(1) These results provide the first demonstration that embryonic neurons supply agrin-like molecules to the synapses they form with embryonic muscle cells.
(2) The stimulation of the expression of agrin-related molecules in these long-term cultures requires the presence of chick embryo extract or fetal calf serum.
(3) Agrin, a protein isolated from the synapse-rich electric organ of Torpedo californica, induces the formation of specializations on myotubes in culture which resemble the post-synaptic apparatus at the vertebrate skeletal neuromuscular junction.
(4) Agrin enriched by immunoaffinity chromatography from the central nervous system induced large numbers of AChR aggregates on cultured myotubes.
(5) We conclude that agrin released by rat motor neurons induced the chick myotubes to aggregate AChRs.
(6) Agrin-induced formation of AChR aggregates was not prevented by inhibition of protein synthesis, consistent with our previous results that agrin-induced accumulation of AChRs occurs by lateral migration.
(7) The rat agrin protein is concentrated at synapses, where it may play a role in development and regeneration.
(8) Immunofluorescence shows that on myotubes incubated with agrin at 4 degrees C, agrin binds in a uniform, finely punctate pattern that correlates poorly with the distribution of AChRs.
(9) By contrast, actin (visualized with fluorescein-phalloidin) and tropomyosin did not show specific associations with agrin-induced AChR clusters.
(10) In the present study we examined the role of extracellular matrix components in agrin-induced differentiation.
(11) Myotubes stimulated with agrin at 37 degrees C for greater than or equal to 2 hr show a coclustering of agrin binding sites and AChRs.
(12) The accumulation of AChE and BuChE into agrin-induced aggregates occurred in the absence of any change in the amount, rate of synthesis, accumulation, and release, or molecular forms of either enzyme.
(13) We also characterized the expression of muscle-derived agrin-like molecules at clusters of AChR.
(14) Here I report that the major agrin-like proteins from the nervous system and other tissues of the chicken are immunochemically and biochemically similar.
(15) Thus, in developing muscle, agrin or a closely related molecule (a) is expressed before AchR clusters are detected; (b) is colocalized with the earliest AchR clusters formed; and (c) can be expressed in muscle and at sites of high AchR density independently of innervation.
(16) These results demonstrate that expression of a single gene encoding agrin confers receptor clustering that is restricted to specific sites of cell-muscle contact.
(17) Other lines of study have provided clues as to how nerve-derived (extracellular) AChR-cluster inducing factors such as agrin might activate 43k-driven postsynaptic membrane specialization.
(18) However, as dorsal and ventral premuscle masses condensed (stage 22-23), mesenchymal immunoreactivity for laminin and agrin-like proteins, but not the proteoglycan, became concentrated in these myogenic regions.
(19) Immunofluorescent staining with an anti-agrin antibody reactive at Rana but not at Xenopus neuromuscular junctions was positive only at cross-species nerve-muscle contacts involving Rana neurons.
(20) Here we present evidence that agrin is highly concentrated in the cell bodies of motor neurons and is transported to axon terminals which is consistent with the agrin hypothesis.
Aurin
Definition:
(n.) A red coloring matter derived from phenol; -- called also, in commerce, yellow corallin.
Example Sentences:
(1) Addition of specific inhibitors of chain initiation (polyinosinic acid and aurin tricarboxylic acid) to the postmitochrondrial supernatant system from DMN-treated rats caused only a slight additional inhibition, indicating that DMN predominantly affects translation by a block of initiation.
(2) Aurin tricarboxylic acid, which blocks the GPIb recognition site on the vWF monomer, and 6D1, a monoclonal antibody to GPIb, also completely inhibited platelet responses to shear stress.
(3) The antibiotic aurin tricarboxylic acid (ATA) at low concentrations induces both RNA and protein synthetic activities of the mitochondrial lysate by several fold.
(4) Using this method, a time-dependent induction of apoptosis by dexamethasone, which was inhibited by cycloheximide, actinomycin D, and aurin tricarboxylate, was observed.
(5) Aurin tricarboxylic acid (ATA) is known to inhibit ristocetin-induced platelet agglutination but not arachidonic acid-, epinephrine- or ADP-induced aggregation.
(6) Binding is not inhibited by Aurin, a dye related to ATA but lacking its anti-HIV effects.
(7) Comparison of commercially available and chemically synthesized analogues of aurintricarboxylic acid indicates that the unique aurin triphenyl methane ring system and the carboxylic acid groups are both necessary for inhibition of cell-free protein synthesis in both systems.
(8) Studies using a number of membrane-active drugs showed that changes in membrane potential or ion fluxes were not involved in the inhibition of binding of rgp120 by Evans blue or aurin tricarboxylic acid.
(9) Progesterone, a glucocorticoid antagonist, and aurin tricarboxylic acid, an inhibitor of protein receptors, protect thymocytes from the effect of glucocorticoids and ionizing radiation.
(10) In the fourth experiment heparin enhanced platelet aggregation to a similar extent (p less than 0.005), regardless of pretreatment of the blood with saline, aurin or monoclonal antibody 6D1 (MAb 6D1), the latter an antagonist at the GP Ib receptor.
(11) Partially purified factor (i) fully maintains the polysomes; (ii) inhibits the association of 40S and 60S ribosomal subunits into single ribosomes; (iii) promotes the quantitative entry of added 60S subunits into polysomes; (iv) allows the accumulation of ribosomal subunits, instead of single ribosomes, when initiation is blocked with aurin tricarboxylate; and (v) is absolutely required for the binding of globin messenger RNA to ribosomes.These properties suggest that this mammalian initiation factor functions analogously to bacterial IF-3.
(12) Aurin tricarboxylic acid (ATA) is a potent inhibitor of ristocetin-mediated platelet agglutination and of shear-induced, von Willebrand factor (vWf)-mediated platelet aggregation, probably via inhibition of vWf interaction with glycoprotein Ib (GPIb).
(13) In addition, aurin tricarboxylic acid, an inhibitor of protein synthesis, reverses this effect by disrupting the S1-RNA complex.
(14) Endo-exonuclease of nucleoplasm, chromatin, and nuclear matrix showed 80-100% cross-reaction with antisera raised to purified extranuclear endoexonuclease and was also strongly inhibited by 20 microM aurin tricarboxylic acid.
(15) Platelet aggregation mediated by vWF was not inhibited by a nonphenolic, polyanionic polymer (polyglutamic acid) or by a polyphenolic ATA-like polymer (aurin) devoid of carboxyl groups.
(16) Triammonium aurin tricarboxylate (aluminon) has been used to localize aluminum in 2 micron sections of undecalcified, methyl methacrylate embedded bone obtained from patients with terminal chronic renal failure.
(17) The triammonium salt of aurin tricarboxylic acid, commonly referred to as aluminon, forms a dye that has been used for the colorimetric determination of Al(III) species.
(18) In the third experiment aurin, an inhibitor of von Willebrand factor and its interaction with the platelet GPIb receptor, decreased platelet aggregation dose-dependently.
(19) Aurin tricarboxylic acid (ATCA) should not be used due to its high toxicity.
(20) Total protein synthesis requires both subcellular components and an exogenous energy source, and is inhibited by the antibiotics puromycin and aurin tricarboxylic acid.