Rab9-dependent autophagy is required for the IGF-IIR triggering mitophagy to eliminate damaged mitochondria.

Mitochondria dysfunction is the major characteristic of mitophagy, which is essential in mitochondrial quality control. However, excessive mitophagy contributes to cell death in a number of diseases, including ischemic stroke and hepatotoxicity. Insulin-like growth factor II (IGF-II) and its receptor (IGF-IIR) play vital roles in the development of heart failure during hypertension. We found that IGF-II triggers IGF-IIR receptor activation, causing mitochondria dysfunction, resulting in mitophagy, and cardiomyocyte cell death. These results indicated that IGF-IIR activation triggers mitochondria fragmentation, leading to autophagosome formation, and loss of mitochondria content. These results are associated with Parkin-dependent mitophagy. Additionally, autophagic proteins Atg5, and Atg7 deficiency did not suppress IGF-IIR-induced mitophagy. However, Rab9 knockdown reduced mitophagy and maintained mitochondrial function. These constitutive mitophagies through IGF-IIR activation trigger mitochondria loss and mitochondrial ROS accumulation for cardiomyocyte viability decrease. Together, our results indicate that IGF-IIR predominantly induces mitophagy through the Rab9-dependent alternative autophagy.

p53-mediated miR-18 repression activates HSF2 for IGF-IIR-dependent myocyte hypertrophy in hypertension-induced heart failure.

Hypertension-induced cardiac hypertrophy and attenuated cardiac function are the major characteristics of early stage heart failure. Cardiomyocyte death in pathological cardiac conditions is the primary cause of heart failure and mortality. Our previous studies found that heat shock factor 1 (HSF1) protected cardiomyocytes from death by suppressing the IGF-IIR signaling pathway, which is critical for hypertensive angiotensin II-induced cardiomyocyte apoptosis. However, the role of heat shock factor 2 (HSF2) in hypertension-induced cardiac hypertrophy is unknown. We identified HSF2 as a miR-18 target for cardiac hypertrophy. p53 activation in angiotensin II (ANG II)-stimulated NRVMs is responsible for miR-18 downregulation both in vitro and in vivo, which triggers HSF2 expression and the activation of IGF-IIR-induced cardiomyocyte hypertrophy. Finally, we provide genetic evidence that miR-18 is required for cardiomyocyte functions in the heart based on the gene transfer of cardiac-specific miR-18 via adenovirus-associated virus 2 (AAV2). Transgenic overexpression of miR-18 in cardiomyocytes is sufficient to protect against dilated cardiomyopathy during hypertension-induced heart failure. Our results demonstrated that the p53-miR-18-HSF2-IGF-IIR axis was a critical regulatory pathway of cardiomyocyte hypertrophy in vitro and in vivo, suggesting that miR-18 could be a therapeutic target for the control of cardiac functions and the alleviation of cardiomyopathy during hypertension-induced heart failure.

E4BP4 is a cardiac survival factor and essential for embryonic heart development.

The bZIP transcription factor E4BP4, has been demonstrated to be a survival factor in pro-B lymphocytes. GATA factors play important roles in transducing the IL-3 survival signal and transactivating the downstream survival gene, E4BP4. In heart, GATA sites are essential for proper transcription of several cardiac genes, and GATA-4 is a mediator of cardiomyocyte survival. However, the role E4BP4 plays in heart is still poorly understood. In this study, Dot-blot hybridization assays using Dig-labeled RNA probes revealed that the E4BP4 gene was expressed in cardiac tissue from several species including, monkey, dog, rabbit, and human. Western blot analysis showed that the E4BP4 protein was consistently present in all of these four species. Furthermore, immunohistochemistry revealed that the E4BP4 protein was overexpressed in diseased heart tissue in comparison with normal heart tissue. In addition, the overexpression of E4BP4 in vitro activated cell survival signaling pathway of cardiomyocytes. At last, siRNA-mediated knock down of E4BP4 in zebrafish resulted in malformed looping of the embryonic heart tube and decreased heart beating. Based on these results, we conclude that E4BP4 plays as a survival factor in heart and E4BP4 is essential for proper embryonic heart development.

An open-label, multicentre study of levocetirizine for the treatment of allergic rhinitis and urticaria in Taiwanese patients.

Levocetirizine has been shown in observational studies in the west as an effective and satisfactory therapy for patients with allergic respiratory and skin disease. An open-label, multicentre observational study was conducted to investigate the patients' perception of levocetirizine in the treatment of allergic rhinitis (AR) and urticaria in Taiwanese patients. Three hundred and thirty-three patients (236 AR and 97 urticaria patients) attending out-patient clinics of medical centres across Taiwan were included in the study. Patients were treated with levocetirizine 5 mg once daily (AR patients for 2-4 weeks and urticaria patients for 2-6 weeks) and at the end of treatment, they evaluated for symptoms of disease, perception of change in symptoms, global efficacy and tolerability, global preference over previous antiallergic treatment, change in quality of sleep/daily activities, and safety and adverse events (AEs). Levocetirizine markedly improved the symptoms of AR and urticaria; with 70-75% of AR patients and 60-80% of urticaria patients reporting complete or marked improvements in individual symptoms. Asthma symptoms were completely or markedly improved in 44% of patients with AR and concomitant asthma. A majority of the patients was satisfied with levocetirizine therapy and 50-70% indicated preference for levocetirizine over previous therapy. Overall, 50-74% of all patients perceived improvements in quality of sleep/daily activities and 50-65% of the patients rated the onset of action for levocetirizine as very rapid or rapid. Somnolence was the most common AE, reported by 7.4% of AR and 7.0% of urticaria patients. The results of this study indicated that levocetirizine is an effective and satisfactory therapy for the management of allergic respiratory and skin disease in Taiwanese subjects.

