Pathways & interactions
Transcription factor COUP (IPR003068)
Short name: COUP_TF
- Steroid hormone receptor (IPR001723)
- Transcription factor COUP (IPR003068)
Steroid or nuclear hormone receptors (4A nuclear receptor, NRs) constitute an important superfamily of transcription regulators that are involved in widely diverse physiological functions, including control of embryonic development, cell differentiation and homeostasis. Members of the superfamily include the steroid hormone receptors and receptors for thyroid hormone, retinoids, 1,25-dihydroxy-vitamin D3 and a variety of other ligands [PMID: 14747695]. The proteins function as dimeric molecules in nuclei to regulate the transcription of target genes in a ligand-responsive manner [PMID: 7899080, PMID: 8165128]. In addition to C-terminal ligand-binding domains, these nuclear receptors contain a highly-conserved, N-terminal zinc-finger that mediates specific binding to target DNA sequences, termed ligand-responsive elements. In the absence of ligand, steroid hormone receptors are thought to be weakly associated with nuclear components; hormone binding greatly increases receptor affinity.
NRs are extremely important in medical research, a large number of them being implicated in diseases such as cancer, diabetes, hormone resistance syndromes, etc. While several NRs act as ligand-inducible transcription factors, many do not yet have a defined ligand and are accordingly termed 'orphan' receptors. During the last decade, more than 300 NRs have been described, many of which are orphans, which cannot easily be named due to current nomenclature confusions in the literature. However, a new system has recently been introduced in an attempt to rationalise the increasingly complex set of names used to describe superfamily members.
Chicken ovalbumin upstream promoter-transcription factor (COUP-TF) genes encode transcription factors that belong to the orphan group of the steroid/thyroid hormone receptor superfamily [PMID: 8183930]. COUP-TF binds to the ovalbumin promoter and, in conjunction with the S300-II protein, stimulates initiation of transcription. The protein binds to both direct repeats and palindromes of the 5'-AGGTCA-3' motif.
Murine homologues of members of the COUP-TF family, COUP-TF1, ARP-1 and EAR2, have been isolated and shown to be highly similar to their human counterparts [PMID: 7947324]. Although these three genes appear to be expressed in tissues derived from all three germ layers, COUP-TF1 and ARP-1 have been found to be expressed predominantly in the developing central nervous system in mutually exclusive domains. Strong ARP-1 expression has also been detected in lung and kidney [PMID: 7947324]. Results from such studies suggest an important role for the members of the COUP-TF family in the hormonal control of gene expression regulating embryogenesis, and in the development and differentiation of the CNS, including the specification of diencephalic neuromeres [PMID: 8183930].
Synonym(s): 2F nuclear receptor
- PR01282 (COUPTNFACTOR)