Effect of Trehalose on the Properties of Mutant γPKC, Which Causes Spinocerebellar Ataxia Type 14, in Neuronal Cell Lines and Cultured Purkinje Cells*

Abstract

Several missense mutations in the protein kinase C␥ (␥PKC) gene have been found to cause spinocerebellar ataxia type 14 (SCA14), an autosomal dominant neurodegenerative disease. We previously demonstrated that the mutant ␥PKC found in SCA14 is susceptible to aggregation, which induces apoptotic cell death. The disaccharide trehalose has been reported to inhibit aggregate formation and to alleviate symptoms in cellular and animal models of Huntington disease, Alzheimer disease, and prion disease. Here, we show that trehalose can be incorporated into SH-SY5Y cells and reduces the aggregation of mutant ␥PKC-GFP, thereby inhibiting apoptotic cell death in SH-SY5Y cells and primary cultured Purkinje cells (PCs). Trehalose acts by directly stabilizing the conformation of mutant ␥PKC without affecting protein turnover. Trehalose was also found to alleviate the improper development of dendrites in PCs expressing mutant ␥PKC-GFP without aggregates but not in PCs with aggregates. In PCs without aggregates, trehalose improves the mobility and translocation of mutant ␥PKC-GFP, probably by inhibiting oligomerization and thereby alleviating the improper development of dendrites. These results suggest that trehalose counteracts various cellular dysfunctions that are triggered by mutant ␥PKC in both neuronal cell lines and primary cultured PCs by inhibiting oligomerization and aggregation of mutant ␥PKC.

Trehalose reduces retinal degeneration, neuroinflammation and storage burden caused by a lysosomal hydrolase deficiency

“…Trehalose has peculiar physical-chemical properties that confer chaperone-like activities [42], such as the ability to stabilize mutant proteins [41,42,58]. Moreover, protein aggregates in neurodegenerative diseases are substrates of autophagy [21,36,59,60], a pathway that is enhanced by trehalose [30–40].…”

Elucidation of the Molecular Mechanism and Exploration of Novel Therapeutics for Spinocerebellar Ataxia Caused by Mutant Protein Kinase Cγ

“…Therefore, compounds that are effective for the treatment of SCA14 could be available for the treatment of other neurodegenerative disorders. Because mutant γPKC-GFP rapidly induced aggregation and apoptosis within a few days in SH-SY5Y cells (31), this screening system could be beneficial for the exploration of novel candidates for therapeutics against SCA14, and these candidates might be effective for other neurodegenerative diseases.…”

“…We have recently demonstrated that trehalose inhibits aggregation and apoptosis induction of mutant γPKC in SH-SY5Y cells and primary cultured PCs (31). Because the inhibition of apoptosis was not observed in PCs with preformed aggregates before trehalose treatment, this effect was mediated by the aggregation inhibitory property of trehalose.…”

“…3, lower panels). In PCs without aggregates, trehalose alleviated the reduced mobility and the attenuated translocation of mutant γPKC (31), which suggested that trehalose ameliorated the dendritic development of PCs through the inhibition of oligomerization of mutant γPKC. Because trehalose is effective by oral administration in a mouse model of Huntington's disease (30), it could reach the brain parenchyma through the bloodbrain barrier (BBB) and be available as a novel therapeutic for the treatment of SCA14.…”

“…Bar = 20 μm. This figure was reproduced from the original publication (31) with permission from the American Society for Biochemistry and Molecular Biology.…”