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Proceedings Paper

Single-molecule fluorescence study of the inhibition of the oncogenic functionality of STAT3
Author(s): Baoxu Liu; Daniel Badali; Steven Fletcher; Miriam Avadisian; Patrick Gunning; Claudiu Gradinaru
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Paper Abstract

Signal-Transducer-and-Activator-of-Transcription 3 (STAT3) protein plays an important role in the onset of cancers such as leukemia and lymphoma. In this study, we aim to test the effectiveness of a novel peptide drug designed to tether STAT3 to the phospholipid bilayer of the cell membrane and thus inhibit unwanted transcription. As a first step, STAT3 proteins were successfully labelled with tetramethylrhodamine (TMR), a fluorescent dye with suitable photostability for single molecule studies. The effectiveness of labelling was determined using fluorescence correlation spectroscopy in a custom built confocal microscope, from which diffusion times and hydrodynamic radii of individual proteins were determined. A newly developed fluorescein derivative label (F-NAc) has been designed to be incorporated into the structure of the peptide drug so that peptide-STAT3 interactions can be examined. This dye is spectrally characterized and is found to be well suited for its application to this project, as well as other single-molecule studies. The membrane localization via high-affinity cholesterol-bound small-molecule binding agents can be demonstrated by encapsulating TMR-labeled STAT3 and inhibitors within a vesicle model cell system. To this end, unilaminar lipid vesicles were examined for size and encapsulation ability. Preliminary results of the efficiency and stability of the STAT3 anchoring in lipid membranes obtained via quantitative confocal imaging and single-molecule spectroscopy using a custom-built multiparameter fluorescence microscope are reported here.

Paper Details

Date Published: 4 August 2009
PDF: 7 pages
Proc. SPIE 7386, Photonics North 2009, 738605 (4 August 2009); doi: 10.1117/12.838943
Show Author Affiliations
Baoxu Liu, Univ. of Toronto Mississauga (Canada)
Daniel Badali, Univ. of Toronto Mississauga (Canada)
Steven Fletcher, Univ. of Toronto Mississauga (Canada)
Miriam Avadisian, Univ. of Toronto Mississauga (Canada)
Patrick Gunning, Univ. of Toronto Mississauga (Canada)
Claudiu Gradinaru, Univ. of Toronto Mississauga (Canada)

Published in SPIE Proceedings Vol. 7386:
Photonics North 2009
Réal Vallée, Editor(s)

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