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71.
Jesús Sánchez-Navarro Thor Fajardo Stefania Zicca Vicente Pallás Livia Stavolone 《Journal of virology》2010,84(8):4109-4112
Plant viruses move through plasmodesmata (PD) either as nucleoprotein complexes (NPCs) or as tubule-guided encapsidated particles with the help of movement proteins (MPs). To explore how and why MPs specialize in one mechanism or the other, we tested the exchangeability of MPs encoded by DNA and RNA virus genomes by means of an engineered alfalfa mosaic virus (AMV) system. We show that Caulimoviridae (DNA genome virus) MPs are competent for RNA virus particle transport but are unable to mediate NPC movement, and we discuss this restriction in terms of the evolution of DNA virus MPs as a means of mediating DNA viral genome entry into the RNA-trafficking PD pathway.Following virus entry and replication, successful infection of a host requires viral spread to distal parts of the organism through the vascular tissue. In plants, virus movement involves mostly symplastic trafficking of different viral components through the connections of plasmodesmata (PD) (13). With this aim, plant viruses encode one or more movement proteins (MPs), which allow viral genomes to cross the host cell wall by altering the size exclusion limit (SEL) or the structure of PD (6, 11). Plant viruses have evolved distinct mechanisms to move their genomes within the host. These mechanisms can be grouped into two general strategies: one in which the genome is transported in the form of a nucleoprotein complex (NPC) and another in which nucleic acids are encapsidated and move as virus particles. In both cases, besides altering PD SEL, MPs are involved either in NPC assembly or in forming tubules traversing modified PD and helping transport of either NPC or virions to the neighboring cell. Within these two major strategies, there exists a wide range of variability in terms of the number and type of viral and host proteins helping MPs to mediate virus spread within the host (11).In spite of such variability, several different MPs have been classified into a 30K superfamily; these MPs, from 20 genera including both RNA and DNA genome viruses, are structurally related to the 30-kDa MP of Tobacco mosaic virus (TMV), independent of the movement strategy followed (14). Members of this family have a common core of predicted secondary structure elements (α-helices and β-elements) containing a nucleic acid binding domain. Distinct MPs belong to this family, including several tubule-forming MPs, although these are phylogenetically separated from the other members (14). Thus, 30K superfamily MPs are closely related, and some of them are functionally interchangeable in the viral context (2, 20). In particular, MPs from five distinct genera with an RNA genome can successfully replace the corresponding gene of Alfalfa mosaic virus (AMV) (19), indicating that one or more basic and fundamental movement properties might be associated with the common 30K structural core.Among all known plant viruses, only three viral families have evolved a DNA genome: Geminiviridae, Caulimoviridae, and Nanoviridae (6). One possible explanation for this restriction is that endogenous cell-to-cell transport via PD is specialized to use RNA as the communication and signaling molecule (12). To circumvent this restriction, and to allow the efficient exploitation of endogenous transport machineries, DNA genome viruses have evolved appropriate mechanisms involving their MPs. Interestingly, Begomovirus and Caulimovirus MPs also belong to the 30K superfamily discussed above (14). The MP encoded by Cauliflower mosaic virus (CaMV), the type member of Caulimoviridae, forms tubules that guide the movement of encapsidated virus via an indirect MP-virion interaction (16, 21), whereas geminivirus MPs selectively bind their genomes and transport them as NPCs (6, 9, 17). In this study, we investigated the evolutionary convergence of MPs encoded by DNA and RNA viruses by testing their exchangeability in the viral context. 相似文献
72.
Identification and activity of a series of azole-based compounds with lactate dehydrogenase-directed anti-malarial activity 总被引:11,自引:0,他引:11
Cameron A Read J Tranter R Winter VJ Sessions RB Brady RL Vivas L Easton A Kendrick H Croft SL Barros D Lavandera JL Martin JJ Risco F García-Ochoa S Gamo FJ Sanz L Leon L Ruiz JR Gabarró R Mallo A Gómez de las Heras F 《The Journal of biological chemistry》2004,279(30):31429-31439
Plasmodium falciparum, the causative agent of malaria, relies extensively on glycolysis coupled with homolactic fermentation during its blood-borne stages for energy production. Selective inhibitors of the parasite lactate dehydrogenase (LDH), central to NAD(+) regeneration, therefore potentially provide a route to new antimalarial drugs directed against a novel molecular target. A series of heterocyclic, azole-based compounds are described that preferentially inhibit P. falciparum LDH at sub-micromolar concentrations, typically at concentrations about 100-fold lower than required for human lactate dehydrogenase inhibition. Crystal structures show these competitive inhibitors form a network of interactions with amino acids within the active site of the enzyme, stacking alongside the nicotinamide ring of the NAD(+) cofactor. These compounds display modest activity against parasitized erythrocytes, including parasite strains with known resistance to existing anti-malarials and against Plasmodium berghei in BALB/c mice. Initial toxicity data suggest the azole derivatives have generally low cytotoxicity, and preliminary pharmoco-kinetic data show favorable bioavailability and circulation times. These encouraging results suggest that further enhancement of these structures may yield candidates suitable for consideration as new therapeutics for the treatment of malaria. In combination these studies also provide strong support for the validity of targeting the Plasmodium glycolytic pathway and, in particular, LDH in the search for novel anti-malarials. 相似文献
73.
