title: Biosynthesis and utilization of extensively undermethylated poly(A)+ RNA in CHO cells during a cycloleucine treatment.
abstract: The role of RNA methylations in the control of mRNA maturation and incorporation into polysomes has been investigated through a study of the effects in vivo of cycloleucine, a specific inhibitor of S-adenosyl-methionine mediated methylation. During the cycloleucine treatment, the rate of biosynthesis of hnRNA and its subsequent polyadenylation were only slightly reduced as compared with untreated cells. However a significant lag-time in the cytoplasmic appearance of poly(A)+ undermethylated molecules was observed, in parallel with a transient shift in the average size of hnRNA towards higher molecular weight. Nevertheless, the total amount of pulse-labelled poly(A)+ mRNA transferred to cytoplasm after a long chase time (3 h.) was approximately the same for both cycloleucine-treated and control cells. Extensively undermethylated poly(A)+ cytoplasmic RNAs, possessing a 5' terminal cap were incorporated into polysomes in proportions very similar to control messenger molecules. These results suggest that a normal level of methylation is not stringently required for the production of the functional mRNA molecules although it appears to be of importance for the kinetics of the maturational process.
mesh_terms: D000596:Amino Acids / Q000494:pharmacology*; D001483:Base Sequence; D002460:Cell Line; D003515:Cycloleucine / Q000494:pharmacology*; D008745:Methylation; D009694:Nucleic Acid Precursors / Q000378:metabolism*; D011061:Poly A / Q000378:metabolism; D011132:Polyribosomes / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D000596:Amino Acids; D009694:Nucleic Acid Precursors; D012333:RNA, Messenger; D003515:Cycloleucine; D011061:Poly A; D012313:RNA