Transcript File

Making sense of the senseless: Evaluating sex differences of ASO
gene therapy in mice with Usher syndrome
Adam M. McNeela1, Kelsey T. Jennings1, Lucia A. Cherep1, Tia N. Donaldson1, Frederic F. Depreux2,
Dr. Michelle L. Hastings2, Dr. Douglas G. Wallace1
Northern Illinois University1
Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin2
.
Introduction
Usher syndrome is an autosomal recessive disorder
which is caused by mutations in the USH1C gene, which
encodes the protein harmonin (Lentz et al., 2013). Harmonin
is responsible for the development and maintenance of
steriocilia in hair and photoreceptor cells. Consequently,
improper splicing of harmonin results in an array of sensory
impairments. Although Usher syndrome accounts for
approximately 50% of deaf-blindness cases, it also causes
vestibular impairments (Ouyang et al., 2004). An antisense
oligonucleotide (ASO) gene therapy has been shown to
correct the improper splicing of harmonin, thereby rescuing
vestibular function (Lentz et al., 2013).
The relationship between spatial navigation and the
vestibular system can be studied using an exploratory task
in rodents. Throughout exploration where environmental
cues are restricted, self-movement cue processing is critical
to maintain spatial orientation (Wallace et al., 2008).
Furthermore, the vestibular system has been shown to play
an important role in self-movement cue processing in
rodents (Wallace et al., 2002).
The current study examines self-movement cue
processing in Usher mice, as well as gender differences in
the effectiveness of an ASO gene therapy. Limited work has
been done regarding the role of gender in gene therapies
and the results have the potential to provide new insights
into effective gene therapies for treating the vestibular
impairments of Usher syndrome in human patients.
Figure 2 – Exploratory behavior topography is
plotted for a representative female mouse.
Results
Figure 3 – Exploratory behavior topography is
plotted for a representative male mouse.
Figure 9 - Distance ratio was plotted for both groups
across the 5 samples. Females exhibited a significantly
greater distance ratio than males, indicating more direct
paths taken throughout exploration.
Figure 4 – Average change in heading was plotted
for both groups across the 5 samples. No significant
group differences were observed.
Figure 5 - Average peak speed was plotted for both
groups across the 5 samples. No significant group
differences were observed.
Methods
Female (n=7) and male (n=7) Usher mice were
administered an ASO gene therapy at post-natal day 5. At 2
months of age, open field exploratory behaviors were
recorded for 50 minutes under dark conditions. Five (5
minute) samples were analyzed for each mouse and motion
capture software was used to quantify kinematic and
topographic aspects of exploratory behavior. The data
obtained represent total distance traveled, peak speed,
distance ratio, movement scaling, and changes in heading
across the five samples.
Figure 1- Photograph of exploratory table (122 cm
diameter)
Figure 8 – Sample progressions are plotted from Figures
2 and 3. These plots demonstrate that females (left
panel) mice follow direct progressions and male (right
panel) mice follow indirect progressions.
Conclusions
Figure 6 - Total distance was plotted for both groups
across the 5 samples. Males traveled a significantly
greater distance throughout exploration than
females.
Figure 7 – Movement scaling was plotted for both
groups across the 5 samples. No significant group
differences were observed.
• Under dark conditions, mice organize their exploratory
behavior into stops and progressions..
• Females exhibited more direct progressions than males,
suggesting that the ASO treatment was more effective in
rescuing vestibular function in females.
• Males traveled a greater distance than females, which is
consistent with the circuitous paths taken by the male
mouse (Figure 8).
• Future research is needed to examine the persistence of
the ASO therapy at 6 months of age as well as the effects
under light conditions. Furthermore, work is needed to
characterize sex differences in harmonin production as
mechanism for the current pattern of results.
References
Lentz, J. J., Jodelka, F. M., Hinrich, A. J., McCaffrey, K. E., Farris, H. E., Spalitta, M.
J., … Hastings, M. L. (2013). Rescue of hearing and vestibular function by
antisense oligonucleotides in a mouse model of human deafness. Nature
Medicine, 1-8.
Ouyang, X. M., Yan, D., Du, L. L., Hejtmancik, J. F., Jacobson, S. G., Nance, W. E.,
…Liu, X. Z. (2005). Characterization of Usher syndrome type I gene
mutations in an Usher syndrome patient population. Human Genetics, 116,
292-299.
Wallace, D. G., Hines, D. J., Pellis, S. M., Whishaw, I. Q., (2002). Vestibular
information is required for dead reckoning in the rat. Journal of
Neuroscience. 22(22): 100009-100017.
Wallace, D. G., Martin, M. M., & Winter, S. S. (2008). Fractionating dead reckoning:
role of the compass, odometer, logbook, and home base establishment in
spatial orientation. Naturwissenschaften, 95(11), 1011-1026.