Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig’s disease, is a neurodegenerative disease that affects nerve cells in the brain and spinal cord. Nowadays, there is no treatment to reverse the damage of motor neurons or cure ALS. The disorders are characterized by the deposition of protein aggregates, which usually consist of fibers containing misfolded protein with a beta-sheet conformation termed amyloid.
Scientists indicate that one of the causes of the development of neurodegenerative diseases is chronic stress associated with the dysfunction of membranelles organelles called stress granules (SGs). These organelles are formed through a process called liquid-liquid phase separation (LLPS) in which a uniform mixture spontaneously divides into two liquid phases, each with varying concentrations of components.
In the project, we aim at the exploration of protein LLPS mechanism on length scales from single protein molecules through small oligomers to stress granules (SGs). We reconstitute some of the most illustrative components of SGs in vitro, including TDP43, hnRNPA2, G3BP1, and FUS. We hypothesize that the nucleation of stress granules consists of two steps: primary and secondary nucleation. During the first step, the protein interacts with each other, forming small nuclei before the appearance of microscopic liquid-like droplets. During the second step, nucleation is initiated by mature droplets, which serve as seeds to fibril and/or amorphous aggregates.
In our project, we aim to solve the following research questions:
1. How do pH and ionic strength influence the effective charge and conformation of main stress granule proteins?
2. How do mutations and/or post-translational modifications influence the physicochemical properties of the stress granule proteins?
3. What is the mechanism of nucleation, and how do the assembly conditions, modifications, and the presence of binding partners influence the resulting structure?
4. To what extent are we able to control such a process? Can we use small molecules to control the phenomenon?