Role of N-WASP in Endothelial Monolayer Formation and Integrity

Endothelial cells (ECs) form a monolayer that serves as a barrier between the blood and the underlying tissue. ECs tightly regulate their cell-cell junctions, controlling the passage of soluble materials and immune cells across the monolayer barrier. We studied the role of N-WASP, a key regulator of Arp2/3 complex and actin assembly, in EC monolayers. We report that N-WASP regulates endothelial monolayer integrity by affecting the organization of cell junctions. Depletion of N-WASP resulted in an increase in transendothelial electrical resistance, a measure of monolayer integrity. N-WASP depletion increased the width of cell-cell junctions and altered the organization of F-actin and VE-cadherin at junctions. N-WASP was not present at cell-cell junctions in monolayers under resting conditions, but it was recruited following treatment with sphingosine-1-phosphate. Taken together, our results reveal a novel role for N-WASP in remodeling EC junctions, which is critical for monolayer integrity and function.     

Long ncRNA expression associates with tissue-specific enhancers

Long non-coding RNAs (ncRNA) have recently been demonstrated to be expressed from a subset of enhancers and to be required for the distant regulation of gene expression. Several approaches to predict enhancers have been developed based on various chromatin marks and occupancy of enhancer-binding proteins. Despite the rapid advances in the field, no consensus how to define tissue specific enhancers yet exists. Here, we identify 2,695 long ncRNAs annotated by ENCODE (corresponding to 28% of all ENCODE annotated long ncRNAs) that overlap tissue-specific enhancers. We use a recently developed algorithm to predict tissue-specific enhancers, PreSTIGE, that is based on the H3K4me1 mark and tissue specific expression of mRNAs. The expression of the long ncRNAs overlapping enhancers is significantly higher when the enhancer is predicted as active in a specific cell line, suggesting a general interdependency of active enhancers and expression of long ncRNAs. This dependency is not identified using previous enhancer prediction algorithms that do not account for expression of their downstream targets. The predicted enhancers that overlap annotated long ncRNAs generally have a lower ratio of H3K4me1 to H3K4me3, suggesting that enhancers expressing long ncRNAs might be associated with specific epigenetic marks. In conclusion, we demonstrate the tissue-specific predictive power of PreSTIGE and provide evidence for thousands of long ncRNAs that are expressed from active tissue-specific enhancers, suggesting a particularly important functional relationship between long ncRNAs and enhancer activity in determining tissue-specific gene expression.     

RNA silencing in Monterey

The tenth annual Keystone Symposium on the Mechanism and Biology of Silencing convened in Monterey, California, in March 2011. Those seeking some West Coast sunshine were, unfortunately, met with incessant precipitation throughout the meeting. Nevertheless, attendees were brightened by enlightening and vigorous scientific discussions. Here, we summarize the results presented at the meeting, which inspire and push this expanding field into new territories.     

Assessing bee species richness in two Mediterranean communities: importance of habitat type and sampling techniques

The decline of bees has raised concerns regarding their conservation and the maintenance of ecosystem services they provide to bee-pollinated wild flowers and crops. Although the Mediterranean region is a hotspot for bee species richness, their status remains poorly studied. There is an urgent need for cost-effective, reliable, and unbiased sampling methods that give good bee species richness estimates. This study aims: (a) to assess bee species richness in two common Mediterranean habitat types: semi-natural scrub (phrygana) and managed olive groves; (b) to compare species richness in those systems to that of other biogeographic regions, and (c) to assess whether six different sampling methods (pan traps, variable and standardized transect walks, observation plots and trap nests), previously tested in other European biogeographic regions, are suitable in Mediterranean communities. Eight study sites, four per habitat type, were selected on the island of Lesvos, Greece. The species richness observed was high compared to other habitat types worldwide for which comparable data exist. Pan traps collected the highest proportion of the total bee species richness across all methods at the scale of a study site. Variable and standardized transect walks detected the highest total richness over all eight study sites. Trap nests and observation plots detected only a limited fraction of the bee species richness. To assess the total bee species richness in bee diversity hotspots, such as the studied habitats, we suggest a combination of transect walks conducted by trained bee collectors and pan trap sampling.     

Regulated reprogramming in the regeneration of sensory receptor cells

Vision, olfaction, hearing, and balance are mediated by receptors that reside in specialized sensory epithelial organs. Age-related degeneration of the photoreceptors in the retina and the hair cells in the cochlea, caused by macular degeneration and sensorineural hearing loss, respectively, affect a growing number of individuals. Although sensory receptor cells in the mammalian retina and inner ear show only limited or no regeneration, in many nonmammalian vertebrates, these sensory epithelia show remarkable regenerative potential. We summarize the current state of knowledge of regeneration in the specialized sense organs in both nonmammalian vertebrates and mammals and discuss possible areas where new advances in regenerative medicine might provide approaches to successfully stimulate sensory receptor cell regeneration. The field of regenerative medicine is still in its infancy, but new approaches using stem cells and reprogramming suggest ways in which the potential for regeneration may be restored in individuals suffering from sensory loss.     

Studies on 6-chloro-5-(1-naphthyloxy)-2-(trifluoromethyl)-1H-benzimidazole/2-hydroxypropyl-β-cyclodextrin association: Characterization, molecular modeling studies, and in vivo anthelminthic activity

The purpose of this work is to study the molecular association that occurs between 2-hydroxypropyl-β-cyclodextrin (HPβCD) and 6-chloro-5-(1-naphthyloxy)-2-(trifluoromethyl)-1H-benzimidazole (RCB20), an antiparasitic compound recently found by our research group, with poor aqueous solubility. The complex stability constant and stoichiometric ratio determined by phase-solubility diagram and Job's plot provided evidence that HPβCD enhanced water solubility of RCB20 through inclusion complex formation. Two-dimensional 1H NMR spectroscopy is used to study the molecular arrangement of inclusion complex in solution. These results are further supported using molecular modeling studies. In the solid state, the complexation is confirmed by differential scanning calorimetry, powder X-ray diffraction, and scanning electron microscopy. Finally, RCB20/HPβCD complex has better activity than RCB20 against the adult and muscle larvae phase of Trichinella spiralis.