A collaboration that made the microscope possible
This project represents a unique collaboration between two complementary laboratories. Dr Gershlick’s lab focuses on protein secretion, that is how proteins move from their site of synthesis to their functional destination, while Prof Lee’s lab specialises in building the tools needed to study these processes one molecule at a time. The lead of the work, Dr Sam Daly, combined the research programs to design the experiments and build the microscope itself, pushing the boundaries of what can be visualised inside living cells.
Until now, most microscopy could only track molecules in two dimensions, which makes it difficult to study the full complexity of three-dimensional cells. The new microscope uses a parallax-based method which allows researchers to look around corners and resolve molecular motion in full three dimensions. By focusing on specific organelles, such as the nucleus and the endoplasmic reticulum, the team can pinpoint exactly where molecules are moving. This precision allows them to detect subtle differences in protein behaviour, particularly within diseased endoplasmic reticulum compartments in cells expressing the Z-α1-antitrypsin variant.
“Without knowing precisely where a molecule is inside the cell, you lose sensitivity,” Dr Sam Daly explained “By looking only at proteins within the diseased endoplasmic reticulum, we were able to uncover differences in molecular motion that were previously invisible.”
Making the invisible visible
Imagine trying to follow one person in a huge, crowded building. People move constantly, new ones enter, and others leave. Traditional microscopy is like placing cameras only on the ground floor. You see some movement, but much goes unnoticed. Three-dimensional microscopy adds cameras to every floor, allowing you to scan the whole building. With so many people moving it is still difficult to find your target.
The new technique allows researchers to scan the whole building while knowing exactly which rooms to focus on. This makes it much easier to track specific molecules even in crowded cellular environments. Using this method, the team discovered that molecules inside diseased cell compartments move in highly varied and sometimes restricted ways, supporting the idea that these compartments undergo a liquid to solid transition.
Why it matters
For non-scientists, the significance is easy to grasp. This microscope allows researchers to watch the fundamental building blocks of life, proteins, move in real time. Proteins can now be observed as they leave their site of synthesis in the endoplasmic reticulum and travel to carry out their functions elsewhere in the cell. It is like following a single player in a game of molecular hopscotch.
The technology has wide-reaching implications for human health, offering new ways to study diseases such as neurodegeneration and respiratory illnesses. It could also benefit pharmaceutical research, biotechnology, and clinical studies by revealing how subtle changes in protein motion are linked to disease.
Next steps and future directions
The researchers plan to apply their technique to study protein secretion in greater detail and explore other biological processes, including viral entry into cells. They also aim to enhance the microscope with pulse laser illumination to track even faster molecular movements.
Current limitations include slightly lower resolution for the three-dimensional organelle map compared with single-molecule tracking and the fact that extremely fast-moving molecules can exceed detector speeds. Despite these challenges, the microscope represents a major step forward in observing life at its most fundamental level.
The results of this pioneering research have been published in a recent article entitled Volumetric Single-Molecule Tracking Inside Subcellular Structures.