Matteo Pappalardo Nir Shachaf Livia Basile Danilo Milardi Mouhammed Zeidan Jamal Raiyn Salvatore Guccione Anwar Rayan 《PloS one》2014,9(10)
The human histamine H4 receptor (hH4R), a member of the G-protein coupled receptors (GPCR) family, is an increasingly attractive drug target. It plays a key role in many cell pathways and many hH4R ligands are studied for the treatment of several inflammatory, allergic and autoimmune disorders, as well as for analgesic activity. Due to the challenging difficulties in the experimental elucidation of hH4R structure, virtual screening campaigns are normally run on homology based models. However, a wealth of information about the chemical properties of GPCR ligands has also accumulated over the last few years and an appropriate combination of these ligand-based knowledge with structure-based molecular modeling studies emerges as a promising strategy for computer-assisted drug design. Here, two chemoinformatics techniques, the Intelligent Learning Engine (ILE) and Iterative Stochastic Elimination (ISE) approach, were used to index chemicals for their hH4R bioactivity. An application of the prediction model on external test set composed of more than 160 hH4R antagonists picked from the chEMBL database gave enrichment factor of 16.4. A virtual high throughput screening on ZINC database was carried out, picking ∼4000 chemicals highly indexed as H4R antagonists'' candidates. Next, a series of 3D models of hH4R were generated by molecular modeling and molecular dynamics simulations performed in fully atomistic lipid membranes. The efficacy of the hH4R 3D models in discrimination between actives and non-actives were checked and the 3D model with the best performance was chosen for further docking studies performed on the focused library. The output of these docking studies was a consensus library of 11 highly active scored drug candidates. Our findings suggest that a sequential combination of ligand-based chemoinformatics approaches with structure-based ones has the potential to improve the success rate in discovering new biologically active GPCR drugs and increase the enrichment factors in a synergistic manner. 相似文献
74.
Dayvison Francis Saraiva Freitas Iluska Augusta Rocha Lima Carolina Lemos Curi Livia Jord?o Rosely Maria Zancopé-Oliveira Antonio Carlos Francesconi do Valle Maria Clara Gutierrez Galhardo Andre Luiz Land Curi 《Memórias do Instituto Oswaldo Cruz》2014,109(2):262-264
Sporotrichosis associated with exposure to domestic cats is hyperendemic in Rio deJaneiro, Brazil. A review of the clinical records at our institute revealed fourpatients with clinical signs of dacryocystitis and a positive conjunctival culturefor Sporothrix who were diagnosed with Sporothrixdacryocystitis. Three patients were children (< 13 years of age) and one patientwas an adult. Two patients reported contact with a cat that had sporotrichosis.Dacryocystitis was associated with nodular, ulcerated lesions on the face of onepatient and with granulomatous conjunctivitis in two patients; however, thiscondition manifested as an isolated disease in another patient. All of the patientswere cured of the fungal infections, but three patients had chronic dacryocystitisand one patient developed a cutaneous fistula. Sporotrichosis is usually a benigndisease, but may cause severe complications when the eye and the adnexa are affected.Physicians, especially ophthalmologists in endemic areas, should be aware of theophthalmological manifestations and complications of sporotrichosis. 相似文献
75.
Livia Garzia Noriyuki Kijima A. Sorana Morrissy Pasqualino De Antonellis Ana Guerreiro-Stucklin Borja L. Holgado Xiaochong Wu Xin Wang Michael Parsons Kory Zayne Alex Manno Claudia Kuzan-Fischer Carolina Nor Laura K. Donovan Jessica Liu Lei Qin Alexandra Garancher Kun-Wei Liu Michael D. Taylor 《Cell》2018,172(5):1050-1062.e14
76.
