Unraveling the molecular mechanisms underlying C9orf72-related ALS and FTD

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder primarily affecting the motor nerves. In the last decade, the field of ALS has seen major discoveries regarding the genetic causes leading to this disease. In particular, the discovery that repeat expansions in C9orf72 are responsible for 60-65% of all familial ALS cases, as well as cases of frontotemporal dementia (FTD). Interestingly, we have proven that this mutation, not only affects motor neurons, but also astrocyte function, thus making them become toxic to motor neurons. The molecular mechanisms leading to the development of ALS and/or FTD are still largely unknown, but it is puzzling how a mutation in the same gene can cause two different disease phenotypes. Three hypotheses have been put forward as potential mechanisms of toxicity for this mutation: 1. Reduction in the protein encoded by C9orf72, involved in autophagy; 2. RNA toxicity, related to the presence of RNA foci from the repeat expansion; 3. Dipeptide repeat (DPR) toxicity from the formation of proteins encoded by the repeat expansion.
To study the effect of all the mechanisms, in this project we will use induced pluripotent stem cells to derive human astrocytes and neurons from C9orf72 patients affected by ALS or FTD to then identify differential mechanisms of disease. We will 1- Conduct co-cultures of control and C9orf72 astrocytes and motor neurones or cortical neurones derived from ALS and FTD patients to determine whether astrocyte toxicity is involved in both ALS and FTD. 2 – We will determine whether astrocytes from C9orf72 patients are differentially toxic to one or the other neuronal population. 3 – With the use of gene therapy tools we will determine whether RNA toxicity or di-peptide repeat toxicity is responsible for the differential phenotype between ALS and FTD. 4 – Using cutting-edge techniques, such as the Nanopore Sequencing, we will investigate the relationship between repeat length and ALS/FTD.
The project will have important therapeutic applications, as discriminating between ALS and FTD will give the opportunity to develop ad hoc therapeutic approaches based upon different molecular pathways.
We expect the student recruited onto this study to learn a number of basic molecular biology techniques, such as cloning, PCR and western blotting, as well as cutting edge techniques such as somatic cell reprogramming and Nanopore Sequencing.