytoplasts (which lack mitochondria) and with PMNs from patients with chronic granulomatous disease (which have impaired nicotinamide adenine dinucleotide phosphate [NADPH] oxidase) indicated that TNF-alpha/zVAD-fmk-induced cell death depends on mitochondria-derived ROS. Thus, TNF-alpha can induce a "classical," caspase-dependent and a "nonclassical" caspase-independent cell death.

Emerging therapeutic targets in chronic heart failure: part II

Chronic heart failure is characterised by functional deficiencies of the myocardium. Structural abnormalities of the left ventricular wall occur in many cases as a consequence of myocardial infarction (MI). The overburdened postMI heart is characterised by an active reorganisation of the remaining myocardium. Increased expression and activity of matrix metalloproteinases lead to altered composition and arrangement of the extracellular matrix, which is accompanied by eccentric hypertrophy of cardiomyocytes. The altered geometry of the heart muscle fosters biomechanical stress, driving the heart into a dead-end situation. Clearly, novel therapeutic concepts must be developed to reverse this process. Part II of the current review will focus on emerging therapeutic targets for small molecule therapeutics in the fields of cardiac remodelling and impaired survival of cardiomyocytes in the diseased heart. Finally, innovative therapeutic concepts for heart gene therapy and replacement options for destroyed post-MI myocardium using embryonic and adult stem cells are described.

Abundant apoptosis in nutmeg liver of cardiomyopathic hamsters. Apoptotic cell death as a possible mechanism of hepatic remodeling by congestion

Chronic congestive heart failure (CHF) causes structural remodeling of the liver, generally leading to nutmeg liver. Male UM-X7.1 hamsters, a strain developing cardiomyopathy, had no CHF and decompensated CHF (n = 6 each) at the age of 10 and 30 weeks, respectively. We used age-matched, male Syrian hamsters without CHF (n = 6 each) as controls. All the 30-week-old UM-X7.1 hamsters had a typical nutmeg liver in which the population of hepatocytes was decreased. Positive in situ nick end labeling (TUNEL) was found in 2.2 +/- 0.74% of hepatocytes in congestive livers, being significantly higher compared with the other groups without CHF (< 0.5%). DNA ladder pattern was also evident in the congestive livers. Electron microscopy revealed a typical apoptotic ultrastructure in the hepatocytes of the 30-week-old UM-X7.1 hamsters. However, many showed secondary necrotic changes. Although hepatocytes undergoing oncosis (primary necrosis) are rare, they were also found. The level of soluble Fas ligand in the plasma was increased, and Fas receptor in the liver was overexpressed in the CHF animals. In addition, both the Bax/Bcl-2 ratio and the Bad/Bcl-xL ratio were increased, and caspase-3 was activated in them. Our findings suggest that hepatocyte apoptosis contributes to hepatic remodeling under conditions of CHF.

Nitric oxide, cell death, and heart failure

Strong evidence links cardiomyocyte loss to the pathology of some forms of heart failure. Both necrotic and apoptotic modes of cell death have been invoked as the mechanism underlying progressive cardiomyocyte dropout. Nitric oxide (NO) has received particular attention as a candidate reactive oxygen intermediate that influences not only cardiac function, but also cell death elicited by both apoptotic and necrotic mechanisms. NO is produced by resident cardiac cells under stress, and is produced in large quantities by activated immune cells that infiltrate the injured heart. A review of the literature, however, reveals that the actions of NO on apoptotic cell death are complex, especially in the context of heart disease, and that the practical contribution of NO to cell death in heart disease is yet to be defined.

Phenylephrine promotes phosphorylation of Bad in cardiac myocytes through the extracellular signal-regulated kinases 1/2 and protein kinase A

Studies in non-cardiomyocytic cells have shown that phosphorylation of the Bcl-2 family protein Bad on Ser-112, Ser-136 and Ser-155 decreases its pro-apoptotic activity. Both phenylephrine (100 microM) and the cell membrane-permeating cAMP analog, 8-(4-chlorophenylthio)-cAMP (100 microM), protected against 2-deoxy-D-glucose-induced apoptosis in neonatal rat cardiac myocytes as assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). In cardiac myocytes, phenylephrine primarily stimulates the alpha-adrenoceptor, but, at high concentrations (100 microM), it also increases the activity of the cAMP-dependent protein kinase, protein kinase A (PKA) through the beta-adrenoceptor. Phenylephrine (100 microM) promoted rapid phosphorylation of Bad(Ser-112) and Bad(Ser-155), though we were unable to detect phosphorylation of Bad(Ser-136). Phosphorylation of Bad(Ser-112) was antagonized by either prazosin or propranolol, indicating that this phosphorylation required stimulation of both alpha(1)- and beta-adrenoceptors. Phosphorylation of Bad(Ser-155) was antagonized only by propranolol and was thus mediated through the beta-adrenoceptor. Inhibitor studies and partial purification of candidate kinases by fast protein liquid chromatography showed that the p90 ribosomal S6 kinases, p90RSK2/3 [which are activated by the extracellular signal-regulated kinases 1 and 2 (ERK1/2)] directly phosphorylated Bad(Ser-112), whereas the PKA catalytic subunit directly phosphorylated Bad(Ser-155). However, efficient phosphorylation of Bad(Ser-112) also required PKA activity. These data suggest that, although p90RSK2/3 phosphorylate Bad(Ser-112) directly, phosphorylation of this site is enhanced by phosphorylation of Bad(Ser-155). These phosphorylations potentially diminish the pro-apoptotic activity of Bad and contribute to the cytoprotective effects of phenylephrine and 8-(4-chlorophenylthio)-cAMP.

Mechanical stress-induced apoptosis in the cardiovascular system

All tissues in the body are subjected to physical forces originating either from tension, created by cells themselves, or from the environment. Particularly, the cardiovascular system is continuously subjected to haemodynamic forces created by blood flow and blood pressure. While biomechanical force at physiological levels is essential to develop and maintain organic structure and function, elevated mechanical stress may result in cell death leading to pathological conditions. In recent years, however, it has been widely recognized that cell death, namely apoptosis, is not just the response to an injury but a highly regulated and controlled process. Therefore, physical stimuli must be sensed by cells and transmitted through intracellular signal transduction pathways to the nucleus, resulting in cell apoptosis. Disturbances in the regulatory mechanisms of apoptosis often precede the development of a disease. Exploration of the molecular signalling mechanisms leading to mechanical stress-induced apoptosis in cardiovascular disorders revealed the crucial role of apoptosis in the pathogenesis of these diseases. For instance, heart failure, hypertension and atherosclerosis are believed to be related to sustained mechanical overloading or stress. In this review we summarize the recent data focusing on molecular mechanisms of mechanical stress-induced apoptosis and highlight the role of apoptosis in the development of cardiovascular disorders, which may lead to new therapeutic strategies for these diseases.

Myocardial gene therapy

Gene therapy is proving likely to be a viable alternative to conventional therapies in coronary artery disease and heart failure. Phase 1 clinical trials indicate high levels of safety and clinical benefits with gene therapy using angiogenic growth factors in myocardial ischaemia. Although gene therapy for heart failure is still at the pre-clinical stage, experimental data indicate that therapeutic angiogenesis using short-term gene expression may elicit functional improvement in affected individuals.