A rapid series of synchronous cell divisions initiates embryogenesis in many animal species, including the frog Xenopus laevis. After many of these cleavage cycles, the nuclear to cytoplasmic ratio increases sufficiently to somehow cause cell cycles to elongate and become asynchronous at the mid-blastula transition (MBT). We have discovered that an unanticipated remodeling of core metabolic pathways occurs during the cleavage cycles and the MBT in X. laevis, as evidenced by widespread changes in metabolite abundance. While many of the changes in metabolite abundance were consistently observed, it was also evident that different female frogs laid eggs with different levels of at least some metabolites. Metabolite tracing with heavy isotopes demonstrated that alanine is consumed to generate energy for the early embryo. dATP pools were found to decline during the MBT and we have confirmed that maternal pools of dNTPs are functionally exhausted at the onset of the MBT. Our results support an alternative hypothesis that the cell cycle lengthening at the MBT is triggered not by a limiting maternal protein, as is usually proposed, but by a decline in dNTP pools brought about by the exponentially increasing demands of DNA synthesis. 相似文献
77.
Vivas L Easton A Kendrick H Cameron A Lavandera JL Barros D de las Heras FG Brady RL Croft SL 《Experimental parasitology》2005,111(2):105-114
Plasmodium falciparum lactate dehydrogenase (PfLDH) is essential for ATP generation. Based on structural differences within the active site between P. falciparum and human LDH, we have identified a series of heterocyclic azole-based inhibitors that selectively bind within the PfLDH but not the human LDH (hLDH) active site and showed anti-malarial activity in vitro and in vivo. Here we expand on an azole, OXD1, from this series and found that the anti-P. falciparum activity was retained against a panel of strains independently of their anti-malarial drug sensitivity profile. Trophozoites had relatively higher PfLDH enzyme activity and PfLDH-RNA expression levels than rings and were the most susceptible stages to OXD1 exposure. This is probably linked to their increased energy requirements and consistent with glycolysis being an essential metabolic pathway for parasite survival within the erythrocyte. Further structural elaboration of these azoles could lead to the identification of compounds that target P. falciparum through such a novel mechanism and with more potent anti-malarial activity. 相似文献
78.
Anti‐HSV‐1 and HSV‐2 Flavonoids and a New Kaempferol Triglycoside from the Medicinal Plant Kalanchoe daigremontiana 下载免费PDF全文
Fernanda Gouvêa Gomes Ürményi Georgia do Nascimento Saraiva Livia Marques Casanova Amanda dos Santos Matos Luiza Maria de Magalhães Camargo Maria Teresa Villela Romanos Sônia Soares Costa 《化学与生物多样性》2016,13(12):1707-1714
Kalanchoe daigremontiana (Crassulaceae) is a medicinal plant native to Madagascar. The aim of this study was to investigate the flavonoid content of an aqueous leaf extract from K. daigremontiana (Kd), and assess its antiherpetic potential. The major flavonoid, kaempferol 3‐O‐β‐d ‐xylopyranosyl‐(1 → 2)‐α‐l ‐rhamnopyranoside ( 1 ), was isolated from the AcOEt fraction (Kd‐AC). The BuOH‐soluble fraction afforded quercetin 3‐O‐β‐d ‐xylopyranosyl‐(1 → 2)‐α‐l ‐rhamnopyranoside ( 2 ) and the new kaempferol 3‐O‐β‐d ‐xylopyranosyl‐(1 → 2)‐α‐l ‐rhamnopyranoside‐7‐O‐β‐d ‐glucopyranoside ( 3 ), named daigremontrioside. The crude extract, Kd‐AC fraction, flavonoids 1 and 2 were evaluated using acyclovir‐sensitive strains of HSV‐1 and HSV‐2. Kd‐AC was highly active against HSV‐1 (EC50 = 0.97 μg/ml, SI > 206.1) and HSV‐2 (EC50 = 0.72 μg/ml, SI > 277.7). Flavonoids 1 and 2 showed anti‐HSV‐1 (EC50 = 7.4 μg/ml; SI > 27 and EC50 = 5.8 μg/ml; SI > 8.6, respectively) and anti‐HSV‐2 (EC50 = 9.0 μg/ml; SI > 22.2 and EC50 = 36.2 μg/ml; SI > 5.5, respectively) activities, suggesting the contribution of additional substances to the antiviral activity. 相似文献
79.
