bluuebunny/crossref_metadata_2025 huggingface dataset:
Toll-like receptor 3 inhibits memory retention and constrains adult hippocampal neurogenesis
Authors: Okun Eitan , Griffioen Kathleen , Barak Boaz , Roberts Nicholas J. , Castro Kamilah , Pita Mario A. , Cheng Aiwu , Mughal Mohamed R. , Wan Ruiqian , Ashery Uri , Mattson Mark P.
Published: August 2010

Toll-like receptors (TLRs) are innate immune receptors that have recently emerged as regulators of neuronal survival and developmental neuroplasticity. Adult TLR3-deficient mice exhibited enhanced hippocampus-dependent working memory in the Morris water maze, novel object recognition, and contextual fear-conditioning tasks. In contrast, TLR3-deficient mice demonstrated impaired amygdala-related behavior and anxiety in the cued fear-conditioning, open field, and elevated plus maze tasks. Further, TLR3-deficient mice exhibited increased hippocampal CA1 and dentate gyrus volumes, increased hippocampal neurogenesis, and elevated levels of the AMPA receptor subunit GluR1 in the CA1 region of the hippocampus. In addition, levels of activated forms of the kinase ERK and the transcription factor CREB were elevated in the hippocampus of TLR3-deficient mice, suggesting that constitutive TLR3 signaling negatively regulates pathways known to play important roles in hippocampal plasticity. Direct activation of TLR3 by intracerebroventricular infusion of a TLR3 ligand impaired working memory, but not reference memory. Our findings reveal previously undescribed roles for TLR3 as a suppressor of hippocampal cellular plasticity and memory retention.
Inhibition of tumorigenesis driven by different Wnt proteins requires blockade of distinct ligand-binding regions by LRP6 antibodies
Authors: Ettenberg Seth A. , Charlat Olga , Daley Michael P. , Liu Shanming , Vincent Karen J. , Stuart Darrin D. , Schuller Alwin G. , Yuan Jing , Ospina Beatriz , Green John , Yu Qunyan , Walsh Renee , Li Sharon , Schmitz Rita , Heine Holger , Bilic Sanela , Ostrom Lance , Mosher Rebecca , Hartlepp K. Felix , Zhu Zhenping , Fawell Stephen , Yao Yung-Mae , Stover David , Finan Peter M. , Porter Jeffery A. , Sellers William R. , Klagge Ingo M. , Cong Feng
Published: August 2010

Disregulated Wnt/β-catenin signaling has been linked to various human diseases, including cancers. Inhibitors of oncogenic Wnt signaling are likely to have a therapeutic effect in cancers. LRP5 and LRP6 are closely related membrane coreceptors for Wnt proteins. Using a phage-display library, we identified anti-LRP6 antibodies that either inhibit or enhance Wnt signaling. Two classes of LRP6 antagonistic antibodies were discovered: one class specifically inhibits Wnt proteins represented by Wnt1, whereas the second class specifically inhibits Wnt proteins represented by Wnt3a. Epitope-mapping experiments indicated that Wnt1 class-specific antibodies bind to the first propeller and Wnt3a class-specific antibodies bind to the third propeller of LRP6, suggesting that Wnt1- and Wnt3a-class proteins interact with distinct LRP6 propeller domains. This conclusion is further supported by the structural functional analysis of LRP5/6 and the finding that the Wnt antagonist Sclerostin interacts with the first propeller of LRP5/6 and preferentially inhibits the Wnt1-class proteins. We also show that Wnt1 or Wnt3a class-specific anti-LRP6 antibodies specifically block growth of MMTV-Wnt1 or MMTV-Wnt3 xenografts in vivo. Therapeutic application of these antibodies could be limited without knowing the type of Wnt proteins expressed in cancers. This is further complicated by our finding that bivalent LRP6 antibodies sensitize cells to the nonblocked class of Wnt proteins. The generation of a biparatopic LRP6 antibody blocks both Wnt1- and Wnt3a-mediated signaling without showing agonistic activity. Our studies provide insights into Wnt-induced LRP5/6 activation and show the potential utility of LRP6 antibodies in Wnt-driven cancer.
Amphiphile regulation of ion channel function by changes in the bilayer spring constant
Authors: Lundbæk Jens A. , Koeppe Roger E. , Andersen Olaf S.
Published: August 2010

Many drugs are amphiphiles that, in addition to binding to a particular target protein, adsorb to cell membrane lipid bilayers and alter intrinsic bilayer physical properties (e.g., bilayer thickness, monolayer curvature, and elastic moduli). Such changes can modulate membrane protein function by altering the energetic cost (ΔGbilayer) of bilayer deformations associated with protein conformational changes that involve the protein-bilayer interface. But amphiphiles have complex effects on the physical properties of lipid bilayers, meaning that the net change in ΔGbilayercannot be predicted from measurements of isolated changes in such properties. Thus, the bilayer contribution to the promiscuous regulation of membrane proteins by drugs and other amphiphiles remains unknown. To overcome this problem, we use gramicidin A (gA) channels as molecular force probes to measure theneteffect of amphiphiles, at concentrations often used in biological research, on the bilayer elastic response to a change in the hydrophobic length of an embedded protein. The effects of structurally diverse amphiphiles can be described by changes in a phenomenological bilayer spring constant (HB) that summarizes the bilayer elastic properties, as sensed by a bilayer-spanning protein. Amphiphile-induced changes inHB, measured using gA channels of a particular length, quantitatively predict changes in lifetime for channels of a different length—as well as changes in the inactivation of voltage-dependent sodium channels in living cells. The use of gA channels as molecular force probes provides a tool for quantitative, predictive studies of bilayer-mediated regulation of membrane protein function by amphiphiles.
Sucrose nonfermenting AMPK-related kinase (SNARK) mediates contraction-stimulated glucose transport in mouse skeletal muscle
Authors: Koh Ho-Jin , Toyoda Taro , Fujii Nobuharu , Jung Michelle M. , Rathod Amee , Middelbeek R. Jan-Willem , Lessard Sarah J. , Treebak Jonas T. , Tsuchihara Katsuya , Esumi Hiroyasu , Richter Erik A. , Wojtaszewski Jørgen F. P. , Hirshman Michael F. , Goodyear Laurie J.
Published: August 2010

