OC-2, a novel mammalian member of the ONECUT class of homeodomain transcription factors whose function in liver partially overlaps with that of hepatocyte nuclear factor-6

Transcription factors of the ONECUT class, whose prototype is hepatocyte nu clear factor (HNF)-6, are characterized by the presence of a single cut dom ain and by a peculiar homeodomain (Lannoy, V. J., Burglin, T. R., Rousseau, G. G., and Lemaigre, F. P. (1998) J. Biol. Chem, 273, 13552-13562), We rep ort here the identification and characterization of human OC-2, the second mammalian member of this class. The OC-2 gene is located on human chromosom e 18, The distribution of OC-2 mRNA in humans is tissue-restricted, the str ongest expression being detected in the liver and skin. The amino acid sequ ence of OC-2 contains several regions of high similarity to HNF-6, The reco gnition properties of OC-2 for binding sites present in regulatory regions of liver-expressed genes differ from, but overlap with, those of HNF 6. Lik e HNF-6, OC-2 stimulates transcription of the hnf-3 beta gene in transient transfection experiments, suggesting that OC-2 participates in the network of transcription factors required for liver differentiation and metabolism.