The NGFI-B family: orphan nuclear receptors of the steroid/thyroid receptor superfamily

摘要

The steroid/thyroid receptor superfamily comprises a group of structurally related transcription factors that program developmental, physiological, and behavioral responses to a variety of signals. NGFI-B, Nurr1 and NOR-1 are members of this superfamily of ligand-inducible transcription factors, and constitute one subgroup called the NGFI-B family. However, ligands have not yet been identified for the family members, and therefore they also belong to the category of "orphan receptors." Although our knowledge of the NGFI-B family is limited, it is clear that these transcription factors have important functions in mediating responses to various signals and play critical roles in biological processes including cell growth, differentiation and apoptosis. In this review, we summarize their structural features, genomic organization, gene expression and transcriptional regulation, and illustrate their biological functions inferred from recent reports.