Home About us Contact
|
Home About us Contact | ||
|
|
||
Novel Pathway (novel + pathway)
Selected AbstractsSuperacid-Catalyzed Dimerization/Cyclization of Isopropenyl-PAHs , Novel Pathways to PAH Dimers, Phenalenes and Their Stable CarbocationsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2008Cédric Brulé Abstract The isopropenyl derivatives of representative classes of polycyclic aromatic hydrocarbons (PAHs) having four and five fused-ring systems, namely pyrene, chrysene, benzo[c]phenanthrene (BcPh), dibenzo[a,c]anthracene (benzo[f]tetraphene) and perylene, were synthesized by Wittig olefination from the corresponding acetyl-PAHs. Under the influence of triflic acid (TfOH), the isopropenyl derivatives were converted to novel PAH dimers and/or phenalenes in a simple one-pot procedure. A plausible mechanism for this process has been outlined, and the synthetic scope of this chemistry has been explored. Structural features in the PAH dimers were examined by DFT. As representative initial and final carbocation intermediates in the reaction sequence, stable carbocations derived from 3-isopropenylperylene and from 4,6,6-trimethyl-6H -dibenzo[a,kl]anthracene were generated and studied directly by NMR spectroscopy. The NMR characteristics and charge delocalization modes in the resulting benzylic carbocations are discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Ageing in Plants: Conserved Strategies and Novel PathwaysPLANT BIOLOGY, Issue 5 2003H.-C. Jing Abstract: Ageing increases chaos and entropy and ultimately leads to the death of living organisms. Nevertheless, single gene mutations substantially alter lifespan, revealing that ageing is subject to genetic control. In higher plants, ageing is most obviously manifested by the senescence of leaves, and recent molecular genetic studies, in particular the isolation of Arabidopsis mutants with altered leaf senescence, have greatly advanced our understanding of ageing regulation in plants. This paper provides an overview of the identified genes and their respective molecular pathways. Hormones, metabolic flux, reactive oxygen species and protein degradation are prominent strategies employed by plants to control leaf senescence. Plants predominantly use similar ageing-regulating strategies as yeast and animals but have evolved different molecular pathways. The senescence window concept is proposed to describe the age-dependent actions of the regulatory genes. It is concluded that the similarities and differences in ageing between plants and other organisms are deeply rooted in the evolution of ageing and we hope to stimulate discussion and research in the fascinating field of leaf senescence. [source] Novel pathways for glycaemic control in type 2 diabetes: focus on bile acid modulationDIABETES OBESITY & METABOLISM, Issue 11 2008Eliot A. Brinton Type 2 diabetes is a common disorder with high risk of macrovascular and microvascular complications. These complications are largely driven by hyperglycaemia, dyslipidaemia and hypertension, for which aggressive treatment is thus warranted. Achieving and maintaining control of all three risk factors is especially difficult, however, and new therapeutic approaches could be useful. Bile acids have a well-established and important role in cholesterol homeostasis. Normally, their levels are maintained primarily by ileal reabsorption and enterohepatic recycling. Bile acid sequestrants bind bile acids in the intestine, reduce this recycling and deplete the bile acid pool, thereby stimulating use of hepatic cholesterol for bile acid synthesis, which leads to accelerated removal of LDL from the plasma and a decrease in LDL-cholesterol levels. Interestingly, recent evidence suggests that bile acid sequestrants can lower glucose levels to a clinically meaningful degree. This review presents this evidence and the possible mechanisms by which these glucose-lowering effects occur and discusses the apparently unique ability of bile acid sequestrants among lipid-lowering agents to significantly improve two cardiovascular risk factors, hyperglycaemia and dyslipidaemia. There is renewed interest in the use of bile acid sequestrants in individuals with type 2 diabetes, most of whom would benefit from additional reductions in both LDL-cholesterol and glycaemia. [source] ,-Dystroglycan is essential for the induction of Egr3, a transcription factor important in muscle spindle formationDEVELOPMENTAL NEUROBIOLOGY, Issue 7 2010Stacey Williams Abstract Muscle spindle fibers are specialized stretch receptors that allow the perception and coordination of limb movement. The differentiation of these specialized structures is initiated by signals derived from the in growing Ia sensory neurons during development. While the direct molecular signaling mechanisms between sensory neurons and developing muscle at nascent spindle fibers have been well documented in past studies the roles of muscle basal lamina components on this process have not previously been described. As such, our initial experiments addressed potential roles for agrin (AGRN) and laminin (LN) in the expression of the transcription factor Egr3. Levels of Egr3 were monitored using immunoblot analysis and both basal lamina molecules proved effective in inducing Erg3 expression. Previous work had established neuregulin (NRG) as a critical signaling component in spindle fiber development so blocking experiments with NRG and ErbB inhibitors were then used to determine if LN-induced Egr3 expression was occurring as a result of NRG-ErbB signaling and not via other, novel pathway. Inhibiting signaling through this pathway did indeed reduce the expression of Egr3. Finally, we looked at ,-dystrogylcan, a shared receptor for AGRN and LN at neuromuscular junctions. Using a ,-dystroglycan (,-DG) silenced muscle cell line and an anti-,-DG antibody we attempted to block basal lamina/,-DG interactions. Again, and in both instances, Egr3 expression was significantly decreased. Taken together, analysis of the results from these experiments revealed that indeed AGRN, LN, and ,-DG influence Egr3 levels and therefore may play an important role in spindle fiber differentiation. