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|Title: ||Investigating the role of eEF1A2 in motor neuron degeneration|
|Authors: ||Griffiths, Lowri Ann|
|Supervisor(s): ||Abbott, Catherine|
|Issue Date: ||25-Nov-2011|
|Publisher: ||The University of Edinburgh|
|Abstract: ||Abnormal expression of the eukaryotic translation elongation factor 1A (eEF1A) has
been implicated in disease states such as motor neuron degeneration and cancer. Two
variants of eEF1A are found in mammals, named eEF1A1 and eEF1A2. These two
variants are encoded by different genes, produce proteins which are 92% identical
but have very different patterns of expression. eEF1A1 is almost ubiquitously
expressed while eEF1A2 is expressed only in specialised cell types such as motor
neurons and muscle.
A spontaneous mutation in eEF1A2 results in the wasted mouse phenotype which
shows similar characteristics in the mouse to those seen in human motor neuron
degeneration. This mutation has been shown to be a 15.8kb deletion resulting in the
complete loss of the promoter region and first non coding exon of eEF1A2 which
completely abolishes protein expression.
The main aim of this project was to further investigate the role of eEF1A2 in motor
Firstly, although the wasted phenotype is considered to be caused by a recessive
mutation, I established a cohort of aged heterozygote mice to evaluate whether any
changes are seen later in life that might model late onset motor neuron degeneration.
A combination of behavioural tests and pathology was used to compare wild type
and heterozygous mice up to 21 months of age. Whilst results indicate that there is
no significant difference between ageing heterozygotes and wildtype controls, there
is an indication that female heterozygote mice perform slightly worse that wildtype
controls on the rotarod (a behavioural test for motor function).
Secondly, I aimed to investigate the primary cause of the wasted pathology by
generating transgenic wasted mice expressing neuronal eEF1A2 only. This would
complement previous experiments in the lab which studied transgenic wasted mice
expressing eEF1A2 in muscle only. Unfortunately the expression of eEF1A2 in the
transgenic animals was not neuronal specific. However a transgenic line with expression of eEF1A2 in neurons and skeletal muscle but not cardiac muscle has
been generated which clearly warrants further investigation.
Thirdly, I wished to assess whether eEF1A2 has any role in human motor neuron
degeneration. To achieve this, eEF1A2 expression was investigated in spinal cords
from human motor neuron disease (MND) patients. Preliminary data suggests that
motor neurons from some MND patients express significantly less eEF1A2 than
motor neurons of control samples. Further work is required to confirm these findings.
Finally, I investigated the individual roles of eEF1A1 and eEF1A2 in the heat shock
response. I used RNAi to ablate each variant separately in cells and subsequently
measured the ability of each variant individually to mount a heat shock response.
Results indicate a clear role for eEF1A1 but not eEF1A2 in the induction of heat
shock. This may explain in part why motor neurons exhibit a poor heat shock
response as they express eEF1A2 and not eEF1A1.
These experiments shed light on our understanding of the role of eEF1A2 in motor
neuron degeneration and uncover many new avenues of future investigation.|
|Sponsor(s): ||Wellcome Trust|
|Keywords: ||eukaryotic translation elongation factor 1A|
motor neuron degeneration
motor neuron disease
|Appears in Collections:||Molecular, Genetic and Population Health Sciences thesis and dissertation collection|
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