The interaction of the estrogen receptor with mononucleosomes.

To directly activate specific gene expression, the estrogen receptor (ER) must bind to estrogen receptor response elements (EREs) in the context of nucleosomes. In order to investigate the interaction of the ER with mononucleosomes, we developed a mononucleosome gel shift assay. A 164 bp high specific activity [(32)P]probe DNA (32 bp consensus ERE with flanking regions separated by 23 nucleotides from an artificial nucleosome positioning sequence) was prepared.

MAPK signaling pathways modulate IL-1beta expression in human keratinocytes.

The signaling pathways that modulate IL-1beta expression in human keratinocytes have not been well defined. We have previously shown that TCDD-stimulated AhR-dependent IL-1beta expression in human keratinocytes is due to posttranscriptional regulation involving mRNA stabilization. Since TCDD activates a variety of cellular signaling pathways such as PKC, JNK, and ERK, we investigated these pathways to determine their roles in TCDD-stimulated IL-1beta expression in the human keratinocyte cell line SCC-12F.

Aryl hydrocarbon receptor-mediated posttranscriptional regulation of IL-1beta.

TCDD stimulated IL-1beta gene expression in differentiating human keratinocyte cell lines in a time- and dose-dependent manner. Increases in prointerleukin-1beta (pIL-1beta) protein and IL-1beta steady state mRNA levels were observed in both SCC-12F and HaCaT cells following TCDD treatment. When pretreated with alpha-naphthoflavone, an AhR antagonist, TCDD-mediated increases in IL-1beta gene expression were attenuated, demonstrating for the first time that the environmental toxin, TCDD, can stimulate cytokine (IL-1beta) gene expression in an AhR-dependent manner.