Structural and functional impairment of endocytic pathways by retinitis pigmentosa mutant rhodopsin-arrestin complexes
Jen-Zen Chuang, … , Wenjin Jun, Ching-Hwa Sung
Jen-Zen Chuang, … , Wenjin Jun, Ching-Hwa Sung
Published July 1, 2004
Citation Information: J Clin Invest. 2004;114(1):131-140. https://doi.org/10.1172/JCI21136.
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Article Neuroscience

Structural and functional impairment of endocytic pathways by retinitis pigmentosa mutant rhodopsin-arrestin complexes

Abstract

Retinitis pigmentosa (RP) is a clinically and genetically heterogeneous degenerative eye disease. Mutations at Arg135 of rhodopsin are associated with a severe form of autosomal dominant RP. This report presents evidence that Arg135 mutant rhodopsins (e.g., R135L, R135G, and R135W) are hyperphosphorylated and bind with high affinity to visual arrestin. Mutant rhodopsin recruits the cytosolic arrestin to the plasma membrane, and the rhodopsin-arrestin complex is internalized into the endocytic pathway. Furthermore, the rhodopsin-arrestin complexes alter the morphology of endosomal compartments and severely damage receptor-mediated endocytic functions. The biochemical and cellular defects of Arg135 mutant rhodopsins are distinct from those previously described for class I and class II RP mutations, and, hence, we propose that they be named class III. Impaired endocytic activity may underlie the pathogenesis of RP caused by class III rhodopsin mutations.

Authors

Jen-Zen Chuang, Carrie Vega, Wenjin Jun, Ching-Hwa Sung

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Figure 1

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Confocal images of WT and mutant rhodopsins expressed in HEK cells. (A a...
Confocal images of WT and mutant rhodopsins expressed in HEK cells. (A and B) Fixed HEK cells transfected with WT (A) or R135L (B) rhodopsin were incubated with anti–rhodopsin mAb B6-30 and detected by Alexa 488 secondary antibodies. (C–K) HEK cells transfected with R135L were incubated with Alexa 594–Tf for 5 minutes to label early endosomes (C–E); incubated with Alexa 594–Tf for 2 minutes followed by a 28-minute chase to label recycling endosomes (F–H); or incubated with rhodamine-labeled dextran for 2 hours to label late endosomes/lysosomes (I–K). Cells were then fixed and permeabilized for rhodopsin immunostaining (green). Rhodopsin immunoreactivity colocalized with the internalized Tf or dextran is marked by arrows, and merge images are shown in E, H, and K. Scale bars: 10 μm.