DNA versus RNA oxidation in Parkinson's disease: Which is more important?

BACKROUND: 8-hydroxy-2 deoxyguanosine (8-OHdG) and the 8-hydroxyguanosine (8-OHG) are the most widely used biomarkers of nucleoside oxidation affecting DNA and RNA and are considered reliable markers of oxidative stress. Increased levels of these markers are found in the various biological fluids of patients with neurodegenerative disorders. OBJECTIVE: The primary aim of our study was to assess the differences of investigated markers between patient groups and subsequently study the influence of clinical factors that might modify the levels of investigated markers during the disease progression. METHODS: In this study, we analysed the 8-OHdG and 8-OHG levels in the cerebrospinal fluid (CSF) and serum from 44 patients with Parkinson's disease (PD) and 32 controls using an ELISA. RESULTS: There were significantly higher CSF levels of both investigated markers in Parkinson's disease patients as compared to controls (p=0.02 and p=0.04). Significantly higher CSF values of 8-OHdG were found in PD patients without dementia (p=0.05), whereas patients with dementia recorded lower 8-OHG CSF levels compared to controls (p=0.04). The disease duration and age influenced the levels of both markers within investigated groups. CONCLUSION: Oxidative DNA damage plays an important role in the early stages of PD, whereas during the progression of the disease the process is more complex, and other mechanisms are in the foreground. The measurement of 8-OHdG might be used as an "early-stage marker", whereas the decrease of 8-OHG in CSF might reflect the degree of neurodegeneration during the disease progression, suggesting its utility as a prognostic marker of advanced PD stages.

Cerebrospinal fluid markers in the differentiation of molecular subtypes of sporadic Creutzfeldt-Jakob disease.

BACKGROUND AND PURPOSE: Cerebrospinal fluid (CSF) analysis supports the clinical diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD) when applied within an adequate clinical context. A diagnostic potential has been attributed to CSF proteins such as 14-3-3, but also tau protein, phosphorylated tau (181P) (p-tau) protein, amyloid ß1-42 , S100B and neuron-specific enolase (NSE). There has been only limited information available about the contribution of CSF analysis in the differentiation of various molecular sCJD subtypes. METHODS: The CSF levels of the aforementioned proteins from 73 sCJD patients with distinct molecular subtypes were determined. RESULTS: Differences in tau values were significant amongst the homozygous patients (MM and VV genotype) compared to the heterozygous group (P = 0.07 and P = 0.02 respectively). Significantly higher CSF tau levels (P = 0.003) and NSE (P = 0.02) but lower p-tau/tau ratio (P = 0.01) were observed in MM1 compared to MM2 patients. The p-tau/tau ratio enabled the differentiation of MV genotype with higher levels in PrP(sc) type 2 (P = 0.04). Elevation of S100B (P < 0.001) and NSE (P = 0.03) was observed in VV2 compared to VV1 subtype. PRNP codon 129 genotype, PrP(sc) isotype, disease duration and clinical stage influenced the test sensitivity in all proteins. CONCLUSIONS: Cerebrospinal fluid protein levels might be useful in the pre-mortem differentiation of molecular sCJD subtypes when the codon 129 genotype is known.

Cellular prion protein overexpression disturbs cellular homeostasis in SH-SY5Y neuroblastoma cells but does not alter p53 expression: a proteomic study.

The definite physiological role of the cellular prion protein (PrP(c)) remains elusive. There is ample in vitro and in vivo evidence suggesting a neuroprotective role for PrP(c). On the other hand, several in vitro and in vivo studies demonstrated detrimental effects of PrP(c) overexpression through activation of a p53 pathway. Recently, we reported that transient overexpression of PrP(c) in human embryonic kidney 293 cells elicits proteome expression changes which point to deregulation of proteins involved in energy metabolism and cellular homeostasis. Here we report proteome expression changes following stable PrP(c) overexpression in human neuronal SH-SY5Y cells. In total 18 proteins that are involved in diverse biological processes were identified as differentially regulated. The majority of these proteins is involved in cell signaling, cytoskeletal organization and protein folding. Annexin V exhibited a several fold up-regulation following stable PrP(c) overexpression in SH-SY5Y cells. This finding has been reproduced in alternative, mouse N2a and human SK-N-LO neuroblastoma cell lines transiently overexpressing PrP(c). Annexin V plays an important role in maintenance of calcium homeostasis which when disturbed can activate a p53-dependent cell death. Although we did not detect changes in p53 expression between PrP(c) overexpressing SH-SY5Y and control cells, deregulation of several proteins including annexin V, polyglutamine tract-binding protein-1, spermine synthase and transgelin 2 indicates disrupted cellular equilibrium. We conclude that stable PrP(c) overexpression in SH-SY5Y cells is sufficient to perturb cellular balance but insufficient to affect p53 expression.

8-OHdG in cerebrospinal fluid as a marker of oxidative stress in various neurodegenerative diseases.

BACKGROUND: The 8-hydroxy-2 deoxyguanosine (8-OHdG) is a product of nucleoside oxidation of DNA and a reliable marker of oxidative stress markers. Increased levels of oxidative stress have been reported in the cerebrospinal fluid (CSF) of patients with various neurodegenerative disorders. OBJECTIVE: In search of a biochemical indicator of Parkinson's disease (PD), we analyzed the levels 8-OHdG in the CSF of 99 patients, using ELISA to assess the differences between various neurodegenerative disorders. RESULTS: Statistically significant higher CSF levels (p = 0.022) of 8-OHdG in non-demented PD patients as compared to the control group were observed. No differences between CSF 8-OHdG levels and age at the time of lumbar puncture, presence or severity of dementia, or gender were found. CONCLUSIONS: 8-OHdG levels could be potentially useful in the neurochemically supported diagnosis of PD.