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Proc Natl Acad Sci U S A. 2016 Aug 9;113(32):E4708-15. doi: 10.1073/pnas.1601091113. Epub 2016 Jul 25.

The neural chaperone proSAAS blocks α-synuclein fibrillation and neurotoxicity.

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School of Medicine, University of Maryland, Baltimore, MD 21201;
Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA 90024;
Interdisciplinary Nanoscience Centre (iNANO), Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus C, Denmark;
Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224.
School of Medicine, University of Maryland, Baltimore, MD 21201;


Emerging evidence strongly suggests that chaperone proteins are cytoprotective in neurodegenerative proteinopathies involving protein aggregation; for example, in the accumulation of aggregated α-synuclein into the Lewy bodies present in Parkinson's disease. Of the various chaperones known to be associated with neurodegenerative disease, the small secretory chaperone known as proSAAS (named after four residues in the amino terminal region) has many attractive properties. We show here that proSAAS, widely expressed in neurons throughout the brain, is associated with aggregated synuclein deposits in the substantia nigra of patients with Parkinson's disease. Recombinant proSAAS potently inhibits the fibrillation of α-synuclein in an in vitro assay; residues 158-180, containing a largely conserved element, are critical to this bioactivity. ProSAAS also exhibits a neuroprotective function; proSAAS-encoding lentivirus blocks α-synuclein-induced cytotoxicity in primary cultures of nigral dopaminergic neurons, and recombinant proSAAS blocks α-synuclein-induced cytotoxicity in SH-SY5Y cells. Four independent proteomics studies have previously identified proSAAS as a potential cerebrospinal fluid biomarker in various neurodegenerative diseases. Coupled with prior work showing that proSAAS blocks β-amyloid aggregation into fibrils, this study supports the idea that neuronal proSAAS plays an important role in proteostatic processes. ProSAAS thus represents a possible therapeutic target in neurodegenerative disease.


Parkinson’s disease; chaperones; neurodegeneration; proSAAS; synuclein

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