Amyotrophic Lateral Sclerosis (ALS) is a lethal neurodegenerative disease that involves the selective loss of motor neurons in the brain and spinal cord. Post-mortem analyses of ALS patients reveal ubiquitinated protein aggregates in motor neurons. Currently, we do not know whether these aggregates are toxic, protective or merely an epiphenomenon of the disease. ALS-associated aggregates often stain positive for Sequestosome-1 (SQSTM1/p62), a ubiquitin binding protein that plays a role in proteasome and autophagy mediated degradation. While some other components of these aggregates are known, a complete proteomic characterization is not currently available. Furthermore, the role of p62 in aggregate formation and degradation is not well understood. The SOD1 G93A mouse model recapitulates many features of ALS, including the accumulation of p62-positive aggregates in motor neurons. To better understand the biological significance of these structures, I have optimized an approach for immunoprecipitating p62 from the SOD1 G93A spinal cord. Preliminary mass spectrometry analysis of these immunoprecipitates reveals that Valosin-containing protein (VCP) is present in p62-positive aggregates. I plan to build on this finding by using unbiased proteomics to identify other p62-interacting proteins. I have also discovered that p62 is phosphorylated in the SOD1 G93A spinal cord, and I will test how this post-translational modification regulates p62 function. Lastly, I will determine the role of p62 in vivo by breeding SOD1 G93A mice to p62 knockout mice and monitoring the disease phenotype.

Public Health Relevance

Characterizing the composition of p62-positive aggregates in a mouse model of Amyotrophic Lateral Sclerosis (ALS) may reveal novel disease mechanisms. Genetic deletion of p62 will help determine whether p62 itself is an important contributor to ALS pathogenesis. The identification of disease mechanisms may lead to improved therapies and quality of life for ALS patients.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
5F31NS089131-02
Application #
8879997
Study Section
NST-2 Subcommittee (NST)
Program Officer
Gubitz, Amelie
Project Start
2014-07-01
Project End
2016-06-30
Budget Start
2015-07-01
Budget End
2016-06-30
Support Year
2
Fiscal Year
2015
Total Cost
Indirect Cost
Name
Columbia University (N.Y.)
Department
Biochemistry
Type
Schools of Medicine
DUNS #
621889815
City
New York
State
NY
Country
United States
Zip Code
10032
Rudnick, Noam D; Griffey, Christopher J; Guarnieri, Paolo et al. (2017) Distinct roles for motor neuron autophagy early and late in the SOD1G93A mouse model of ALS. Proc Natl Acad Sci U S A 114:E8294-E8303