49 / 88
45
New Biological Frontiers Illuminated by Molecular Sensors and Actuators
Poster Abstracts
11-POS
Board 11
Revealing Proteostasis Capacity in Cells by a Fluorescent Sensor
Yuning Hong
.
University of Melbourne, Melbourne, Australia.
Maintaining proteostasis is an essential housekeeping function for cell survival. Proteostasis is in
principle affected in any disease that involves misfolded or mutant proteins that do not fold with
normal efficiencies; and hence overdraw on the finite proteostasis resources of the cell. Tracking
the proteostasis capacity of cells has the generic potential to track neurodegenerative diseases of
diverse specific molecular origins. Building new approaches to identify the efficiency of
proteostasis is thus highly desired in order to track the risk of cells succumbing to damage from
protein misfolding and aggregation. Here we describe our approach to revealing the proteostasis
states in Huntington’s disease cell culture models by a cysteine-reactive aggregation-induced
emission (AIE) fluorogen. Stress conditions, such as protein misfolding and environmental
stimuli, will lead to an elevated level of unfolded proteins. The fluorogen, TPE-MI, can react
with the unfolded proteins with free cysteine residue exposed and turns on its fluorescence.
Because of the unique AIE characteristic, reacting with small biothiols, such as glutathione,
would not change the fluorescence of TPE-MI. The signal from TPE-MI can thus be correlated
to the amount of unfolded proteins and reflect the proteostasis capacity in cells. We then apply
this method to investigate the proteostasis capacity in the subpathogenic and pathogenic Httexon
1 cells by using flow cytometry. Our results show distinct fluorescence signals between the
pathogenic and subpathogenic cells. By incorporating pulse shape analysis, we are able to
differentiate the signals from the non-inclusion and inclusion cell population within the same
sample. Our results suggest that the collapse of proteostasis is one of the features for
Huntington’s diseases and such effect emerges in cells prior to the formation of visible
aggregates.