Characterization of detergent-insoluble proteins in ALS indicates a causal link between nitrative stress and aggregation in pathogenesis.
BACKGROUND
Amyotrophic lateral sclerosis (ALS) is a progressive and fatal motor neuron disease, and protein aggregation has been proposed as a possible pathogenetic mechanism. However, the aggregate protein constituents are poorly characterized so knowledge on the role of aggregation in pathogenesis is limited.


RESULTS
We carried out a proteomic analysis of the protein composition of the insoluble fraction, as a model of protein aggregates, from familial ALS (fALS) mouse model at different disease stages. We identified several proteins enriched in the detergent-insoluble fraction already at a preclinical stage, including intermediate filaments, chaperones and mitochondrial proteins. Aconitase, HSC70 and cyclophilin A were also significantly enriched in the insoluble fraction of spinal cords of ALS patients. Moreover, we found that the majority of proteins in mice and HSP90 in patients were tyrosine-nitrated. We therefore investigated the role of nitrative stress in aggregate formation in fALS-like murine motor neuron-neuroblastoma (NSC-34) cell lines. By inhibiting nitric oxide synthesis the amount of insoluble proteins, particularly aconitase, HSC70, cyclophilin A and SOD1 can be substantially reduced.


CONCLUSIONS
Analysis of the insoluble fractions from cellular/mouse models and human tissues revealed novel aggregation-prone proteins and suggests that nitrative stress contribute to protein aggregate formation in ALS.
Basso
Manuela
M
Dulbecco Telethon Institute, Milan, Italy.
Samengo
Giuseppina
G
Nardo
Giovanni
G
Massignan
Tania
T
D'Alessandro
Giuseppina
G
Tartari
Silvia
S
Cantoni
Lavinia
L
Marino
Marianna
M
Cheroni
Cristina
C
De Biasi
Silvia
S
Giordana
Maria Teresa
MT
Strong
Michael J
MJ
Estevez
Alvaro G
AG
Salmona
Mario
M
Bendotti
Caterina
C
Bonetto
Valentina
V
D000154:Aconitate Hydratase / Q000378:metabolism / Q000648:ultrastructure; D019943:Amino Acid Substitution / Q000235:genetics; D000690:Amyotrophic Lateral Sclerosis / Q000201:enzymology / Q000473:pathology*; D000818:Animals; D003902:Detergents / Q000494:pharmacology*; D004195:Disease Models, Animal; D018450:Disease Progression; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D020836:Protein Structure, Quaternary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D040901:Proteomics; D015203:Reproducibility of Results; D012995:Solubility / Q000187:drug effects; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013116:Spinal Cord / Q000187:drug effects / Q000648:ultrastructure; D013312:Stress, Physiological / Q000187:drug effects*; D013482:Superoxide Dismutase / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D003902:Detergents; D011506:Proteins; C000606290:SOD1 protein, human; C002744:3-nitrotyrosine; D014443:Tyrosine; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D000154:Aconitate Hydratase; D019331:NG-Nitroarginine Methyl Ester