If you look at a picture of a cell in a science textbook, the internal structures look static and neatly organized. But living cells are bustling with numerous processes, converting nutrients into energy and making proteins that the body’s tissues and organs need to function and grow. Proteins must fold into specific 3D shapes so they can perform their tasks correctly. Misfolded proteins, as they occur in ALS, are not only unable to perform their jobs; they become toxic.

Healthy cells use three main responses to protect themselves from misbehaving proteins: (1) the heat shock response and 2) the unfolded protein response that reduce damage caused by misfolded proteins; (3) the antioxidant response that reduces amounts of reactive oxygen species, natural by-products of metabolism that are toxic in large quantities.

One theory about how ALS begins is that one of these three stress responses stops working properly in motor neurons. As the disease progresses, the other stress responses also become overwhelmed and unable to protect cells. The presence of an underlying gene mutation that causes motor neurons to overproduce ALS-associated misfolded proteins may speed up the onset and progression of the disease.

Sonja Di Gregorio, a PhD student in the lab of Dr. Martin Duennwald at Western University in London, Ontario studies cellular stress responses in yeast cells that have been altered to express proteins associated with human ALS. “At first, it may be hard to imagine that a single-cell organism like yeast could relate to the complexity of a human motor neuron,” said Di Gregorio. “But their cellular stress responses are very similar to those found in humans, making them an ideal research model.” Research in yeast is much quicker to conduct than research in animal models: it takes only three days to a week to complete a yeast experiment compared to a few months to years with animal research models.

Di Gregorio recently received a Trainee Award of $50,000 from ALS Canada to study cellular stress responses in yeast modified with ALS-associated proteins — TDP-43, FUS and RGNEF. “We know that when these proteins aggregate in motor neurons, they cause toxicity that leads to ALS. My research project will investigate if they interfere with cellular stress response processes and if so, the mechanisms that make that possible,” said Di Gregorio. “I’m not just looking at what a mutation does; I’m looking at the processes that fail so that I can understand why they fail. These cellular ‘police’ mechanisms may also influence each other.” By adding substances that light up with red or green colour under a microscope to the cells, she will identify which of the three cellular stress responses are activated or impaired in the presence of ALS proteins.

RGNEF was recently discovered by Dr. Michael Strong and colleagues in his lab at Western University as an ALS-associated protein. How it functions is not well understood yet, either in healthy motor neurons or motor neurons affected by ALS. Di Gregorio, the first scientist in the world to incorporate RGNEF into a yeast cell, will be laying the foundation for future RGNEF studies by investigating the cellular processes that take place when it is misfolded and aggregated. If she identifies processes that merit further investigation, she plans to explore RGNEF in animal models and human tissue samples available at the Strong Lab in the future.

“In some other neurodegenerative disorders, you could say that the yeast model has shed as much or even more light than any other model system. Many Nobel prizes in were granted for work in yeast models and many major scientific findings come from studies in yeast,” said Di Gregorio. “In a few years, I hope to have much more new information about what ALS-associated proteins are doing in cells, what their functions are, and how those functions are related to ALS disease progression,” Di Gregorio said.

ALS Canada Trainee Awards support Canada’s emerging ALS researchers, whether they are doctoral students, post-doctoral researchers, or clinical research fellows. Trainee awards encourage young researchers to choose ALS as their area of focus, helping to ensure that Canada has a strong base of talented ALS researchers today and into the future.

This research project is one of 12 funded by the ALS Canada Research Program in 2017 following a rigorous scientific assessment by panels of global ALS experts. The panelists evaluated a larger pool of applications to identify the projects that are grounded in scientific excellence and have the potential to most quickly advance the field of ALS research in order to develop effective treatments.

This research project is one of 12 funded by the ALS Canada Research Program in 2017 following a rigorous scientific assessment by panels of global ALS experts. The panelists evaluated a larger pool of applications to identify the projects that are grounded in scientific excellence and have the potential to most quickly advance the field of ALS research in order to develop effective treatments.

Posted in: Research