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Mutant Rhodopsins in Autosomal Dominant Retinitis Pigmentosa Display Variable Aggregation Properties

Gragg, Megan Ellen
http://orcid.org/0000-0003-3722-9493
http://rave.ohiolink.edu/etdc/view?acc_num=case1522935340252319

Abstract Details

2018, Doctor of Philosophy, Case Western Reserve University, Molecular Medicine.
Rhodopsin mutations are the leading cause of autosomal dominant retinitis pigmentosa (adRP), a retinal degenerative disease. Rhodopsin is the light receptor in rod photoreceptors that plays a central role in phototransduction and rod photoreceptor health. A majority of rhodopsin mutations cause misfolding and aggregation of the apoprotein opsin. The structure adopted by misfolded opsin mutants and the associated cell toxicity is poorly understood; and the pathogenesis of adRP caused by misfolded opsin remains unclear. Physical interactions between wild-type opsin and misfolded opsin mutants have been proposed to underlie the autosomal dominant phenotype in the literature. The misfolding mutants have been characterized biochemically and categorized as either partial or complete misfolding mutants. This classification is incomplete and does not provide sufficient information to fully understand rhodopsin aggregation, disease pathogenesis, and evaluate therapeutic strategies. To better understand misfolded rhodopsin aggregation, a Forster resonance energy transfer (FRET) assay was developed to monitor interactions between fluorescently tagged opsins expressed in live cells. The FRET detergent assay employed discriminated between properly folded opsin oligomers and misfolded opsin aggregates. Using the FRET method established, Complete and partial misfolding mutants were characterized to reveal variability in aggregation properties, showing the current rhodopsin mutant classification system to incompletely describe the possible rhodopsin interactions. The complete misfolding mutants examined behaved similarly: forming aggregates when expressed alone, minimally interacting with the wild-type receptor when coexpressed, and not responding to the pharmacological chaperone 9-cis retinal. In contrast, variability was observed between the partial misfolding mutants. The partial misfolding mutants reacted similarly to the pharmacological chaperone 9-cis retinal, displaying improved folding and oligomerization when expressed alone, but aggregating with wildtype rhodopsin when coexpressed. The aggregation differences and 9-cis retinal effect predict different outcomes in disease pathophysiology, suggesting retinoid-based chaperones will be ineffective for complete misfolded rhodopsins or even detrimental for partial misfolded rhodopsins.
Paul Park, Ph.D. (Advisor)
Marvin Nieman, Ph.D. (Committee Chair)
Bela Anand-Apte, M.D., Ph.D (Committee Member)
Danny Manor, Ph.D. (Committee Member)
174 p.
Biochemistry; Molecular Biology
rhodopsin; retinitis pigmentosa; fluorescence resonance energy transfer; aggregation; retinal degeneration; G-protein coupled receptor; protein misfolding; conformational disease; membrane protein; protein structure; oligomerization

Recommended Citations

Citations

  • Gragg, M. E. (2018). Mutant Rhodopsins in Autosomal Dominant Retinitis Pigmentosa Display Variable Aggregation Properties [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1522935340252319

    APA Style (7th edition)

  • Gragg, Megan. Mutant Rhodopsins in Autosomal Dominant Retinitis Pigmentosa Display Variable Aggregation Properties. 2018. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1522935340252319.

    MLA Style (8th edition)

  • Gragg, Megan. "Mutant Rhodopsins in Autosomal Dominant Retinitis Pigmentosa Display Variable Aggregation Properties." Doctoral dissertation, Case Western Reserve University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1522935340252319

    Chicago Manual of Style (17th edition)

case1522935340252319
254
© 2018, some rights reserved.Creative Commons License Mutant Rhodopsins in Autosomal Dominant Retinitis Pigmentosa Display Variable Aggregation Properties by Megan Ellen Gragg is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.