Deficiency of Nardilysin in the Liver Reduces Serum Cholesterol Levels.

Nardilysin (NRDC) has been shown to be involved in post-translational histone modifications, in addition to enhancement in ectodomain shedding of membrane-anchored protein, which play significant roles in various pathophysiology, including glucose homeostasis, inflammatory diseases and cancer. The present study sought to determine roles of NRDC in the liver on lipid and lipoprotein metabolism. We established liver-specific NRDC deficient mice by use of NRD1 floxed mice and albumin promoter-Cre recombinase (Cre) transgenic mice, and found that their serum low-density lipoprotein (LDL) cholesterol levels were significantly lower than those in control littermate mice. In the liver, LDL receptor (LDLR) mRNA expression was significantly upregulated, while inducible degrader of LDLR (IDOL) and microsomal triglyceride transfer protein (MTP) mRNA expression was significantly downregulated, in liver-specific NRDC deficient mice. Hepatic cell-surface LDLR expression levels were significantly elevated and serum pro-protein convertase subtilisin-kexin type 9 (PCSK9) levels were significantly reduced in mice with hepatic NRDC deficiency. In cultured hepatocytes, NRDC deficiency significantly reduced secreted PCSK9 and increased cell-surface LDLR expression. On the other hand, NRDC overexpression in cultured hepatocytes significantly increased secreted PCSK9 and lowered cell-surface LDLR expression. Thus, NRDC in murine hepatocytes appears to play key roles in cholesterol homeostasis, although the precise molecular mechanisms remain to be determined.

MicroRNA-33 Controls Adaptive Fibrotic Response in the Remodeling Heart by Preserving Lipid Raft Cholesterol.

RATIONALE: Heart failure and atherosclerosis share the underlying mechanisms of chronic inflammation followed by fibrosis. A highly conserved microRNA (miR), miR-33, is considered as a potential therapeutic target for atherosclerosis because it regulates lipid metabolism and inflammation. However, the role of miR-33 in heart failure remains to be elucidated. OBJECTIVE: To clarify the role of miR-33 involved in heart failure. METHODS AND RESULTS: We first investigated the expression levels of miR-33a/b in human cardiac tissue samples with dilated cardiomyopathy. Increased expression of miR-33a was associated with improving hemodynamic parameters. To clarify the role of miR-33 in remodeling hearts, we investigated the responses to pressure overload by transverse aortic constriction in miR-33-deficient (knockout [KO]) mice. When mice were subjected to transverse aortic constriction, miR-33 expression levels were significantly upregulated in wild-type left ventricles. There was no difference in hypertrophic responses between wild-type and miR-33KO hearts, whereas cardiac fibrosis was ameliorated in miR-33KO hearts compared with wild-type hearts. Despite the ameliorated cardiac fibrosis, miR-33KO mice showed impaired systolic function after transverse aortic constriction. We also found that cardiac fibroblasts were mainly responsible for miR-33 expression in the heart. Deficiency of miR-33 impaired cardiac fibroblast proliferation, which was considered to be caused by altered lipid raft cholesterol content. Moreover, cardiac fibroblast-specific miR-33-deficient mice also showed decreased cardiac fibrosis induced by transverse aortic constriction as systemic miR-33KO mice. CONCLUSION: Our results demonstrate that miR-33 is involved in cardiac remodeling, and it preserves lipid raft cholesterol content in fibroblasts and maintains adaptive fibrotic responses in the remodeling heart.

EP4 Receptor-Associated Protein in Macrophages Ameliorates Colitis and Colitis-Associated Tumorigenesis.

