In summary, our footprint-free LRRK2-G2019S isogenic cell lines allow standardized, genetic background independent, in vitro PD modeling and provide new insights into the role of LRRK2-G2019S and S129P-αS in the pathogenesis of PD.
Alpha-synuclein was implicated in Parkinson's disease when missense mutations in the alpha-synuclein gene were found in autosomal dominant Parkinson's disease and alpha-synuclein was shown to be a major constituent of protein aggregates in sporadic Parkinson's disease and other synucleinopathies.
No mutations were found in any of the patients, suggesting that a mutation at the coding region of the alpha-synuclein gene is unlikely to be responsible for nigrostriatal degeneration in typical sporadic Parkinson's disease.
We found that the levels of these interactions were aberrantly increased by the I93M mutation, and that expression of I93M UCH-L1 in cells induced the CMA inhibition-associated increase in the amount of alpha-synuclein, a risk factor for PD.
Furthermore, to enhance the pathological properties of α-synuclein, we inserted into SNCA an A53T mutation, two single-nucleotide polymorphisms identified in a genome-wide association study in Parkinson's disease and a Rep1 polymorphism, all of which are causal of familial Parkinson's disease or increase the risk of sporadic Parkinson's disease.
Increased availability of the fibrillogenic protein substrates of the pathological aggregates that define several neurodegenerative proteopathies, eg α-synuclein in PD, β-amyloid in AD and tau in the tauopathies, contributes to causation and risk in the familial and sporadic forms of these disorders, respectively.
Alpha-synuclein accumulates in the brains of sporadic Parkinson's disease patients as a major component of Lewy bodies, and mutations in alpha-synuclein are associated with familial forms of Parkinson's disease.
A recent study showed significant association of sporadic Parkinson's disease with a polymorphism within the alpha-synuclein gene and closely linked DNA markers on chromosome 4q and the APOE epsilon4 allele.