Molecular cloning of a novel thyroid/steroid receptor superfamily gene from cultured rat neuronal cells.

Brain neuronal cells in primary culture provide one system for the analysis of neuronal development, including apoptosis. By PCR amplification, with primers designed from conserved sequences among nuclear receptors, a novel member of the thyroid/steroid receptor superfamily was identified from forebrain neuronal cells undergoing apoptosis and designated as NOR-1 (neuron derived orphan receptor). A cDNA clone of NOR-1 encodes a 68kDa, 628 amino acid residue-containing protein, with an amino acid sequence highly homologous to the Nur77 family in its DNA-binding domain and moderately so in its putative ligand-binding domain. Using mobility shift assay, we showed that the NOR-1 protein binds to the B1a response-element which has been identified as the target sequence of the Nur77 family, suggesting that three members of the Nur77 family may transactivate common target gene(s) at different situations.