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Volume 10 Journal of Neurology & Neurophysiology
ISSN: 2155-9562
Neurology Congress 2019
Vascular Dementia Congress 2019
July 22-24, 2019
JOINT EVENT
conferenceseries.com
July 22-24, 2019 London, UK
&
12th International Conference on Vascular Dementia
32nd European Neurology Congress
Alanine rich dipeptide repeat proteins sequester arginine rich dipeptide repeat proteins in a cellular model
of C9orf72
Katherine Radcliffe
University of Manchester, UK
Ahexanucleotide repeat expansion in the C9orf72 gene is the most common genetic cause of frontotemporal
dementia and motor neuron disease. Carriers present with both conditions concurrently, so they are considered
a continuum. The RNA from the hexanucleotide expansion is translated by repeat associated non-ATG (RAN)
translation; producing five dipeptide repeat (DPR) proteins. These are the alanine rich polyAP and polyGA, the
arginine-rich polyGR and polyPR, and polyGP. Previous in vitro studies show that the arginine-rich DPRs are toxic
because they localise to the nucleolus, causing nucleolar stress. However, preliminary research showed sequestration
of polyGR by polyGA when they were co-expressed in HeLa cells, Drosophila and human neurons. Our aim was to
determine whether alanine-rich DPR proteins sequester arginine-rich DPR proteins when the two are co-expressed
in vitro. This was investigated using alternative coding sequences for the DPR proteins, cloned into mCherry-
tagged plasmids. Next, two DPR proteins with different fluorescent tags were co-transfected into HeLa cells and
the subcellular locations of the DPR proteins were visualised using immunofluorescence. Our results showed
cytoplasmic co-localisation of the arginine-rich DPRs with polyGA. This was replicated 3 times in HeLa cells and
once in SH-SY5Y cells. Co-transfection, but no colocalisation, was seen when two alanine-rich or two arginine-
rich DPR proteins were co-expressed. Overall, our findings suggest that the arginine-rich DPRs are sequestered
by polyGA in the cytoplasm, meaning they are unlikely to cause nucleolar stress. This demonstrates that single
transfections of DPR proteins may not be a good model to study DPR protein function or toxicity.
Biography
Katherine Radcliffe conducted this original research whilst incalating and studying MRes Translational Medicine at the University of Manchester. She has just
graduated from Manchester Medical School and is due to start as an FY1 doctor in August. This research earned her the best poster prize within her course and
she has presented posters at multiple conferences including a European Congress whilst studying.
Katherine Radcliffe, J Neurol Neurophysiol 2019, Volume 10