Annica Sjölander

Ubiquitin carboxy-terminal hydrolase L1 (UCHL1) S18Y polymorphism in Alzheimer's disease

Alzheimers disease (AD) is characterized by protein aggregates, i.e. senile plaques and neurofibrillary tangles. The ubiquitin-proteasome system has been proposed a role in proteolytic removal of these protein aggregates. Ubiquitin carboxy-terminal hydrolase L1 (UCHL1) is a de-ubiquitinating enzyme with important functions in recycling of ubiquitin. The S18Y polymorphism of the UCHL1 gene confers protection against Parkinsons disease. In this study, the genotype and allele frequencies of the UCHL1 S18Y polymorphism were investigated in 452 AD patients and 234 control subjects, recruited from four memory clinics in Sweden. Using a binary logistic regression model including UCHL1 allele A and APOE ε4 allele positivity, age and sex as covariates with AD diagnosis as dependent variable, an adjusted OR of 0.82 ([95% CI 0.55-1.24], P = 0.35) was obtained for a positive UCHL1 allele A carrier status. The present study thus do not support a protective effect of the UCHL1 S18Y polymorphism against AD.

Genetic Variants of GSK3B are Associated with Biomarkers for Alzheimer's Disease and Cognitive Function.

BACKGROUND Glycogen synthase kinase 3 beta (GSK3B) is the major kinase phosphorylating tau protein. Hyperphosphorylated tau is one of the hallmarks of Alzheimers disease (AD). Despite extensive research, the role of GSK3B in AD pathogenesis is not fully understood. OBJECTIVE To evaluate possible associations between gene variants of GSK3B and risk of AD. METHODS Twelve GSK3B tag single-nucleotide polymorphisms (SNPs), together with the previously AD-associated rs334558, were analyzed in 583 AD patients and 673 controls. Analyses on single marker and haplotype levels were done to relate to risk of AD, Mini-Mental State Examination (MMSE) scores, and cerebrospinal fluid (CSF) biomarker levels of total tau (T-tau), hyperphosphorylated tau (P-tau181), and amyloid-β (Aβ42). RESULTS After correction for multiple testing, we found a number of associations of gene variants with CSF biomarker levels and cognitive function in the AD patients. Firstly, rs334558 was associated with elevated T-tau levels (pc = 0.04). Next, rs1154597 showed association with reduced Aβ42 levels (pc = 0.007). Lastly, rs3107669 was associated with lower MMSE scores (pc = 0.03). In addition, one more SNP was nominally significantly associated with reduced Aβ42 levels and another was associated with reduced MMSE. CONCLUSION We found GSK3B gene variants associated with cognitive function and CSF biomarkers T-tau and Aβ42. To our knowledge, this is the first time GSK3B has been associated with cognitive function or CSF biomarkers reflecting neuronal degeneration (T-tau) and brain amyloid load (Aβ42). The regulation of GSK3B needs to be investigated further, to fully understand how these GSK3B gene variants are involved in AD pathogenesis.

The PPAR-alpha gene in Alzheimer's disease: Lack of replication of earlier association

Recently, a single nucleotide polymorphism (SNP, rs1800206) in the peroxisome proliferator-activated receptor alpha (PPAR-alpha) gene has been proposed to be associated with Alzheimers disease (AD). To verify this finding, we analyzed the PPAR-alpha SNP in 461 patients with AD and 1395 controls. In subgroups, PPAR-alpha gene data could be investigated in relation to biochemical and neuropathological markers for AD. We found no significant differences in genotype or allele distributions between AD patients and controls. None of the PPAR-alpha gene variants influenced markers for AD.

