Primary structure, chromosomal mapping, expression and transcriptional activity of murine hepatocyte nuclear factor 4gamma.

We demonstrate the presence of a new member of the orphan nuclear receptor hepatocyte nuclear factor 4 (HNF4) subfamily in mouse which is genetically distinct from the previously characterized mouse HNF4alpha gene. The new member of the HNF4 subfamily shows highest amino acid identity, similar tissue distribution and syntenous chromosomal localization to the recently described human HNF4gamma (NR2A2), we therefore classify it as mouse HNF4gamma (mHNF4gamma). A combination of RT-PCR and immunohistochemical analysis showed expression of mHNF4gamma mRNA and protein in the endocrine pancreas, testes, kidney and gut. By co-transfection experiments, we show that mHNF4gamma is able to activate transcription, acting through binding sites that have been previously characterized as HNF4alpha binding sites. The presence of HNFgamma in human and mouse implies that a complex transcriptional network exists in higher vertebrates involving a number of HNF4 members with overlapping yet distinct function and tissue distribution.