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 6

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The altered endocytic activity of Tf and LDL in cells that expressed R13...
The altered endocytic activity of Tf and LDL in cells that expressed R135L/v-arr. Cells transfected with R135L/GFPv-arr (A and B, E and F, I and J, M and N) and WT rhodopsin/GFPv-arr (C and D, G and H, K and L, O and P) were incubated with Alexa 594–conjugated Tf at 37–C for 5 minutes (A and B, C and D), for 2 hours (E and F, G and H), or for 2 hours plus a 30-minute chase (I and J, K and L) before fixation and visualization. Alternatively, cells were treated with DiI-LDL for 2 minutes followed by a 28-minute chase before the fixation (M and N, O and P). Confocal images of GFPv-arr (green) and internalized Tf (red) or LDL (red) are shown. In J and L, the DAPI nuclear labeling demonstrated that the nontransfected cells (in J and L) and WT/GFPv-arr–transfected cells (in L) have no Tf signals, as the Tf was completely expelled from cells. Scale bars: 20 μm.