Identification of Ser465 as a novel PINK1 autophosphorylation site.

BACKGROUND: PINK1 (PTEN-induced putative kinase 1) gene is the causal gene for recessive familial type 6 of Parkinson's disease (PARK6), which is an early-onset autosomal recessive inherited neurodegenerative disease. PINK1 has been reported to exert both autophosphorylation and phosphorylation activity, affecting cell damage under stress and other physiological responses. However, there has been no report on the identification of PINK1 autophosphorylation sites and their physiological functions. METHODS: (1) We adopted mass spectrometry assay to identify the autophosphorylation site of PINK1, and autoradiography assay was further conducted to confirm this result. (2) Kinase activity assay was used to compare the kinase activity of both Ser465 mutant PINK1 and disease-causing mutant PINK1. (3) We use Pulse-chase analysis to measure whether Ser465 may affect PINK1 degradation. (4) Immunocytochemistry staining was used to study the PINK1 subcellular localization and Parkin transition in subcellular level. RESULT: In our study, we identified the 465th serine residue (Ser465) as one of the autophosphorylation sites in PINK1 protein. The inactivation of Ser465 can decrease the kinase activity of PINK1. Either dissipated or excessive Ser465 site phosphorylation of PINK1 can slow down its degradation. PINK1 autophosphorylation contributes to the transit of Parkin to mitochondria, and has no effect on its subcellular localization. PARK6 causal mutations, T313 M and R492X, display the same characteristics as Ser465A mutation PINK1 protein, such as decreasing PINK1 kinase activity and affecting its interaction with Parkin. CONCLUSION: Ser465 was identified as one of the autophosphorylation sites of PINK1, which affected PINK1 kinase activity. In addition, Ser465 is involved in the degradation of PINK1 and the transit of Parkin to mitochondria. T313 M and R492X, two novel PARK6 mutations on Thr313 and Arg492, were similar to Ser465 mutation, including decreasing PINK1 phosphorylation activity and Parkin subcellular localization.

Relationship between Alzheimer's disease GWAS-linked top hits and risk of Parkinson's disease with or without cognitive decline: a Chinese population-based study.

Alzheimer's disease (AD), Parkinson's disease (PD), and cognitive impairment in PD have overlapping clinical and pathological features. To examine whether there is a genetic link for these diseases, we performed a case-control study in Chinese population to evaluate the association of AD genome-wide association studies top hits with both PD and cognitive function in PD, investigating 13 single-nucleotide polymorphisms in 9 genes (BIN1, CLU, ABCA7, CR1, PICALM, MS4A6A, CD33, MS4A4E, and CD2AP). A total of 454 controls and 442 PD patients were genotyped, including 75 mild cognitive impairment and 99 dementia. As a result, no significant association of the AD-susceptibility loci was identified in PD cases, PD-dementia, or PD-mild cognitive impairment. Our findings imply that the 13 single-nucleotide polymorphisms from AD genome-wide association studies may not play major role in the genetic predisposition with PD and cognitive function in PD in a Chinese population.