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A4223
October 25, 2016
10/25/2016 3:15:00 PM - 10/25/2016 5:15:00 PM
Room Hall F Foyer-Area C
Neuron-targeted Caveolin-1 Delays Onset and Extends Survival in the hSOD1G93A Mouse Model of Amyotrophic Lateral Sclerosis
Atsushi Sawada, M.D.,Ph.D., Benjamin E. Illum, M.D., Minyu Jian, M.D., Jesse Wackerbarth, Student, Junji Egawa, M.D., Jan M. Schilling, M.D.,Ph.D., Martin Marsala, M.D., Michiaki Yamakage, M.D.,Ph.D., Piyush M. Patel, M.D., Brian Head, Ph.D.
VASDHS/UCSD, San Diego, California, United States
Disclosures:  A. Sawada: None. B.E. Illum: None. M. Jian: None. J. Wackerbarth: None. J. Egawa: None. J.M. Schilling: None. M. Marsala: None. M. Yamakage: None. P.M. Patel: None. B. Head: None.
Background: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by loss of somatic upper and lower motor neuron pathways and is associated with diffuse muscle weakness, paralysis, and shorter longevity. Caveolin (Cav), a cholesterol-binding and scaffolding protein present in membrane/lipid rafts (MLR), regulates pro-growth signaling. Because previous work from our group demonstrated neuron-targeted Cav-1 overexpression (SynCav1) enhances MLR formation, augments pro-growth signaling, and promotes neuroplasticity in vitro and in vivo, we therefore hypothesized that enhanced expression of Cav-1 in motor neurons through SynCav1 may provide neuroprotection, prolong motor neuron survival and function, and attenuate disease progression. The present study crossed our SynCav1 transgenic mouse (SynCav1 TG) with the SOD1+ mutant mouse model of ALS to test whether the offspring exhibited delayed onset of disease.

Method: All animals were treated in compliance with the Guide for the Care and Use of Laboratory Animals. The protocols were approved by the Veterans Administration San Diego Healthcare System Institutional Animal Care and Use Committee prior to procedures performed. TG mice expressing ALS-linked human SOD1 mutant protein (hSOD1G93A) exhibit an ALS-like neurodegenerative phenotype. C57BL/6 wild type (WT), hSOD1G93A TG (SOD1), SynCav1 TG positive, and hSOD1G93A -SynCav1 (SOD1-SynCav1) TG double positive mice were used for this study. Body weight was obtained weekly between 6 and 17 weeks. Survival analyses were performed using Kaplan-Meier estimator. Voluntary running wheel test was performed at 8, 12, and 16 weeks. Recordings of electromyography (EMG) and motor-evoked potentials (MEP) in upper and lower limbs were performed at 12 and 16 weeks. After completion of all electrophysiological recordings, postmortem tissue was prepared for histology (immunofluorescence confocal microscopy) to quantify number of α motor neurons in the ventral horns throughout the vertebral column.

Result: hSOD1G93A and SynCav1 TG positive mice were confirmed by PCR and ethidium bromide DNA gel electrophoresis. SOD1-SynCav1 double positive mice (n = 19) significantly extended survival compared to SOD1 TG positive mice (p = 0.0006, n = 18; Median survival days: 153 for SOD1 and 182 for SOD1-SynCav1). SOD1+ mouse exhibited significant weight loss between 11 and 12 weeks with a ~23% drop at 17 weeks (relative to maximum weight at 10 wk). SOD1+/SynCav1+ mice never exhibited > 6% weight loss at any time point (5.3%, 17 wk relative to 12 wk max. weight) and was significantly heavier than SOD1+ at 16 and 17 weeks (p = 0.0027, n = 20 mice/group). On the voluntary running wheel, SOD1-SynCav1 mice performed better as exhibited by greater velocity and total distance versus SOD1 TG positive mice at 12 weeks (p = 0.0045, n = 9-10 mice/group) but not at 16 weeks. MEP measurements revealed greater amplitude (lower and upper limb) in SOD1-SynCav1 mice compared to SOD1 mice at 14 weeks (p = 0.003, n = 9-10 mice/group) and lower latency (lower limb) when compared to SOD1 mice from 12 to 16 weeks (p < 0.05, n = 9-10 mice/group). SOD1-SynCav1 mice had significantly greater number of α motor neurons in the ventral horns in the thoracic and lumber vertebral column at 12 weeks (p = 0.02, n = 4 mice/group) when compared to SOD1 mice but not at 16 weeks.

Conclusion: When compared to SOD1+, SOD1+/SynCav1+ mice demonstrated preserved body weight, greater neuro-muscular function, better running wheel performance, and delayed onset of disease by one month. Future studies will test whether SynCav1 gene therapy can be used asa potential therapeutic means to delay the progression of ALS.

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