RESUMO
Human embryonic fibroblasts produce interferon when incubated at 37 degrees C after being treated at 4 degrees C with poly(rI) - poly(rC), either by addition of the double-stranded duplex or by sequential addition of the constitutent single-stranded polynucleotides. Cells which have been incubated with double-stranded poly(rI) - poly(rC) can be prevented from forming interferon by washing the cells with high concentrations of salt, immediately after adsorption of polynucleotides, or by incubation of the cells with single-stranded polynucleotides. The inhibition is probably due to displacement of the inducing molecule from the cell surface. Interferon production by cells treated sequentially with poly(rI) and poly(rC) is not inhibited by either of these treatments and the polynucleotides are not easily displaced from the cell surface.
Assuntos
Fibroblastos/metabolismo , Interferons/biossíntese , Poli I-C/metabolismo , Sítios de Ligação , Fibroblastos/efeitos dos fármacos , Humanos , Cinética , Poli C/metabolismo , Poli C/farmacologia , Poli I/metabolismo , Poli I/farmacologia , Poli I-C/farmacologia , TemperaturaRESUMO
The plant alkaloid comptothecin inhibits interferon production induced by Newcastle disease virus (NDV) or ultraviolet-irradiated NDV in chick and human cells, and by Sindbis virus in chick cells. It has no effect on interferon production induced by poly (rI).poly(rC) in chick and human cells. No effect of comptothecin could be detected on the multiplication of NDV, and it is concluded that the inhibition reflects a difference between interferon induction by viruses and by polynucleotides.
Assuntos
Camptotecina/farmacologia , Interferons/biossíntese , Vírus da Doença de Newcastle/crescimento & desenvolvimento , Poli I-C/farmacologia , Sindbis virus/crescimento & desenvolvimento , Animais , Embrião de Galinha , Técnicas de Cultura , Humanos , Vírus da Doença de Newcastle/efeitos da radiação , Biossíntese de Proteínas , RNA/biossíntese , Efeitos da Radiação , Raios Ultravioleta , Replicação Viral/efeitos dos fármacosRESUMO
Three different inhibitors of RNA synthesis, actinomycin, alpha-amanitin and camptothecin, and five different inhibitors of protein synthesis were able to superinduce interferon production in human diploid fibroblasts treated with poly(rI).poly(rC). Camptothecin was shown to be a reversible inhibitor of virus induced interferon formation. It also substantially reduced the interferon yield from human diploid fibroblasts which had been superinduced with actinomycin D and cycloheximide. This suggests that the previously reported failure of camptothecin to inhibit interferon production in human diploid cells after induction with poly(rI).poly(rC) is the result of two mutually opposing effects: a marked inhibition of interferon messenger RNA synthesis, but a stimulation of the activity of the interferon messenger RNA that is formed.
Assuntos
Antimetabólitos/farmacologia , Interferons/biossíntese , Amanitinas/farmacologia , Camptotecina/farmacologia , Linhagem Celular , Cicloeximida/farmacologia , Dactinomicina/farmacologia , Humanos , Poli I-C/farmacologia , Biossíntese de Proteínas , RNA/biossíntese , RNA Mensageiro/biossínteseRESUMO
The glutamate dehydrogenase gene of Escherichia coli has been cloned into broad host-range plasmids and can complement glutamate synthase mutants of Methylophilus methylotrophus. Assimilation of ammonia via glutamate dehydrogenase is more energy-efficient than via glutamate synthase, thus the recombinant organism converts more growth substrate, methanol, into cellular carbon.