Astrocyte-specific inactivation of the neurofibromatosis 1 gene (NF1) is insufficient for astrocytoma formation 总被引:8,自引:0,他引:8 下载免费PDF全文
Bajenaru ML Zhu Y Hedrick NM Donahoe J Parada LF Gutmann DH 《Molecular and cellular biology》2002,22(14):5100-5113
Individuals with the neurofibromatosis 1 (NF1) inherited tumor syndrome develop low-grade gliomas (astrocytomas) at an increased frequency, suggesting that the NF1 gene is a critical growth regulator for astrocytes. In an effort to determine the contribution of the NF1 gene product, neurofibromin, to astrocyte growth regulation and NF1-associated astrocytoma formation, we generated astrocyte-specific Nf1 conditional knockout mice (Nf1(GFAP)CKO) by using Cre/LoxP technology. Transgenic mice were developed in which Cre recombinase was specifically expressed in astrocytes by embryonic day 14.5. Successive intercrossing with mice bearing a conditional Nf1 allele (Nf1flox) resulted in GFAP-Cre Nf1flox/flox (Nf1(GFAP)CKO) animals. No astrocytoma formation or neurological impairment was observed in Nf1(GFAP)CKO mice after 20 months, but increased numbers of proliferating astrocytes were observed in several brain regions. To determine the consequence of Nf1 inactivation at different developmental times, the growth properties of embryonic day 12.5 and postnatal day 2 Nf1 null astrocytes were analyzed. Nf1 null astrocytes exhibited increased proliferation but lacked tumorigenic properties in vitro and did not form tumors when injected into immunocompromised mouse brains in vivo. Collectively, our results suggest that loss of neurofibromin is not sufficient for astrocytoma formation in mice and that other genetic or environmental factors might influence NF1-associated glioma tumorigenesis. 相似文献
80.
Alessandra Cesano Sophie Visonneau Livia Cioé Steven C. Clark Daniela Santoli 《Cancer immunology, immunotherapy : CII》1995,40(3):139-151
The TALL-104 cell line, originally derived from a patient with T cell leukemia, can be maintained indefinitely in culture in the presence of interleukin-2 (IL-2) and is endowed with a highly potent major-histocompatibilitycomplex (MHC)-non-restricted tumoricidal activity both in vitro and in animal models. The present study analyzes in detail the short- and long-term effects of irradiation and cyclosporin A (CsA) treatment on the growth and tumoricidal function of this T cell clone as compared to polyclonal lymphokine-activated killer (LAK) cell preparations from healthy donors. DNA and RNA syntheses by both TALL-104 and LAK cells were irreversibly arrested a few hours after irradiation with 40 Gy. However, 4-h51Cr-release assays, performed on different days (day 1 to day 7) after irradiation, showed that the cytotoxic efficiency of TALL-104 cells against hematopoietic and solid tumor targets was only modestly reduced, whereas that of LAK cells was severely inhibited. Moreover, the cytotoxic responses to recombinant human IL-2 and IL-12, measured 18 h after irradiation and cytokine addition, were normal in the case of TALL-104 cells but were abolished in the case of LAK cells. Co-culture of IL-2-or IL-12-preactivated TALL-104 cells with a tumor target for 5 days in the absence of cytokines resulted in a lower efficiency of lysis, as compared to the non-irradiated effectors, especially if the initial stimulus was IL-12. These findings suggest the requirement of multiple cytokine stimulation for optimal expression of tumoricidal activity by lethally irradiated TALL-104 cells. CsA, while abrogating TALL-104 cell proliferation at the low dose of 0.5 g/ml, inhibited their cytotoxic function marginally only at high doses (100 g/ml). By contrast, CsA reduced dose-dependently the cytotoxicity of LAK cells starting at very low doses (0.5 g/ml). CsA did not impair the ability of TALL-104 and LAK cells to produce interferon (IFN), tumor necrosis factor (TNF) , and granulocyte/macrophage-colony-stimulatory factor (GM-CSF) in response to IL-2, IL-12, or tumor targets. Irradiation reduced drastically IFN production by LAK, but not TALL-104 cells; release of TNF and GM-CSF by either type of effector was inhibited by 10%–50%, depending on the stimulus. The high resistance of the TALL-104 cells' tumoricidal function to irradiation and immunosuppressive drugs renders this immortal T cell clone a potentially safe and effective reagent for new adoptive-transfer approaches to cancer in MHC-incompatible recipients. 相似文献