Prostaglandin E2 plays important roles in the maintenance of colonic homeostasis. The recently identified prostaglandin E receptor (EP) 4-associated protein (EPRAP) is essential for an anti-inflammatory function of EP4 signaling in macrophages in vitro. To investigate the in vivo roles of EPRAP, we examined the effects of EPRAP on colitis and colitis-associated tumorigenesis. In mice, EPRAP deficiency exacerbated colitis induced by dextran sodium sulfate (DSS) treatment. Wild-type (WT) or EPRAP-deficient recipients transplanted with EPRAP-deficient bone marrow developed more severe DSS-induced colitis than WT or EPRAP-deficient recipients of WT bone marrow. In the context of colitis-associated tumorigenesis, both systemic EPRAP null mutation and EPRAP-deficiency in the bone marrow enhanced intestinal polyp formation induced by azoxymethane (AOM)/DSS treatment. Administration of an EP4-selective agonist, ONO-AE1-329, ameliorated DSS-induced colitis in WT, but not in EPRAP-deficient mice. EPRAP deficiency increased the levels of the phosphorylated forms of p105, MEK, and ERK, resulting in activation of stromal macrophages in DSS-induced colitis. Macrophages of DSS-treated EPRAP-deficient mice exhibited a marked increase in the expression of pro-inflammatory genes, relative to WT mice. By contrast, forced expression of EPRAP in macrophages ameliorated DSS-induced colitis and AOM/DSS-induced intestinal polyp formation. These data suggest that EPRAP in macrophages functions crucially in suppressing colonic inflammation. Consistently, EPRAP-positive macrophages were also accumulated in the colonic stroma of ulcerative colitis patients. Thus, EPRAP may be a potential therapeutic target for inflammatory bowel disease and associated intestinal tumorigenesis.

MicroRNA-451 exacerbates lipotoxicity in cardiac myocytes and high-fat diet-induced cardiac hypertrophy in mice through suppression of the LKB1/AMPK pathway.

RATIONALE: In some patients with type 2 diabetes mellitus (DM) without hypertension, cardiac hypertrophy and attenuated cardiac function are observed, and this insult is termed diabetic cardiomyopathy. To date, microRNA (miRNAs or miR) functions in diabetic cardiomyopathy remain to be elucidated. OBJECTIVE: To clarify the functions of miRNAs involved in diabetic cardiomyopathy caused by type 2 DM. METHODS AND RESULTS: C57BL/6 mice were fed a high-fat diet (HFD) for 20 weeks, which induced obesity and type 2 DM. miRNA microarray analyses and real-time polymerase chain reaction revealed that miR-451 levels were significantly increased in the type 2 DM mouse hearts. Because excess supply of saturated fatty acids is a cause of diabetic cardiomyopathy, we stimulated neonatal rat cardiac myocytes with palmitic acid and confirmed that miR-451 expression was increased in a dose- and time-dependent manner. Loss of miR-451 function ameliorated palmitate-induced lipotoxicity in neonatal rat cardiac myocytes. Calcium-binding protein 39 (Cab39) is a scaffold protein of liver kinase B1 (LKB1), an upstream kinase of AMP-activated protein kinase (AMPK). Cab39 was a direct target of miR-451 in neonatal rat cardiac myocytes and Cab39 overexpression rescued the lipotoxicity. To clarify miR-451 functions in vivo, we generated cardiomyocyte-specific miR-451 knockout mice. HFD-induced cardiac hypertrophy and contractile reserves were ameliorated in cardiomyocyte-specific miR-451 knockout mice compared with control mice. Protein levels of Cab39 and phosphorylated AMPK were increased and phosphorylated mammalian target of rapamycin (mTOR) was reduced in cardiomyocyte-specific miR-451 knockout mouse hearts compared with control mouse hearts. CONCLUSIONS: Our results demonstrate that miR-451 is involved in diabetic cardiomyopathy through suppression of the LKB1/AMPK pathway.

MicroRNA-33a/b in lipid metabolism ­ novel "thrifty" models.

