Repression of the human dihydrofolate reductase gene by a non-coding interfering transcript

• Published in: Nature Vol. 445; no. 7128; pp. 666 - 670
• Main Authors: Akoulitchev, Alexandre, Chow, Natalie, Serra Barros, Ana, Ramadass, Aroul, Martianov, Igor
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 08.02.2007; Nature Publishing Group
• Subjects: Biochemistry, Molecular Biology; Biological and medical sciences; Cellular biology; Chromatin; Epistasis, Genetic; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Enzymologic - genetics; Gene Silencing; Genetics; Humans; Life Sciences; Molecular and cellular biology; Molecular biology; Molecular genetics; Promoter Regions (Genetics); Promoter Regions, Genetic - genetics; Ribonucleic acid; RNA; RNA, Untranslated; RNA, Untranslated - genetics; RNA, Untranslated - metabolism; Substrate Specificity; TATA-Box Binding Protein; TATA-Box Binding Protein - metabolism; Tetrahydrofolate Dehydrogenase; Tetrahydrofolate Dehydrogenase - genetics; Transcription Factor TFIIB; Transcription Factor TFIIB - metabolism; Transcription, Genetic; Transcription, Genetic - genetics; Transcription. Transcription factor. Splicing. Rna processing; Human; Regulation(control); Gene; Enzyme; Transcription promoter; Oxidoreductases; Dihydrofolate reductase; Repression; Gene expression
• ISSN: 0028-0836; 1476-4687; 1476-4679
• DOI: 10.1038/nature05519

Alternative promoters within the same gene are a general phenomenon in gene expression. Mechanisms of their selective regulation vary from one gene to another and are still poorly understood. Here we show that in quiescent cells the mechanism of transcriptional repression of the major promoter of the gene encoding dihydrofolate reductase depends on a non-coding transcript initiated from the upstream minor promoter and involves both the direct interaction of the RNA and promoter-specific interference. The specificity and efficiency of repression is ensured by the formation of a stable complex between non-coding RNA and the major promoter, direct interaction of the non-coding RNA with the general transcription factor IIB and dissociation of the preinitiation complex from the major promoter. By using in vivo and in vitro assays such as inducible and reconstituted transcription, RNA bandshifts, RNA interference, chromatin immunoprecipitation and RNA immunoprecipitation, we show that the regulatory transcript produced from the minor promoter has a critical function in an epigenetic mechanism of promoter-specific transcriptional repression.