18 S Ribosomal RNA Is Degraded during Ribosome Maturation in Irradiated HeLa Cells

• Published in: Radiation research Vol. 118; no. 2; pp. 330 - 340
• Main Authors: Krolak, John M., McClain, David, Snyder, Stephen L., Fuchs, Pinhas, Minton, Kenneth W.
• Format: Journal Article
• Language: English
• Published: Oak Brook, Il Academic Press, Inc 01-05-1989; Radiation Research Society
• Subjects: 550501 - Metabolism- Tracer Techniques; 560120 - Radiation Effects on Biochemicals, Cells, & Tissue Culture; ALKALI METAL ISOTOPES; Animal cells; ANIMALS; BASIC BIOLOGICAL SCIENCES; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; Biological and medical sciences; BIOLOGICAL EFFECTS; Biological effects of radiation; BIOLOGICAL RADIATION EFFECTS; Cell growth; CESIUM 137; CESIUM ISOTOPES; Cesium Radioisotopes; ELECTROPHORESIS; Fundamental and applied biological sciences. Psychology; Gels; GROWTH; HELA CELLS; Humans; HYDROGEN COMPOUNDS; INHIBITION; Ionizing radiations; Irradiation; ISOTOPE APPLICATIONS; ISOTOPES; Lymphocytes; MAMMALS; MAN; METABOLISM; NUCLEI; NUCLEIC ACIDS; ODD-EVEN NUCLEI; ORGANIC COMPOUNDS; PRIMATES; Radiation dosage; RADIATION EFFECTS; RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT; RADIOISOTOPES; RIBOSOMAL RNA; Ribosomes; RNA; RNA, Neoplasm - radiation effects; RNA, Ribosomal - radiation effects; RNA, Ribosomal, 18S - radiation effects; RNA, Ribosomal, 28S - radiation effects; Space life sciences; STOICHIOMETRY; Tissues, organs and organisms biophysics; TRACER TECHNIQUES; TRANSCRIPTION; TRITIUM COMPOUNDS; VERTEBRATES; YEARS LIVING RADIOISOTOPES; Ribosomal RNA; Hela cell line; Ionizing irradiation
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3577447

The effects of ionizing radiation (137 Cs) on processing of ribosomal RNA (rRNA) were studied by pulse-labeling HeLa S3 cells with [3 H]uridine immediately prior to irradiation. The 45 S rRNA precursor, and its two major daughter species, 28 and 18 S rRNA, were separated by gel electrophoresis and the extent of radiolabel incorporation into each was determined at various times after irradiation. This approach permitted kinetic analysis of processing of the 45 S rRNA which had been predominantly synthesized (radiolabeled) prior to irradiation. Since they both derive from the same 45 S pre-rRNA transcript, 28 and 18 S rRNA are produced with a stoichiometry of 1:1, as observed in control cells in the present studies. However, within 1 h following 10 Gy an altered stoichiometry of 28 S: 18 S rRNA was apparent, reaching 1.6:1 by 5-7 h following irradiation. This alteration was also observed following the higher dose of 20 Gy, but not following exposures of 5 Gy or less. The 18 S portion of the 45 S pre-rRNA is transcribed prior to the 28 S portion. Consequently, an increase in the 28 S/18 S ratio can only be due to degradation of the 18 S species during or after processing. This alteration may represent a response to radiation-induced growth arrest, by reducing the number of newly synthesized ribosomes that would otherwise be required for cell propagation.