MicroRNAs (miRNAs; miRs) are small non-protein-coding RNAs that negatively regulate gene expression. They bind to the 3' UTR of specific mRNAs and either inhibit translation or promote mRNA degradation. There is emerging evidence linking miR-33a/b to lipid homoeostasis, targeting ABCA1,SREBF1, etc and it would appear that they have acted as "thrifty genes" during evolution to maintain cholesterol levels both at the cellular and whole body level. As we are now living in a period of "satiation", miR-33a/b no longer seem to be useful and could be potential therapeutic targets for lipid disorders and/or atherosclerosis. In this review, we describe the current understanding of the function of miR-33a/b in lipid homeostasis, focusing on the "thrifty" aspect.

Mitral annular morphology in mitral valve disease with three-dimensional transesophageal echocardiography.

BACKGROUND AND AIM OF THE STUDY: Three-dimensional (3D) transesophageal echocardiography (TEE) is useful for the quantification of mitral valve structures. The study aim was to investigate, in quantitative manner, any differences in mitral valve anatomy among patients with mitral valve prolapse (MVP) or functional mitral regurgitation (FMR), compared to normal control subjects. METHODS: 3D-TEE was performed in 20 MVP patients, 10 FMR patients and in 15 control subjects. Analyses of the full-volume 3D mitral valve data sets were performed offline, using Q-Lab software. RESULTS: Distinctive patterns were identified in annular geometric changes in normal subjects compared to patients with MVP or FMR. Patients with FMR showed significant annular anterior to posterior dilatation (34.6 +/- 8.3 mm versus 28.4 +/- 2.9 mm, p < 0.04: FMR versus control), whereas in patients with MVP dilatation in the anterolateral to posteromedial diameter was more prominent (41.0 +/- 5.9 mm versus 36.6 +/- 2.4 mm, p < 0.03; MVP versus control). CONCLUSION: 3D-TEE represents a useful method for the evaluation of mitral valve geometry.

Benefits of off-pump coronary artery bypass grafting in high-risk patients.

BACKGROUND: The benefits of off-pump coronary artery bypass graft (OPCAB) compared with conventional on-pump coronary artery bypass graft (CCAB) remain controversial. Thus, it is important to investigate which patient subgroups may benefit the most from OPCAB rather than CCAB. METHODS AND RESULTS: Among the patients undergoing first coronary revascularization enrolled in the CREDO-Kyoto Registry (a registry of first-time percutaneous coronary intervention and coronary artery bypass graft patients in Japan), 2468 patients undergoing coronary artery bypass graft were entered into the study (mean age, 67 ± 9 years). Predicted risk of operative mortality (PROM) of each patient was calculated by logistic EuroSCORE. Patients were divided into tertile based on their PROM. Mortality rates and the incidences of cardiovascular events were compared between CCAB and OPCAB within each PROM tertile using propensity score analysis. A total of 1377 patients received CCAB whereas 1091 received OPCAB. Adjusted 30-day mortality was not significantly different between CCAB and OPCAB patients regardless of their PROM range. However, the odds ratio of 30-day stroke in CCAB compared with OPCAB in the high-risk tertile was 8.30 (95% confidence interval, 2.25-30.7; P<0.01). Regarding long-term outcomes, hazard ratio of stroke in CCAB compared with OPCAB in the high-risk tertile was 1.80 (95% confidence interval, 1.07-3.02; P=0.03). Nevertheless, hazard ratio of overall mortality in the high-risk tertile was 1.44 (95% confidence interval, 0.98-2.11; P=0.06), indicating no statistically significant difference between the 2 procedures. CONCLUSIONS: OPCAB as opposed to CCAB is associated with short-term and long-term benefits in stroke prevention in patients at higher risk as estimated by EuroSCORE. No survival benefit of OPCAB was shown regardless of preoperative risk level.

Ultrastructural maturation of human-induced pluripotent stem cell-derived cardiomyocytes in a long-term culture.