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 70:498,507, 2010 [source] An Efficient Synthesis of Substituted meta -Halophenols and Their Methyl Ethers: Insight into the Reaction MechanismEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2010Faiz Ahmed Khan Abstract An expeditious synthetic methodology leading to substituted meta -halophenols and their corresponding methyl ether derivatives through acid-mediated fragmentation of suitably substituted dihalonorbornyl ketones has been devised. The reaction sequence consists of TBTH-mediated (TBTH is tri- n -butyltin hydride) selective bridgehead halogen reduction of easily accessible Diels,Alder adducts derived from 1,2,3,4-tetrahalo-5,5-dimethoxycyclopentadiene and ,-substituted vinyl acetates, with subsequent conversion into the requisite bicyclic ketones by a two-step hydrolysis/oxidation approach. An extensive mechanistic investigation based on isotope labeling and cross experiments has been carried out and plausible mechanistic pathways based on these results have been proposed. The absence of halogen atoms at the bridgehead positions steers the reaction through a novel pathway involving the incorporation of proton (or deuterium) followed by elimination of HX (or DX), so the described methodology also provides a reliable route to ortho-para dideuteratedphenolic derivatives. [source] Phosphorylation of NF-,B proteins by cyclic GMP-dependent kinaseFEBS JOURNAL, Issue 10 2003A noncanonical pathway to NF-, B activation The transcription factor NF-,B is activated in cellular stress responses. This requires rapid regulation of its function, which is accomplished, in part, by various modes of phosphorylation. Even though diverse DNA binding subunits of NF-,B proteins may transactivate from distinct recognition sequences, the differential regulation of transcription from the large number of NF-,B responsive sites in various gene promoters and enhancers has been incompletely understood. The cyclic GMP-dependent kinase (PKG) is an important mediator of signal transduction that may induce gene expression through cAMP response element binding protein (CREB) and through other, yet undefined, mechanisms. We have previously characterized a signal transduction pathway that leads to activation-induced cell death in T-lymphocytes and involves the activation of PKG. Here we demonstrate that the NF-,B proteins p65, p49 (also called p52), and p50 are specific substrates for this kinase. PKG dose-dependently increases the transactivating activity of p65 from the NF-,B consensus sequence. It also mediates dose-dependently an increase in transcriptional activity by p49 or p50 from a unique CCAAT/enhance binding protein (C/EBP)-associated NF-,B site, but not from the consensus site. Phosphorylation of p65, p50, or p49 does not alter their subcellular distribution. Because the release of cytosolic p65/p50 heterodimers into the nucleus is by itself insufficient to differentiate all the numerous NF-,B promoter sequences, phosphorylation of the DNA-binding subunits reveals a form of differential regulation of NF-,B activity and it implies a novel pathway for PKG-induced gene transcription. These observations may bear on mechanisms of programmed cell death in T-lymphocytes. They may also be relevant to ongoing efforts to induce cancer cell apoptosis through activation of PKG. [source] Activation of hepatic stellate cells after phagocytosis of lymphocytes: A novel pathway of fibrogenesis,HEPATOLOGY, Issue 3 2008Nidal Muhanna Increased CD8-T lymphocytes and reduced natural killer (NK) cells contribute to hepatic fibrosis. We have characterized pathways regulating the interactions of human hepatic stellate cells (HSCs) with specific lymphocyte subsets in vivo and in vitro. Fluorescence-activated cell sorting (FACS) was used to characterize human peripheral blood lymphocytes (PBLs) and intrahepatic lymphocytes (IHLs) obtained from healthy controls and from patients with either hepatitis B virus (HBV) or hepatitis C virus (HCV) with advanced fibrosis. Liver sections were analyzed by immunohistochemistry and confocal microscopy. To investigate in vitro interactions, PBLs from healthy controls or patients with HCV cirrhosis were co-cultured with an immortalized human HSC line (LX2 cells) or with primary HSCs. Significant alterations in lymphocyte distribution were identified in IHLs but not PBLs. The hepatic CD4/CD8 ratio and NK cells were significantly reduced in HBV/HCV patients. Expression of alpha-smooth muscle actin and infiltration of CD4, CD8, and NK cells were readily apparent in liver sections from patients with cirrhosis but not in healthy controls. Lymphocytes from each subset were in proximity to HSCs primarily within the periportal regions, and some were directly attached or engulfed. In culture, HSC activation was stimulated by HCV-derived CD8-subsets but attenuated by NK cells. Confocal microscopy identified lymphocyte phagocytosis within HSCs that was completely prevented by blocking intracellular adhesion molecule 1 (ICAM-1) and integrin molecules, or by irradiation of HSCs. LX2 knockdown of either Cdc42 or Rac1 [members of the Rho-guanosine triphosphatase (GTPase) family] prevented both phagocytosis and the activation of HSC by HCV-derived lymphocytes. Conclusion: The CD4/CD8 ratio and NK cells are significantly decreased in livers with advanced human fibrosis. Moreover, disease-associated but not healthy lymphocytes are engulfed by cultured HSCs, which is mediated by the Rac1 and Cdc42 pathways. Ingestion of lymphocytes by HSCs in hepatic fibrosis is a novel and potentially important pathway regulating the impact of lymphocytes on the course of hepatic fibrosis. (HEPATOLOGY 2008.) [source] Thirty-kilodalton Tat-interacting protein suppresses tumor metastasis by inhibition of osteopontin transcription in human hepatocellular carcinoma,HEPATOLOGY, Issue 1 2008Jian Zhao It has been previously demonstrated that the 30-kDa Tat-interacting protein (TIP30) plays an important role in the suppression of hepatocarcinogenesis by acting as a tumor suppressor. Here we report that TIP30 suppresses metastasis of