Young Kuk Cho

Casein Kinase-2α1 Induces Hypertrophic Response by Phosphorylation of Histone Deacetylase 2 S394 and its Activation in the Heart

Background— Cardiac hypertrophy is characterized by transcriptional reprogramming of fetal gene expression, and histone deacetylases (HDACs) are tightly linked to the regulation of those genes. We previously demonstrated that activation of HDAC2, 1 of the class I HDACs, mediates hypertrophy. Here, we show that casein kinase-2&agr;1 (CK2&agr;1)–dependent phosphorylation of HDAC2 S394 is required for the development of cardiac hypertrophy. Methods and Results— Hypertrophic stimuli phosphorylated HDAC2 S394, which was necessary for its enzymatic activation, and therefore the development of hypertrophic phenotypes in rat neonatal cardiomyocytes or in isoproterenol-administered mice hearts. Transgenic mice overexpressing HDAC2 wild type exhibited cardiac hypertrophy, whereas those expressing phosphorylation-resistant HDAC2 S394A did not. Compared with that in age-matched normal human hearts, phosphorylation of HDAC2 S394 was dramatically increased in patients with hypertrophic cardiomyopathy. Hypertrophy-induced phosphorylation of HDAC2 S394 and its enzymatic activity were completely blocked either by CK2 blockers or by CK2&agr;1 short interfering RNA. Hypertrophic stimuli led CK2&agr;1 to be activated, and its chemical inhibitors blocked hypertrophy in both phenylephrine-treated cardiomyocytes and isoproterenol-administered mice. CK2&agr;1-transgenic mice developed hypertrophy, which was attenuated by administration of trichostatin A, an HDAC inhibitor. Overexpression of CK2&agr;1 caused hypertrophy in cardiomyocytes, whereas chemical inhibitors of both CK2 and HDAC as well as HDAC2 S394A blunted it. Hypertrophy in CK2&agr;1-transgenic mice was exaggerated by crossing these mice with wild-type-HDAC2-overexpressing mice. By contrast, however, it was blocked when CK2&agr;1-transgenic mice were crossed with HDAC2 S394A-transgenic mice. Conclusions— We have demonstrated a novel mechanism in the development of cardiac hypertrophy by which CK2 activates HDAC2 via phosphorylating HDAC2 S394.

Priming of Mesenchymal Stem Cells with Oxytocin Enhances the Cardiac Repair in Ischemia/Reperfusion Injury

Oxytocin stimulates the cardiomyogenesis of embryonic stem cells and adult cardiac stem cells. We previously reported that oxytocin has a promigratory effect on umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs). In this study, UCB-MSCs were cultured with oxytocin and examined for their therapeutic effect in an infarcted heart. UCB-MSCs were pretreated with 100 nM oxytocin and cardiac markers were assessed by immunofluorescence staining. Next, oxytocin-supplemented USC-MSCs (OT-USCs) were cocultured with hypoxia/reoxygenated neonatal rat cardiomyocytes and cardiac markers and dye transfer were then examined. For the in vivo study, ischemia/reperfusion was induced in rats, and phosphate-buffered saline (group 1), 1-day OT-USCs (group 2), or 7-day OT-USCs (group 3) were injected into the infarcted myocardium. Two weeks after injection, histological changes and cardiac function were examined. UCB-MSCs expressed connexin 43 (Cnx43), cardiac troponin I (cTnI), and α-sarcomeric actin (α-SA) after oxytocin supplementation and coculture with cardiomyocytes. Functional gap junction formation was greater in group 3 than in groups 1 and 2. Cardiac fibrosis and macrophage infiltration were lower in group 3 than in group 2. Restoration of Cnx43 expression was greater in group 3 than in group 2. Cnx43- and cTnI-positive OT-USCs in the peri-infarct zone were observed in group 2 and more frequently in group 3. The ejection fraction (EF) was increased in groups 2 and 3 in 2 weeks. The improved EF was sustained for 4 weeks only in group 3. Our findings suggest that the supplementation of UCB-MSCs with oxytocin can contribute to the cardiogenic potential for cardiac repair.

Curcumin reduces the cardiac ischemia-reperfusion injury: involvement of the toll-like receptor 2 in cardiomyocytes.

