The elastic fibre system has a principal role in the structure and function of various types of organs that require elasticity, such as large arteries, lung and skin. Although elastic fibres are known to be composed of microfibril proteins (for example, fibrillins and latent transforming growth factor (TGF)-beta-binding proteins) and polymerized elastin, the mechanism of their assembly and development is not well understood. Here we report that fibulin-5 (also known as DANCE), a recently discovered integrin ligand, is an essential determinant of elastic fibre organization. fibulin-5-/- mice generated by gene targeting exhibit a severely disorganized elastic fibre system throughout the body. fibulin-5-/- mice survive to adulthood, but have a tortuous aorta with loss of compliance, severe emphysema, and loose skin (cutis laxa). These tissues contain fragmented elastin without an increase of elastase activity, indicating defective development of elastic fibres. Fibulin-5 interacts directly with elastic fibres in vitro, and serves as a ligand for cell surface integrins alphavbeta3, alphavbeta5 and alpha9beta1 through its amino-terminal domain. Thus, fibulin-5 may provide anchorage of elastic fibres to cells, thereby acting to stabilize and organize elastic fibres in the skin, lung and vasculature.

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.A TP-binding cassette transporter A1 (ABCA1), a 254-kDa cytoplasmic membrane protein, is a pivotal regulator of lipid efflux from cells to apolipoproteins (1). ABCA1 mediates the ratecontrolling step in HDL particle formation and plays an important role in reverse cholesterol transfer (2, 3). Mutations in the ABCA1 gene cause Tangier disease, which is characterized by the near absence of plasma HDL cholesterol associated with storage of cholesterol esters in reticuloendothelial tissues (4-7). Abca1 mRNA and protein are very unstable, with a half life of 1-2 h in murine macrophages (8), which indicates that new transcription and translation are major factors in ensuring constant and inducible ABCA1 expression.Sterol regulatory element-binding proteins (SREBPs), including SREBP-1a, -1c, and -2, modulate the transcription of a number of genes involved in the synthesis and receptor-mediated uptake of cholesterol and fatty acids (9-11). In sterol-depleted cells, SREBPs are cleaved by proteases in the Golgi, releasing the N-termini, which translocate into the nucleus and bind to SREs in the enhancers of multiple genes encoding enzymes and proteins involved in cholesterol biosynthesis and lipid uptake (11-13). Results to date support the notion that SREBP-1 primarily activates the fatty acid triglyceride and phospholipid pathways, whereas SREBP-2 is the prominent isoform for cholesterol synthesis and uptake (9,10,12).MicroRNAs (miRs) are small, non-protein-coding RNAs that base pair with specific mRNAs and inhibit translation or promote mRNA degradation. Recent reports have indicated that miR-33 controls cholesterol homeostasis based on knockdown experiments using antisense technology (14-16). Antisense inhibition of miRNA function has been an important tool for elucidating miRNA biology. However, to determine the potential developmental function of specific miRNAs and to perform longer-term studies, it is necessary to generate mice lacking each miRNA. We generated miR-33-deficient mice, which were born at the expected Mendelian ratio, a...

The present study shows that plasma BNP levels reflect left ventricular EDWS more than any other parameter previously reported, not only in patients with SHF, but also in patients with DHF. The relationship of left ventricular EDWS to plasma BNP may provide a better fundamental understanding of the interindividual heterogeneity in BNP levels and their clinical utility in the diagnosis and management of HF.