hepatocellular carcinoma (HCC) through inhibiting the transcription of osteopontin (OPN), a key molecule in the development of tumor metastasis. The expression of TIP30 messenger RNA was reverse to that of OPN messenger RNA in HCC cell lines. Ectopic expression of TIP30 greatly suppressed OPN expression, inhibited invasion of HCC cells through extracellular matrix (ECM) and adhesion with fibronectin in vitro, whereas down-regulation of TIP30 by RNA-mediated interference enhanced OPN expression and promoted metastatic abilities of HCC cells in vitro. Moreover, overexpression of TIP30 significantly inhibited the growth and lung metastases of HCC cells in nude mice. In contrast, down-regulation of TIP30 greatly promoted tumor cell growth and metastases in vivo. TIP30 repressed OPN transcription through interaction with Ets-1 and suppressed the transcriptional activity of Ets-1 and synergistic actions of Ets-1 and alkaline phosphatase-1. Thus, TIP30 may act as an Ets-1 modulator and inhibit tumor metastasis through abrogating Ets-1,dependent transcription. Moreover, expression of TIP30 was inversely associated with OPN expression in HCC tissue samples as detected by immunohistochemistry assay. Conclusion: Our results reveal a novel pathway by which OPN and possibly other Ets-1 target genes involved in tumor metastasis are regulated by TIP30 and elucidate a mechanism for metastasis promoted by TIP30 deficiency. (HEPATOLOGY 2008.) [source] Effect of tauroursodeoxycholic acid on endoplasmic reticulum stress,induced caspase-12 activationHEPATOLOGY, Issue 3 2002Qing Xie Activation of death receptors and mitochondrial damage are well-described common apoptotic pathways. Recently, a novel pathway via endoplasmic reticulum (ER) stress has been reported. We assessed the role of tauroursodeoxycholic acid (TUDCA) in inhibition of caspase-12 activation and its effect on calcium homeostasis in an ER stress-induced model of apoptosis. The human liver-derived cell line, Huh7, was treated with thapsigargin (TG) to induce ER stress. Typical morphologic changes of ER stress preceded development of apoptotic changes, including DNA fragmentation and cleavage of poly (adenosine diphosphate-ribose) polymerase (PARP), as well as activation of caspase-3 and -7. Elevation of intracellular calcium levels without loss of mitochondrial membrane potential (MMP) was shown using Fluo-3/Fura-red labeling and flow cytometry, and confirmed by induction of Bip/GRP78, a calcium-dependent chaperon of ER lumen. These changes were accompanied by procaspase-12 processing. TUDCA abolished TG-induced markers of ER stress; reduced calcium efflux, induction of Bip/GRP78, and caspase-12 activation; and subsequently inhibited activation of effector caspases and apoptosis. In conclusion, we propose that mitochondria play a secondary role in ER-mediated apoptosis and that TUDCA prevents apoptosis by blocking a calcium-mediated apoptotic pathway as well as caspase-12 activation. This novel mechanism of TUDCA action suggests new intervention methods for ER stress-induced liver disease. [source] A novel mechanism for mitogenic signaling via pro,transforming growth factor , within hepatocyte nucleiHEPATOLOGY, Issue 6 2002Bettina Grasl-Kraupp Transforming growth factor (TGF) ,, an important mediator of growth stimulation, is known to act via epidermal growth factor receptor (EGF-R) binding in the cell membrane. Here we show by immunohistology, 2-dimensional immunoblotting, and mass spectrometry of nuclear fractions that the pro-protein of wild-type TGF-, occurs in hepatocyte nuclei of human, rat, and mouse liver. Several findings show a close association between nuclear pro-TGF-, and DNA synthesis. (1) The number of pro-TGF-,+ nuclei was low in resting liver and increased dramatically after partial hepatectomy and after application of hepatotoxic chemicals or the primary mitogen cyproterone acetate (CPA); in any case, S phase occurred almost exclusively in pro-TGF-,+ nuclei. The same was found in human cirrhotic liver. (2) In primary culture, 7% of hepatocytes synthesized pro-TGF-,, which then translocated to the nucleus; 70% of these nuclei subsequently entered DNA replication, whereas only 2% of pro-TGF-,, hepatocytes were in S phase. (3) The frequency of hepatocytes coexpressing pro-TGF-, and DNA synthesis was increased by the hepatomitogens CPA or prostaglandin E2 and was decreased by the growth inhibitor TGF-,1. (4) Treatment with mature TGF-, increased DNA synthesis exclusively in pro-TGF-,, hepatocytes, which was abrogated by the EGF-R tyrosine kinase inhibitor tyrphostin A25. In conclusion, TGF-, gene products may exert mitogenic effects in hepatocytes via 2 different signaling mechanisms: (1) the "classic" pathway of mature TGF-, via EGF-R in the membrane and (2) a novel pathway involving the presence of pro-TGF-, in the nucleus. [source] Inhibition of prostaglandin synthesis and actions by genistein in human prostate cancer cells and by soy isoflavones in prostate cancer patientsINTERNATIONAL JOURNAL OF CANCER, Issue 9 2009Srilatha Swami Abstract Soy and its constituent isoflavone genistein inhibit the development and progression of prostate cancer (PCa). Our study in both cultured cells and PCa patients reveals a novel pathway for the actions of genistein, namely the inhibition of the synthesis and biological actions of prostaglandins (PGs), known stimulators of PCa growth. In the cell culture experiments, genistein decreased cyclooxygenase-2 (COX-2) mRNA and protein expression in both human PCa cell lines (LNCaP and PC-3) and primary prostate epithelial cells and increased 15-hydroxyprostaglandin dehydrogenase (15-PGDH) mRNA levels in primary prostate cells. As a result genistein significantly reduced the secretion of PGE2 by these cells. EP4 and FP PG receptor mRNA were also reduced by genistein, providing an additional mechanism for the suppression of PG biological effects. Further, the growth stimulatory effects of both exogenous PGs and endogenous PGs derived from precursor arachidonic acid were attenuated by genistein. We also performed a pilot randomised double blind clinical study in which placebo or soy