Biology:RAR-related orphan receptor
| RAR-related orphan receptor A (alpha) | |
|---|---|
| Identifiers | |
| Symbol | RORA |
| Alt. symbols | RZRA, ROR1, ROR2, ROR3, NR1F1 |
| NCBI gene | 6095 |
| HGNC | 10258 |
| OMIM | 600825 |
| PDB | 1N83 |
| RefSeq | NM_002943 |
| UniProt | P35398 |
| Other data | |
| Locus | Chr. 15 q21-q22 |
| RAR-related orphan receptor B (beta) | |
|---|---|
| Identifiers | |
| Symbol | RORB |
| Alt. symbols | RZRB, NR1F2, ROR-BETA |
| NCBI gene | 6096 |
| HGNC | 10259 |
| OMIM | 601972 |
| PDB | 1NQ7 |
| RefSeq | NM_006914 |
| UniProt | Q92753 |
| Other data | |
| Locus | Chr. 9 q22 |
| RAR-related orphan receptor C (gamma) | |
|---|---|
| Identifiers | |
| Symbol | RORC |
| Alt. symbols | RZRG, RORG, NR1F3, TOR |
| NCBI gene | 6097 |
| HGNC | 10260 |
| OMIM | 602943 |
| RefSeq | NM_005060 |
| UniProt | P51449 |
| Other data | |
| Locus | Chr. 1 q21 |
The RAR-related orphan receptors (RORs) are members of the nuclear receptor family of intracellular transcription factors.[1][2] 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.[3] They bind to DNA elements called ROR response elements (RORE).[4]
Ligands
While the identity of natural ligands for the RORs remains controversial, similar to the liver X receptors (LXRs), it appears that the RORs are activated by oxysterols.[5][6] Furthermore, the RORs appear to be constitutively active (absence of ligand) and that activity may be due to continuously bound natural ligands.[5] Side chain oxygenated sterols (e.g., 20α-hydroxycholesterol, 22R-hydroxycholesterol, and 25-hydroxycholesterol) are high affinity RORγ agonists[7] while sterols oxygenated at the 7-position, (e.g., (7-hydroxycholesterol and 7-ketocholesterol) function as inverse agonists for both RORa and RORγ.[5] A number of other natural substances have also been reported to bind to the RORs. These include all-trans retinoic acid binds with high affinity to ROR-β and -γ but not ROR-α.[8] Finally the RORs may function as lipid sensors and hence may play a role in the regulation of lipid metabolism.[5]
Melatonin has been claimed to be an endogenous ligand for ROR-α while CGP 52608 has been identified as a ROR-α selective synthetic ligand.[9]
Tissue distribution
RORα, RORβ, and RORγ are primarily expressed the following tissues:[7]
- ROR-α – widely expressed in liver, skeletal muscle, skin, lung, adipose tissue, kidney, thymus, and brain.
- ROR-β – expression restricted to the brain and retina.
- ROR-γ – highly expressed in thymus (the thymus-specific isoform is referred to as RORγt), muscle, testis, pancreas, prostate, heart, and liver.
Function
The three forms of RORs fulfill a number of critical roles[10] including:
- ROR-α – Involved in the maintenance of the circadian rhythm by positively regulating the expression of BMAL1.[5] Development of the cerebellum and lymph nodes, lipid metabolism, immune response, maintenance of bone.[11]
- ROR-β – Circadian rhythm, bone metabolism, and retinal neurogenesis.[12]
- ROR-γ – Lymph node development and immune response, survival of T helper 17 cells.
As drug targets
A number of synthetic RORγt inverse agonists are in various stages of drug development for the treatment of inflammatory diseases. RORγt agonists have also been proposed for use as immunooncology agents to activate the immune system to treat cancer.[13][14]
See also
- Retinoid receptor
References
- ↑ "Isoform-specific amino-terminal domains dictate DNA-binding properties of ROR alpha, a novel family of orphan hormone nuclear receptors". Genes & Development 8 (5): 538–53. March 1994. doi:10.1101/gad.8.5.538. PMID 7926749.
- ↑ "ROR gamma: the third member of ROR/RZR orphan receptor subfamily that is highly expressed in skeletal muscle". Biochemical and Biophysical Research Communications 205 (3): 1976–83. December 1994. doi:10.1006/bbrc.1994.2902. PMID 7811290. https://zenodo.org/record/1229422.