Curcumin, a polyphenolic compound derived from turmeric, has protective effects on myocardial injury through attenuation of oxidative stress and inflammation. Toll-like receptor 2 (TLR2), a key mediator of the innate immune system, is involved in myocardial infarction and examined if controlled by curcumin. Rat cardiomyocytes (CMs) were stimulated with tumor necrosis factor (TNF)-α, peptidoglycan (PGN) or hypoxia/reoxygenation (H/R) with or without curcumin pretreatment. Sprague-Dawley rats were fed curcumin (300 mg/kg/day) 1 week before cardiac ischemia/reperfusion (I/R) injury. The expression level of TLR2 and cardiac function were assessed. Both mRNA and protein of TLR2 were up-regulated in infarcted myocardium, while TLR4 remained unchanged. In CMs, TLR2 and monocyte chemoattractant protein (MCP)-1 mRNAs were increased by TNF-α, PGN or H/R, whereas they were blunted by curcumin. Immunofluorescence staining of CMs also showed that TLR2 and MCP-1 were increased after H/R, whereas curcumin-pretreated CMs were not. In animal study, 2 weeks after I/R, TLR2 was increased in the infarct zone, whereas it stayed unchanged in the Cur+I/R group. Macrophage infiltration (CD68), high-mobility group box 1 and fibrosis were increased in the I/R group, whereas they were decreased in the Cur+I/R group. Connexin 43 was reduced in the I/R group, while it recovered significantly in the Cur+I/R group. Cardiac contractility in the Cur+I/R group was also improved compared with that in the I/R group (max dp/dt in Cur+I/R group: 9660±612 vs. I/R group: 8119±366, P<.05). These results suggest that selective inhibition of TLR2 by curcumin could be preventive and therapeutic for myocardial infarction.

Estrogen-related receptor gamma induces cardiac hypertrophy by activating GATA4

Estrogen-related receptor gamma (ERRγ) is an orphan nuclear receptor that has biological roles mainly in metabolism and that controls metabolic switching in perinatal heart. In adult heart diseases, however, the functional roles of ERRγ have not yet been elucidated. In the present study, we aimed to characterize the role of ERRγ in cardiac hypertrophy. The functional roles of ERRγ in the development of cardiac hypertrophy were examined in primary cultured cardiomyocytes and in animal models. ERRγ expression was increased in hearts from human hypertrophic cardiomyopathy patients and in both cellular and animal models of cardiac hypertrophy. Transgenic overexpression in mouse heart as well as forced expression of ERRγ in cardiomyocytes induced hypertrophic phenotypes. Knock-down of ERRγ blocked agonist-induced hypertrophic phenotypes. ERRγ bound directly to the proximal ERR-responsive element in the GATA4 promoter in a sequence-specific manner and thereby induced transcription. ERRγ-induced hypertrophy was blocked by inhibition of GATA4. GSK-5182, an inverse agonist of ERRγ, completely blocked cardiac hypertrophy in cardiomyocytes. It also prevented aortic banding-induced cardiac hypertrophy and fibrosis in mouse heart. These findings demonstrate a novel ERRγ/GATA4 signal cascade in the development of cardiac hypertrophy and suggest GSK-5182 as a possible therapeutic.

Coronary vasculature patterning requires a novel endothelial ErbB2 holoreceptor

Organogenesis and regeneration require coordination of cellular proliferation, regulated in part by secreted growth factors and cognate receptors, with tissue nutrient supply provided by expansion and patterning of blood vessels. Here we reveal unexpected combinatorial integration of a growth factor co-receptor with a heterodimeric partner and ligand known to regulate angiogenesis and vascular patterning. We show that ErbB2, which can mediate epidermal growth factor (EGF) and neuregulin signalling in multiple tissues, is unexpectedly expressed by endothelial cells where it partners with neuropilin 1 (Nrp1) to form a functional receptor for the vascular guidance molecule semaphorin 3d (Sema3d). Loss of Sema3d leads to improper patterning of the coronary veins, a phenotype recapitulated by endothelial loss of ErbB2. These findings have implications for possible cardiovascular side-effects of anti-ErbB2 therapies commonly used for cancer, and provide an example of integration at the molecular level of pathways involved in tissue growth and vascular patterning.

Right ventricular failure in congenital heart disease

Despite developments in surgical techniques and other interventions, right ventricular (RV) failure remains an important clinical problem in several congenital heart diseases (CHD). RV function is one of the most important predictors of mortality and morbidity in patients with CHD. RV failure is a progressive disorder that begins with myocardial injury or stress, neurohormonal activation, cytokine activation, altered gene expression, and ventricular remodeling. Pressure-overload RV failure caused by RV outflow tract obstruction after total correction of tetralogy of Fallot, pulmonary stenosis, atrial switch operation for transposition of the great arteries, congenitally corrected transposition of the great arteries, and systemic RV failure after the Fontan operation. Volume-overload RV failure may be caused by atrial septal defect, pulmonary regurgitation, or tricuspid regurgitation. Although the measurement of RV function is difficult because of many reasons, the right ventricle can be evaluated using both imaging and functional modalities. In clinical practice, echocardiography is the primary mode for the evaluation of RV structure and function. Cardiac magnetic resonance imaging is increasingly used for evaluating RV structure and function. A comprehensive evaluation of RV function may lead to early and optimal management of RV failure in patients with CHD.

