Abstract
In absence of their natural ligand, 11-cis-retinal, cone opsin G-protein-coupled receptors fail to traffic normally, a condition associated with photoreceptor degeneration and blindness. We created a mouse with a point mutation (F81Y) in cone S-opsin. As expected, cones with this knock-in mutation respond to light with maximal sensitivity red-shifted from 360 to 420 nm, consistent with an altered interaction between the apoprotein and ligand, 11-cis-retinal. However, cones expressing F81Y S-opsin showed an ~3-fold reduced absolute sensitivity that was associated with a corresponding reduction in S-opsin protein expression. The reduced S-opsin expression did not arise from decreased S-opsin mRNA or cone degeneration, but rather from enhanced endoplasmic reticulum (ER)-associated degradation of the nascent protein. Exogenously increased 11-cis-retinal restored F81Y S-opsin protein expression to normal levels, suggesting that ligand binding in the ER facilitates proper folding. Immunohistochemistry and electron microscopy of normal retinas showed that Mueller cells, which synthesize a precursor of 11-cis-retinal, are closely adjoined to the cone ER, so they could deliver the ligand to the site of opsin synthesis. Together, these results suggest that the binding of 11-cis-retinal in the ER is important for normal folding during cone opsin biosynthesis.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 8094-8104 |
| Number of pages | 11 |
| Journal | Journal of Neuroscience |
| Volume | 32 |
| Issue number | 23 |
| DOIs | |
| State | Published - Jun 6 2012 |
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ASJC Scopus subject areas
- Neuroscience(all)
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An S-opsin knock-in mouse (F81Y) reveals a role for the native ligand 11-cis-retinal in cone opsin biosynthesis. / Insinna, Christine; Daniele, Lauren L.; Davis, Jason A.; Larsen, DeLaine D.; Kuemmel, Colleen; Wang, Jinhua; Nikonov, Sergei S.; Knox, Barry E.; Pugh Jr, Edward N.
In: Journal of Neuroscience, Vol. 32, No. 23, 06.06.2012, p. 8094-8104.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - An S-opsin knock-in mouse (F81Y) reveals a role for the native ligand 11-cis-retinal in cone opsin biosynthesis
AU - Insinna, Christine
AU - Daniele, Lauren L.
AU - Davis, Jason A.
AU - Larsen, DeLaine D.
AU - Kuemmel, Colleen
AU - Wang, Jinhua
AU - Nikonov, Sergei S.
AU - Knox, Barry E.
AU - Pugh Jr, Edward N
PY - 2012/6/6
Y1 - 2012/6/6
N2 - In absence of their natural ligand, 11-cis-retinal, cone opsin G-protein-coupled receptors fail to traffic normally, a condition associated with photoreceptor degeneration and blindness. We created a mouse with a point mutation (F81Y) in cone S-opsin. As expected, cones with this knock-in mutation respond to light with maximal sensitivity red-shifted from 360 to 420 nm, consistent with an altered interaction between the apoprotein and ligand, 11-cis-retinal. However, cones expressing F81Y S-opsin showed an ~3-fold reduced absolute sensitivity that was associated with a corresponding reduction in S-opsin protein expression. The reduced S-opsin expression did not arise from decreased S-opsin mRNA or cone degeneration, but rather from enhanced endoplasmic reticulum (ER)-associated degradation of the nascent protein. Exogenously increased 11-cis-retinal restored F81Y S-opsin protein expression to normal levels, suggesting that ligand binding in the ER facilitates proper folding. Immunohistochemistry and electron microscopy of normal retinas showed that Mueller cells, which synthesize a precursor of 11-cis-retinal, are closely adjoined to the cone ER, so they could deliver the ligand to the site of opsin synthesis. Together, these results suggest that the binding of 11-cis-retinal in the ER is important for normal folding during cone opsin biosynthesis.
AB - In absence of their natural ligand, 11-cis-retinal, cone opsin G-protein-coupled receptors fail to traffic normally, a condition associated with photoreceptor degeneration and blindness. We created a mouse with a point mutation (F81Y) in cone S-opsin. As expected, cones with this knock-in mutation respond to light with maximal sensitivity red-shifted from 360 to 420 nm, consistent with an altered interaction between the apoprotein and ligand, 11-cis-retinal. However, cones expressing F81Y S-opsin showed an ~3-fold reduced absolute sensitivity that was associated with a corresponding reduction in S-opsin protein expression. The reduced S-opsin expression did not arise from decreased S-opsin mRNA or cone degeneration, but rather from enhanced endoplasmic reticulum (ER)-associated degradation of the nascent protein. Exogenously increased 11-cis-retinal restored F81Y S-opsin protein expression to normal levels, suggesting that ligand binding in the ER facilitates proper folding. Immunohistochemistry and electron microscopy of normal retinas showed that Mueller cells, which synthesize a precursor of 11-cis-retinal, are closely adjoined to the cone ER, so they could deliver the ligand to the site of opsin synthesis. Together, these results suggest that the binding of 11-cis-retinal in the ER is important for normal folding during cone opsin biosynthesis.
UR - http://www.scopus.com/inward/record.url?scp=84861843353&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84861843353&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.0131-12.2012
DO - 10.1523/JNEUROSCI.0131-12.2012
M3 - Article
C2 - 22674284
AN - SCOPUS:84861843353
VL - 32
SP - 8094
EP - 8104
JO - Journal of Neuroscience
JF - Journal of Neuroscience
SN - 0270-6474
IS - 23
ER -