The signaling mechanisms that mediate the important effects of contraction to increase glucose transport in skeletal muscle are not well understood, but are known to occur through an insulin-independent mechanism. Muscle-specific knockout of LKB1, an upstream kinase for AMPK and AMPK-related protein kinases, significantly inhibited contraction-stimulated glucose transport. This finding, in conjunction with previous studies of ablated AMPKα2 activity showing no effect on contraction-stimulated glucose transport, suggests that one or more AMPK-related protein kinases are important for this process. Muscle contraction increased sucrose nonfermenting AMPK-related kinase (SNARK) activity, an effect blunted in the muscle-specific LKB1 knockout mice. Expression of a mutant SNARK in mouse tibialis anterior muscle impaired contraction-stimulated, but not insulin-stimulated, glucose transport. Whole-body SNARK heterozygotic knockout mice also had impaired contraction-stimulated glucose transport in skeletal muscle, and knockdown of SNARK in C2C12 muscle cells impaired sorbitol-stimulated glucose transport. SNARK is activated by muscle contraction and is a unique mediator of contraction-stimulated glucose transport in skeletal muscle.
Comparative surface dynamics of amorphous and semicrystalline polymer films
Authors: Becker James S. , Brown Ryan D. , Killelea Daniel R. , Yuan Hanqiu , Sibener S. J.
Published: August 2010

The surface dynamics of amorphous and semicrystalline polymer films have been measured using helium atom scattering. Time-of-flight data were collected to resolve the elastic and inelastic scattering components in the diffuse scattering of neutral helium atoms from the surface of a thin poly(ethylene terephthalate) film. Debye–Waller attenuation was observed for both the amorphous and semicrystalline phases of the polymer by recording the decay of elastically scattered helium atoms with increasing surface temperature. Thermal attenuation measurements in the specular scattering geometry yielded perpendicular mean-square displacements of 2.7•10
-4
 
Å
2
 K
-1
and 3.1•10
-4
 
Å
2
 K
-1
for the amorphous and semicrystalline surfaces, respectively. The semicrystalline surface was consistently ∼15% softer than the amorphous across a variety of perpendicular momentum transfers. The Debye–Waller factors were also measured at off-specular angles to characterize the parallel mean-square displacements, which were found to increase by an order of magnitude over the perpendicular mean-square displacements for both surfaces. In contrast to the perpendicular motion, the semicrystalline state was ∼25% stiffer than the amorphous phase in the surface plane. These results were uniquely accessed through low-energy neutral helium atom scattering due to the highly surface-sensitive and nonperturbative nature of these interactions. The goal of tailoring the chemical and physical properties of complex advanced materials requires an improved understanding of interfacial dynamics, information that is obtainable through atomic beam scattering methods.
Uterine FK506-binding protein 52 (FKBP52)–peroxiredoxin-6 (PRDX6) signaling protects pregnancy from overt oxidative stress
Authors: Hirota Yasushi , Acar Nuray , Tranguch Susanne , Burnum Kristin E. , Xie Huirong , Kodama Ako , Osuga Yutaka , Ustunel Ismail , Friedman David B. , Caprioli Richard M. , Daikoku Takiko , Dey Sudhansu K.
Published: August 2010

Immunophilin FK506-binding protein 52 (FKBP52) is a cochaperone that binds to the progesterone receptor (PR) to optimize progesterone (P
4
)-PR signaling. We recently showed that
Fkbp52
-deficient (
Fkbp52
−/−
) mice have reduced uterine PR responsiveness and implantation failure which is rescued by excess P
4
supplementation in a genetic background-dependent manner. This finding led us to hypothesize that FKBP52 has functions in addition to optimizing PR activity. Using proteomics analysis, we found that uterine levels of peroxiredoxin-6 (PRDX6), a unique antioxidant, are significantly lower in
Fkbp52
−/−
mice than in WT and PR-null (
Pgr
−/−
) mice. We also found that
Fkbp52
−/−
mice with reduced uterine PRDX6 levels are susceptible to paraquat-induced oxidative stress (OS), leading to implantation failure even with P
4
supplementation. The same dose of paraquat did not interfere with implantation in WT mice. Moreover, treatment with antioxidants α-tocopherol and N-acetylcysteine (NAC) attenuated paraquat-induced implantation failure in P
4
-treated
Fkbp52
−/−
mice. Functional analyses using mouse embryonic fibroblasts show that
Fkbp52
deficiency associated with reduced PRDX6 levels promotes H
2
O
2
-induced cell death, which is reversed by the addition of NAC or by forced expression of PRDX6, suggesting that
Fkbp52
deficiency diminishes the threshold against OS by reducing PRDX6 levels. These findings provide evidence that heightened uterine OS in
Fkbp52
−/−
females with reduced PRDX6 levels induces implantation failure even in the presence of excess P
4
. This study shows that FKBP52–PRDX6 signaling protects pregnancy from overt OS.
TGF-β IL-6 axis mediates selective and adaptive mechanisms of resistance to molecular targeted therapy in lung cancer
Authors: Yao Zhan , Fenoglio Silvia , Gao Ding Cheng , Camiolo Matthew , Stiles Brendon , Lindsted Trine , Schlederer Michaela , Johns Chris , Altorki Nasser , Mittal Vivek , Kenner Lukas , Sordella Raffaella
Published: August 2010

