SMG1 identified as a regulator of Parkinson's disease-associated alpha-synuclein through siRNA screening.

Abstract

Synucleinopathies are a broad class of neurodegenerative disorders characterized by the presence of intracellular protein aggregates containing α-synuclein protein. The aggregated α-synuclein protein is hyperphosphorylated on serine 129 (S129) compared to the unaggregated form of the protein. While the precise functional consequences of S129 hyperphosphorylation are still being clarified, numerous in vitro and in vivo studies suggest that S129 phosphorylation is an early event in α-synuclein dysfunction and aggregation. Identifying the kinases and phosphatases that regulate this critical phosphorylation event may ultimately prove beneficial by allowing pharmacological mitigation of synuclein dysfunction and toxicity in Parkinson's disease and other synucleinopathies. We report here the development of a high-content, fluorescence-based assay to quantitate levels of total and S129 phosphorylated α-synuclein protein. We have applied this assay to conduct high-throughput loss-of-function screens with siRNA libraries targeting 711 known and predicted human kinases and 206 phosphatases. Specifically, knockdown of the phosphatidylinositol 3-kinase related kinase SMG1 resulted in significant increases in the expression of pS129 phosphorylated α-synuclein (p-syn). Moreover, SMG1 protein levels were significantly reduced in brain regions with high p-syn levels in both dementia with Lewy bodies (DLB) and Parkinson's disease with dementia (PDD). These findings suggest that SMG1 may play an important role in increased α-synuclein pathology during the course of PDD, DLB, and possibly other synucleinopathies.

• Authors: Adrienne Henderson-Smith, Donald Chow, Bessie Meechoovet, Meraj Aziz, Sandra A Jacobson, Holly A Shill, Marwan N Sabbagh, John N Caviness, Charles H Adler, Erika D Driver-Dunckley, Thomas G Beach, Hongwei Yin, Travis Dunckley
• Journal: PloS one (PLoS One) Vol. 8 Issue 10 Pg. e77711 ( 2013) ISSN: 1932-6203 [Electronic] United States
• PMID: 24204929 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Poly(A)-Binding Proteins
• RNA, Small Interfering
• T-Cell Intracellular Antigen-1
• TIA1 protein, human
• Tumor Suppressor Protein p53
• alpha-Synuclein
• Protein Serine-Threonine Kinases
• SMG1 protein, human

Topics

• Brain (metabolism)
• Cells, Cultured
• Dementia (genetics, metabolism)
• Down-Regulation (genetics)
• Humans
• Lewy Body Disease (genetics, metabolism)
• Parkinson Disease (genetics, metabolism)
• Phosphatidylinositol 3-Kinases (genetics, metabolism)
• Phosphorylation (genetics)
• Poly(A)-Binding Proteins (genetics, metabolism)
• Protein Serine-Threonine Kinases
• RNA, Small Interfering (genetics, metabolism)
• T-Cell Intracellular Antigen-1
• Tumor Suppressor Protein p53 (genetics, metabolism)
• alpha-Synuclein (genetics, metabolism)