Erythrocytic α-Synuclein as a potential biomarker for Parkinson’s disease

Background:Erythrocytes are a major source of peripheralα-synuclein(α-Syn).The goal of the current investigation is to evaluate erythrocytic total,oligomeric/aggregated,and phosphorylatedα-Syn species as biomarkers of Parkinson’s disease(PD).PD and healthy control blood samples were collected along with extensive clinical history to determine whether total,phosphorylated,or aggregatedα-Syn derived from erythrocytes(the major source of bloodα-Syn)are more promising and consistent biomarkers for PD than are freeα-Syn species in serum or plasma.Methods:Using newly developed electrochemiluminescence assays,concentrations of erythrocytic total,aggregated and phosphorylated at Ser129(pS129)α-Syn,separated into membrane and cytosolic components,were measured in 225 PD patients and 133 healthy controls and analyzed with extensive clinical measures.Results:The total and aggregatedα-Syn levels were significantly higher in the membrane fraction of PD patients compared to healthy controls,but without alterations in the cytosolic component.The pS129 level was remarkably higher in PD subjects than in controls in the cytosolic fraction,and to a lesser extent,higher in the membrane fraction.Combining age,erythrocytic membrane aggregatedα-Syn,and cytosolic pS129 levels,a model generated by using logistic regression analysis was able to discriminate patients with PD from neurologically normal controls,with a sensitivity and a specificity of 72 and 68%,respectively.Conclusions:These results suggest that total,aggregated and phosphorylatedα-Syn levels are altered in PD erythrocytes and peripheral erythrocyticα-Syn is a potential PD biomarker that needs further validation.

Methylation status of DJ-1 in leukocyte DNA of Parkinson’s disease patients

Background:DJ-1 has been thought as a candidate biomarker for Parkinson’s disease(PD).It was found reduced in PD brains,CSF and saliva,although there were conflicting results.How DJ-1 expression may be regulated is not clear.Recently,blood-based DNA methylation represents a highly promising biomarker for PD by regulating the causative gene expression.Thus,in this study,we try to explore whether blood-based DNA methylation of DJ-1 could be used as a biomarker to differentiate PD patients from normal control(NC),and whether DNA methylation could regulate DJ-1 expression in a SH-SY5Y cell model.Methods:Forty PD patients and 40 NC were recruited in this study.DNA was extracted from peripheral blood leukocytes(PBLs).Methylation status of two CpG islands(CpG1 and CpG2)in promoter region of DJ-1 was explored by bisulfite specific PCR-based sequencing method.Methylation inhibitor 5-Aza-dC was used to treat SH-SY5Y cell line,DJ-1 level was detected in both mRNA and protein level.Results:CpG sites in these two CpG islands(CpG1 and CpG2)of DJ-1 were unmethylated in both PD and NC group.In SH-SY5Y cell model treated by methylation inhibitor,there was no significant change of DJ-1 expression in either mRNA level or protein level.Conclusions:Our results indicated that DNA methylation inhibitor didn’t alter DJ-1 gene expression in SH-SY5Y cell model,and DNA methylation of DJ-1 promoter region in PBLs level might not be an efficient biomarker for PD patients.

Different Gene Networks Are Disturbed by Zika Virus Infection in A Mouse Microcephaly Model

The association of Zika virus(ZIKV)infection with microcephaly has raised alarm worldwide.Their causal link has been confirmed in different animal models infected by ZIKV.However,the molecular mechanisms underlying ZIKV pathogenesis are far from clear.Hence,we performed global gene expression analysis of ZIKV-infected mouse brains to unveil the biological and molecular networks underpinning microcephaly.We found significant dysregulation of the sub-networks associated with brain development,immune response,cell death,microglial cell activation,and autophagy amongst others.We provided detailed analysis of the related complicated gene networks and the links between them.Additionally,we analyzed the signaling pathways that were likely to be involved.This report provides systemic insights into not only the pathogenesis,but also a path to the development of prophylactic and therapeutic strategies against ZIKV infection.

Rare TBK1 variants in patients with frontotemporal dementia and amyotrophic lateral sclerosis in a Chinese cohort

Background:The TANK-Binding Kinase 1(TBK1)gene has recently been identified as the third or fourth most frequent cause of frontotemporal dementia(FTD)and amyotrophic lateral sclerosis(ALS).The aim of this study was to assess the genetic contribution of TBK1 in a Chinese cohort.Methods:A total of 270 cases with ALS,FTD,or their combination were recruited into this study.All the coding exons of TBK1 and intron-exon boundaries were sequenced using Sanger sequencing.The frequency of TBK1 variants and the correlation with clinical phenotypes were analyzed.Results:A novel mutation(c.1959_1960insGT,p.E653fs)was identified in a sporadic case with semantic dementia,secondarily developing ALS.Another novel variant(c.2063_2064delTT,p.L688Rfs*14)was found in an ALS-FTD family.Totally,the TBK1 variants could only account for 0.7% of cases.Conclusions:This study enlarges the genetic and phenotypic spectrum of TBK1 mutation in a Chinese cohort.Our data indicates that TBK1 mutation is not a common cause for ALS and FTD in Chinese patients.

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.