The epidermal growth-factor receptor (EGFR) tyrosine kinase inhibitor erlotinib has been proven to be highly effective in the treatment of nonsmall cell lung cancer (NSCLC) harboring oncogenic EGFR mutations. The majority of patients, however, will eventually develop resistance and succumb to the disease. Recent studies have identified secondary mutations in the EGFR (EGFR T790M) and amplification of the N-Methyl-N′-nitro-N-nitroso-guanidine (MNNG) HOS transforming gene (MET) oncogene as two principal mechanisms of acquired resistance. Although they can account for approximately 50% of acquired resistance cases together, in the remaining 50%, the mechanism remains unknown. In NSCLC-derived cell lines and early-stage tumors before erlotinib treatment, we have uncovered the existence of a subpopulation of cells that are intrinsically resistant to erlotinib and display features suggestive of epithelial-to-mesenchymal transition (EMT). We showed that activation of TGF-β–mediated signaling was sufficient to induce these phenotypes. In particular, we determined that an increased TGF-β–dependent IL-6 secretion unleashed previously addicted lung tumor cells from their EGFR dependency. Because IL-6 and TGF-β are prominently produced during inflammatory response, we used a mouse model system to determine whether inflammation might impair erlotinib sensitivity. Indeed, induction of inflammation not only stimulated IL-6 secretion but was sufficient to decrease the tumor response to erlotinib. Our data, thus, argue that both tumor cell-autonomous mechanisms and/or activation of the tumor microenvironment could contribute to primary and acquired erlotinib resistance, and as such, treatments based on EGFR inhibition may not be sufficient for the effective treatment of lung-cancer patients harboring mutant EGFR.
Temperatures and cyclones strongly associated with economic production in the Caribbean and Central America
Authors: Hsiang Solomon M.
Published: August 2010

Understanding the economic impact of surface temperatures is an important question for both economic development and climate change policy. This study shows that in 28 Caribbean-basin countries, the response of economic output to increased temperatures is structurally similar to the response of labor productivity to high temperatures, a mechanism omitted from economic models of future climate change. This similarity is demonstrated by isolating the direct influence of temperature from that of tropical cyclones, an important correlate. Notably, output losses occurring in nonagricultural production (–2.4%/+1 °C) substantially exceed losses occurring in agricultural production (–0.1%/+1 °C). Thus, these results suggest that current models of future climate change that focus on agricultural impacts but omit the response of workers to thermal stress may underestimate the global economic costs of climate change.
Cancer-derived mutations in the regulatory subunit p85α of phosphoinositide 3-kinase function through the catalytic subunit p110α
Authors: Sun Minghao , Hillmann Petra , Hofmann Bianca T. , Hart Jonathan R. , Vogt Peter K.
Published: August 2010

Cancer-specific mutations in the iSH2 (inter-SH2) and nSH2 (N-terminal SH2) domains of p85α, the regulatory subunit of phosphatidylinositide 3-kinase (PI3K), show gain of function. They induce oncogenic cellular transformation, stimulate cellular proliferation, and enhance PI3K signaling. Quantitative determinations of oncogenic activity reveal large differences between individual mutants of p85α. The mutant proteins are still able to bind to the catalytic subunits p110α and p110β. Studies with isoform-specific inhibitors of p110 suggest that expression of p85 mutants in fibroblasts leads exclusively to an activation of p110α, and p110α is the sole mediator of p85 mutant-induced oncogenic transformation. The characteristics of the p85 mutants are in agreement with the hypothesis that the mutations weaken an inhibitory interaction between p85α and p110α while preserving the stabilizing interaction between p85α iSH2 and the adapter-binding domain of p110α.
Tracking, tuning, and terminating microbial physiology using synthetic riboregulators
Authors: Callura Jarred M. , Dwyer Daniel J. , Isaacs Farren J. , Cantor Charles R. , Collins James J.
Published: August 2010

The development of biomolecular devices that interface with biological systems to reveal new insights and produce novel functions is one of the defining goals of synthetic biology. Our lab previously described a synthetic, riboregulator system that affords for modular, tunable, and tight control of gene expression in vivo. Here we highlight several experimental advantages unique to this RNA-based system, including physiologically relevant protein production, component modularity, leakage minimization, rapid response time, tunable gene expression, and independent regulation of multiple genes. We demonstrate this utility in four sets of in vivo experiments with various microbial systems. Specifically, we show that the synthetic riboregulator is well suited for GFP fusion protein tracking in wild-type cells, tight regulation of toxic protein expression, and sensitive perturbation of stress response networks. We also show that the system can be used for logic-based computing of multiple, orthogonal inputs, resulting in the development of a programmable kill switch for bacteria. This work establishes a broad, easy-to-use synthetic biology platform for microbiology experiments and biotechnology applications.
Six and Eya promote apoptosis through direct transcriptional activation of the proapoptotic BH3-only geneegl-1inCaenorhabditis elegans
Authors: Hirose Takashi , Galvin Brendan D. , Horvitz H. Robert
Published: August 2010

