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Spinocerebellar Ataxia type 2 (Atxn2); mass spectrometry; proteome profiling; metabolome profiling; multiple reaction monitoring (MRM); protein - protein interaction network
(PPI) analysis; pathway analysis
Abstract:
Human Ataxin-2 (ATXN2) gene locus variants have been associated with obesity, diabetes mellitus type 1 and hypertension in genome-wide association studies, while mouse studies
showed the knock-out of Atxn2
to lead to obesity, insulin resistance and dyslipidemia.
Intriguingly, the deficiency of ATXN2 protein orthologues in yeast and flies rescues the neurodegeneration process triggered by TDP-43 and Ataxin-1 toxicity. To understand the
molecular effects of ATXN2 deficiency by unbiased approaches, we quantified the global proteome and metabolome of
Atxn2-knock-out mice with label-free mass spectrometry. In liver tissue, significant downregulations of the proteins ACADS, ALDH6A1, ALDH7A1, IVD, MCCC2,
PCCA, OTC, together with bioinformatic enrichment of downregulated pathways for branched chain and other amino acid metabolism, fatty acids and citric acid cycle were observed.
Statistical trends in the cerebellar proteome and in the metabolomic profiles supported these
findings. They are in good agreement with recent claims that PBP1, the yeast orthologue of ATXN2, sequestrates the nutrient sensor TORC1 in periods of cell stress. Overall, ATXN2 appears to modulate nutrition and metabolism, and its activity changes are determinants of
growth excess or cell atrophy.
