Search results for "Poly A"
showing 10 items of 59 documents
Differential effect of insulin and epidermal growth factor on the mRNA translocation system and transport of specific poly(A+) mRNA and poly(A-) mRNA…
1990
The efficiency of efflux of rapidly labeled poly(A)-containing mRNA from isolated rat liver nuclei was found to be modulated by insulin and epidermal growth factor (EGF) in a biphasic but opposite way. At physiological concentrations (10 pM insulin and 1 pM EGF), maximal stimulation of the transport rate by insulin (to 137%) and maximal inhibition by EGF (to 69%) were obtained; at higher concentrations (greater than 100 pM and greater than 10 pM, respectively), the amount of poly(A)-containing mRNA released into the postnuclear supernatant was nearly identical with the level found in untreated nuclei (= 100%). Using mRNA entrapped into closed nuclear envelope (NE) vesicles as a model system…
Proteins from rat liver cytosol which stimulate mRNA transport. Purification and interactions with the nuclear envelope mRNA translocation system.
1986
Two polysome-associated proteins with particular affinities for poly(A) have been purified from rat liver. These proteins stimulate the efflux of mRNA from isolated nuclei in conditions under which such efflux closely stimulates mRNA transport in vivo, and they are therefore considered as mRNA-transport-stimulatory proteins. Their interaction with the mRNA-translocation system in isolated nuclear envelopes has been studied. The results are generally consistent with the most recently proposed kinetic model of mRNA translocation. One protein, P58, has not been described previously. It inhibits the protein kinase that down-regulates the NTPase, it enhances the NTPase activity in both the prese…
Acute ammonia intoxication induces an NMDA receptor-mediated increase in poly(ADP-ribose) polymerase level and NAD+ metabolism in nuclei of rat brain…
2004
Acute ammonia toxicity is mediated by excessive activation of NMDA receptors. Activation of NMDA receptors leads to activation of poly(ADP-ribose) polymerase (PARP) which mediates NMDA excitotoxicity. PARP is activated following DNA damage and may lead to cell death via NAD+ and ATP depletion. The aim of the present work was to assess whether acute ammonia intoxication in vivo leads to increased PARP in brain cells nuclei and to altered NAD+ and superoxide metabolism and the contribution of NMDA receptors to these alterations. Acute ammonia intoxication increases PARP content twofold in brain cells nuclei.NAD+ content decreased by 55% in rats injected with ammonia. This was not due to decre…
Les followers ont-ils vraiment de l'importance dans le modèle de Stackelberg?
2011
In this paper, we consider a T-stage linear model of Stackelberg oligopoly. First, we show geometrically and analytically that under the two conditions of linear market demand and identical constant marginal costs, the T-stage Stackelberg model reduces to a model where T oligopolies exploit residual demand sequentially. At any stage, leaders behave as if followers did not matter. Second, we study social welfare and convergence toward competitive equilibrium. Especially, we consider the velocity of convergence as the number of firms increases. The convergence is faster when reallocating firms from the most to the less populated cohort until equalizing the size of all cohorts.
Selective targeting of PARP-1 zinc finger recognition domains with Au(III) organometallics
2018
The binding of Au(iii) complexes to the zinc finger domain of the anticancer drug target PARP-1 was studied using a hyphenated mass spectrometry approach combined with quantum mechanics/molecular mechanics (QM/MM) studies. Competition experiments were carried out, whereby each Au complex was exposed to two types of zinc fingers. Notably, the cyclometallated Au-C^N complex was identified as the most selective candidate to disrupt the PARP-1 zinc finger domain, forming distinct adducts compared to the coordination compound Auphen.
Dramatic selectivity differences in the association of DNA and RNA models with new ethylene- and propylene diamine derivatives and their copper compl…
2006
The affinities of polyamines consisting of ethylenediamine units equipped with either one or two terminal naphthyl-, anthryl-, or acridyl units towards PolyA.PolyU as an RNA model, and Poly(dA).Poly(dT) as a DNA model are screened by measuring the melting point changes (DeltaT(m)) of the double strands, and also partially by a fluorimetric binding assay using ethidium bromide. The larger aromatic moieties with long spacers between them allow bisintercalation; this leads to an increased preference for DNA in comparison to RNA, where ion pairing of the ammonium centers with the major RNA groove phosphates dominates. Allosteric affinity control by metalation is achieved e.g. with Cu(2+) ions, …
Lauroside B, a Megastigmane Glycoside from Laurus Nobilis (Bay Laurel) Leaves, Induces Apoptosis in Human Melanoma Cell Lines by Inhibiting NF-κB Act…
2010
Malignant melanoma is a highly aggressive tumor that frequently resists chemotherapy, so the search for new agents for its treatment is of great importance. In the present study, the antiproliferative propensity against human melanoma cell lines of lauroside B (1), a megastigmane glycoside isolated from Laurus nobilis (bay laurel) leaves, was investigated. This compound suppressed the proliferation of three human melanoma cell lines, namely, A375, WM115, and SK-Mel-28. The 1-induced inhibition of human melanoma cell proliferation was due to the induction of apoptosis, as demonstrated by FACS analysis with annexin V/PI staining and confirmed by activation of caspase-3 and by the cleavage of …
Presence of phosphorylatedO-ribosyl-adenosine In T-ψ-stem of yeast methlonine initiator tRNA
1989
We report in this paper on isolation and characterization of two unknown nucleosides G* and [A*] located in the T-psi-stem of yeast methionine initiator tRNA, using the combined means of HPLC protocols, real time UV-absorption spectrum, and post-run mass spectrometry by electron impact or fast atom bombardment. The G* nucleoside in position 65 was identified as unmodified guanosine. The structure of the unknown [A*] in position 64 was characterized as an isomeric form of O-ribosyl-adenosine by comparison of its chromatographic, UV-spectral and mass spectrometric properties with those of authentic O-alpha-ribofuranosyl-(1"----2')-adenosine isolated from biosynthetic poly(adenosine diphosphat…
Poly-ADP-Ribose (PAR) as an epigenetic flag
2009
Epigenetics is the study of hereditable chromatin modifications, such as DNA methylation, histone modifications, and nucleosome-remodelling, which occur without alterations to the DNA sequence. The establishment of different epigenetic states in eukaryotes depends on regulatory mechanisms that induce structural changes in chromatin in response to environmental and cellular cues. Two classes of enzymes modulate chromatin accessibility: chromatin-covalent modifiers and ATP-dependent chromatin remodelling complexes. The first class of enzymes catalyzes covalent modifications of DNA as well as the amino- and carboxy-terminal tails of histones, while the second uses the energy of ATP hydrolysis …
The nucleosome-remodeling ATPase ISWI is regulated by poly-ADP-ribosylation.
2008
ATP-dependent nucleosome-remodeling enzymes and covalent modifiers of chromatin set the functional state of chromatin. However, how these enzymatic activities are coordinated in the nucleus is largely unknown. We found that the evolutionary conserved nucleosome-remodeling ATPase ISWI and the poly-ADP-ribose polymerase PARP genetically interact. We present evidence showing that ISWI is target of poly-ADP-ribosylation. Poly-ADP-ribosylation counteracts ISWI function in vitro and in vivo. Our work suggests that ISWI is a physiological target of PARP and that poly-ADP-ribosylation can be a new, important post-translational modification regulating the activity of ATP-dependent nucleosome remodel…