Elucidating the role of a potential new therapeutic target to inhibit RAN translation in C9ORF72-ALS-driven neurodegeneration (360G-Wellcome-206929_Z_17_Z)

The most prevalent form of familial Motor Neurone Disease (MND) is caused by a hexanucleotide repeat expansion (HRE) of the C9ORF72 gene. This hexanucleotide sequence (GGGGCC) is within a non-coding region of the first intron of the C9ORF72 gene with repeat expansions of this sequence ranging from 50 to thousands of repeats. This HRE results in the generation of a guanine rich nucleic acid capable of forming stable G-quadraplex structures. Interactions of this G-quadraplex structure with RNA-processing factors allows the HRE to undergo Repeat-Associated Non-ATG-dependant (RAN) translation, an abnormal translation initiation event occuring in the absence of a start codon. RAN translation can occur from the sense or antisense strand and in all three frames, leading to the production of 5 different dipeptide repeat (DPR) proteins. It has been implicated that aggregation of these DPR proteins is responsible for motor neuron toxicity and accounts for the neurodegeneration seen in MND. This project aims to explore the role of eukaryotic translation initiation factor 4B (eIF4B) in RAN translation of the C9ORF72 HRE. eIF4B knockdown will be achieved through RNAi and the subsequent effects of this on DPR production and cell proliferation will be investigated using Western Blotting, Immunofluorescence and MTT assays.