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PubMed1988

RNA polymerase III promoter elements enhance transcription of RNA polymerase II genes.

Using transient expression assays in cultured human cells we have observed that RNA Polymerase III promoter sequences exert a positive cis-acting enhancer effect on RNA Polymerase II transcription. A DNA segment containing a copy of the Alu repeated element enhances transcription of the liver specific Haptoglobin related (Hpr) promoter in Hepatoma cell lines but not in HeLa cells. A tRNA(pro) gene acts as enhancer of the SV40 promoter both in Hepatoma and in HeLa cell lines. Transcription from the SV40 promoter is also enhanced by DNA segments containing only the box A or the box B of the tRNA(pro) promoter.

Carcinoma, Hepatocellular↗

PubMed1988

Two different liver-specific factors stimulate in vitro transcription from the human alpha 1-antitrypsin promoter.

The region from -137 to -2 of the human alpha 1-antitrypsin (alpha 1AT) promoter directs liver-specific in vitro transcription. Two cis-acting elements, A and B, have been identified within this segment by site-directed mutagenesis. Competition with synthetic oligonucleotides corresponding either to the A or to the B sequence inhibits transcription from the wild-type promoter in vitro. Cis-linked A and B elements mediate liver-specific transcription from a truncated HSV-TK promoter in vitro. Five different proteins, LF-A1, LF-A2, LF-B1, LF-B2 and LF-C, bind to the alpha 1AT promoter in liver extracts. LF-A1 and LF-B1 are positive transcriptional factors which bind to the A and B elements respectively. Their absence in spleen provides an explanation for the liver specificity of transcription. A protein similar to LF-B2 is present in spleen. Binding of LF-B1 and LF-B2 to the alpha 1AT promoter is mutually exclusive, suggesting that LF-B2 might be a repressor.

Base Sequence↗