Molecular insight into mechanisms of cag-repeat RNA toxicity in polyglutamine disease from drosophila / Shin-Yi Shieh.

Format:

Book

Manuscript

Thesis/Dissertation

Author/Creator:

Shieh, Shin-Yi.

Contributor:

Bonini, Nancy M., advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Penn dissertations--Biology.

Biology--Penn dissertations.

Local Subjects:

Penn dissertations--Biology.

Biology--Penn dissertations.

Physical Description:

xiii, 204 pages : illustrations (some color) ; 29 cm

Production:

2011.

Summary:

Spinocerebellar ataxia type 3 is one of the polyglutamine (polyQ) diseases, which are caused by a CAG repeat expansion within the coding region of the associated genes. The CAG repeat specifies glutamine, and the expanded polyQ domain confers dominant toxicity on the protein. Recent findings demonstrate that the CAG-repeat RNA, which encodes the toxic polyQ protein, also contributes to the toxicity in Drosophila. In this dissertation, I took both genetic and genomic approaches to provide insight into the nature of the RNA toxicity. A Drosophila model of CAG-repeat RNA toxicity was established that was appropriate for genetic screens. This expressed the repeat ubiquitously in flies, and lead to climbing and wing posture deficits. These flies were sensitive to the level of the toxic CAG-repeat, and showed modification by Mbl, a known modifier of the repeat. Microarray analysis then identified 160 genes that differentially expressed specifically in flies expressing toxic CAG-repeat RNA. Functional annotation clustering analysis revealed several enriched classes, including iron ion binding and nucleotide binding. Further, expression changes of Hsp70 were identified by microarray analysis. We then tested and found that that modulation of Hsp70 levels in flies suppressed the CAG-repeat RNA toxicity. Hsp70 is a powerful modulator of the pathogenic polyQ protein and therefore these findings suggested a potential overlap with polyQ protein modifiers. Known pathogenic polyQ protein modifiers were then tested for effects on the RNA toxicity. Besides Hsp70, the co-chaperone Tpr2, the transcriptional regulator Dpld, and the RNA-binding protein Orb2 were also identified as modifiers of the CAG-repeat RNA toxicity in this dissertation. These results highlight an overlap in mechanisms between RNA and protein-based toxicity, and provide a foundation for future work on the molecular pathogenicity of the RNA in disease.

Notes:

Adviser: Nancy M. Bonini.

Thesis (Ph.D. in Biology) -- University of Pennsylvania, 2011.

Includes bibliographical references.

OCLC:

793488939