Trafficking of membrane-associated proteins to cone photoreceptor outer segments requires the chromophore 11-cis-retinal

J Neurosci. 2008 Apr 9;28(15):4008-14. doi: 10.1523/JNEUROSCI.0317-08.2008.

Abstract

Lecithin retinol acyl transferase (LRAT) and retinal pigment epithelium protein 65 (RPE65) are key enzymes of the retinoid cycle. In Lrat(-/-) and Rpe65(-/-) mice, models of human Leber congenital amaurosis, the retinoid cycle is disrupted and 11-cis-retinal, the chromophore of visual pigments, is not produced. The Lrat(-/-) and Rpe65(-/-) retina phenotype presents with rapid sectorial cone degeneration, and the visual pigments, S-opsin and M/L-opsin, fail to traffic to cone outer segments appropriately. In contrast, rod opsin traffics normally in mutant rods. Concomitantly, guanylate cyclase 1, cone T alpha-subunit, cone phosphodiesterase 6alpha' (PDE6alpha'), and GRK1 (G-protein-coupled receptor kinase 1; opsin kinase) are not transported to Lrat(-/-) and Rpe65(-/-) cone outer segments. Aberrant localization of these membrane-associated proteins was evident at postnatal day 15, before the onset of ventral and central cone degeneration. Protein levels of cone T alpha and cone PDE6alpha' were reduced, whereas their transcript levels were unchanged, suggesting posttranslational degradation. In an Rpe65(-/-)Rho(-/-) double knock-out model, trafficking of cone pigments and membrane-associated cone phototransduction polypeptides to the outer segments proceeded normally after 11-cis-retinal administration. These results suggest that ventral and central cone opsins must be regenerated with 11-cis-retinal to permit transport to the outer segments. Furthermore, the presence of 11-cis-retinal is essential for proper transport of several membrane-associated cone phototransduction polypeptides in these cones.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyltransferases / deficiency
  • Acyltransferases / metabolism
  • Animals
  • Blindness / congenital
  • Blindness / genetics
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Disease Models, Animal
  • Eye Proteins / genetics
  • Eye Proteins / metabolism
  • Guanylate Cyclase / metabolism
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Knockout
  • Nerve Degeneration / etiology
  • Nerve Degeneration / physiopathology
  • Protein Isoforms / metabolism
  • Protein Transport / drug effects
  • Receptors, Cell Surface / metabolism
  • Retinal Cone Photoreceptor Cells / metabolism*
  • Retinal Cone Photoreceptor Cells / physiopathology
  • Retinal Pigments / metabolism
  • Retinaldehyde / deficiency
  • Retinaldehyde / metabolism*
  • Retinaldehyde / pharmacology
  • Rod Opsins / metabolism
  • Time Factors
  • Vision, Ocular
  • cis-trans-Isomerases

Substances

  • Carrier Proteins
  • Eye Proteins
  • Membrane Proteins
  • Protein Isoforms
  • R9AP protein, mouse
  • Receptors, Cell Surface
  • Retinal Pigments
  • Rod Opsins
  • guanylate cyclase 1
  • Acyltransferases
  • lecithin-retinol acyltransferase
  • retinoid isomerohydrolase
  • Guanylate Cyclase
  • cis-trans-Isomerases
  • Retinaldehyde