Down regulation of IGF-I and IGF-IR gene expression in right atria tissue of ventricular septal defect infants with right atria hypoxemia.

BACKGROUND: Our previous studies showed serum insulin-like growth factor-I (IGF-I) concentrations significantly decreased in infants with congenital ventricular septal defect (VSD) and that they were associated with increased concentrations of growth hormone. In order to confirm the relationship between IGF-I axis and VSD, we further compared the IGF-I and insulin-like growth factor-I receptor(IGF-IR) gene expressions in the cardiac tissue of VSD infants. METHODS: Right atrium biopsies of 27 infants were studied. Five infants not having VSD were classified as controls (Group I). Twenty VSD patients were then divided into 2 groups according to their shunting magnitude index (level of pulmonary vascular resistance compared with systemic vascular resistance, Qp/Qs). VSD patients with minor shunts (Qp/Qs<1.7) were classified as Group II; VSD patients with larger shunts (Qp/Qs> or =2) as Group III. Besides, seven tetralogy of fallot (TOF) with shunt (Qp/Qs>4) infants were classified as the Group IV. A non-radioactive DIG-RNA probe detection system, western blotting and immunohistochemistry were used to detect the gene expression levels and protein products of IGF-I and IGF-IR in the right atrium samples of VSD infants. RESULTS: The relative protein levels of IGF-I were 0.96+/-0.05, 0.43+/-0.03, 0.15+/-0.04, 0.12+/-0.03 and IGF-IR were 0.80+/-0.08, 0.57+/-0.03, 0.38+/-0.02, 0.24+/-0.04 in the right atrium of 4 group patients. The relative mRNA levels of IGF-I were 0.95+/-0.01, 0.41+/-0.03, 0.29+/-0.05, 0.15+/-0.01 and IGF-IR were 0.85+/-0.05, 0.56+/-0.03, 0.17+/-0.01, 0.18+/-0.01, respectively. There was a significantly greater but more gradual decrease in protein levels and in mRNA levels of IGF-I and IGF-IR in Group II (p<0.05), Group III and IV (p<0.01) than in Group I. The results of immunohistochemistry also demonstrated a similar decrease in VSD patients. In addition, the decrease of mRNA and protein levels in IGF-I/IGF-IR of VSD patients show related to the saturation of oxygen in the right atrium and the ratio of systolic right ventricular pressure to left ventricular pressure. CONCLUSION: We further confirmed the down regulation of IGF-I/IGF-IR in cardiac tissue of VSD infants and the decrease to be associated with shunt magnitude and the severity of hypoxemia in the cardiac chamber of VSD.

Role of calcineurin in Porphyromonas gingivalis-induced myocardial cell hypertrophy and apoptosis.

BACKGROUND AND OBJECTIVE: Periodontal pathogen Porphyromonas gingivalis (P. gingivalis) increased cardiomyocyte hypertrophy and apoptosis whereas Actinobaeillus actinomycetemcomitans and Prevotella intermedia had no effects. The purpose of this study is to clarify the role of calcineurin signaling pathway in P. gingivalis-induced H9c2 myocardial cell hypertrophy and apoptosis. METHODS: DNA fragmentation, nuclear condensation, cellular morphology, calcineurin protein, Bcl2-associated death promoter (Bad) and nuclear factor of activated T cell (NFAT)-3 protein products in cultured H9c2 myocardial cell were measured by agarose gel electrophoresis, DAPI, immunofluorescence, and Western blotting following P. gingivalis and/or pre-administration of CsA (calcineurin inhibitors cyclosporin A). RESULTS: P. gingivalis not only increased calcineurin protein, NFAT-3 protein products and cellular hypertrophy, but also increased DNA fragmentation, nuclear condensation and Bad protein products in H9c2 cells. The increased cellular sizes, DNA fragmentation, nuclear condensation, and Bad of H9c2 cells treated with P. gingivalis were all significantly reduced after pre-administration of CsA. CONCLUSION: Our findings suggest that the activity of calcineurin signal pathway may be initiated by P. gingivalis and further lead to cell hypertrophy and death in culture H9c2 myocardial cells.

The profile of cardiac cytochrome c oxidase (COX) expression in an accelerated cardiac-hypertrophy model.

The contribution of the mitochondrial components, the main source of energy for the cardiac hypertrophic growth induced by pressure overload, is not well understood. In the present study, complete coarctation of abdominal aorta was used to induce the rapid development of cardiac hypertrophy in rats. One to two days after surgery, we observed significantly higher blood pressure and cardiac hypertrophy, which remained constantly high afterwards. We found an early increased level of cytochrome c oxidase (COX) mRNA determined by in-situ hybridization and dot blotting assays in the hypertrophied hearts, and a drop to the baseline 20 days after surgery. Similarly, mitochondrial COX protein level and enzyme activity increased and, however, dropped even lower than baseline 20 days following surgery. In addition, in natural hypertension-induced hypertrophic hearts in genetically hypertensive rats, the COX protein was significantly lower than in normotensive rats. Taken together, the lower efficiency of mitochondrial activity in the enlarged hearts of long-term complete coarcted rats or genetically hypertensive rats could be, at least partially, the cause of hypertensive cardiac disease. Additionally, the rapid complete coarctation-induced cardiac hypertrophy was accompanied by a disproportionate COX activity increase, which was suggested to maintain the cardiac energy-producing capacity in overloaded hearts.