Mammalian ribosomal and chaperone protein RPS3A counteracts α-synuclein aggregation and toxicity in a yeast model system

Stijn De Graeve,Johan M Thevelein,Sarah Marinelli,Yves Engelborghs,Jelle Hendrix,Patrick Van Dijck,Frank Stolz,Jurgen Vandamme

doi:10.1042/bj20130417

Stijn De Graeve, Johan M Thevelein + Show 6 more

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https://doi.org/10.1042/bj20130417

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Abstract

Accumulation of aggregated forms of αSyn (α-synuclein) into Lewy bodies is a known hallmark associated with neuronal cell death in Parkinson's disease. When expressed in the yeast Saccharomyces cerevisiae, αSyn interacts with the plasma membrane, forms inclusions and causes a concentration-dependent growth defect. We have used a yeast mutant, cog6Δ, which is particularly sensitive to moderate αSyn expression, for screening a mouse brain-specific cDNA library in order to identify mammalian proteins that counteract αSyn toxicity. The mouse ribosomal and chaperone protein RPS3A was identified as a suppressor of αSyn [WT (wild-type) and A53T] toxicity in yeast. We demonstrated that the 50 N-terminal amino acids are essential for this function. The yeast homologues of RPS3A were not effective in suppressing the αSyn-induced growth defect, illustrating the potential of our screening system to identify modifiers that would be missed using yeast gene overexpression as the first screening step. Co-expression of mouse RPS3A delayed the formation of αSyn–GFP inclusions in the yeast cells. The results of the present study suggest that the recently identified extraribosomal chaperonin function of RPS3A also acts on the neurodegeneration-related protein αSyn and reveal a new avenue for identifying promising candidate mammalian proteins involved in αSyn functioning.

Highlights

Since the discovery that a point mutation (A53T) in SNCA, the gene encoding αSyn (α-synuclein), causes an autosomal dominant form of PD (Parkinson’s disease) [1], there has been a strong interest in the physiological function of this protein and its connection with PD. αSyn is a highly conserved, vertebratespecific, 140-amino-acid protein that consists of an amphipathic N-terminal domain, an internal hydrophobic region and an acidic C-terminal tail
A strong growth defect was observed in the vps52 strain, but the cog6 strain was most sensitive to galactose-induced expression of αSyn (Figure 1A)
In the present study we show that mouse ribosomal protein S3A (RPS3A) can counteract toxicity caused by human WT αSyn, in several αSyn-sensitive yeast deletion mutants, as well as in WT cells treated with DMSO or ZnSO4, a strong indication that RPS3A directly affects αSyn, rather than reducing the sensitivity of the yeast cells

Summary

Introduction

Since the discovery that a point mutation (A53T) in SNCA, the gene encoding αSyn (α-synuclein), causes an autosomal dominant form of PD (Parkinson’s disease) [1], there has been a strong interest in the physiological function of this protein and its connection with PD. αSyn is a highly conserved, vertebratespecific, 140-amino-acid protein that consists of an amphipathic N-terminal domain, an internal hydrophobic region and an acidic C-terminal tail. Since the discovery that a point mutation (A53T) in SNCA, the gene encoding αSyn (α-synuclein), causes an autosomal dominant form of PD (Parkinson’s disease) [1], there has been a strong interest in the physiological function of this protein and its connection with PD. Additional point mutations (A30P and E46K) in αSyn and mutations that lead to increased αSyn expression have been linked to autosomal dominant PD (as reviewed in [4]). Cytosolic protofibrils are thought to inhibit proteasomal protein degradation [10]. In dopamineproducing neurons these events lead to cell death through pathways that involve oxidative stress, mitochondrial dysfunction, ER stress and accumulation of misfolded proteins (as reviewed in [11])

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