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The feasibility of gene therapy for cardiomyopathy, heart failure and other chronic cardiac muscle diseases is so far unproven. Here, we developed an in vivo recombinant adeno-associated virus (rAAV) transcoronary delivery system that allows stable, high efficiency and relatively cardiac-selective gene expression. We used rAAV to express a pseudophosphorylated mutant of human phospholamban (PLN), a key regulator of cardiac sarcoplasmic reticulum (SR) Ca(2+) cycling in BIO14.6 cardiomyopathic hamsters. The rAAV/S16EPLN treatment enhanced myocardial SR Ca(2+) uptake and suppressed progressive impairment of left ventricular (LV) systolic function and contractility for 28-30 weeks, thereby protecting cardiac myocytes from cytopathic plasma-membrane disruption. Low LV systolic pressure and deterioration in LV relaxation were also largely prevented by rAAV/S16EPLN treatment. Thus, transcoronary gene transfer of S16EPLN via rAAV vector is a potential therapy for progressive dilated cardiomyopathy and associated heart failure.

Background-Congestive heart failure (CHF) is associated with a change in cardiac energy metabolism. However, the mechanism by which this change is induced and causes the progression of CHF is unclear. Methods and Results-We analyzed the cardiac energy metabolism of Dahl salt-sensitive rats fed a high-salt diet, which showed a distinct transition from compensated left ventricular hypertrophy to CHF. Glucose uptake increased at the left ventricular hypertrophy stage, and glucose uptake further increased and fatty acid uptake decreased at the CHF stage. The gene expression related to glycolysis, fatty acid oxidation, and mitochondrial function was preserved at the left ventricular hypertrophy stage but decreased at the CHF stage and was associated with decreases in levels of transcriptional regulators. In a comprehensive metabolome analysis, the pentose phosphate pathway that regulates the cellular redox state was found to be activated at the CHF stage. Dichloroacetate (DCA), a compound known to enhance glucose oxidation, increased energy reserves and glucose uptake. DCA improved cardiac function and the survival of the animals. DCA activated the pentose phosphate pathway in the rat heart. DCA activated the pentose phosphate pathway, decreased oxidative stress, and prevented cell death of cultured cardiomyocytes. Conclusions-Left ventricular hypertrophy or CHF is associated with a distinct change in the metabolic profile of the heart. DCA attenuated the transition associated with increased energy reserves, activation of the pentose phosphate pathway, and reduced oxidative stress. (Circ Heart Fail. 2010;3:420-430.)

Background-Heart failure is a typical age-associated disease. Although age-related changes of heart are likely to predispose aged people to heart failure, little is known about the molecular mechanism of cardiac aging. Methods and Results-We analyzed age-associated changes in murine heart and the manner in which suppression of the p110␣ isoform of phosphoinositide 3-kinase activity modified cardiac aging. Cardiac function declined in old mice associated with the expression of senescence markers. Accumulation of ubiquitinated protein and lipofuscin, as well as comprehensive gene expression profiling, indicated that dysregulation of protein quality control was a characteristic of cardiac aging. Inhibition of phosphoinositide 3-kinase preserved cardiac function and attenuated expression of the senescence markers associated with enhanced autophagy. Suppression of target of rapamycin, a downstream effector of phosphoinositide 3-kinase, also prevented lipofuscin accumulation in the heart. Conclusions-Suppression of phosphoinositide 3-kinase prevented many age-associated changes in the heart and preserved cardiac function of aged mice.

GLUT4 shows decreased levels in failing human adult hearts. We speculated that GLUT4 expression in cardiac muscle may be fine-tuned by microRNAs. Forced expression of miR-133 decreased GLUT4 expression and reduced insulin-mediated glucose uptake in cardiomyocytes. A computational miRNA target prediction algorithm showed that KLF15 is one of the targets of miR-133. It was confirmed that over-expression of miR-133 reduced the protein level of KLF15, which reduced the level of the downstream target GLUT4. Cardiac myocytes infected with lenti-decoy, in which the 3'UTR with tandem sequences complementary to miR-133 was linked to the luciferase reporter gene, had decreased miR-133 levels and increased levels of GLUT4. The expression levels of KLF15 and GLUT4 were decreased at the left ventricular hypertrophy and congestive heart failure stage in a rat model. The present results indicated that miR-133 regulates the expression of GLUT4 by targeting KLF15 and is involved in metabolic control in cardiomyocytes.