isoflavone supplements were given to PCa patients in the neo-adjuvant setting for 2 weeks before prostatectomy. Gene expression changes were measured in the prostatectomy specimens. In PCa patients ingesting isoflavones, we observed significant decreases in prostate COX-2 mRNA and increases in p21 mRNA. There were significant correlations between COX-2 mRNA suppression, p21 mRNA stimulation and serum isoflavone levels. We propose that the inhibition of the PG pathway contributes to the beneficial effect of soy isoflavones in PCa chemoprevention and/or treatment. © 2008 Wiley-Liss, Inc. [source] LIGHTing up dendritic cell activation: Immune regulation and viral exploitationJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2005Gabriele Pollara The maturation state of dendritic cells (DC) is regulated by a variety of factors. These include ligands expressed by T cells, such as members of the TNF superfamily. Recent studies have highlighted the role of one such molecule, LIGHT, as a positive regulator of DC biology, promoting the maturation of these cells through the activation of NF-,B pathways. In addition, HSV-1 envelope glycoproteins can also bind the LIGHT receptor, herpes virus entry mediator (HVEM), and activate similar downstream signalling pathways in DC. The consequence of this host-viral interaction may be a novel pathway of viral immune evasion. © 2005 Wiley-Liss, Inc. [source] Soluble and particulate Co-Cr-Mo alloy implant metals activate the inflammasome danger signaling pathway in human macrophages: A novel mechanism for implant debris reactivityJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 7 2009Marco S. Caicedo Abstract Immune reactivity to soluble and particulate implant debris remains the primary cause of aseptic inflammation and implant loosening. However, the intracellular mechanisms that trigger immune cells to sense and respond to exogenous nonbiological agents such as metal particles or metal ions released from orthopedic implants remain unknown. Recent studies in immunology have outlined the importance of the intracellular inflammasome complex of proteins in sensing danger/stress signals triggered by nonbiological agents in the cytosol of macrophages. We hypothesized that metal implant debris can activate the inflammasome pathway in macrophages that causes caspase-1-induced cleavage of intracellular pro-IL-1, into its mature form, resulting in IL-1, secretion and induction of a broader proinflammatory response. We tested this hypothesis by examining whether soluble cobalt, chromium, molybdenum, and nickel ions and Co-Cr-Mo alloy particles induce inflammasome- mediated macrophage reactivity. Our results demonstrate that these agents stimulate IL-1, secretion in human macrophages that is inflammasome mediated (i.e., NADPH-, caspase-1-, Nalp3-, and ASC-dependent). Thus, metal ion- and particle-induced activation of the inflammasome in human macrophages provides evidence of a novel pathway of implant debris-induced inflammation, where contact with implant debris is sensed and transduced by macrophages into a proinflammatory response. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 847,854, 2009 [source] Gluconic acid production by Aspergillus terreusLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2010C. Dowdells Abstract Aim:,Aspergillus terreus produces itaconic acid at low pH but lovastatin and other secondary metabolites at higher pH in the fermentation. The utilization of glucose as a carbon substrate was investigated for secondary metabolite production by A. terreus. Methods and Results:, With a starting pH of 6·5, glucose was rapidly metabolized to gluconic acid by the wild-type strain and by transformants harbouring Aspergillus niger genes encoding 6-phosphofructo-1-kinases with superior kinetic and regulatory properties for bioproduction of metabolites from glucose. On exhaustion of the glucose in batch fermentations, the accumulated gluconic acid was utilized as a carbon source. Conclusions:, A novel pathway of glucose catabolism was demonstrated in A. terreus, a species whose wild type is, without any strain development, capable of producing gluconic acid at high molar conversion efficiency (up to 0·7 mol mol,1 glucose consumed). Significance and Impact of the Study:,Aspergillus terreus is a potential novel producer organism for gluconic acid, a compound with many uses as a bulk chemical. With a new knowledge of glucose catabolism by A. terreus, fermentation strategies for secondary metabolite production can be devised with glucose feeding using feedback regulation by pH. [source] Assimilation of NAD+ precursors in Candida glabrataMOLECULAR MICROBIOLOGY, Issue 1 2007Biao Ma Summary The yeast pathogen Candida glabrata is a nicotinamide adenine dinucleotide (NAD+) auxotroph and its growth depends on the environmental supply of vitamin precursors of NAD+. C. glabrata salvage pathways defined in this article allow NAD+ to be synthesized from three compounds , nicotinic acid (NA), nicotinamide (NAM) and nicotinamide riboside (NR). NA is salvaged through a functional Preiss,Handler pathway. NAM is first converted to NA by nicotinamidase and then salvaged by the Preiss,Handler pathway. Salvage of NR in C. glabrata occurs via two routes. The first, in which NR is phosphorylated by the NR kinase Nrk1, is independent of the Preiss,Handler pathway. The second is a novel pathway in which NR is degraded by the nucleosidases Pnp1 and Urh1, with a minor role for Meu1, and ultimately converted to NAD+ via the nicotinamidase Pnc1 and the Preiss,Handler pathway. Using C. glabrata mutants whose growth depends exclusively on the external NA or NR supply, we also show that C. glabrata utilizes NR and to a lesser extent NA as NAD+ sources during disseminated infection. [source] Biosynthesis of the red antibiotic, prodigiosin, in Serratia: identification of a novel 2-methyl-3-n-amyl-pyrrole (MAP) assembly pathway, definition of the terminal condensing enzyme, and implications for undecylprodigiosin biosynthesis in StreptomycesMOLECULAR MICROBIOLOGY, Issue 4 2005Neil R. Williamson Summary The biosynthetic pathway of the red-pigmented