Transcriptional ``Silencer'' Element in Rat Repetitive Sequences Associated with the Rat Insulin 1 Gene Locus

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 83; no. 10; pp. 3151 - 3155
• Main Authors: Laimins, Laimonis, Holmgren-König, Monika, Khoury, George
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.05.1986; National Acad Sciences
• Subjects: Animals; Biological and medical sciences; Cercopithecus aethiops; DNA, Recombinant; Enhancer Elements, Genetic; Exons; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation; Genes; Genes, Regulator; Genetic loci; Globins - genetics; Insulin; Insulin - genetics; L cells; L Cells (Cell Line); Mice; Molecular and cellular biology; Molecular genetics; Plasmids; Rats; Repetitive sequences; Repetitive Sequences, Nucleic Acid; Silencers; Simian virus 40 - genetics; Transcription, Genetic; Transcription. Transcription factor. Splicing. Rna processing; Transfection; Interspersed repeated sequence; Vertebrata; Regulation(control); Mammalia; Gene; Rat; Transcription; Animal; DNA; Rodentia; Gene expression; Insulin
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.83.10.3151

The enhancer elements from either simian virus 40 or murine sarcoma virus activate the expression of a transfected rat insulin 1 (rI1) gene when placed within 2.0 kilobases or less of the rI1 gene cap site. Inclusion of 4.0 kilobases of upstream rI1 sequence, however, results in a substantial reduction in the enhancer-dependent insulin gene expression. These observations suggested that a negative transcriptional regulatory element was present between 2.0 and 4.0 kilobases of the rI1 sequence. To test this notion, we employed a heterologous enhancer-dependent transcription assay in which the simian virus 40 72-base-pair repeat is linked to a human β -globin gene. Addition of the upstream rI1 element to this system decreased the level of enhancer-dependent β -globin transcription by a factor of 5 to 15. This rI1 ``silencer'' element functions in a manner relatively independent of position and orientation and requires a cis-dependent relationship to the transcription unit on which it acts. Thus, the silencer sequence seems to have a number of the characteristics of enhancer elements, and we suggest that it may function by the converse of the enhancer mechanism. The rI1 silencer sequence was identified as a member of a long interspersed rat repetitive family. Thus, a potential role for certain repetitive sequences interspersed throughout the eukaryotic genome may be to regulate gene expression by retaining transcriptional activity within defined domains.