- ↑ The ROR nuclear orphan receptor subfamily: critical regulators of multiple biological processes. Progress in Nucleic Acid Research and Molecular Biology. 69. 2001. pp. 205–47. doi:10.1016/S0079-6603(01)69048-2. ISBN 978-0-12-540069-5. https://archive.org/details/progressinnuclei0069unse/page/205.
- ↑ Jetten, A. M.; Kurebayashi, S.; Ueda, E. (2001). "The ROR nuclear orphan receptor subfamily: critical regulators of multiple biological processes". Progress in Nucleic Acid Research and Molecular Biology 69: 205–247. doi:10.1016/s0079-6603(01)69048-2. ISBN 9780125400695. ISSN 0079-6603. PMID 11550795. https://zenodo.org/record/1259755.
- ↑ 5.0 5.1 5.2 5.3 5.4 "Action of RORs and their ligands in (patho)physiology". Trends in Endocrinology and Metabolism 23 (12): 619–27. December 2012. doi:10.1016/j.tem.2012.05.012. PMID 22789990.
- ↑ "Nuclear hormone receptors put immunity on sterols". European Journal of Immunology 45 (10): 2730–41. 2015. doi:10.1002/eji.201545712. PMID 26222181.
- ↑ 7.0 7.1 "ROR nuclear receptors: structures, related diseases, and drug discovery". Acta Pharmacologica Sinica 36 (1): 71–87. January 2015. doi:10.1038/aps.2014.120. PMID 25500868.
- ↑ "All-trans retinoic acid is a ligand for the orphan nuclear receptor ROR beta". Nature Structural Biology 10 (10): 820–5. October 2003. doi:10.1038/nsb979. PMID 12958591.
- ↑ "Transcriptional activation of the nuclear receptor RZR alpha by the pineal gland hormone melatonin and identification of CGP 52608 as a synthetic ligand". Nucleic Acids Research 23 (3): 327–33. February 1995. doi:10.1093/nar/23.3.327. PMID 7885826.
- ↑ "Recent advances in the mechanisms of action and physiological functions of the retinoid-related orphan receptors (RORs)". Current Drug Targets. Inflammation and Allergy 3 (4): 395–412. December 2004. doi:10.2174/1568010042634497. PMID 15584888.
- ↑ "Retinoid-related Orphan Receptors (RORs): Roles in Cellular Differentiation and Development". Advances in Developmental Biology (Amsterdam, Netherlands). Advances in Developmental Biology 16: 313–355. 2006. doi:10.1016/S1574-3349(06)16010-X. ISBN 9780444528735. PMID 18418469.
- ↑ "Retinoic acid-related orphan receptor RORβ, circadian rhythm abnormalities and tumorigenesis (Review)". International Journal of Molecular Medicine 35 (6): 1493–500. 2015. doi:10.3892/ijmm.2015.2155. PMID 25816151.
- ↑ "Recent progress on nuclear receptor RORγ modulators". Bioorganic & Medicinal Chemistry Letters 26 (18): 4387–93. 2016. doi:10.1016/j.bmcl.2016.08.012. PMID 27542308.
- ↑ "RORγ antagonists and inverse agonists: a patent review". Expert Opinion on Therapeutic Patents 27 (1): 101–112. 2017. doi:10.1080/13543776.2017.1236918. PMID 27629281.
Further reading
- "Ligand regulation of retinoic acid receptor-related orphan receptors: implications for development of novel therapeutics". Current Opinion in Lipidology 21 (3): 204–11. June 2010. doi:10.1097/MOL.0b013e328338ca18. PMID 20463469.
- "RORs in Autoimmune Disease". Sphingosine-1-Phosphate Signaling in Immunology and Infectious Diseases. Current Topics in Microbiology and Immunology. 378. 2014. pp. 171–82. doi:10.1007/978-3-319-05879-5_8. ISBN 978-3-319-05878-8.
External links
- RAR-related+orphan+receptor+A at the US National Library of Medicine Medical Subject Headings (MeSH)
- RAR-related+orphan+receptor+B at the US National Library of Medicine Medical Subject Headings (MeSH)
- RAR-related+orphan+receptor+C at the US National Library of Medicine Medical Subject Headings (MeSH)
Template:Receptor/signaling modulators
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