antibiotic, prodigiosin, produced by Serratia sp. is known to involve separate pathways for the production of the monopyrrole, 2-methyl-3-n-amyl-pyrrole (MAP) and the bipyrrole, 4-methoxy-2,2,-bipyrrole-5-carbaldehyde (MBC) which are then coupled in the final condensation step. We have previously reported the cloning, sequencing and heterologous expression of the pig cluster responsible for prodigiosin biosynthesis in two Serratia sp. In this article we report the creation of in-frame deletions or insertions in every biosynthetic gene in the cluster from Serratia sp. ATCC 39006. The biosynthetic intermediates accumulating in each mutant have been analysed by LC-MS, cross-feeding and genetic complementation studies. Based on these results we assign specific roles in the biosynthesis of MBC to the following Pig proteins: PigI, PigG, PigA, PigJ, PigH, PigM, PigF and PigN. We report a novel pathway for the biosynthesis of MAP, involving PigD, PigE and PigB. We also report a new chemical synthesis of MAP and one of its precursors, 3-acetyloctanal. Finally, we identify the condensing enzyme as PigC. We reassess the existing literature and discuss the significance of the results for the biosynthesis of undecylprodigiosin by the Red cluster in Streptomyces coelicolor A3(2). [source] Phosphate Induces Rapid H2O2 Generation in Soybean Suspension CellsPLANT BIOLOGY, Issue 2 2000T. Shigaki Abstract: Involvement of reactive oxygen species has been implicated in plant defence against pathogens. We report here a novel pathway of H2O2 generation induced by the addition of phosphate in soybean (Glycine max L.) cell suspension cultures. This H2O2 generation was initiated shortly after the addition of phosphate, and lasted only approximately one hour, as opposed to several hours observed during an attack by an avirulent strain of the bacterial pathogen Pseudomonas syringae pv. glycinea (Psg). In addition, when cell cultures were treated with both phosphate and the avirulent pathogen, two distinct oxidative burst events were observed. In contrast to DPI-sensitive Psg -induced H2O2 generation, phosphate-induced H2O2 generation was insensitive to this NADPH oxidase inhibitor. This suggests that an NADPH oxidase-independent pathway may be involved in the phosphate-induced H2O2 accumulation, which could be involved in sensing of phosphate availability in the environment. [source] Poly(ethyleneimine) microcapsules: glutaraldehyde-mediated assembly and the influence of molecular weight on their propertiesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7 2008Weijun Tong Abstract Poly(ethyleneimine) (PEI) microcapsules were prepared via the method of glutaraldehyde (GA)-mediated covalent layer-by-layer (LbL) assembly, which utilized GA to cross-link the adsorbed PEI layer and to introduce free aldehyde group on the surface for the next PEI adsorption on MnCO3 microparticles, followed by core removal. Evidenced by ellipsometry, the PEI multilayers grew nearly linearly along with the layer number and their thickness was controlled at the nanometer scale. The hollow structure, morphology, and wall thickness were characterized by scanning electron microscopy (SEM), scanning force microscopy (SFM), and confocal laser scanning microscopy (CLSM), revealing that the capsule structure as well as the cut-off molecular weight of the capsule wall could be tuned by the molecular weight of PEI. This offers a general and novel pathway to fabricate single component capsules with pre-designed structure (size, shape, and wall thickness) and properties. Copyright © 2007 John Wiley & Sons, Ltd. [source] Packaging of prions into exosomes is associated with a novel pathway of PrP processing,THE JOURNAL OF PATHOLOGY, Issue 5 2007LJ Vella Abstract Prion diseases are fatal, transmissible neurodegenerative disorders associated with conversion of the host-encoded prion protein (PrPC) into an abnormal pathogenic isoform (PrPSc). Following exposure to the infectious agent (PrPSc) in acquired disease, infection is propagated in lymphoid tissues prior to neuroinvasion and spread within the central nervous system. The mechanism of prion dissemination is perplexing due to the lack of plausible PrPSc -containing mobile cells that could account for prion spread between infected and uninfected tissues. Evidence exists to demonstrate that the culture media of prion-infected neuronal cells contain PrPSc and infectivity but the nature of the infectivity remains unknown. In this study we have identified PrPC and PrPSc in association with endogenously expressing PrP neuronal cell-derived exosomes. The exosomes from our prion-infected neuronal cell line were efficient initiators of prion propagation in uninfected recipient cells and to non-neuronal cells. Moreover, our neuronal cell line was susceptible to infection by non-neuronal cell-derived exosome PrPSc. Importantly, these exosomes produced prion disease when inoculated into mice. Exosome-associated PrP is packaged via a novel processing pathway that involves the N-terminal modification of PrP and selection of distinct PrP glycoforms for incorporation into these vesicles. These data extend our understanding of the relationship between PrP and exosomes by showing that exosomes can establish infection in both neighbouring and distant cell types and highlight the potential contribution of differentially processed forms of PrP in disease distribution. These data suggest that exosomes represent a potent pool of prion infectivity and provide a mechanism for studying prion spread and PrP processing in cells endogenously expressing PrP. