Search results for "guanosine"

Selective Stimulation of Hepatitis C Virus and Pestivirus NS5B RNA Polymerase Activity by GTP

1999

NS5B of the hepatitis C virus is an RNA template-dependent RNA polymerase and therefore the key player of the viral replicase complex. Using a highly purified enzyme expressed with recombinant baculoviruses in insect cells, we demonstrate a stimulation of RNA synthesis up to 2 orders of magnitude by high concentrations of GTP but not with ATP, CTP, UTP, GDP, or GMP. Enhancement of RNA synthesis was found with various heteropolymeric RNA templates, with poly(C)-oligo(G)12 but not with poly(A)-oligo(U)12. Several amino acid substitutions in polymerase motifs B, C, and D previously shown to be crucial for RdRp activity were tested for GTP stimulation of RNA synthesis. Most of these mutations, …

Nitric Oxide/Cyclic Guanosine Monophosphate Signaling via Guanylyl Cyclase Isoform 1 Mediates Early Changes in Synaptic Transmission and Brain Edema …

2021

Traumatic brain injury (TBI) often induces structural damage, disruption of the blood-brain barrier (BBB), neurodegeneration, and dysfunctions of surviving neuronal networks. Nitric oxide (NO) signaling has been suggested to affect brain functions after TBI. The NO exhibits most of its biological effects by activation of the primary targets-guanylyl cyclases (NO-GCs), which exists in two isoforms (NO-GC1 and NO-GC2), and the subsequently produced cyclic guanosine monophosphate (cGMP). However, the specific function of the NO-NO-GCs-cGMP pathway in the context of brain injury is not fully understood. To investigate the specific role of the isoform NO-GC1 early after brain injuries, we perfor…

Purification and evaluation of large clostridial cytotoxins that inhibit small GTPases of Rho and ras subfamilies

2000

Publisher Summary This chapter discusses the purification and evaluation of large clostridia cytotoxins (LCTs) that inhibit small guanosine 5'-triphosphates (GTPases) of Rho and Ras subfamilies. LCTs are glycosyltransferases that inactivate GTPases of the Rho and Ras subfamilies by covalently coupling a sugar moiety (mostly glucose) to the conserved threonine residue in region switch 1 of the GTPases (T35 in Ras). This glycosylation functionally inactivates the GTPases leading to the collapse of the actin cytoskeleton and ultimately induces apoptosis of the cells. Small GTP-binding proteins are key players in the regulation of signal transducing networks of eukaryotic cells. Their regulator…

Inter-laboratory validation of procedures for measuring 8-oxo-7,8-dihydroguanine/8-oxo-7,8-dihydro-2’-deoxyguanosine in DNA.

2002

The aim of ESCODD, a European Commission funded Concerted Action, is to improve the precision and accuracy of methods for measuring 8-oxo-7,8-dihydroguanine (8-oxoGua) or the nucleoside (8-oxodG). On two occasions, participating laboratories received samples of different concentrations of 8-oxodG for analysis. About half the results returned (for 8-oxodG) were within 20% of the median values. Coefficients of variation (for three identical samples) were commonly around 10%. A sample of calf thymus DNA was sent, dry, to all laboratories. Analysis of 8-oxoGua/8-oxodG in this sample was a test of hydrolysis methods. Almost half the reported results were within 20% of the median value, and half …

Closer to nature: an ATP-driven bioinspired catalytic oxidation process

2013

The capability of DNA to acquire enzyme-like properties has led to the emergence of the so-called DNAzyme field; herein, we take a further leap along this nature-inspired road, demonstrating that a template assembled synthetic G-quartet (TASQ) can act as a pre-catalyst for catalytic peroxidase-mimicking oxidation reactions, whatever its nature (guanine or guanosine-based G-quartets), in an ATP-dependent manner, thereby bringing this bioinspired TASQzyme process even closer to nature.

Brain expression and 3H-Guanosine binding analysis of novel G protein-coupled receptor for guanosine (GPR23/LPA4)

2012

Several studies have shown that guanine-based purines exert biological effects on the central nervous system, possibly through membrane receptor. In a parallel work, we have identified the first guanosine G protein-coupled receptor GPR23, known as LPA4 receptor, involved in the modulation of guanosine-mediated antiproliferative effects in human glioma cell lines. Here, we performed in different brain areas the following studies: by PCR, the expression levels of GPR23; by [3H]-Guanosine radioligand binding assay, the binding properties of GPR23; by [35S] GTPγS binding assay, the receptor activation properties of guanosine. Among the examined areas, the cerebral cortex showed the highest GPR2…

Identification of GPR23/LPA4 as a candidate G protein-coupled receptor for Guanosine

2012

Guanosine-Induced Antiproliferative Effects Are Modulated by GPCR Expression in Human Glioma and Melanoma Cell Lines.

2012

Guanosine-Induced Antiproliferative Effects Are Modulated by GPCR Expression in Human Glioma and Melanoma Cell Lines.

Relaxation Induced By Guanosine in Mouse Stomach

2012

Guanine-based purines are part of the purinergic system and recently have been shown to act as neuromodulators, interfering with acetylcholine release by enteric neurons in mouse colon. Due to the pivotal role played by enteric neurons in the control of gastrointestinal motility, the aim of the present study was to verify whether guanosine may affect gastric emptying and the mechanical tone, detected in vitro as changes in intraluminal pressure, of the isolated mouse stomach. Guanosine induced a TTX-insensitive concentration-dependent relaxation of isolated stomach, which at the maximal concentration tested (1 mM), reached about 60% of the relaxation induced by 1 µM isoproterenol. The inhib…

Extracellular cyclic GMP and its derivatives GMP and guanosine protect from oxidative glutamate toxicity.

2013

Cell death in response to oxidative stress plays a role in a variety of neurodegenerative diseases and can be studied in detail in the neuronal cell line HT22, where extracellular glutamate causes glutathione depletion by inhibition of the glutamate/cystine antiporter system xc(-), elevation of reactive oxygen species and eventually programmed cell death caused by cytotoxic calcium influx. Using this paradigm, we screened 54 putative extracellular peptide or small molecule ligands for effects on cell death and identified extracellular cyclic guanosine monophosphate (cGMP) as a protective substance. Extracellular cGMP was protective, whereas the cell-permeable cGMP analog 8-pCPT-cGMP or the …