BACKGROUND: In the short- to mid-term, cardiomyocytes generated from human-induced pluripotent stem cells (hiPSC-CMs) have been reported to be less mature than those of adult hearts. However, the maturation process in a long-term culture remains unknown. METHODS AND RESULTS: A hiPSC clone generated from a healthy control was differentiated into CMs through embryoid body (EB) formation. The ultrastructural characteristics and gene expressions of spontaneously contracting EBs were analyzed through 1-year of culture after cardiac differentiation was initiated. The 14-day-old EBs contained a low number of myofibrils, which lacked alignment, and immature high-density Z-bands lacking A-, H-, I-, and M-bands. Through the long-term culture up to 180 days, the myofibrils became more tightly packed and formed parallel arrays accompanied by the appearance of mature Z-, A-, H-, and I-bands, but not M-bands. Notably, M-bands were finally detected in 360-day-old EBs. The expression levels of the M-band-specific genes in hiPSC-CMs remained lower in comparison with those in the adult heart. Immunocytochemistry indicated increasing number of MLC2v-positive/MLC2a-negative cells with decreasing number of MLC2v/MLC2a double-positive cells, indicating maturing of ventricular-type CMs. CONCLUSIONS: The structural maturation process of hiPSC-CMs through 1-year of culture revealed ultrastructural sarcomeric changes accompanied by delayed formation of M-bands. Our study provides new insight into the maturation process of hiPSC-CMs.

Sex-based differences in clinical practice and outcomes for Japanese patients with acute myocardial infarction undergoing primary percutaneous coronary intervention.

BACKGROUND: Limited data are available for sex-based differences in Japanese patients with acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI). METHODS AND RESULTS: The study patients comprised 1,197 women and 3,182 men who underwent primary PCI for AMI in 2005-2007. Compared with the men, the women were significantly older, and had significantly longer onset-to-balloon time and lower rate of follow-up coronary angiography. In-hospital mortality was higher among women than men (8.7% vs. 4.9%, P<0.001). Although the cumulative incidence of all-cause death at 3 years was also higher for women (17.7% vs. 10.7%, P<0.001), the adjusted risk for all-cause death was comparable [hazard ratio (HR, women vs. men)=0.94, 95% confidence interval (CI): 0.71-1.24, P=0.66]. The incidence (12.1% vs. 12.4%, P=0.77) and the adjusted risk (HR=0.99, 95% CI 0.78-1.24, P=0.92) for any clinically-driven coronary revascularization were both comparable. However, regarding any non-clinically-driven coronary revascularization, the incidence (19.6% vs. 27.8%, P<0.001) and the adjusted risk (HR=0.79, 95% CI 0.65-0.95, P=0.012) were both lower in women relative to men. CONCLUSIONS: In current Japanese clinical practice for AMI, onset-to-balloon time was significantly longer in women than in men. Female sex was associated with lower follow-up coronary angiography rate and lower incidence of any non-clinically-driven coronary revascularization, whereas the incidence of any clinically-driven coronary revascularization was comparable between the sexes.

MicroRNA-33 encoded by an intron of sterol regulatory element-binding protein 2 (Srebp2) regulates HDL in vivo.

Sterol regulatory element-binding protein 2 (SREBP-2) transcription factor has been identified as a key protein in cholesterol metabolism through the transactivation of the LDL receptor and cholesterol biosynthesis genes. Here, we generated mice lacking microRNA (miR)-33, encoded by an intron of the Srebp2, and showed that miR-33 repressed the expression of ATP-binding cassette transporter A1 (ABCA1) protein, a key regulator of HDL synthesis by mediating cholesterol efflux from cells to apolipoprotein A (apoA)-I. In fact, peritoneal macrophages derived from miR-33-deficient mice showed a marked increase in ABCA1 levels and higher apoA-I-dependent cholesterol efflux than those from WT mice. ABCA1 protein levels in liver were also higher in miR-33-deficient mice than in WT mice. Moreover, miR-33-deficient mice had significantly higher serum HDL cholesterol levels than WT mice. These data establish a critical role for miR-33 in the regulation of ABCA1 expression and HDL biogenesis in vivo.