Ubiquitin Carboxyl-Terminal Esterase L1 (UCHL1) S18Y Polymorphism In Patients With Cataracts

Background: Cataract is characterized by light-scattering protein aggregates. The ubiquitin-proteasome system has been proposed a role in proteolytic removal of these protein aggregates. Ubiquitin carboxyl-terminal esterase L1 (UCHL1) is a de-ubiquitinating enzyme with important functions in recycling of ubiquitin. A protective role of the p.S18Y polymorphism of the UCHL1 gene has been shown in Parkinson`s disease. The current study aimed to examine possible effects on cataract formation. Methods: Patients with cataract (n = 493) and controls (n = 142) were analyzed for the UCHL1 p.S18Y polymorphism using dynamic allele-specific hybridization. Results: Significant differences were observed in allele and genotype frequencies of the p.S18Y polymorphism between controls and cataract patients, where a positive UCHL1 allele A carrier status was associated with the cataract diagnosis (adjusted OR 1.7 [95% CI = 1.1–2.6] p = 0.02). No significant differences were seen in genotype distribution when stratifying for type of cataract. Nor did the mean age at cataract surgery differ between genotypes. Conclusion: The current study does not support a protective role for the UCHL1 S18Y polymorphism in cataract development, but may instead suggest a disease-promoting effect.

Genetic Variation of Superoxide Dismutases in Patients with Primary Open-angle Glaucoma

Abstract Purpose: Oxidative stress has been described as an underlying pathogenetic mechanism in retinal ganglion cell apoptosis, which is a hallmark of primary open-angle glaucoma (POAG). Superoxide dismutases (SODs) are enzymes involved in the protection against oxidative stress by detoxification of superoxide. In this study, we investigated a number of disease-associated single nucleotide polymorphisms (SNPs) in the copper-zinc-containing SOD1 and SOD3, and in the manganese superoxide dismutase SOD2, in POAG patients. Methods: The study included 239 patients with POAG and 185 controls, all of Estonian origin, recruited at two ophthalmic clinics in Tartu, Estonia. Eleven SNPs, either functional, disease-associated or tag SNPs in SOD1, SOD2 and SOD3 were genotyped using TaqMan Allelic Discrimination. Haplotype analysis was performed on the SNPs in SOD2. Results: Using binary logistic regression in an additive model, the rs2842980 SNP in SOD2 was significantly associated with POAG diagnosis (p = 0.03) at a univariate level. None of the studied SNPs showed an association with risk of POAG in a multivariate analysis, including age and current smoking as covariates. Analysis of SOD2 haplotypes did not show any association with risk of POAG. Conclusions: If oxidative stress is an important mechanism in POAG-related retinal ganglion cell death, genetic variations in SOD1, SOD2 and SOD3 are not major contributors in the pathogenesis.

Functional Mannose-Binding Lectin Haplotype Variants are Associated with Alzheimer's Disease

Mannan-Binding lectin (MBL) is a serum lectin and an important constituent of the innate immune system. Processes linked to the innate immune response have previously been implicated in Alzheimers disease (AD). MBL is associated with blood vessels in the brain and AD patients demonstrate lower MBL levels in the cerebrospinal fluid compared to controls. We investigated six single nucleotide polymorphisms, linked to MBL deficiency, in the corresponding MBL2 gene in AD patients and controls. Two MBL2 haplotypes, LXP and LYQ, were significantly associated with AD risk (OR = 1.6, p = 0.01 and OR = 1.5, p = 0.02, respectively). The present study is the first investigating MBL2 genotypes and haplotypes in relation to AD. Our findings support that the MBL2 gene impact the disease risk.

BACE1 gene variants do not influence BACE1 activity, levels of APP or Aβ isoforms in CSF in Alzheimer's disease

The BACE1 gene encodes the beta-site APP-cleaving enzyme 1 and has been associated with Alzheimers disease (AD). BACE1 is the most important β-secretase responsible for the generation of Alzheimer-associated amyloid β-proteins (Aβ) and may play a role in the amyloidogenic process in AD. We hypothesized that BACE1 gene variants might influence BACE1 activity or other markers for APP metabolism in the cerebrospinal fluid (CSF) and thereby contribute to the development of AD. We genotyped a Swedish sample of 269 AD patients for the rs638405 single nucleotide polymorphism (SNP) in the BACE1 gene and correlated genotype data to a broad range of amyloid-related biomarkers in CSF, including BACE1 activity, levels of Aβ40, Aβ42, α- and β-cleaved soluble APP (α-sAPP and β-sAPP), as well as markers for Alzheimer-type axonal degeneration, i.e., total-tau and phospho-tau181. Gene variants of BACE1 were neither associated with amyloid-related biomarkers, nor with markers for axonal degeneration in AD.