The decision of a cell to undergo programmed cell death is tightly regulated during animal development and tissue homeostasis. Here, we show that theCaenorhabditis elegansSix family homeodomain proteinC. eleganshomeobox (CEH-34) and the Eyes absent ortholog EYA-1 promote the programmed cell death of a specific pharyngeal neuron, the sister of the M4 motor neuron. Loss of eitherceh-34oreya-1function causes survival of the M4 sister cell, which normally undergoes programmed cell death. CEH-34 physically interacts with the conserved EYA domain of EYA-1 in vitro. We identify anegl-15′cis-regulatory element that controls the programmed cell death of the M4 sister cell and show that CEH-34 binds directly to this site. Expression of the proapoptotic geneegl-1in the M4 sister cell requiresceh-34andeya-1function. We conclude that an evolutionarily conserved complex that includes CEH-34 and EYA-1 directly activatesegl-1expression through a 5′cis-regulatory element to promote the programmed cell death of the M4 sister cell. We suggest that the regulation of apoptosis by Six and Eya family members is conserved in mammals and involved in human diseases caused by mutations inSixandEya.
High-throughput screens in diploid cells identify factors that contribute to the acquisition of chromosomal instability
Authors: Conery Andrew R. , Harlow Ed
Published: August 2010

Chromosomal instability and the subsequent genetic mutations are considered to be critical factors in the development of the majority of solid tumors, but the mechanisms by which a stable diploid cell loses the ability to maintain genomic integrity are not well characterized. We have approached this critical issue through the use of high-throughput screens in untransformed diploid epithelial cells. In a screen of a cDNA library, we identified 13 kinases whose overexpression leads to increased ploidy. In a series of shRNA screens, we identified 16 kinases whose loss leads to increased ploidy. In both cDNA and shRNA screens, the majority of hits have not been linked previously to genomic stability. We further show that sustained loss of the shRNA screening hits leads to multipolar spindles and heterogeneous chromosome content, two characteristics of chromosomal instability. Loss of several of the kinases leads to loss of contact inhibition and to anchorage-independent growth, vital traits acquired during tumor development. We anticipate that this work will serve as a template for the comprehensive identification of pathways whose dysregulation can drive tumorigenesis through impaired karyotypic maintenance.
Nucleoside diphosphate kinase Nm23-H1 regulates chromosomal stability by activating the GTPase dynamin during cytokinesis
Authors: Conery Andrew R. , Sever Sanja , Harlow Ed
Published: August 2010

Chromosomal instability and the subsequent genetic mutations are considered to be critical factors in the development of the majority of solid tumors. Here, we describe how the nucleoside diphosphate kinase Nm23-H1, a protein with a known link to cancer progression, regulates a critical step during cytokinesis. Nm23-H1 acts to provide a local source of GTP for the GTPase dynamin. Loss of Nm23-H1 in diploid cells leads to cytokinetic furrow regression, followed by cytokinesis failure and generation of tetraploid cells. Loss of dynamin phenocopies loss of Nm23-H1, and ectopic overexpression of WT dynamin complements the loss of Nm23-H1. In the absence of p53 signaling, the tetraploid cells resulting from loss of Nm23-H1 continue cycling and develop classic hallmarks of tumor cells. We thus provide evidence that the loss of Nm23-H1, an event suspected to promote metastasis, may additionally function at an earlier stage of tumor development to drive the acquisition of chromosomal instability.
BAG-6 is essential for selective elimination of defective proteasomal substrates
Authors: Minami Ryosuke , Hayakawa Atsuko , Kagawa Hiroki , Yanagi Yuko , Yokosawa Hideyoshi , Kawahara Hiroyuki
Published: August 2010

BAG-6/Scythe/BAT3 is a ubiquitin-like protein that was originally reported to be the product of a novel gene located within the human major histocompatibility complex, although the mechanisms of its function remain largely obscure. Here, we demonstrate the involvement of BAG-6 in the degradation of a CL1 model defective protein substrate in mammalian cells. We show that BAG-6 is essential for not only model substrate degradation but also the ubiquitin-mediated metabolism of newly synthesized defective polypeptides. Furthermore, our in vivo and in vitro analysis shows that BAG-6 interacts physically with puromycin-labeled nascent chain polypeptides and regulates their proteasome-mediated degradation. Finally, we show that knockdown of BAG-6 results in the suppressed presentation of MHC class I on the cell surface, a procedure known to be affected by the efficiency of metabolism of defective ribosomal products. Therefore, we propose that BAG-6 is necessary for ubiquitin-mediated degradation of newly synthesized defective polypeptides.
Autophagy requires endoplasmic reticulum targeting of the PI3-kinase complex via Atg14L
Authors: Matsunaga Kohichi , Morita Eiji , Saitoh Tatsuya , Akira Shizuo , Ktistakis Nicholas T. , Izumi Tetsuro , Noda Takeshi , Yoshimori Tamotsu
Published: August 2010

Autophagy is a catabolic process that allows cells to digest their cytoplasmic constituents via autophagosome formation and lysosomal degradation. Recently, an autophagy-specific phosphatidylinositol 3-kinase (PI3-kinase) complex, consisting of hVps34, hVps15, Beclin-1, and Atg14L, has been identified in mammalian cells. Atg14L is specific to this autophagy complex and localizes to the endoplasmic reticulum (ER). Knockdown of Atg14L leads to the disappearance of the DFCP1-positive omegasome, which is a membranous structure closely associated with both the autophagosome and the ER. A point mutation in Atg14L resulting in defective ER localization was also defective in the induction of autophagy. The addition of the ER-targeting motif of DFCP1 to this mutant fully complemented the autophagic defect in Atg14L knockout embryonic stem cells. Thus, Atg14L recruits a subset of class III PI3-kinase to the ER, where otherwise phosphatidylinositol 3-phosphate (PI3P) is essentially absent. The Atg14L-dependent appearance of PI3P in the ER makes this organelle the platform for autophagosome formation.
Regulation of the autophagy protein LC3 by phosphorylation
Authors: Cherra Salvatore J. , Kulich Scott M. , Uechi Guy , Balasubramani Manimalha , Mountzouris John , Day Billy W. , Chu Charleen T.
Published: August 2010

