Biology:Photoreceptor cell-specific nuclear receptor

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Short description: Protein-coding gene in the species Homo sapiens


A representation of the 3D structure of the protein myoglobin showing turquoise α-helices.
Generic protein structure example

The photoreceptor cell-specific nuclear receptor (PNR), also known as NR2E3 (nuclear receptor subfamily 2, group E, member 3), is a protein that in humans is encoded by the NR2E3 gene.[1] PNR is a member of the nuclear receptor super family of intracellular transcription factors.

Function

PNR is exclusively expressed in the retina. The main target genes of PNR are rhodopsin and several opsins which are essential for sight.[2]

Structure and ligands

The crystal structure of PNR's ligand-binding domain is known. It self-dimerizes into, by default, a repressor state. Computer simulations based on this model shows that a ligand could possibly fit into PNR and switch it into a transcription activator. 13-cis retinoic acid is a known weak agonist that fits into such a pocket, but no physiologic ligand is known. Two synthetic compounds, 11A and 11B, appear to be agonists but do not go into the pocket and instead work as allosteric modulators.[3] A more recent screening identifies another compound called photoregulin-1 (PR1) that functions as a reverse agonist, an activity possibly useful in the management of retinitis pigmentosa.[4]

Clinical significance

Mutations in the NR2E3 gene have been linked to several inherited retinal diseases, including enhanced S-cone syndrome (ESCS),[5] a form of retinitis pigmentosa,[6] and Goldmann-Favre syndrome.[7]

References

  1. "Identification of a photoreceptor cell-specific nuclear receptor". Proceedings of the National Academy of Sciences of the United States of America 96 (9): 4814–9. April 1999. doi:10.1073/pnas.96.9.4814. PMID 10220376. Bibcode1999PNAS...96.4814K. 
  2. "The nuclear receptor NR2E3 plays a role in human retinal photoreceptor differentiation and degeneration". Proceedings of the National Academy of Sciences of the United States of America 99 (1): 473–8. January 2002. doi:10.1073/pnas.022533099. PMID 11773633. 
  3. "The crystal structure of the orphan nuclear receptor NR2E3/PNR ligand binding domain reveals a dimeric auto-repressed conformation". PLOS ONE 8 (9): e74359. 2013. doi:10.1371/journal.pone.0074359. PMID 24069298. Bibcode2013PLoSO...874359T. 
  4. "Potential of Small Molecule-Mediated Reprogramming of Rod Photoreceptors to Treat Retinitis Pigmentosa". Investigative Ophthalmology & Visual Science 57 (14): 6407–6415. November 2016. doi:10.1167/iovs.16-20177. PMID 27893103. 
  5. "Mutation of a nuclear receptor gene, NR2E3, causes enhanced S cone syndrome, a disorder of retinal cell fate". Nature Genetics 24 (2): 127–31. February 2000. doi:10.1038/72777. PMID 10655056. 
  6. "The photoreceptor cell-specific nuclear receptor gene (PNR) accounts for retinitis pigmentosa in the Crypto-Jews from Portugal (Marranos), survivors from the Spanish Inquisition". Human Genetics 107 (3): 276–84. September 2000. doi:10.1007/s004390000350. PMID 11071390. 
  7. "An Arg311Gln NR2E3 mutation in a family with classic Goldmann-Favre syndrome". The British Journal of Ophthalmology 89 (8): 1065–6. August 2005. doi:10.1136/bjo.2005.068130. PMID 16024868. 

Further reading

External links