Detection of intimal defect by 64-row multidetector computed tomography in patients with acute aortic intramural hematoma.

BACKGROUND: Previous pathological and clinical studies demonstrated an intimal defect in patients with acute aortic intramural hematoma (IMH). The purpose of this study was to investigate the prevalence and clinical outcome of intimal defect detected by multidetector computed tomography (MDCT) in patients with IMH. METHODS AND RESULTS: We retrospectively analyzed 38 consecutive patients with IMH in whom 64-row MDCT was performed during the acute phase (median, 5 days from the onset). Intimal defect was defined as continuity disruption of the inner layer of thrombosed false lumen, which could be detected by 1-mm axial and longitudinal interactive multiplanar reformation images. Clinical outcome of intimal defect was assessed in patients with type B IMH (n=32). A total of 48 lesions in 27 (71%) patients were recognized as intimal defects. The incidence of intimal defect was not affected by the timing of MDCT examination (1 to 3 days, 79%; 4 to 7 days, 58%; 8 to 14 days, 75%; P=0.56). In type B IMH, 16 (76%) of 21 patients with intimal defect showed progression (enlargement or progression to aortic aneurysm) in the chronic phase. In contrast, all 11 patients without intimal defect had complete resorption of hematoma. In lesion-based analysis, a depth of intimal defect of ≥ 5 mm predicted progression with sensitivity, specificity, and positive and negative predictive values of 84%, 95%, 94%, and 86%, respectively. CONCLUSIONS: A considerable portion of patients with IMH showed intimal defect detected by MDCT even in the very early stage, and defects frequently enlarged. Patients with intimal defect should be carefully followed up with serial imaging.

Fibulin-5/DANCE has an elastogenic organizer activity that is abrogated by proteolytic cleavage in vivo.

Elastic fibers are required for the elasticity and integrity of various organs. We and others previously showed that fibulin-5 (also called developing arteries and neural crest EGF-like [DANCE] or embryonic vascular EGF-like repeat-containing protein [EVEC]) is indispensable for elastogenesis by studying fibulin-5-deficient mice, which recapitulate human aging phenotypes caused by disorganized elastic fibers (Nakamura, T., P.R. Lozano, Y. Ikeda, Y. Iwanaga, A. Hinek, S. Minamisawa, C.F. Cheng, K. Kobuke, N. Dalton, Y. Takada, et al. 2002. Nature. 415:171-175; Yanagisawa, H., E.C. Davis, B.C. Starcher, T. Ouchi, M. Yanagisawa, J.A. Richardson, and E.N. Olson. 2002. Nature. 415:168-171). However, the molecular mechanism by which fiblin-5 contributes to elastogenesis remains unknown. We report that fibulin-5 protein potently induces elastic fiber assembly and maturation by organizing tropoelastin and cross-linking enzymes onto microfibrils. Deposition of fibulin-5 on microfibrils promotes coacervation and alignment of tropoelastins on microfibrils, and also facilitates cross-linking of tropoelastin by tethering lysyl oxidase-like 1, 2, and 4 enzymes. Notably, recombinant fibulin-5 protein induced elastogenesis even in serum-free conditions, although elastogenesis in cell culture has been believed to be serum-dependent. Moreover, the amount of full-length fibulin-5 diminishes with age, while truncated fibulin-5, which cannot promote elastogenesis, increases. These data suggest that fibulin-5 could be a novel therapeutic target for elastic fiber regeneration.

Predicting long-term mortality after first coronary revascularization: ­ the Kyoto model ­.

