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Abstract #18202 Published in IGR 9-2
Sodium 4-phenylbutyrate acts as a chemical chaperone on misfolded myocilin to rescue cells from endoplasmic reticulum stress and apoptosis
Yam GH; Gaplovska-Kysela K; Zuber C; Roth JInvestigative Ophthalmology and Visual Science 2007; 48: 1683-1690
PURPOSE: To evaluate the effect of chemical chaperones on the trafficking of secretion-incompetent primary open-angle glaucoma-associated mutant myocilin and the possibility to rescue cells coexpressing mutant and wild-type myocilin from endoplasmic reticulum (ER) stress and apoptosis. METHODS: CHO-K1, HEK293 and human trabecular meshwork cells were transfected to express wild-type or mutant (C245Y, G364V, P370L, Y437H) myocilin-green fluorescent protein fusion protein and were treated or not with various chemical chaperones (glycerol, dimethylsulfoxide, or sodium 4-phenylbutyrate) for different time periods. The secretion, Triton X-100 solubility, and intracellular distribution of wild-type and mutant myocilin were analyzed by immunoprecipitation, Western blotting, and confocal double immunofluorescence. The effect of sodium 4-phenylbutyrate on ER stress proteins and apoptosis was examined in cells coexpressing mutant and wild-type myocilin. RESULTS: Treatment with sodium 4-phenylbutyrate, but not with glycerol or dimethylsulfoxide, reduced the amount of detergent-insoluble myocilin aggregates, diminished myocilin interaction with calreticulin, and restored the secretion of mutant myocilin. Heteromeric complexes formed by mutant and wild-type myocilin induced the ER stress-associated phosphorylated form of ER-localized eukaryotic initiation factor (eIF)-2α kinase and the active form of caspase 3, which resulted in an increased rate of apoptosis. Sodium 4-phenylbutyrate treatment of cells coexpressing mutant and wild-type myocilin relieved ER stress and significantly reduced the rate of apoptosis. CONCLUSIONS: These findings indicate that sodium 4-phenylbutyrate protects cells from the deleterious effects of ER-retained aggregated mutant myocilin. These data point to the possibility of a chemical chaperone treatment for myocilin-caused primary open-angle glaucoma.
Dr. G.H. Yam, Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, Schmelzbergstrasse 12, CH-8091 Zurich, Switzerland
Classification:
3.5 Molecular biology incl. SiRNA (Part of: 3 Laboratory methods)
11.14 Investigational drugs; pharmacological experiments (Part of: 11 Medical treatment)
