Rapid induction of rat liver S14 gene transcription by thyroid hormone.
The mRNA coding for the rat liver S14 protein (Mr 17,000; pI 4.9) is rapidly induced by triiodothyronine (T3) (Jump, D. B., Narayan, P., Towle, H. C., and Oppenheimer, J. H. (1984) J. Biol. Chem. 259, 2789-2797). In an effort to define the molecular basis for the rapid increase in mRNAS14, the in vitro run-on activity and chromatin structure of the S14 gene was examined. Following injection of hypothyroid rats with a receptor-saturating dose of T3, a 5-min lag period preceded a rapid increase in S14 gene transcription. S14 transcriptional activity was induced 3.8-fold within 15 min and reached nearly 70% of the maximal 9-fold induction within 60 min of T3 administration. Hepatic mRNAS14 levels were induced 2.4-, 19-, and 24-fold within 15 min, 4 h, and 24 h, respectively. Thus, the rapid T3-mediated induction of mRNAS14 was due, in large part, to a rapid and apparent direct effect of T3 on S14 transcriptional activity. Analysis of S14 chromatin structure showed that the Hss-3 DNase I hypersensitive site located 3.3 kilobases (kb) upstream from the hepatic S14 cap site was present in both euthyroid and hyperthyroid states, but either absent or present at diminished DNase I sensitivity in the hypothyroid state. However, within 5 min of T3 administration to hypothyroid rats, the Hss-3 DNase I hypersensitive site was significantly induced. The induction of this structure preceded T3 induction of S14 gene transcription. Other DNase I hypersensitive sites located adjacent to the S14 cap site at -65 to -265 base pairs (Hss-1) or upstream at -1.3 kb (Hss-2), -2.1 kb (Hss-3'), -5.3 kb (Hss-4), and -6.2 kb (Hss-5) remained unaffected by changes in S14 gene transcription. The rapid T3 effect on the Hss-3 DNase I hypersensitive site may reflect the presence of T3 receptors in the vicinity of this chromatin locus. Modification of chromatin structure in the vicinity of the Hss-3 site may be an important antecedent event for T3-mediated induction of S14 gene transcription.
Jump
D B
DB
Department of Physiology, Michigan State University, East Lansing 48824.
D000818:Animals; D002843:Chromatin / Q000187:drug effects / Q000648:ultrastructure; D004247:DNA / Q000235:genetics / Q000378:metabolism; D015342:DNA Probes; D003850:Deoxyribonuclease I / Q000378:metabolism; D005091:Exons; D006980:Hyperthyroidism / Q000378:metabolism; D007037:Hypothyroidism / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D009687:Nuclear Proteins; D009693:Nucleic Acid Hybridization; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000187:drug effects*; D014284:Triiodothyronine / Q000494:pharmacology*
D002843:Chromatin; D015342:DNA Probes; D009687:Nuclear Proteins; D011506:Proteins; D012333:RNA, Messenger; C051065:THRSP protein, human; C501478:Thrsp protein, rat; D014157:Transcription Factors; D014284:Triiodothyronine; D004247:DNA; D003850:Deoxyribonuclease I