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Proceedings Paper

Fluorescence lifetime dynamics of eGFP in protein aggregates with expanded polyQ
Author(s): Vladimir Ghukasyan; Chih-Chun Hsu; Chia-Rung Liu; Fu-Jen Kao; Tzu-Hao Cheng
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Paper Abstract

Expanding a polyglutamine (polyQ) stretch at the N-terminus of huntingtin protein is the main cause of the neurodegenerative disorder Huntington's disease (HD). Expansion of polyQ above 39 residues has an inherent propensity to form amyloid-like fibrils and aggregation of the mutant protein is found to be a critical component for abnormal pathology of HD. Using yeast Saccharomyces cerevisiae as a model system, we have observed a decrease in fluorescence lifetime of the enhanced green fluorescence protein (eGFP) fused to 97 successive glutamine residues (97Q). Compared to the sample expressing evenly distributed eGFP, the 97Q-eGFP fusion proteins show the formation of grain-like particles and the reduction of eGFP lifetime by ~250 ps as measured by time-correlated single-photon counting technique (TCSPC). More importantly, this phenomenon does not appear in Hsp104-deficient cells. The gene product of HSP104 is required for the formation of polyQ aggregates in yeast cells; therefore, the cellular 97Q-eGFP become soluble and evenly distributive in the absence of Hsp104. Under this condition, the lifetime value of 97Q-eGFP is close to the one exhibited by eGFP alone. The independence of the effect of the environmental parameters, such as pH and refraction index is demonstrated. These data indicate that the fluorescence lifetime dynamics of eGFP is linked to the process of polyQ protein aggregation per se.

Paper Details

Date Published: 25 February 2009
PDF: 8 pages
Proc. SPIE 7183, Multiphoton Microscopy in the Biomedical Sciences IX, 718327 (25 February 2009); doi: 10.1117/12.809403
Show Author Affiliations
Vladimir Ghukasyan, National Yang-Ming Univ. (Taiwan)
Chih-Chun Hsu, National Yang-Ming Univ. (Taiwan)
Chia-Rung Liu, National Yang-Ming Univ. (Taiwan)
Fu-Jen Kao, National Yang-Ming Univ. (Taiwan)
Tzu-Hao Cheng, National Yang-Ming Univ. (Taiwan)

Published in SPIE Proceedings Vol. 7183:
Multiphoton Microscopy in the Biomedical Sciences IX
Ammasi Periasamy; Peter T. C. So, Editor(s)

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