a-synuclein oligomers visualized by FLIM

Detection of novel intracellular a-synuclein oligomeric species by fluorescence lifetime imaging
Jochen Klucken^*,, Tiago F. Outeiro^*, Paul Nguyen^*, Pamela J. McLean^*,1 and Bradley T. Hyman^*
MassGeneral Institute for Neurodegenerative Disease, Alzheimer’s Disease Research Unit, Massachusetts General Hospital, Charlestown, Massachusetts, USA;
Department of Neurology, University of Regensburg, Regensburg, Germany

¹Correspondence: MassGeneral Institute for Neurodegenerative Disease, Alzheimer’s Disease Research Unit, Massachusetts General Hospital, 114 16^th St., Charlestown, MA 02129 USA

Oligomerization and aggregation of a-synuclein molecules are believed to play a major role in neuronal dysfunction and loss in Parkinson’s disease (PD) and dementia with Lewy bodies. However, a-synuclein oligomerization and aggregation have been detected only indirectly in cells using detergent extraction methods. Here, we show for the first time intracellular a-synuclein oligomerization using fluorescence lifetime imaging (FLIM). Two forms of a-synuclein homomeric interactions were detected: an antiparallel amino terminus-carboxyl terminus interaction between a-synuclein molecules, and a close amino terminus-carboxy terminus interaction within single a-synuclein molecules. Coexpression of the chaperone protein Hsp70, which can block a-synuclein toxicity in several systems, causes a-synuclein to adopt a different, open conformation, but Hsp70 does not alter a-synuclein–a-synuclein interactions. Thus, the neuroprotective effect of Hsp70 can be explained by its chaperone activity on a-synuclein molecules, rather than alteration of a-synuclein–a-synuclein interactions.

in FASEB J. 2006 Oct;20(12):2050-7.