The rockefeller university

The Mediator is an evolutionarily conserved, multiprotein complex that is a key regulator of protein-coding genes. In metazoan cells, multiple pathways that are responsible for homeostasis, cell growth and differentiation converge on the Mediator through transcriptional activators and repressors that target one or more of the almost 30 subunits of this complex. Besides interacting directly with RNA polymerase II, Mediator has multiple functions and can interact with and coordinate the action of numerous other co-activators and co-repressors, including those acting at the level of chromatin. These interactions ultimately allow the Mediator to deliver outputs that range from maximal activation of genes to modulation of basal transcription to long-term epigenetic silencing.

Recent metagenomic sequencing studies of uncultured viral populations have provided novel insights into the ecology of environmental bacteriophage. At the same time, viral metagenomes could also represent a potential source of recombinant proteins with biotechnological value. In order to identify such proteins, a novel two-step screening technique was devised for cloning phage lytic enzymes from uncultured viral DNA. This plasmid-based approach first involves a primary screen in which transformed Escherichia coli clones that demonstrate colony lysis following exposure to inducing agent are identified. This effect, which can be due to the expression of membrane-permeabilizing phage holins, is discerned by the development a hemolytic effect in surrounding blood agar. In a secondary step, the clones identified in the primary screen are overlaid with autoclaved Gram-negative bacteria (specifically Pseudomonas aeruginosa) to assay directly for recombinant expression of lytic enzymes, which are often encoded proximally to holins in phage genomes. As proof-ofprinciple, the method was applied to a viral metagenomic library constructed from mixed animal feces, and 26 actively expressed lytic enzymes were cloned. These proteins include both Gram-positive-like and Gram-negative-like enzymes, as well as several atypical lysins whose predicted structures are less common among known phage. Overall, this study represents one of the first functional screens of a viral metagenomic population, and it provides a general approach for characterizing lysins from uncultured phage.

ADP-ribosylation is an important post-translational modification involved in processes including cellular replication, DNA repair, and cell death. Despite these roles, the functions of ADP-ribosylation, in particular mono-ADP-ribosylation, remain poorly understood. The development of a technique to generate large amounts of site-specific, ADP-ribosylated peptides would provide a useful tool for deconvoluting the biochemical roles of ADP-ribosylation. Here we demonstrate that synthetic histone H2B tail peptides, incorporating aminooxy or N-methyl aminooxy functionalized amino acids, can be site-specifically conjugated to ADP-ribose. These peptides are recognized as substrates by the ADP-ribosylation biochemical machinery (PARP1), can interact with the ADP-ribose binding proteins macroH2A1.1 and PARP9, and demonstrate superior enzymatic and chemical stability when compared to ester-linked ADP-ribose. In addition, the incorporation of benzophenone photo-cross-linkers into these peptides is demonstrated to provide a means to probe for and enrich ADP-ribose binding proteins.

Heme oxygenase-1 (HO-1) and its catabolic by-products have potent anti-inflammatory activity in many models of disease. It is not known, however, if HO-1 also plays a role in the homeostatic control of T cell activation and proliferation. We demonstrate here that the HO-1 inhibitor tin mesoporphyrin (SnMP) induces activation, proliferation, and maturation of naive CD4(+) and CD8(+) T cells via interactions with CD14(+) monocytes in vitro. This response is dependent upon interactions of T cells with MHC class I and II on the surface of CD14(+) monocytes. Furthermore, CD4(+)CD25(+)FoxP3(+) regulatory T cells were able to suppress this proliferation, even though their suppressive activity was itself impaired by SnMP. Given the magnitude of the Ag-independent T cell response induced by SnMP, we speculate that HO-1 plays an important role in dampening nonspecific T cell activation. Based on these findings, we propose a potential role for HO-1 in the control of naive T cell homeostatic proliferation. The Journal of Immunology, 2010, 185: 5279-5288.