Macroautophagy is a major catabolic pathway that impacts cell survival, differentiation, tumorigenesis, and neurodegeneration. Although bulk degradation sustains carbon sources during starvation, autophagy contributes to shrinkage of differentiated neuronal processes. Identification of autophagy-related genes has spurred rapid advances in understanding the recruitment of microtubule-associated protein 1 light chain 3 (LC3) in autophagy induction, although braking mechanisms remain less understood. Using mass spectrometry, we identified a direct protein kinase A (PKA) phosphorylation site on LC3 that regulates its participation in autophagy. Both metabolic (rapamycin) and pathological (MPP+) inducers of autophagy caused dephosphorylation of endogenous LC3. The pseudophosphorylated LC3 mutant showed reduced recruitment to autophagosomes, whereas the nonphosphorylatable mutant exhibited enhanced puncta formation. Finally, autophagy-dependent neurite shortening induced by expression of a Parkinson disease–associated G2019S mutation in leucine-rich repeat kinase 2 was inhibited by dibutyryl–cyclic adenosine monophosphate, cytoplasmic expression of the PKA catalytic subunit, or the LC3 phosphorylation mimic. These data demonstrate a role for phosphorylation in regulating LC3 activity.
Clathrin-independent carriers form a high capacity endocytic sorting system at the leading edge of migrating cells
Authors: Howes Mark T. , Kirkham Matthew , Riches James , Cortese Katia , Walser Piers J. , Simpson Fiona , Hill Michelle M. , Jones Alun , Lundmark Richard , Lindsay Margaret R. , Hernandez-Deviez Delia J. , Hadzic Gordana , McCluskey Adam , Bashir Rumasia , Liu Libin , Pilch Paul , McMahon Harvey , Robinson Phillip J. , Hancock John F. , Mayor Satyajit , Parton Robert G.
Published: August 2010

Although the importance of clathrin- and caveolin-independent endocytic pathways has recently emerged, key aspects of these routes remain unknown. Using quantitative ultrastructural approaches, we show that clathrin-independent carriers (CLICs) account for approximately three times the volume internalized by the clathrin-mediated endocytic pathway, forming the major pathway involved in uptake of fluid and bulk membrane in fibroblasts. Electron tomographic analysis of the 3D morphology of the earliest carriers shows that they are multidomain organelles that form a complex sorting station as they mature. Proteomic analysis provides direct links between CLICs, cellular adhesion turnover, and migration. Consistent with this, CLIC-mediated endocytosis of key cargo proteins, CD44 and Thy-1, is polarized at the leading edge of migrating fibroblasts, while transient ablation of CLICs impairs their ability to migrate. These studies provide the first quantitative ultrastructural analysis and molecular characterization of the major endocytic pathway in fibroblasts, a pathway that provides rapid membrane turnover at the leading edge of migrating cells.
Viral entry and escape from antibody-mediated neutralization influence hepatitis C virus reinfection in liver transplantation
Authors: Fafi-Kremer Samira , Fofana Isabel , Soulier Eric , Carolla Patric , Meuleman Philip , Leroux-Roels Geert , Patel Arvind H. , Cosset François-Loïc , Pessaux Patrick , Doffoël Michel , Wolf Philippe , Stoll-Keller Françoise , Baumert Thomas F.
Published: August 2010

End-stage liver disease caused by chronic hepatitis C virus (HCV) infection is a leading cause for liver transplantation (LT). Due to viral evasion from host immune responses and the absence of preventive antiviral strategies, reinfection of the graft is universal. The mechanisms by which the virus evades host immunity to reinfect the liver graft are unknown. In a longitudinal analysis of six HCV-infected patients undergoing LT, we demonstrate that HCV variants reinfecting the liver graft were characterized by efficient entry and poor neutralization by antibodies present in pretransplant serum compared with variants not detected after transplantation. Monoclonal antibodies directed against HCV envelope glycoproteins or a cellular entry factor efficiently cross-neutralized infection of human hepatocytes by patient-derived viral isolates that were resistant to autologous host-neutralizing responses. These findings provide significant insights into the molecular mechanisms of viral evasion during HCV reinfection and suggest that viral entry is a viable target for prevention of HCV reinfection of the liver graft.
Nontoxigenic protein A vaccine for methicillin-resistant Staphylococcus aureus infections in mice
Authors: Kim Hwan Keun , Cheng Alice G. , Kim Hye-Young , Missiakas Dominique M. , Schneewind Olaf
Published: August 2010

The current epidemic of hospital- and community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections has caused significant human morbidity, but a protective vaccine is not yet available. Prior infection with S. aureus is not associated with protective immunity. This phenomenon involves staphylococcal protein A (SpA), an S. aureus surface molecule that binds to Fcγ of immunoglobulin (Ig) and to the Fab portion of VH3-type B cell receptors, thereby interfering with opsonophagocytic clearance of the pathogen and ablating adaptive immune responses. We show that mutation of each of the five Ig-binding domains of SpA with amino acid substitutions abolished the ability of the resulting variant SpAKKAA to bind Fcγ or Fab VH3 and promote B cell apoptosis. Immunization of mice with SpAKKAA raised antibodies that blocked the virulence of staphylococci, promoted opsonophagocytic clearance, and protected mice against challenge with highly virulent MRSA strains. Furthermore, SpAKKAA immunization enabled MRSA-challenged mice to mount antibody responses to many different staphylococcal antigens.
Type 1 IP3 receptors activate BKCa channels via local molecular coupling in arterial smooth muscle cells
Authors: Zhao Guiling , Neeb Zachary P. , Leo M. Dennis , Pachuau Judith , Adebiyi Adebowale , Ouyang Kunfu , Chen Ju , Jaggar Jonathan H.
Published: August 2010