BACKGROUND: We explored the determinants of mortality in order to develop and validate the Kyoto model, which predicts outcomes after percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). METHODS AND RESULTS: A total of 9,393 patients who underwent their first coronary revascularization without concomitant valvular, left ventricular, or major vascular surgery were followed over a median follow-up of 3.5 years in the CREDO-Kyoto Registry. We fitted separate Cox regression to mortality after PCI and CABG. The best-fitting model was internally validated by 10-fold cross-validation. The Cox regression identified the following predictors: age, sex, body mass index, ejection fraction, atrial fibrillation, diabetes mellitus, hyperlipidemia, current smoker, stroke, peripheral vascular disease, chronic obstructive pulmonary disease, malignancy, kidney disease, anemia, liver cirrhosis, diseased vessel, left main disease, proximal left anterior descending artery disease, and total occlusion. This model simulated that the 3-year mortality for a hypothetical 70-year-old man with 2-vessel disease is 2.0% after PCI and 2.6% after CABG, or 4.2% and 5.1% if he has diabetes and chronic kidney disease. The Hosmer-Lemeshow test showed no significant deviations between the observed and predicted events. The C statistics were greater than 0.78. CONCLUSIONS: The Kyoto model can assist clinicians and patients in adherence to medication and lifestyle changes after revascularization and in individualized decision making. A web application is available at http://www.biostatistics.jp/prediction/kyoto-model.

Intensity of statin therapy, achieved low-density lipoprotein cholesterol levels and cardiovascular outcomes in Japanese patients after coronary revascularization. Perspectives from the CREDO-Kyoto registry cohort-2.

BACKGROUND: Association of the type of statin and the achieved level of low-density lipoprotein cholesterol (LDL-C) with cardiovascular outcome has not been fully elucidated. METHODS AND RESULTS: The study included 14,866 patients who underwent a first coronary revascularization in 2005-2007. We identified 7,299 patients with statin therapy at discharge (so-called strong statins [atorvastatin, rosuvastatin, and pitavastatin]: 4,742 patients; standard statins [pravastatin, simvastatin, and fluvastatin]: 2,557 patients). Unadjusted 3-year incidence of major adverse cardiovascular events (MACE: composite of cardiovascular death, myocardial infarction and stroke) was significantly lower (7.5% vs. 9.6%, P=0.0008) in the strong statin group, and there was a trend in adjusted risk of MACE favoring strong statins (hazard ratio [HR] 0.87, [95% confidence interval (CI) 0.73-1.04], P=0.13). Among 4,846 patients with follow-up LDL-C data available, outcomes were evaluated according to achieved LDL-C level (<80, 80-99 [reference], 100-119, ≥120 mg/dl). Compared with the reference group, the risk for MACE was significantly higher in the ≥120 mg/dl group (adjusted HR 1.74 [95%CI 1.11-2.71], P=0.01), although it was comparable in the 100-119 mg/dl group (adjusted HR 1.23 [95%CI 0.78-1.94], P=0.38) and in the <80 mg/dl group (adjusted HR 1.15 [95%CI 0.75-1.75], P=0.52). CONCLUSIONS: Strong statin therapy was associated with a trend toward lower cardiovascular risk compared with standard statin therapy. When LDL-C <120 mg/dl was achieved, risks for cardiovascular events were comparable irrespective of achieved LDL-C level.

Early surgery for asymptomatic mitral regurgitation: importance of atrial fibrillation.