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Glutamate-mediated astrocyte-to-neuron signalling in the rat dorsal hornTHE JOURNAL OF PHYSIOLOGY, Issue 5 2010Rita Bardoni By releasing neuroactive agents, including proinflammatory cytokines, prostaglandins and neurotrophins, microglia and astrocytes are proposed to be involved in nociceptive transmission, especially in conditions of persistent, pathological pain. The specific action on dorsal horn neurons of agents released from astrocytes, such as glutamate, has been, however, poorly investigated. By using patch-clamp and confocal microscope calcium imaging techniques in rat spinal cord slices, we monitored the activity of dorsal horn lamina II neurons following astrocyte activation. Results obtained revealed that stimuli that triggered Ca2+ elevations in astrocytes, such as the purinergic receptor agonist BzATP and low extracellular Ca2+, induce in lamina II neurons slow inward currents (SICs). Similarly to SICs triggered by astrocytic glutamate in neurons from other central nervous system regions, these currents (i) are insensitive to tetrodotoxin (TTX), (ii) are blocked by the NMDA receptor (NMDAR) antagonist d -AP5, (iii) lack an AMPA component, and (iv) have slow rise and decay times. Ca2+ imaging also revealed that astrocytic glutamate evokes NMDAR-mediated episodes of synchronous activity in groups of substantia gelatinosa neurons. Importantly, in a model of peripheral inflammation, the development of thermal hyperalgesia and mechanical allodynia was accompanied by a significant increase of spontaneous SICs in dorsal horn neurons. The NMDAR-mediated astrocyte-to-neuron signalling thus represents a novel pathway that may contribute to the control of central sensitization in pathological pain. [source] Regulation of STARS and its downstream targets suggest a novel pathway involved in human skeletal muscle hypertrophy and atrophyTHE JOURNAL OF PHYSIOLOGY, Issue 8 2009Séverine Lamon Skeletal muscle atrophy is a severe consequence of ageing, neurological disorders and chronic disease. Identifying the intracellular signalling pathways controlling changes in skeletal muscle size and function is vital for the future development of potential therapeutic interventions. Striated activator of Rho signalling (STARS), an actin-binding protein, has been implicated in rodent cardiac hypertrophy; however its role in human skeletal muscle has not been determined. This study aimed to establish if STARS, as well as its downstream signalling targets, RhoA, myocardin-related transcription factors A and B (MRTF-A/B) and serum response factor (SRF), were increased and decreased respectively, in human quadriceps muscle biopsies taken after 8 weeks of both hypertrophy-stimulating resistance training and atrophy-stimulating de-training. The mRNA levels of the SRF target genes involved in muscle structure, function and growth, such as ,-actin, myosin heavy chain IIa (MHCIIa) and insulin-like growth factor-1 (IGF-1), were also measured. Following resistance training, STARS, MRTF-A, MRTF-B, SRF, ,-actin, MHCIIa and IGF-1 mRNA, as well as RhoA and nuclear SRF protein levels were all significantly increased by between 1.25- and 3.6-fold. Following the de-training period all measured targets, except for RhoA, which remained elevated, returned to base-line. Our results show that the STARS signalling pathway is responsive to changes in skeletal muscle loading and appears to play a role in both human skeletal muscle hypertrophy and atrophy. [source] AtMBD9: a protein with a methyl-CpG-binding domain regulates flowering time and shoot branching in ArabidopsisTHE PLANT JOURNAL, Issue 2 2006Mingsheng Peng Summary The functional characterization of mammalian proteins containing a methyl-CpG-binding domain (MBD) has revealed that MBD proteins can decipher the epigenetic information encoded by DNA methylation, and integrate DNA methylation, modification of chromatin structure and repression of gene expression. The Arabidopsis genome has 13 putative genes encoding MBD proteins, and no specific biological function has been defined for any AtMBD genes. In this study, we identified three T-DNA insertion mutant alleles at the AtMBD9 locus, and found that all of them exhibited obvious developmental abnormalities. First, the atmbd9 mutants flowered significantly earlier than wild-type plants. The expression of FLOWERING LOCUS C (FLC), a major repressor of Arabidopsis flowering, was markedly attenuated by the AtMBD9 mutations. This FLC transcription reduction was associated with a significant decrease in the acetylation level in histone H3 and H4 of FLC chromatin in the atmbd9 mutants. Secondly, the atmbd9 mutants produced more shoot branches by increasing the outgrowth of axillary buds when compared with wild-type plants. The two known major factors controlling the outgrowth of axillary buds in Arabidopsis, auxin and the more axillary growth (MAX) pathway, were found not to be involved in producing this enhanced shoot branching phenotype in atmbd9 mutants, indicating that AtMBD9 may regulate a novel pathway to control shoot branching. This pathway is not related to FLC expression as over-expression of FLC in atmbd9-2 restored its flowering time to one similar to that of the wild type, but did not alter the shoot branching phenotype. [source] Potential Role of NKG2D and Its Ligands in Organ Transplantation: New Target for ImmunointerventionAMERICAN JOURNAL OF TRANSPLANTATION, Issue 2 2009B. Suárez-Álvarez NKG2D is one of the best characterized activating receptors on Natural Killer (NK) and CD8+ T cells. This receptor recognizes several different ligands (MICA/MICB and ULBPs) induced by cellular stress and infection. In addition to the role described in cancer surveillance, recent data highlight the importance of NKG2D and its ligands in organ transplantation. Allografts show evidence of MICA and MICB expression in both acute and chronic rejection. The presence of anti-MICA antibodies has been correlated with incidence of graft rejection. Furthermore, NKG2D-ligand engagement activates NK cells, which provides T-cell costimulation, and enhances antigen specific CTL-mediated cytotoxicity. Activated NK cells may function as a bridge between innate and adaptive immunity associated with transplantation. Activated NK cells in response to IL-15 can also trigger organ rejection through NKG2D and affect the maturation of both donor and recipient antigen presenting cells (APCs) and ultimately the T-cell allogeneic response. Regulatory T cells, which modulate T-cell responses in organ transplantation and infections, were reduced in numbers by NK cells exposed to intracellular pathogens, possibly via interaction with