The facile synthesis and photophysical properties of three nonhydrolyzable thioglycosylated porphyrinoids are reported. Starting from meso-perfluorophenylporphyrin, the nonhydrolyzable thioglycosylated porphyrin (PGlc(4)), chlorin (CGlc(4)), isobacteriochlorin (IGlc(4)), and bacteriochlorin (BGlc(4)) can be made in 2-3 steps. The ability to append a wide range of targeting agents onto the perfluorophenyl moieties, the chemical stability, and the ability to fine-tune the photophysical properties of the chromophores make this a suitable platform for development of biochemical tags, diagnostics, or as photodynamic therapeutic agents. Compared to the porphyrin in phosphate buffered saline, CGlc(4) has a markedly greater absorbance of red light near 650 nm and a 6-fold increase in fluorescence quantum yield, whereas IGlc(4) has broad Q-bands and a 12-fold increase in fluorescence quantum yield. BGlc(4) has a similar fluorescence quantum yield to PGlc(4) (<10%), but the lowest-energy absorption/emission peaks of BGlc(4) are considerably red-shifted to near 730 nm with a nearly 50-fold greater absorbance, which may allow this conjugate to be an effective PDT agent. The uptake of CGlc(4), IGlc(4), and BGlc(4) derivatives into cells such as human breast cancer cells MDA-MB-231 and K:Molv NTH 3T3 mouse fibroblast cells can be observed at nanomolar concentrations. Photobleaching under these conditions is minimal.

High-fructose corn syrup (HFCS) accounts for as much as 40% of caloric sweeteners used in the United States Some studies have shown that short-term access to HFCS can cause increased body weight but the findings are mixed The current study examined both short and long-term effects of HFCS on body weight body fat and circulating triglycerides In Experiment 1 male Sprague-Dawley rats were maintained or short term (8 weeks) on (1) 12 h/day of 8% HFCS (2) 12 h/day 10% sucrose (3) 24 h/day HFCS all with ad libitum rodent chow or (4) ad libitum chow alone Rats with 12-h access to HFCS gained significantly more body weight than animals given equal access to 10% sucrose even though they consumed the same number of total calories but fewer calories from HFCS than sucrose In Experiment 2 the long-term effects of HFCS on body weight and obesogenic parameters as well as gender differences were explored Over the course of 6 or 7 months both male and female rats with access to HFCS gained significantly more body weight than control groups This increase in body weight with HFCS was accompanied by an increase in adipose fat notably in the abdominal region and elevated circulating triglyceride levels Translated to humans these results suggest that excessive consumption of HFCS may contribute to the incidence of obesity (C) 2010 Elsevier Inc All rights reserved

We present a search for the lightest supersymmetric partner of the top quark in proton-antiproton collisions at a center-of-mass energy root s = 1: 96 TeV. This search was conducted within the framework of the R parity conserving minimal supersymmetric extension of the standard model, assuming the stop decays dominantly to a lepton, a sneutrino, and a bottom quark. We searched for events with two oppositely-charged leptons, at least one jet, and missing transverse energy in a data sample corresponding to an integrated luminosity of 1 fb(-1) collected by the Collider Detector at Fermilab experiment. No significant evidence of a stop quark signal was found. Exclusion limits at 95% confidence level in the stop quark versus sneutrino mass plane are set. Stop quark masses up to 180 GeV/c(2) are excluded for sneutrino masses around 45 GeV/c(2), and sneutrino masses up to 116 GeV/c(2) are excluded for stop quark masses around 150 GeV/c(2).

Mutations in the X-linked MECP2 gene, which encodes the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2), cause Rett syndrome and several neurodevelopmental disorders including cognitive disorders, autism, juvenile-onset schizophrenia and encephalopathy with early lethality. Rett syndrome is characterized by apparently normal early development followed by regression, motor abnormalities, seizures and features of autism, especially stereotyped behaviours. The mechanisms mediating these features are poorly understood. Here we show that mice lacking Mecp2 from GABA (c-aminobutyric acid)-releasing neurons recapitulate numerous Rett syndrome and autistic features, including repetitive behaviours. Loss of MeCP2 from a subset of forebrain GABAergic neurons also recapitulates many features of Rett syndrome. MeCP2-deficient GABAergic neurons show reduced inhibitory quantal size, consistent with a presynaptic reduction in glutamic acid decarboxylase 1 (Gad1) and glutamic acid decarboxylase 2 (Gad2) levels, and GABA immunoreactivity. These data demonstrate that MeCP2 is critical for normal function of GABA-releasing neurons and that subtle dysfunction of GABAergic neurons contributes to numerous neuropsychiatric phenotypes.

To achieve high compaction, most genomic DNA in eukaryotes is incorporated into nucleosomes; however, regulatory factors and transcriptional machinery must gain access to chromatin to extract genetic information. This conflict is partially resolved by a particular arrangement of nucleosome locations on the genome. Across all eukaryotic species, promoters and other regulatory sequences are more nucleosome-depleted, whereas transcribed regions tend to be occupied with well-positioned, high-density nucleosomal arrays. This nucleosome positioning pattern, as well as its dynamic regulation, facilitates the access of transcription factors to their target sites and plays a crucial role in determining the transcription level, cell-to-cell variation and activation or repression dynamics.