BACKGROUND AND AIM OF THE STUDY: It remains controversial whether early mitral valve (MV) repair should be performed for severe degenerative mitral regurgitation (MR) without symptoms, left ventricular (LV) dilatation or dysfunction, atrial fibrillation (AF) or pulmonary artery hypertension (PH), even at experienced surgical centers. The study aim was to reconsider the optimal timing of intervention for asymptomatic patients with severe degenerative MR at experienced surgical centers. METHODS: Clinical outcomes were reviewed retrospectively for 298 consecutive asymptomatic patients (mean age 57 +/- 12 years) who underwent MV surgery for degenerative MR. The patients were allocated to two groups based on the following comorbid conditions: LVEF < or = 60%, LV end-systolic dimension 40 mm, AF, and PH. Group A comprised 122 patients with none of these conditions, while group B comprised 176 patients with any one of the conditions. The clinical outcomes were compared between the two groups at a mean of 7.0 +/- 4.5 years after surgery. RESULTS: MV repair had been attempted in all patients, with a success rate of 100%. At 10 years, survival among group B patients was poorer than in group A (93% and 81%, respectively; p = 0.02), and there was a lower freedom from valve-related events (89% and 71%, respectively; p < 0.01). The independent predictors of valve-related events were preoperative AF (hazard ratio 3.34; p < 0.001) and age > 60 years (hazard ratio 2.50; p < 0.01). CONCLUSION: Early MV repair is a reasonable option in asymptomatic patients, while preoperative AF may be a more appropriate predictor of an adverse outcome than LV function, as is currently recommended.

Left ventricular systolic dyssynchrony index by three-dimensional echocardiography in patients with decreased left ventricular function: comparison with tissue Doppler echocardiography.

BACKGROUND: Three-dimensional echocardiography (3DE) can simultaneously assess left ventricular (LV) regional systolic motion and global LV mechanical dyssynchrony. METHODS: We used 3DE to measure systolic dyssynchrony index (SDI) (standard deviation of the time from cardiac cycle onset to minimum systolic volume in 17 LV segments) in 100 patients and analyzed the association of SDI with other parameters for LV systolic function or dyssynchrony. Eighteen patients who underwent cardiac resynchronization therapy (CRT) were also evaluated at 6 months after CRT, and the association of baseline SDI and tissue Doppler imaging (TDI) dyssynchrony index (Ts-SD) with the change of LV end-systolic volume (ESV) analyzed. Ts-SD was calculated using the standard deviation of the time from the QRS complex to peak systolic velocity. RESULTS: There was a significant inverse correlation between LVEF and SDI (r =-0.686, P < 0.0001). QRS duration was also significantly correlated to SDI (r = 0.407, P < 0.0001). There was a significant positive correlation between baseline SDI and the decrease in LVESV after CRT (r = 0.42). Baseline SDI was significantly greater in responders (10 patients) than in nonresponders (16.4 ± 5.1 vs. 7.9 ± 2.4%, P < 0.01), but there was no significant difference in Ts-SD. SDI > 11.9% predicted CRT response with a sensitivity of 90% and a specificity of 75%. CONCLUSIONS: SDI derived from 3DE is a useful parameter to assess global LV systolic dyssynchrony and predict responses to CRT.

Fibulin-4 conducts proper elastogenesis via interaction with cross-linking enzyme lysyl oxidase.

Great arteries, as well as lungs and skin, contain elastic fibers as important components to maintain their physiological functions. Although recent studies have revealed that a glycoprotein fibulin-4 (FBLN4) is indispensable for the assembly of mature elastic fibers, it remains to be elucidated how FBLN4 takes part in elastogenesis. Here, we report a dose-dependent requirement for FBLN4 in the development of the elastic fibers in arteries, and a specific role of FBLN4 in recruiting the elastin-cross-linking enzyme, lysyl oxidase (LOX). Reduced expression of Fbln4, which was achieved with a smooth muscle-specific Cre-mediated gene deletion, caused arterial stiffness. Electron-microscopic examination revealed disorganized thick elastic laminae with aberrant deposition of elastin. Aneurysmal dilation of the ascending aorta was found when the Fbln4 expression level was reduced to an even lower level, whereas systemic Fbln4 null mice died perinatally from rupture of the diaphragm. We also found a specific interaction between FBLN4 and the propeptide of LOX, which efficiently promotes assembly of LOX onto tropoelastin. These data suggest a mechanism of elastogenesis, in which a sufficient amount of FBLN4 is essential for tethering LOX to tropoelastin to facilitate cross-linking.

