Estrogen-related receptor gamma (ERR-gamma), also known as NR3B3 (nuclear receptor subfamily 3, group B, member 3), is a nuclear receptor that in humans is encoded by the ESRRG (EStrogen Related Receptor Gamma) gene. [5] [6] [7] It behaves as a constitutive activator of transcription. [8]
This protein is a member of nuclear hormone receptor family of steroid hormone receptors. No physiological activating ligand is known for this orphan receptor, but 4-hydroxytamoxifen and diethylstilbestrol act as inverse agonists and deactivate ESRRG. [9] It also seems to be the target of bisphenol A (see below).
There is evidence that bisphenol A functions as a xenoestrogen by binding strongly to ERR-γ. [8] BPA as well as its nitrated and chlorinated metabolites seems to binds strongly to ERR-γ (dissociation constant = 5.5 nM), but not to the estrogen receptor (ER)., [8] [10] BPA binding to ERR-γ preserves its basal constitutive activity. [8] It can also protect it from deactivation from the selective estrogen receptor modulator 4-hydroxytamoxifen. [8]
Different expression of ERR-γ in different parts of the body may account for variations in bisphenol A effects. For instance, ERR-γ has been found in high concentration in the placenta, explaining reports of high bisphenol A accumulation there. [11]
The aryl hydrocarbon receptor is a protein that in humans is encoded by the AHR gene. The aryl hydrocarbon receptor is a transcription factor that regulates gene expression. It was originally thought to function primarily as a sensor of xenobiotic chemicals and also as the regulator of enzymes such as cytochrome P450s that metabolize these chemicals. The most notable of these xenobiotic chemicals are aromatic (aryl) hydrocarbons from which the receptor derives its name.
Estrogen receptor alpha (ERα), also known as NR3A1, is one of two main types of estrogen receptor, a nuclear receptor that is activated by the sex hormone estrogen. In humans, ERα is encoded by the gene ESR1.
The ERRs are orphan nuclear receptors, meaning the identity of their endogenous ligand has yet to be unambiguously determined. They are named because of sequence homology with estrogen receptors, but do not appear to bind estrogens or other tested steroid hormones.
The RAR-related orphan receptors (RORs) are members of the nuclear receptor family of intracellular transcription factors. There are three forms of ROR, ROR-α, -β, and -γ and each is encoded by a separate gene, RORA, RORB, and RORC respectively. The RORs are somewhat unusual in that they appear to bind as monomers to hormone response elements as opposed to the majority of other nuclear receptors which bind as dimers. They bind to DNA elements called ROR response elements (RORE).
The nuclear receptor 4A1 also known as Nur77, TR3, and NGFI-B is a protein that in humans is encoded by the NR4A1 gene.
The germ cell nuclear factor (GCNF), also known as RTR or NR6A1, is a protein that in humans is encoded by the NR6A1 gene. GCNF is a member of the nuclear receptor family of intracellular transcription factors.
The small heterodimer partner (SHP) also known as NR0B2 is a protein that in humans is encoded by the NR0B2 gene. SHP is a member of the nuclear receptor family of intracellular transcription factors. SHP is unusual for a nuclear receptor in that it lacks a DNA binding domain. Therefore, it is technically neither a transcription factor nor nuclear receptor but nevertheless it is still classified as such due to relatively high sequence homology with other nuclear receptor family members.
Peroxisome proliferator-activated receptor gamma, also known as the glitazone reverse insulin resistance receptor, or NR1C3 is a type II nuclear receptor functioning as a transcription factor that in humans is encoded by the PPARG gene.
RAR-related orphan receptor alpha (RORα), also known as NR1F1 is a nuclear receptor that in humans is encoded by the RORA gene. RORα participates in the transcriptional regulation of some genes involved in circadian rhythm. In mice, RORα is essential for development of cerebellum through direct regulation of genes expressed in Purkinje cells. It also plays an essential role in the development of type 2 innate lymphoid cells (ILC2) and mutant animals are ILC2 deficient. In addition, although present in normal numbers, the ILC3 and Th17 cells from RORα deficient mice are defective for cytokine production.
Rev-Erb beta (Rev-Erbβ), also known as nuclear receptor subfamily 1 group D member 2 (NR1D2), is a member of the Rev-Erb protein family. Rev-Erbβ, like Rev-Erbα, belongs to the nuclear receptor superfamily of transcription factors and can modulate gene expression through binding to gene promoters. Together with Rev-Erbα, Rev-Erbβ functions as a major regulator of the circadian clock. These two proteins are partially redundant. Current research suggests that Rev-Erbβ is less important in maintaining the circadian clock than Rev-Erbα; knock-out studies of Rev-Erbα result in significant circadian disruption but the same has not been found with Rev-Erbβ. Rev-Erbβ compensation for Rev-Erbα varies across tissues, and further research is needed to elucidate the separate role of Rev-Erbβ.
Estrogen receptor beta (ERβ) also known as NR3A2 is one of two main types of estrogen receptor—a nuclear receptor which is activated by the sex hormone estrogen. In humans ERβ is encoded by the ESR2 gene.
Hepatocyte nuclear factor 4 alpha (HNF4A) also known as NR2A1 is a nuclear receptor that in humans is encoded by the HNF4A gene.
Estrogen-related receptor beta (ERR-β), also known as ESRRB or NR3B2, is a nuclear receptor that in humans is encoded by the ESRRB gene.
Estrogen-related receptor alpha (ERRα), also known as NR3B1, is a nuclear receptor that in humans is encoded by the ESRRA gene. ERRα was originally cloned by DNA sequence homology to the estrogen receptor alpha, but subsequent ligand binding and reporter-gene transfection experiments demonstrated that estrogens did not regulate ERRα. Currently, ERRα is considered an orphan nuclear receptor.
The testicular receptor 2 (TR2) also known as NR2C1 is protein that in humans is encoded by the NR2C1 gene. TR2 is a member of the nuclear receptor family of transcription factors.
E3 SUMO-protein ligase PIAS3 is an enzyme that in humans is encoded by the PIAS3 gene.
Steroid receptor RNA activator 1 also known as steroid receptor RNA activator protein (SRAP) is a protein that in humans is encoded by the SRA1 gene. The mRNA transcribed from the SRA1 gene is a component of the ribonucleoprotein complex containing NCOA1. This functional RNA also encodes a protein.
Peroxisome proliferator-activated receptor gamma coactivator 1-beta is a protein that in humans is encoded by the PPARGC1B gene.
Proline-rich nuclear receptor coactivator 2 is a protein that in humans is encoded by the PNRC2 gene.
3,3'-Dinitrobisphenol A is an organic compound with the formula (HO(O2N)C6H3)2C(CH3)2. It is a yellow-orange solid prepared by nitration of bisphenol A