Degradation of pre-messenger RNA in bovine thyroid slices; effect of thyrotropin.
Bovine thyroid RNA labeled by incubation of slices in the presence of 32P-orthophosphate were fractionated by a two-step procedure. Total RNA were extracted by gel filtration on AcA 22 in the presence of pronase and separated by Sepharose 2B chromatography. A small fraction of heavily-labeled RNA (giant RNA) was obtained in the void volume (peak I); the major fraction of RNA (smaller than 45 S) was retarded on the column (peak II) and had a low specific radioactivity. Labeled and total RNA of peak I and labeled RNA species of peak II had a DNA-like nucleotide composition and were polyadenylated. In contrast, the nucleotide composition of total RNA of peak II was similar to that of ribosomal RNA and had a very low poly (adenylic acid) content. Pulse-chase experiments showed a precursor-product relationship between the two RNA fractions. These data indicate that labeled RNA of peak I and peak II likely correspond to newly-synthetized pre-mRNA and mRNA, respectively. Thyrotropin induced a decrease in the amount of 32P-labeled pre-mRNA and a proportional increase of 32P-labeled mRNA suggesting a stimulatory effect of the hormone on the degradation of pre-mRNA.
D000818:Animals; D001482:Base Composition; D002417:Cattle; D002850:Chromatography, Gel; D066298:In Vitro Techniques; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis*; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology*
D012333:RNA, Messenger; D013972:Thyrotropin