one NK2GD receptor. Blockage of NKG2D-NKG2D-L interactions provides a novel pathway for development of inhibitors. These studies have important clinical and therapeutic implications in solid organ transplantation. [source] Identification of a novel susceptibility locus for juvenile idiopathic arthritis by genome-wide association analysisARTHRITIS & RHEUMATISM, Issue 1 2009Anne Hinks Objective Juvenile idiopathic arthritis (JIA) is a chronic rheumatic disease of childhood. Two well-established genetic factors known to contribute to JIA susceptibility, HLA and PTPN22, account for less than half of the genetic susceptibility to disease; therefore, additional genetic factors have yet to be identified. The purpose of this study was to perform a systematic search of the genome to identify novel susceptibility loci for JIA. Methods A genome-wide association study using Affymetrix GeneChip 100K arrays was performed in a discovery cohort (279 cases and 184 controls). Single-nucleotide polymorphisms (SNPs) showing the most significant differences between cases and controls were then genotyped in a validation sample of cases (n = 321) and controls, combined with control data from the 1958 UK birth cohort (n = 2,024). In one region in which association was confirmed, fine-mapping was performed (654 cases and 1,847 controls). Results Of the 112 SNPs that were significantly associated with JIA in the discovery cohort, 6 SNPs were associated with JIA in the independent validation cohort. The most strongly associated SNP mapped to the HLA region, while the second strongest association was with a SNP within the VTCN1 gene. Fine-mapping of that gene was performed, and 10 SNPs were found to be associated with JIA. Conclusion This study is the first to successfully apply a SNP-based genome-wide association approach to the investigation of JIA. The replicated association with markers in the VTCN1 gene defined an additional susceptibility locus for JIA and implicates a novel pathway in the pathogenesis of this chronic disease of childhood. [source] In vivo inhibition of angiogenesis by interleukin-13 gene therapy in a rat model of rheumatoid arthritisARTHRITIS & RHEUMATISM, Issue 8 2007Christian S. Haas Objective Interleukin-13 (IL-13) is a pleiotropic cytokine that can affect vessel formation, an important component of the rheumatoid arthritis (RA) synovial tissue pannus. The purpose of this study was to use a gene therapy approach to investigate the role of IL-13 in angiogenesis in vivo, using a rat adjuvant-induced arthritis model of RA. Methods Ankle joints of female rats were injected preventatively with an adenovirus vector containing human IL-13 (AxCAIL-13), a control vector with no insert (AxCANI), or phosphate buffered saline (PBS). Joints were harvested at the peak of arthritis, and histologic and biochemical features were evaluated. Results AxCAIL-13,treated joint homogenates had lower hemoglobin levels, suggesting reduced joint vascularity, and both endothelial cell migration and tube formation were significantly inhibited (P < 0.05). Similarly, AxCAIL-13 inhibited capillary sprouting in the rat aortic ring assay and vessel growth in the Matrigel plug in vivo assay. IL-13 gene delivery resulted in up-regulation and association of phosphorylated ERK-1/2 and protein kinase C,/,II, suggesting a novel pathway in IL-13,mediated angiostasis. The angiostatic effect of AxCAIL-13 was associated with down-regulation of proangiogenic cytokines (IL-18, cytokine-induced neutrophil chemoattractant 1/CXCL1, lipopolysaccharide-induced CXC chemokine/CXCL5) and up-regulation of the angiogenesis inhibitor endostatin. The expression and activity of matrix metalloproteinases 2 and 9, which participate in angiogenesis, was impaired in response to IL-13 as compared with AxCANI and PBS treatment. Conclusion Our findings support a role for IL-13 as an in vivo antiangiogenic factor and provide a rationale for its use in RA to control pathologic neovascularization. [source] New directions and interactions in metagenomics researchFEMS MICROBIOLOGY ECOLOGY, Issue 3 2006Naomi Ward Abstract Metagenomics, which aims to access the genomic potential of an environmental sample directly, is a burgeoning area that is generating enormous amounts of biological information. An examination of recent metagenomics literature reveals the discipline to be heading in new and interesting directions, including the investigation of the normal flora of mammals, analysis of ancient genomes, and exploration of the distribution of novel pathways. In addition, the development of new bioinformatics approaches and tools is allowing innovative mining of both existing and new data. Finally, there are indications that the integration of metagenomics with complementary approaches in microbial ecology is beginning. [source] Chromosome 8 BAC array comparative genomic hybridization and expression analysis identify amplification and overexpression of TRMT12 in breast cancer,GENES, CHROMOSOMES AND CANCER, Issue 7 2007Virginia Rodriguez Genomic changes in chromosome 8 are commonly observed in breast cancer cell lines and tumors. To fine map such genomic changes by comparative genomic hybridization (CGH), a high resolution (100 kb) chromosome 8 array that can detect single copy changes was developed using Phi29 DNA polymerase amplified BAC (bacterial artificial chromosome) DNA. The BAC array CGH resolved the two known amplified regions (8q21 and 8q24) of a breast cancer cell line (SKBR3) into nine separate regions including six amplicons and three deleted regions, all of which were verified by Fluorescence in situ hybridization. The extent of the gain/loss for each region was validated by qPCR. CGH was performed with a total of 8 breast cancer cell lines, and common regions of genomic amplification/deletion were identified by segmentation analysis. A 1.2-Mb region (125.3,126.5 Mb) and a 1.0-Mb region (128.1,129.1 Mb) in 8q24 were amplified in 7/8 cell lines. A global expression analysis was performed to evaluate expression changes associated with genomic amplification/deletion: a novel gene, TRMT12 (at 125.5 Mb), amplified in 7/8 cell lines, showed highest expression in these cell lines. Further analysis by RT-qPCR using RNA from 30 breast tumors showed that TRMT12 was overexpressed >2 fold in 87% (26/30) of the tumors. TRMT12 is a homologue of a yeast gene encoding a tRNA methyltransferase involved in the posttranscriptional modification of tRNAPhe, and exploring the biological consequence of its altered expression, may reveal novel pathways in tumorigenesis. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat. Published 2007 Wiley-Liss, Inc. [source] Gene Expression Profiling in Paget's Disease of Bone: Upregulation of Interferon Signaling Pathways in Pagetic Monocytes and Lymphocytes,,§JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2008Zsolt B Nagy Abstract We examined the gene expression profile of genes involved in bone metabolism in 23 patients with PD compared with 23 healthy controls. We found a significant overexpression of the genes of the IFN pathway along with a downregulation of tnf-,. Our result suggest that IFN-mediated signaling may play important roles in aberrant osteoclastogenesis of PD. Introduction: Paget's disease of bone (PD) is characterized by focal regions of highly exaggerated bone remodeling and aberrant osteoclastogenesis. Under physiological conditions, circulating monocytes may serve as early progenitors of osteoclasts and along with peripheral blood lymphocytes produce a wide variety of factors important in bone metabolism. Nevertheless, little is known about the roles of circulating monocytes and lymphocytes in relation to the pathological bone turnover in PD. Materials and Methods: In this study, we aimed at investigating the gene expression pattern of PD using quantitative real-time PCR in monocytes and lymphocytes isolated from peripheral blood mononuclear cells (PBMCs). Fifteen genes known to be involved in osteoclastogenesis were studied in cells from 23 patients with PD and in cells from 23 healthy controls. Eight human genes including ifn-, (3.48-fold, p < 0.001), ifn-, (2.68-fold, p < 0.001), ifn-, (1.98-fold, p = 0.002), p38 ,2 mapk (2.47-fold, p = 0.002), ifn-,r1 (2.03-fold, p = 0.01), ifn-,r2 (1.81-fold, p = 0.02), stat1 (1.57-fold, p = 0.037), and tnf-, (,2.34, p < 0.001) were found to be significantly altered in pagetic monocytes compared with monocytes of healthy controls. Results: In pagetic lymphocytes, significant changes in the expression of ifn-, (2.17-fold, p < 0.001), ifn-, (2.13-fold, p = 0.005), ifn-, (1.89-fold, p < 0.001), ifn-,r1 (1.02-fold, p = 0.04), ifn-,r2 (1.01-fold, p = 0.031), stat2 (1.79-fold, p < 0.001), and tnf-, (,1.49, p < 0.001) were found compared with lymphocytes of healthy controls. Furthermore, IFN-, protein was significantly elevated in the sera of PD patients (18.7 ± 6.69 pg/ml) compared with healthy controls (3.87 ± 6.48 pg/ml, p = 0.042). Conclusions: In conclusion, our data suggest that novel pathways mainly related to the IFN-mediated signaling may play important roles in the aberrant osteoclastogenesis of PD. [source] Suppression of nNOS expression in rat enteric neurones by the receptor for advanced glycation end-productsNEUROGASTROENTEROLOGY & MOTILITY, Issue 5 2006K. Korenaga Abstract, Diabetes mellitus results in a loss of neuronal nitric oxide synthase (nNOS) expression in the myenteric plexus but the underlying mechanisms remain unknown. We hypothesized that this may be mediated by advanced glycation end-products (AGEs), a class of modified protein adducts formed by non-enzymatic glycation that interact with the receptor for AGE (RAGE) and which are important in the pathogenesis of other diabetic complications. Whole mount preparations of longitudinal muscles with adherent myenteric plexus (LM-MPs) from the duodenum of adult male rats were exposed to glycated bovines serum albumin (AGE-BSA) or BSA for 24 h. Western blotting, immunohistochemistry and real-time reverse transcriptase polymerase chain reaction (RT-PCR) for mRNA showed a significant reduction in nNOS expression in LM-MPs after exposure to AGE-BSA. NO release, as measured by the Griess reaction, was also significantly reduced by AGE-BSA. A neutralizing antibody against RAGE attenuated the reduction of nNOS protein caused by AGE-BSA. Immunohistochemistry revealed co-localization of RAGE expression with Hu, a marker for neuronal cells but not for S-100, a glial marker. Advanced glycation end-products reduce nNOS expression in the rat myenteric neurones acting via the receptor RAGE. Our results suggest novel pathways for disruption of the nitrergic phenotype in diabetes. [source] MscL of Bacillus subtilis prevents selective release of cytoplasmic proteins in a hypotonic environmentPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 4 2009Thijs R. H. M. Kouwen Abstract Bacillus subtilis serves as an excellent model to study protein secretion at a proteomic scale. Most of the extracellular proteins are exported from the cytoplasm via the secretory (Sec) pathway. Despite extensive studies, the secretion mechanisms of about 25% of the extracellular proteins are unknown. This suggests that B. subtilis makes use of alternative mechanisms to release proteins into its environment. In search for novel pathways, which contribute to biogenesis of the B. subtilis exoproteome, we investigated a possible role of the large conductance mechanosensitive channel protein MscL. We compared protein secretion by MscL deficient and proficient B. subtilis cells. MscL did not contribute to secretion under standard growth conditions. Unexpectedly, we discovered that under hypo-osmotic shock conditions specific, normally cytoplasmic proteins were released by mscL mutant cells. This protein release was selective since not all cytoplasmic proteins were equally well released. We established that this protein release by mscL mutant cells cannot be attributed to cell death or lysis. The presence of MscL, therefore, seems to prevent the specific release of cytoplasmic proteins by B. subtilis during hypo-osmotic shock. Our unprecedented findings imply that an unidentified system for selective release of cytoplasmic proteins is active in B. subtilis. [source] | ||||||||||||||||