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R Desrosiers

Publications and source records attributed to R Desrosiers.

25 records · Page 2Linked to original sources
PubMed1977

Messenger RNA methylation, translation and degradation in extracts of interferon-treated cells.

Extracts from interferon-treated, not virus infected EAT cells differ in several biochemical characteristics from extracts of untreated cells. Some of these differences are manifested only if the extracts are supplemented with ds RNA and ATP. Thus, in the extracts from interferon-treated cells these supplements activate a protein kinase and an endonuclease activity as well as an inhibitor of the translation of messenger RNA. The effect of the same supplements in extracts of untreated cells is much less pronounced. Other differences between the two types of extracts do not seem to depend on the addition of ds RNA and ATP. These include an impairment of mRNA cap methylation and an inhibition of peptide chain elongation that can be overcome by the addition of tRNA. The treatment of human (HeLa S3) cells with human interferon is manifested in the cell extract similarly to the treatment of EAT cells with mouse interferon. Studies are underway to isolate and characterize the ds RNA activated enzymes and the inhibitors and to establish how the presence of these in extracts from interferon-treated cells can account for the impairment of virus replication by interferon.

Adenosine Triphosphate↗
PubMed1974

Identification of methylated nucleosides in messenger RNA from Novikoff hepatoma cells.

The poly(A) tract found in eukaryotic mRNA was used to study methylation in mRNA obtained from Novikoff hepatoma cells. Methyl labeling of RNA was achieved with L-[methyl-(3)H]methionine under conditions that suppress radioactive incorporation into the purine ring. RNA that contains a poly(A) segment was obtained from polysomal RNA by chromatography on oligo(dT)-cellulose. Sucrose density gradient centrifugation of this RNA revealed a pattern expected for mRNA. The composition of the methyl-labeled nucleosides in the RNA was analyzed after complete enzymatic degradation to nucleosides. By use of DEAE-cellulose (borate) chromatography, which separates 2'-O-methylnucleosides from normal and base-methylated nucleosides, about 50% of the radioactivity was recovered in the 2'-O-methylnucleoside fraction and 50% in the base-methylnucleoside fraction. High-speed liquid chromatography (Aminex A-5) of the 2'-O-methylnucleoside fraction produced four peaks coincident with the four 2'-O-methylnucleoside standards. Analysis of the base-methylnucleoside fraction revealed a unique pattern. While ribosomal RNA and tRNA possessed complex base-methylnucleoside patterns, the distribution in mRNA was quite simple, consisting predominantly of N(6)-methyladenosine. These results demonstrate a unique distribution of methylated nucleosides in mRNA. By analogy to ribosomal RNA synthesis, the presence of methylnucleosides in mRNA may reflect a cellular mechanism for the selective processing of certain mRNA sequences.

Adenosine↗