Unbiased Expression Profiling Identifies a Novel Notch Signaling Target RND1 as Regulator of Angiogenesis

Notch signaling controls normal and pathological angiogenesis through transcriptional regulation of a wide network of target genes. Despite intensive studies of the endothelial Notch function, a comprehensive list of Notch-regulated genes, especially direct transcriptional targets, has not been assembled in endothelial cells (ECs). Here we uncovered novel EC Notch targets that are rapidly regulated by Notch signaling using several unbiased in vivo and in vitro screening approaches that captured genes regulated within 6 hours or less of Notch signal activation. We used a gamma-secretase inhibitor in neonates to profile Notch targets in the brain endothelium using the RiboTag technique, allowing for isolation of endothelial specific mRNA from a complex tissue without disrupting cell-cell contact. We used two types of primary cultured endothelial cells to define ligand-specific Notch targets by tethered-ligand stimulation. The identified Notch targets were validated by determining their regulation within one to two hours of EGTA-mediated Notch activation. By comparing significantly regulated genes in each of the screens, we assembled a comprehensive database of potential Notch targets in endothelial cells. Of particular interest, we uncovered G protein pathway related genes as potential novel Notch targets. We focused on a novel candidate target passing selection criteria after all screens, a small GTPase RND1. RND1(Rho GTPase1) regulates cytoskeleton arrangement through Rho and Ras signaling. RND1 was validated as an endothelial Notch target in multiple endothelial cell types. In Human Umbilical Vein Endothelial Cells (HUVECs) we established angiogenic activity for RND1 that included regulation of cell migration towards VEGF and function in sprouting angiogenesis. We established that Notch and RND1 suppressed Ras activation but had no effects on Rho activation in HUVECs. These results demonstrate that RND1 expression is regulated by Notch signaling in endothelium and suggest that RND1 functions downstream of Notch in sprouting angiogenesis, revealing an unexplored role of endothelial Notch in regulating G protein pathways

Discovery and characterization of pentose-specific transporters in Saccharomyces cerevisiae

Saccharomyces cerevisiae is considered one of the most promising organisms for ethanol production from lignocellulosic feedstock. Unfortunately, pentose sugars, which make up to 30% of lignocellulose, cannot be utilized by S. cerevisiae. Pentoses can only enter yeast cells through hexose transporters, which have two orders of magnitude lower affinities for pentose sugars. Additionally, inefficient pentose uptake has been shown to be the limiting step for some D-xylose metabolizing yeast strains. In this thesis, we report the discovery of seven active pentose transporters from pentose assimilating fungal species Pichia stipitis and Neurospora crassa based on sequence homology with the glucose/xylose/H+ symporter (GXS1) in Candida intermedia. These transporters were cloned and heterologously expressed in S. cerevisiae and their sugar uptake activities were studied by analysis of intracellular sugar accumulation using HPLC. Among the seven active transporters, one L-arabinose-specific and two D-xylose-specific transporters were identified. These transporters were functionally expressed and properly localized in S. cerevisiae as indicated by HPLC analysis and immunofluorescence microscopy, respectively. Kinetic parameters of the transporters were determined using a 14C-labeled sugar uptake assay. Sugar uptake assay in un-buffered cell suspension indicated the sugar uptake through these three transporters was not coupled with proton uptake, revealing that these three sugar transporters are facilitators. Introduction of these pentose-specific transporters may facilitate pentose sugar utilization in S. cerevisiae by improving pentose uptake. More efficient utilization of pentose sugars will lower the cost for lignocellulosic ethanol production

Determination of f0−σf_0-\sigma mixing angle through Bs0→J/Ψ f0(980)(σ)B_s^0 \to J/\Psi~f_0(980)(\sigma) decays

We study $B_s^0 \to J/\psi f_0(980)$ decays, the quark content of $f_0(980)$ and the mixing angle of $f_0(980)$ and $\sigma(600)$. We calculate not only the factorizable contribution in QCD facorization scheme but also the nonfactorizable hard spectator corrections in QCDF and pQCD approach. We get consistent result with the experimental data of $B_s^0 \to J/\psi f_0(980)$ and predict the branching ratio of $B_s^0 \to J/\psi \sigma$. We suggest two ways to determine $f_0-\sigma$ mixing angle $\theta$. Using the experimental measured branching ratio of $B_s^0 \to J/\psi f_0(980)$, we can get the $f_0-\sigma$ mixing angle $\theta$ with some theoretical uncertainties. We suggest another way to determine $f_0-\sigma$ mixing angle $\theta$ using both of experimental measured decay branching ratios $B_s^0 \to J/\psi f_0(980) (\sigma)$ to avoid theoretical uncertainties.Comment: arXiv admin note: substantial text overlap with arXiv:0707.263

The study of B→J/Ψη(′)B\to J/\Psi \eta^{(\prime)} decays and determination of η−η′\eta-\eta^{\prime} mixing angle

We study $B\to J/\Psi \eta^{(\prime)}$ decays and suggest two methods to determine the $\eta-\eta^{\prime}$ mixing angle. We calculate not only the factorizable contribution in QCD facorization scheme but also the nonfactorizable hard spectator corrections in pQCD approach. We get the branching ratio of $B\to J/\Psi \eta$ which is consistent with recent experimental data and predict the branching ratio of $B\to J/\Psi \eta^{\prime}$ to be $7.59\times 10^{-6}$. Two methods for determining $\eta-\eta^{\prime}$ mixing angle are suggested in this paper. For the first method, we get the $\eta-\eta^{\prime}$ mixing angle to be about $-13.1^{\circ}$, which is in consistency with others in the literature. The second method depends on less parameters so can be used to determine the $\eta-\eta^{\prime}$ mixing angle with better accuracy but needs, as an input, the branching ratio for $B\to J/\Psi \eta^{\prime}$which should be measured in the near future.Comment: 16pages,4figure