Plasma membrane large-conductance Ca2+-activated K+ (BKCa) channels and sarcoplasmic reticulum inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) are expressed in a wide variety of cell types, including arterial smooth muscle cells. Here, we studied BKCa channel regulation by IP3 and IP3Rs in rat and mouse cerebral artery smooth muscle cells. IP3 activated BKCa channels both in intact cells and in excised inside-out membrane patches. IP3 caused concentration-dependent BKCa channel activation with an apparent dissociation constant (Kd) of ∼4 µM at physiological voltage (−40 mV) and intracellular Ca2+ concentration ([Ca2+]i; 10 µM). IP3 also caused a leftward-shift in BKCa channel apparent Ca2+ sensitivity and reduced the Kd for free [Ca2+]i from ∼20 to 12 µM, but did not alter the slope or maximal Po. BAPTA, a fast Ca2+ buffer, or an elevation in extracellular Ca2+ concentration did not alter IP3-induced BKCa channel activation. Heparin, an IP3R inhibitor, and a monoclonal type 1 IP3R (IP3R1) antibody blocked IP3-induced BKCa channel activation. Adenophostin A, an IP3R agonist, also activated BKCa channels. IP3 activated BKCa channels in inside-out patches from wild-type (IP3R1+/+) mouse arterial smooth muscle cells, but had no effect on BKCa channels of IP3R1-deficient (IP3R1−/−) mice. Immunofluorescence resonance energy transfer microscopy indicated that IP3R1 is located in close spatial proximity to BKCa α subunits. The IP3R1 monoclonal antibody coimmunoprecipitated IP3R1 and BKCa channel α and β1 subunits from cerebral arteries. In summary, data indicate that IP3R1 activation elevates BKCa channel apparent Ca2+ sensitivity through local molecular coupling in arterial smooth muscle cells.
Clinical Outcomes of Carbapenem-Resistant Acinetobacter baumannii Bloodstream Infections: Study of a 2-State Monoclonal Outbreak
Authors: Munoz-Price L. Silvia , Zembower Teresa , Penugonda Sudhir , Schreckenberger Paul , Lavin Mary Alice , Welbel Sharon , Vais Dana , Baig Mirza , Mohapatra Sunita , Quinn John P. , Weinstein Robert A.
Published: August 2010

Objective.

To characterize the clinical outcomes of patients with bloodstream infection caused by carbapenem-resistant Acinetobacter baumannii during a 2-state monoclonal outbreak.

Design.

Multicenter observational study.

Setting.

Four tertiary care hospitals and 1 long-term acute care hospital.

Methods.

A retrospective medical chart review was conducted for all consecutive patients during the period January 1, 2005, through April 30, 2006, for whom 1 or more blood cultures yielded carbapenem-resistant A. baumannii.

Results.

We identified 86 patients from the 16-month study period. Their mortality rate was 41%; of the 35 patients who died, one-third (13) had positive blood culture results for carbapenem-resistant A. baumannii at the time of death. Risk factors associated with mortality were intensive care unit stay, malignancy, and presence of fever and/or hypotension at the time blood sample for culture was obtained. Only 5 patients received adequate empirical antibiotic treatment, but the choice of treatment did not affect mortality.

Fifty-seven patients (66.2%) had a single positive blood culture result for carbapenem-resistant A. baumannii; the only factor associated with a single positive blood culture result was the presence of decubitus ulcers. Interestingly, during the study period, a transition from single to multiple positive blood culture results was observed. Four patients, 3 of whom were in a burn intensive care unit, were bacteremic for more than 30 days (range, 36–86 days).

Conclusions.

To our knowledge, this is the first time a study has described 2 patterns of bloodstream infection with A. baumannii: single versus multiple positive blood culture results, as well as a subset of patients with prolonged bacteremia.
Cotranscriptional recruitment of She2p by RNA pol II elongation factor Spt4–Spt5/DSIF promotes mRNA localization to the yeast bud
Authors: Shen Zhifa , St-Denis Anik , Chartrand Pascal
Published: August 2010

Pre-mRNA processing is coupled with transcription. It is still unclear if the transcription machinery can also directly affect the cytoplasmic fate of a transcript, such as its intracellular localization. In yeast, the RNA-binding protein She2p binds several mRNAs and targets them for localization at the bud. Here we report that She2p is recruited cotranscriptionally to the nascent bud-localized ASH1, IST2, and EAR1 mRNA. She2p interacts in vivo with the elongating forms of RNA polymerase II (pol II) via the transcription elongation factor Spt4–Spt5. Mutations in either SPT4 or SPT5 reduce the cotranscriptional recruitment of She2p on the ASH1 gene, disrupt the proper localization of ASH1 mRNA at the bud tip, and affect Ash1p sorting to the daughter cell nucleus. We propose that She2p is recruited by the RNA pol II machinery prior to its transfer to nascent bud-localized mRNAs. Indeed, She2p is present with RNA pol II on genes coding for localized or nonlocalized transcripts, but is associated with nascent mRNA only on genes coding for bud-localized transcripts. Moreover, a She2p mutant defective in RNA binding still associates with RNA pol II transcribed genes. This study uncovers a novel mechanism for the cotranscriptional assembly of mRNP complexes primed for localization in the cytoplasm.
Structural basis for methylarginine-dependent recognition of Aubergine by Tudor
Authors: Liu Haiping , Wang Ju-Yu S. , Huang Ying , Li Zhizhong , Gong Weimin , Lehmann Ruth , Xu Rui-Ming
Published: August 2010

