Selective expression of RT6 superfamily in human bronchial epithelial cells.

RT6 proteins are glycosylphosphatidylinositol (GPI)-linked alloantigens that are localized to cytotoxic T lymphocytes and that have nicotinamide adenine dinucleotide glycohydrolase and adenosine diphosphate (ADP)-ribosyltransferase activities. In view of the importance of GPI-linked surface proteins in mediating interactions of cells with their milieu, and the varied functions of airway cells in inflammation, we undertook the present study to determine whether human homologues of the RT6 superfamily of ADP-ribosyltransferases (ART) are expressed in pulmonary epithelial cells. We hypothesized that these surface proteins or related family members may be present in cells that interact with inflammatory cells, and that they may thereby be involved in intercellular signaling. Using in situ analysis and Northern blot analysis, we identified ART1 messenger RNA (mRNA) in airway epithelial cells. As expected for GPI-anchored proteins, the localization of ART1 at the apical surface of ciliated epithelial cells was demonstrated by staining with polyclonal anti-ART1 antibody, and was confirmed by loss of this immunoreactivity after treatment with phosphatidylinositol-specific phospholipase C (PI-PLC), which selectively cleaves GPI anchors and releases proteins from the plasma membrane. Using in situ hybridization with specific ART3 and ART4 oligonucleotides, we also identified two additional members of the RT6 superfamily in epithelial cells. In accord with these findings, we identified ART3 and ART4 mRNAs through reverse transcription- polymerase chain reaction of polyadenine-positive RNA from human trachea. Interestingly, these proteins appeared to be preferentially localized to the airway epithelium. The localized expression of these members of the RT6 superfamily in human pulmonary epithelial cells may reflect a role for them in cell-cell signaling during immune responses within the airwa

Is there a role of statins in the prevention of aortic biological prostheses degeneration

It has been recently observed that statins might slow the progression of aortic stenosis or sclerosis. Preliminary reports suggested a similar positive effect in reducing the degeneration of aortic valve bioprostheses even though this hypothesis should be further proven and supported by new data. In this review the present evidences of the possible effects of statins in this field are discussed

The R403Q Myosin Mutation Implicated in Familial Hypertrophic Cardiomyopathy Causes Disorder at the Actomyosin Interface

Mutations in virtually all of the proteins comprising the cardiac muscle sarcomere have been implicated in causing Familial Hypertrophic Cardiomyopathy (FHC). Mutations in the beta-myosin heavy chain (MHC) remain among the most common causes of FHC, with the widely studied R403Q mutation resulting in an especially severe clinical prognosis. In vitro functional studies of cardiac myosin containing the R403Q mutation have revealed significant changes in enzymatic and mechanical properties compared to wild-type myosin. It has been proposed that these molecular changes must trigger events that ultimately lead to the clinical phenotype.Here we examine the structural consequences of the R403Q mutation in a recombinant smooth muscle myosin subfragment (S1), whose kinetic features have much in common with slow beta-MHC. We obtained three-dimensional reconstructions of wild-type and R403Q smooth muscle S1 bound to actin filaments in the presence (ADP) and absence (apo) of nucleotide by electron cryomicroscopy and image analysis. We observed that the mutant S1 was attached to actin at highly variable angles compared to wild-type reconstructions, suggesting a severe disruption of the actin-myosin interaction at the interface.These results provide structural evidence that disarray at the molecular level may be linked to the histopathological myocyte disarray characteristic of the diseased state

Secretome of apoptotic peripheral blood cells (APOSEC) confers cytoprotection to cardiomyocytes and inhibits tissue remodelling after acute myocardial infarction: a preclinical study

Heart failure following acute myocardial infarction (AMI) is a major cause of morbidity and mortality. Our previous observation that injection of apoptotic peripheral blood mononuclear cell (PBMC) suspensions was able to restore long-term cardiac function in a rat AMI model prompted us to study the effect of soluble factors derived from apoptotic PBMC on ventricular remodelling after AMI. Cell culture supernatants derived from irradiated apoptotic peripheral blood mononuclear cells (APOSEC) were collected and injected as a single dose intravenously after myocardial infarction in an experimental AMI rat model and in a porcine closed chest reperfused AMI model. Magnetic resonance imaging (MRI) and echocardiography were used to quantitate cardiac function. Analysis of soluble factors present in APOSEC was performed by enzyme-linked immunosorbent assay (ELISA) and activation of signalling cascades in human cardiomyocytes by APOSEC in vitro was studied by immunoblot analysis. Intravenous administration of a single dose of APOSEC resulted in a reduction of scar tissue formation in both AMI models. In the porcine reperfused AMI model, APOSEC led to higher values of ejection fraction (57.0 vs. 40.5%, p < 0.01), a better cardiac output (4.0 vs. 2.4 l/min, p < 0.001) and a reduced extent of infarction size (12.6 vs. 6.9%, p < 0.02) as determined by MRI. Exposure of primary human cardiac myocytes with APOSEC in vitro triggered the activation of pro-survival signalling-cascades (AKT, Erk1/2, CREB, c-Jun), increased anti-apoptotic gene products (Bcl-2, BAG1) and protected them from starvation-induced cell death. Intravenous infusion of culture supernatant of apoptotic PBMC attenuates myocardial remodelling in experimental AMI models. This effect is probably due to the activation of pro-survival signalling cascades in the affected cardiomyocytes

Heavy and light roles: myosin in the morphogenesis of the heart

Myosin is an essential component of cardiac muscle, from the onset of cardiogenesis through to the adult heart. Although traditionally known for its role in energy transduction and force development, recent studies suggest that both myosin heavy-chain and myosin lightchain proteins are required for a correctly formed heart. Myosins are structural proteins that are not only expressed from early stages of heart development, but when mutated in humans they may give rise to congenital heart defects. This review will discuss the roles of myosin, specifically with regards to the developing heart. The expression of each myosin protein will be described, and the effects that altering expression has on the heart in embryogenesis in different animal models will be discussed. The human molecular genetics of the myosins will also be reviewed