ISOLATION AND CHARACTERIZATION OF A NOVEL GENE INDUCED BY 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN IN RAT-LIVER

The differential display technique was used to identify genes whose ex pression was regulated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), Expression of a novel sequence was up-regulated in a dose-dependent fa shion in liver of Sprague-Dawley male rats exposed to both chronic and acute treatment with TCDD, as measured by densitometry of Northern bl ot analyses (P < 0.01). A rapid amplification of cDNA ends (RACE) proc edure was used to isolate a 1.8 kb cDNA from a rat liver cDNA preparat ion, This cloned cDNA, called 25-Dx, was sequenced and found to encode a peptide of 223 amino acids, In control rats, the 25-Dx gene was exp ressed at high levels in lung and liver, A hydrophobic domain of 14 re sidues followed by a proline-rich domain, both located in the N-termin al region, showed 71% homology with the transmembrane domain of the pr ecursor for the interleukin-6 receptor and a conserved consensus seque nce found in the cytokine/growth factor/prolactin receptor superfamily respectively.