Ret finger protein mediates Pax7-induced ubiquitination of MyoD in skeletal muscle atrophy.

Skeletal muscle atrophy results from the net loss of muscular proteins and organelles and is caused by pathologic conditions such as nerve injury, immobilization, cancer, and other metabolic diseases. Recently, ubiquitination-mediated degradation of skeletal-muscle-specific transcription factors was shown to be involved in muscle atrophy, although the mechanisms have yet to be defined. Here we report that ret finger protein (RFP), also known as TRIM27, works as an E3 ligase in Pax7-induced degradation of MyoD. Muscle injury induced by sciatic nerve transection up-regulated RFP and RFP physically interacted with both Pax7 and MyoD. RFP and Pax7 synergistically reduced the protein amounts of MyoD but not the mRNA. RFP-induced reduction of MyoD protein was blocked by proteasome inhibitors. The Pax7-induced reduction MyoD was attenuated by RFP siRNA and by MG132, a proteasome inhibitor. RFPΔR, an RFP construct that lacks the RING domain, failed to reduce MyoD amounts. RFP ubiquitinated MyoD, but RFPΔR failed to do so. Forced expression of RFP, but not RFPΔR, enhanced Pax7-induced ubiquitination of MyoD, whereas RFP siRNA blocked the ubiquitination. Sciatic nerve injury-induced muscle atrophy as well the reduction in MyoD was attenuated in RFP knockout mice. Taken together, our results show that RFP works as a novel E3 ligase in the Pax7-mediated degradation of MyoD in response to skeletal muscle atrophy.

Random Urinary Calcium/Creatinine Ratio for Screening Hypercalciuria in Children with Hematuria

Background Hypercalciuria is one of the most common causes of unexplained isolated hematuria. The diagnostic methods for hypercalciuria have not yet been standardized. The aim of this study was to assess whether random urinary calcium/creatinine ratio could be used as a screening tool for hypercalciuria in children with hematuria. Methods This prospective study included 264 children with primary hematuria for whom both random and 24 hr urinary evaluations were performed. Pearson correlation and ROC curve were used to assess the correlations. A multiple linear regression model was used to analyze effects of age, weight, height, body mass index, and body surface area on random urinary calcium/creatinine ratio. Results There was a moderately strong correlation between random urinary calcium/creatinine ratio and 24 hr urinary calcium excretion (r=0.584, P<0.001). The most appropriate cutoff value of random urinary calcium/creatinine ratio for the estimation of hypercalciuria was 0.075 mg/mg (sensitivity, 77.8%; specificity, 64.3%; area under the curve, 0.778). Body mass index and 24 hr urinary calcium excretion significantly affected random urinary calcium/creatinine ratio with a low coefficient of determination (r2=0.380, P<0.001). Conclusions Random urinary calcium/creatinine ratio is not suitable for screening hypercalciuria in children with hematuria. Twenty-four hour urinary analysis should be performed to diagnose hypercalciuria in children with hematuria.

Clinical significance of pleural effusion in the new influenza A (H1N1) viral pneumonia in children and adolescent

Parapneumonic effusion has been reported to develop either in typical bacterial infection or in viral pneumonia with bacterial co‐infection and to cause death. Swine‐origin influenza A (H1N1) virus infection can be accompanied with pleural effusion; however, there are no reports about the significance of pleural effusion in H1N1 pneumonia. We retrospectively analyzed both the clinical characteristics and the significance of pleural effusion associated with H1N1 pneumonia in children and adolescent.

Mosaic Ring Chromosome 6 in an Infant with Significant Patent Ductus Arteriosus and Multiple Congenital Anomalies

The clinical features of ring chromosome 6 include central nervous system anomalies, growth retardation, facial dysmorphism and other congenital anomalies. Ring chromosome 6 occurs rarely and manifests as various phenotypes. We report the case of mosaic ring chromosome 6 by conventional karyotyping in a 7-day-old male infant diagnosed with a large patent ductus arteriosus (PDA) with hypoplasia of aortic valve and aortic arch. These have not been previously reported with ring chromosome 6. He recovered from heart failure symptoms after ligation of the PDA. He showed infantile failure to thrive and delayed milestone in a follow-up evaluation. To the best of our knowledge, this is the first report of a Korean individual with ring chromosome 6 and hemodynamically significant PDA.