Piwi proteins are modified by symmetric dimethylation of arginine (sDMA), and the methylarginine-dependent interaction with Tudor domain proteins is critical for their functions in germline development. Cocrystal structures of an extended Tudor domain (eTud) of Drosophila Tudor with methylated peptides of Aubergine, a Piwi family protein, reveal that sDMA is recognized by an asparagine-gated aromatic cage. Furthermore, the unexpected Tudor-SN/p100 fold of eTud is important for sensing the position of sDMA. The structural information provides mechanistic insights into sDMA-dependent Piwi–Tudor interaction, and the recognition of sDMA by Tudor domains in general.
The B-3 Ethylene Response Factor MtERF1-1 Mediates Resistance to a Subset of Root Pathogens inMedicago truncatulawithout Adversely Affecting Symbiosis with Rhizobia
Authors: Anderson Jonathan P. , Lichtenzveig Judith , Gleason Cynthia , Oliver Richard P. , Singh Karam B.
Published: August 2010

The fungal necrotrophic pathogen Rhizoctonia solani is a significant constraint to a range of crops as diverse as cereals, canola, and legumes. Despite wide-ranging germplasm screens in many of these crops, no strong genetic resistance has been identified, suggesting that alternative strategies to improve resistance are required. In this study, we characterize moderate resistance to R. solani anastomosis group 8 identified in Medicago truncatula. The activity of the ethylene- and jasmonate-responsive GCC box promoter element was associated with moderate resistance, as was the induction of the B-3 subgroup of ethylene response transcription factors (ERFs). Genes of the B-1 subgroup showed no significant response to R. solani infection. Overexpression of a B-3 ERF, MtERF1-1, in Medicago roots increased resistance to R. solani as well as an oomycete root pathogen, Phytophthora medicaginis, but not root knot nematode. These results indicate that targeting specific regulators of ethylene defense may enhance resistance to an important subset of root pathogens. We also demonstrate that overexpression of MtERF1-1 enhances disease resistance without apparent impact on nodulation in the A17 background, while overexpression in sickle reduced the hypernodulation phenotype. This suggests that under normal regulation of nodulation, enhanced resistance to root diseases can be uncoupled from symbiotic plant-microbe interactions in the same tissue and that ethylene/ERF regulation of nodule number is distinct from the defenses regulated by B-3 ERFs. Furthermore, unlike the stunted phenotype previously described for Arabidopsis (Arabidopsis thaliana) ubiquitously overexpressing B-3 ERFs, overexpression of MtERF1-1 in M. truncatula roots did not show adverse effects on plant development.
Children's and Adolescent's Views on Family Therapy
Authors: Strickland‐Clark Lisa , Campbell David , Dallos Rudi
Published: August 2010

Family therapy has made a considerable contribution to our understanding of the experiences of children and families and especially how various symptoms can be understood as their response to distressing family dynamics. Though family therapy has found ways of alleviating children’s distress we still know relatively little about how children experience the process of family therapy. Such knowledge is important for ethical as well as pragmatic reasons – to be able to offer a more sensitive and effective experience. This paper reports a study employing qualitative methods whereby children were interviewed about their experience of family therapy. Semi‐structured interviews were conducted after family therapy sessions, and children were invited to recall what they perceived to be helpful and unhelpful. Helpful events or moments were then identified and replayed on the videotape of the sessions to assist children’s memory. The results suggest a diversity of experiences according to the children’s ages, gender and role in the family. Some common assumptions were challenged by the findings, for example, that some children preferred more directive and focused aspects of the therapy, rather than systemic questions which could inspire feelings of confusion and inadequacy.
WITHDRAWN; Recent progress in studies of infantile hemangioma
Authors: JINNIN Masatoshi , ISHIHARA Tsuyoshi , BOYE Eileen , OLSEN Bjorn R.
Published: August 2010

A hallmark of infantile hemangioma, the most common tumor of infancy, is its dramatic growth after birth, by diffuse proliferation of immature endothelial cells, followed by spontaneous regression. The growth and involution of infantile hemangioma is quite different from other vascular anomalies, which do not regress and can occur at any time during life. Some hemangioma lesions can be extremely disfiguring and destructive to normal tissue and may even be life‐threatening. Unfortunately, existing therapeutic approaches have limited success and significant adverse effects of some treatment modalities limit their use. Better understanding of the pathogenesis of hemangioma will enable the development of better therapeutic strategies. Herein, we review recent studies and new hypotheses on the pathogenesis of the tumor. Detailed mechanisms of activated vascular endothelial growth factor (VEGF) signaling in tumor cells, identification of their origin and characterization of multipotent stem cells that can give rise to infantile hemangioma are shedding new light on this intriguing vascular tumor.
The quality of sleep in patients with coeliac disease
Authors: Zingone F. , Siniscalchi M. , Capone P. , Tortora R. , Andreozzi P. , Capone E. , Ciacci C.
Published: August 2010

Aliment Pharmacol Ther 2010; 32: 1031–1036

Background  Coeliac disease is a chronic disease with a various clinical presentation, including anxiety and depression.

Aim  To investigate the quality of sleep in coeliac disease.

Methods  The participants were coeliacs at diagnosis; coeliacs on a gluten‐free diet at follow‐up and healthy volunteers. Participants completed the Pittsburgh Sleep Quality Index (PSQI), SF36, Zung and Fatigue scales and State‐Trait Anxiety Inventory (STAI).