Integrated Analysis of Two Probucol Trials for the Secondary Prevention of Atherosclerotic Cardiovascular Events: PROSPECTIVE and IMPACT.

AIMS: In this study, we integrated two randomized control trials, PROSPECTIVE and IMPACT, to address the effect of probucol on cerebrocardiovascular events and carotid intima-media thickness (IMT) in Japanese, Korean, and Chinese patients with coronary artery disease (CAD). METHODS: A total of 1,025 patients from the PROSPECTIVE and IMPACT studies were enrolled. The time to the first major adverse cerebrocardiovascular event, in addition to carotid IMT and lipid levels, was compared between the control and probucol groups. RESULTS: In the integrated analysis, the adjusted hazard ratio (HR) and 95% confidence interval (CI) were 0.67 and 0.44-1.03, respectively, indicating a tendency to show the effect of probucol on cerebrocardiovascular events in secondary prevention. We also found no significant differences between the control and probucol groups in the mean IMT of the carotid arteries and its changes. However, we found a significant decrease in cerebrocardiovascular events in patients with reduced levels of HDL cholesterol (HDL-C) (≥ 6.25 mg/dL) compared with those with levels ＜6.25 mg/dL (p=0.024), without any increase in adverse events such as severe ventricular arrhythmias. CONCLUSION: We demonstrated a marginal effect of probucol on cerebrocardiovascular events in Asian patients with CAD, with reasonable safety profiles. A larger study may be needed to support the effect of probucol for cardiovascular prevention.

Constitutive SIRT1 overexpression impairs mitochondria and reduces cardiac function in mice.

Heart failure is associated with a change in cardiac energy metabolism. SIRT1 is a NAD(+)-dependent protein deacetylase, and important in the regulation of cellular energy metabolism. To examine the role of SIRT1 in cardiac energy metabolism, we created transgenic mice overexpressing SIRT1 in a cardiac-specific manner, and investigated cardiac functional reserve, energy reserve, substrate uptake, and markers of mitochondrial function. High overexpression of SIRT1 caused dilated cardiomyopathy. Moderate overexpression of SIRT1 impaired cardiac diastolic function, but did not cause heart failure. Fatty acid uptake was decreased and the number of degenerated mitochondria was increased dependent on SIRT1 gene dosage. Markers of reactive oxygen species were decreased. Changes in morphology and reactive oxygen species were associated with the reduced expression of genes related to mitochondrial function and autophagy. In addition, the respiration of isolated mitochondria was decreased. Cardiac function was normal in transgenic mice expressing a low level of SIRT1 at baseline, but the mice developed cardiac dysfunction upon pressure overload. In summary, the constitutive overexpression of SIRT1 reduced cardiac function associated with impaired mitochondria in mice.

Cyclin-dependent kinase-9 is a component of the p300/GATA4 complex required for phenylephrine-induced hypertrophy in cardiomyocytes.

A zinc finger protein GATA4 is one of the hypertrophy-responsive transcription factors and forms a complex with an intrinsic histone acetyltransferase, p300. Disruption of this complex results in the inhibition of cardiomyocyte hypertrophy and heart failure in vivo. By tandem affinity purification and mass spectrometric analyses, we identified cyclin-dependent kinase-9 (Cdk9) as a novel GATA4-binding partner. Cdk9 also formed a complex with p300 as well as GATA4 and cyclin T1. We showed that p300 was required for the interaction of GATA4 with Cdk9 and for the kinase activity of Cdk9. Conversely, Cdk9 kinase activity was required for the p300-induced transcriptional activities, DNA binding, and acetylation of GATA4. Furthermore, the kinase activity of Cdk9 was required for the phosphorylation of p300 as well as for cardiomyocyte hypertrophy. These findings demonstrate that Cdk9 forms a functional complex with the p300/GATA4 and is required for p300/GATA4- transcriptional pathway during cardiomyocyte hypertrophy.