An interaction network of mental disorder proteins in neural stem cells.

Mental disorders (MDs) such as intellectual disability (ID), autism spectrum disorders (ASD) and schizophrenia have a strong genetic component. Recently, many gene mutations associated with ID, ASD or schizophrenia have been identified by high-throughput sequencing. A substantial fraction of these mutations are in genes encoding transcriptional regulators. Transcriptional regulators associated with different MDs but acting in the same gene regulatory network provide information on the molecular relation between MDs. Physical interaction between transcriptional regulators is a strong predictor for their cooperation in gene regulation. Here, we biochemically purified transcriptional regulators from neural stem cells, identified their interaction partners by mass spectrometry and assembled a protein interaction network containing 206 proteins, including 68 proteins mutated in MD patients and 52 proteins significantly lacking coding variation in humans. Our network shows molecular connections between established MD proteins and provides a discovery tool for novel MD genes. Network proteins preferentially co-localize on the genome and cooperate in disease-relevant gene regulation. Our results suggest that the observed transcriptional regulators associated with ID, ASD or schizophrenia are part of a transcriptional network in neural stem cells. We find that more severe mutations in network proteins are associated with MDs that include lower intelligence quotient (IQ), suggesting that the level of disruption of a shared transcriptional network correlates with cognitive dysfunction.

Detection of Alpha-Toxin and Other Virulence Factors in Biofilms of Staphylococcus aureus on Polystyrene and a Human Epidermal Model.

BACKGROUND & AIM: The ability of Staphylococcus aureus to successfully colonize (a)biotic surfaces may be explained by biofilm formation and the actions of virulence factors. The aim of the present study was to establish the presence of 52 proteins, including virulence factors such as alpha-toxin, during biofilm formation of five different (methicillin resistant) S. aureus strains on Leiden human epidermal models (LEMs) and polystyrene surfaces (PS) using a competitive Luminex-based assay. RESULTS: All five S. aureus strains formed biofilms on PS, whereas only three out of five strains formed biofilms on LEMs. Out of the 52 tested proteins, six functionally diverse proteins (ClfB, glucosaminidase, IsdA, IsaA, SACOL0688 and nuclease) were detected in biofilms of all strains on both PS and LEMs. At the same time, four toxins (alpha-toxin, gamma-hemolysin B and leukocidins D and E), two immune modulators (formyl peptide receptor-like inhibitory protein and Staphylococcal superantigen-like protein 1), and two other proteins (lipase and LytM) were detectable in biofilms by all five S. aureus strains on LEMs, but not on PS. In contrast, fibronectin-binding protein B (FnbpB) was detectable in biofilms by all S. aureus biofilms on PS, but not on LEMs. These data were largely confirmed by the results from proteomic and transcriptomic analyses and in case of alpha-toxin additionally by GFP-reporter technology. CONCLUSION: Functionally diverse virulence factors of (methicillin-resistant) S. aureus are present during biofilm formation on LEMs and PS. These results could aid in identifying novel targets for future treatment strategies against biofilm-associated infections.

Identification by a differential proteomic approach of the induced stress and redox proteins by resveratrol in the normal and diabetic rat heart.

A recent study showed cardioprotective effects of resveratrol on the diabetic heart. The present study sought to compare the protein profiles of the normal versus diabetic hearts after resveratrol treatment using differential proteomic analysis. Rats were randomly divided into two groups: control and diabetic. Both groups of rats were fed resveratrol (2.5 mg/kg/day) for 7 days, and then the rats were sacrificed, hearts were isolated and cytoplasmic fraction from left ventricular tissue was collected to carry out proteomic profiling as well as immunoblotting. Compared to normal hearts, diabetic hearts show increased myocardial infarct size and cardiomy-ocyte apoptosis upon ex vivo global ischaemia of 30 min. followed by 2 hrs of reperfusion. Resveratrol reduced infarct size and apop-totic cell death for both the groups, but the extent of infarct size and apoptosis remained higher for the diabetic group compared to the normal group. The left ventricular cytoplasmic proteins were analysed by 2D-DIGE and differentially displayed bands were further analysed by nano Liquid Chromatography-Mass Spectroscopy (LC-MS/MS). The results showed differential regulation of normal versus diabetic hearts treated with resveratrol of many proteins related to energy metabolism of which several were identified as mitochondrial proteins. Of particular interest is the increased expression of several chaperone proteins and oxidative stress and redox proteins in the diabetic group including Hsc70, HSPp6, GRP75, peroxiredoxin (Prdx)-1 and Prdx-3 whose expression was reversed by resveratrol. Western blot analysis was performed to validate the up- or down-regulation of these stress proteins. The results indicate the differential regulation by resveratrol of stress proteins in diabetic versus normal hearts, which may explain in part the beneficial effects of resveratrol in diabetic induced cardiovascular complications.

Alterations in myofilament function contribute to left ventricular dysfunction in pigs early after myocardial infarction.

Myocardial infarction (MI) initiates cardiac remodeling, depresses pump function, and predisposes to heart failure. This study was designed to identify early alterations in Ca2+ handling and myofilament proteins, which may contribute to contractile dysfunction and reduced beta-adrenergic responsiveness in postinfarct remodeled myocardium. Protein composition and contractile function of skinned cardiomyocytes were studied in remote, noninfarcted left ventricular (LV) subendocardium from pigs 3 weeks after MI caused by permanent left circumflex artery (LCx) ligation and in sham-operated pigs. LCx ligation induced a 19% increase in LV weight, a 69% increase in LV end-diastolic area, and a decrease in ejection fraction from 54+/-5% to 35+/-4% (all P<0.05), whereas cardiac responsiveness to exercise-induced increases in circulating noradrenaline levels was blunted. Endogenous protein kinase A (PKA) was significantly reduced in remote myocardium of MI animals, and a negative correlation (R=0.62; P<0.05) was found between cAMP levels and LV weight-to-body weight ratio. Furthermore, SERCA2a expression was 23% lower after MI compared with sham. Maximal isometric force generated by isolated skinned myocytes was significantly lower after MI than in sham (15.4+/-1.5 versus 19.2+/-0.9 kN/m2; P<0.05), which might be attributable to a small degree of troponin I (TnI) degradation observed in remodeled postinfarct myocardium. An increase in Ca2+ sensitivity of force (pCa50) was observed after MI compared with sham (DeltapCa50=0.17), which was abolished by incubating myocytes with exogenous PKA, indicating that the increased Ca2+ sensitivity resulted from reduced TnI phosphorylation. In conclusion, remodeling of noninfarcted pig myocardium is associated with decreased SERCA2a and myofilament function, which may contribute to depressed LV function. The full text of this article is available online at http://circres.ahajournals.org.