Results  The PSQI score was higher in coeliacs at diagnosis and in a gluten‐free diet than in healthy volunteers (P < 0.001). A gluten‐free diet did not improve the PSQI score (P = 0.245) in coeliac disease. The other test scores were similar between coeliacs at diagnosis and those on a gluten‐free diet, whereas significant differences were found between coeliacs and volunteers. PSQI score was inversely associated with the quality of the physical (r = −0.327, P = 0.002) and mental (r = −0.455, P < 0.001) component scores. The sleep quality scores were related to depression (r = 0.633, P < 0.001), fatigue (r = 0.377, P < 0.001), state anxiety (r = 0.484, P < 0.001) and trait anxiety (r = 0.467, P < 0.001).

Conclusions  Sleep disorders are common in coeliac disease not only at diagnosis but also during treatment with a gluten‐free diet. Sleep disorders are related to depression, anxiety and fatigue, and inversely related to quality of life scale scores.
REVIEW ARTICLE: Reducing fracture risk with calcium and vitamin D
Authors: Lips Paul , Bouillon Roger , Van Schoor Natasja M. , Vanderschueren Dirk , Verschueren Sabine , Kuchuk Natalia , Milisen Koen , Boonen Steven
Published: August 2010

Studies of vitamin D and calcium for fracture prevention have produced inconsistent results, as a result of different vitamin D status and calcium intake at baseline, different doses and poor to adequate compliance. This study tries to define the types of patients, both at risk of osteoporosis and with established disease, who may benefit from calcium and vitamin D supplementation. The importance of adequate compliance in these individuals is also discussed. Calcium and vitamin D therapy has been recommended for older persons, either frail and institutionalized or independent, with key risk factors including decreased bone mineral density (BMD), osteoporotic fractures, increased bone remodelling as a result of secondary hyperparathyroidism and increased propensity to falls. In addition, treatment of osteoporosis with a bisphosphonate was less effective in patients with vitamin D deficiency. Calcium and vitamin D supplementation is a key component of prevention and treatment of osteoporosis unless calcium intake and vitamin D status are optimal. For primary disease prevention, supplementation should be targeted to those with dietary insufficiencies. Several serum 25‐hydroxyvitamin D (25(OH)D) cut‐offs have been proposed to define vitamin D insufficiency (as opposed to adequate vitamin D status), ranging from 30 to 100 nmol/l. Based on the relationship between serum 25(OH)D, BMD, bone turnover, lower extremity function and falls, we suggest that 50 nmol/l is the appropriate serum 25(OH)D threshold to define vitamin D insufficiency. Supplementation should therefore generally aim to increase 25(OH)D levels within the 50–75 nmol/l range. This level can be achieved with a dose of 800 IU/day vitamin D, the dose that was used in succesfull fracture prevention studies to date; a randomized clinical trial assessing whether higher vitamin D doses achieve a greater reduction of fracture incidence would be of considerable interest. As calcium balance is not only affected by vitamin D status but also by calcium intake, recommendations for adequate calcium intake should also be met. The findings of community‐based clinical trials with vitamin D and calcium supplementation in which compliance was moderate or less have often been negative, whereas studies in institutionalized patients in whom medication administration was supervised ensuring adequate compliance demonstrated significant benefits.
Gene analysis and prenatal diagnosis for two families of congenital factor V deficiency
Authors: CAO L. , WANG Z. , LI H. , WANG W. , ZHAO X. , ZHANG W. , DING J. , RUAN C.
Published: August 2010

Summary.  We studied two families in which the probands had severe bleeding tendency and showed low plasma levels of coagulation factor V (FV) antigen and activity. Sequence analysis of the FV gene on proband 1 demonstrated a novel G16088C homozygous missense mutation in exon 3 resulting in an Asp 68 to His substitution and on proband 2, a C69969T homozygous missense mutation in exon 23 leading to Gly2079Val. The parents of both families were each heterozygous for the corresponding FV gene defect. During their second pregnancy, the two families requested prenatal diagnosis. Chorionic villi were analysed at 12 weeks of gestation and cord blood samples were tested at 22 weeks. Microsatellite analysis performed in family 1 showed that the foetus sample was not contaminated by maternal tissue. The foetus 1 was found to be heterozygous for the familiar G16088C mutation with lower FV activity in the cord blood; the foetus 2 was a normal one. The diagnosis was confirmed after the birth. This is the first report of prenatal diagnosis for FV deficiency.
Novel role of regulatory T cells in limiting early neutrophil responses in skin
Authors: Richards Hannah , Williams Anwen , Jones Emma , Hindley James , Godkin Andrew , Simon Anna Katharina , Gallimore Awen
Published: August 2010

It is clear that CD4+ CD25+ Foxp3+regulatory T (Treg) cells inhibit chronic inflammatory responses as well as adaptive immune responses. Among the CD4+T‐cell population in the skin, at least one‐fifth express Foxp3. As the skin is constantly exposed to antigenic challenge and is a common site of vaccination, understanding the role of these skin‐resident Treg cells is important. Although the suppressive effect of Treg cells on T cells is well documented, less is known about the types of innate immune cells influenced by Treg cells and whether the Treg cells suppress acute innate immune responsesin vivo. To address this we used a mouse melanoma cell line expressing Fas ligand (B16FasL), which induces an inflammatory response following subcutaneous injection of mice. We demonstrate that Treg cells limit this response by inhibiting neutrophil accumulation and survival within hours of tumour cell inoculation. This effect, which was associated with decreased expression of the neutrophil chemoattractants CXCL1 and CXCL2, promoted survival of the inoculated tumour cells. Overall, these data imply that Treg cells in the skin are rapidly mobilized and that this activity serves to limit the amplification of inflammatory responses at this site.