Live-cell super-resolution microscopy reveals a primary role for diffusion in polyglutamine-driven aggresome assembly

Area of Science:

• Cell biology
• Biophysics
• Neuroscience

Background:

• Amyloid aggregates, like those formed by misfolded proteins, are implicated in various diseases.
• In vitro studies provide insights into protein self-assembly but may not fully represent cellular conditions.

Purpose of the Study:

• To investigate the mechanisms of protein aggregate formation and aggresome assembly within live cells.
• To compare in vivo protein aggregation pathways with in vitro observations.
• To elucidate the role of diffusion and active transport in aggresome development.

Main Methods:

• Super-resolution imaging of live cells to visualize protein aggregation dynamics.
• Mathematical modeling to analyze the kinetics of aggresome expansion.
• Tracking of polyglutamine-containing protein aggregates in the cytosol and at the microtubule-organizing center.

Main Results:

• Amyloidogenic proteins initially form small, amorphous cytosolic clusters via diffusion.
• Aggregate clusters exhibit branched morphology in cells, unlike linear fibrils in vitro.
• Diffusion, rather than solely active transport, is the primary driver of aggresome expansion.
• Aggresomes mature and compact over time, impacting cell health.

Conclusions:

• Cellular protein aggregation and aggresome formation involve dynamic processes distinct from in vitro models.
• Diffusion plays a crucial role in the expansion and assembly of aggresomes.
• Understanding these dynamic mechanisms is vital for developing therapeutic strategies against proteinopathies.