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ILL-Raga G.,University Pompeu Fabra | Palomer E.,University Pompeu Fabra | Wozniak M.A.,University of Manchester | Ramos-Fernandez E.,University Pompeu Fabra | And 12 more authors.
PLoS ONE | Year: 2011

BACE1 is a key enzyme involved in the production of amyloid ß-peptide (Aß) in Alzheimer's disease (AD) brains. Normally, its expression is constitutively inhibited due to the presence of the 5′untranslated region (5′UTR) in the BACE1 promoter. BACE1 expression is activated by phosphorylation of the eukaryotic initiation factor (eIF)2-alpha, which reverses the inhibitory effect exerted by BACE1 5′UTR. There are four kinases associated with different types of stress that could phosphorylate eIF2-alpha. Here we focus on the double-stranded (ds) RNA-activated protein kinase (PKR). PKR is activated during viral infection, including that of herpes simplex virus type 1 (HSV1), a virus suggested to be implicated in the development of AD, acting when present in brains of carriers of the type 4 allele of the apolipoprotein E gene. HSV1 is a dsDNA virus but it has genes on both strands of the genome, and from these genes complementary RNA molecules are transcribed. These could activate BACE1 expression by the PKR pathway. Here we demonstrate in HSV1-infected neuroblastoma cells, and in peripheral nervous tissue from HSV1-infected mice, that HSV1 activates PKR. Cloning BACE1 5′UTR upstream of a luciferase (luc) gene confirmed its inhibitory effect, which can be prevented by salubrinal, an inhibitor of the eIF2-alpha phosphatase PP1c. Treatment with the dsRNA analog poly (I:C) mimicked the stimulatory effect exerted by salubrinal over BACE1 translation in the 5′UTR-luc construct and increased Aß production in HEK-APPsw cells. Summarizing, our data suggest that PKR activated in brain by HSV1 could play an important role in the development of AD. © 2011 ILL-Raga et al. Source

Boada M.,Catalan Institute of Applied Neurosciences | Boada M.,University of Barcelona | Antunez C.,University of Murcia | Lopez-Arrieta J.,University Hospital la Paz Cantoblanco | And 20 more authors.
Neurobiology of Aging | Year: 2012

The present research is aimed at assessing the role of 3 estrogen receptor alpha (ESR1) gene variants in late onset Alzheimer's disease (AD) susceptibility. One thousand one hundred thirteen unrelated late onset sporadic AD patients, 1109 healthy controls and 121 neurologically healthy elderly controls were used to carry out case-control genetic association studies with ESR1 rs3844508, rs2234693, and ESR1 noncoding deletion 1 (ESR1-NCD1) polymorphisms. Thirty-five healthy male samples were used for molecular analyses. The rs2234693 polymorphism is associated with AD in our population (odds ratio [OR], 1.29; p = 0.008). The rs3844508 marker confers protection against AD in males (OR, 0.57; p = 0.001) and the deletion ESR1-NCD1 is a risk factor for AD in women (OR, 1.67; p < 0.001). Molecular analyses on ESR1-NCD1 indicate that this deletion confers a higher response to estradiol activity on ESR1 receptor and it is also associated with differential expression of ESR1 isoforms. Our results support the involvement of ESR1 gene in AD and point to the existence of sexual dimorphism for ESR1 markers. In addition, carriers of ESR1-NCD1 deletion could overrespond to estradiol action. © 2012 Elsevier Inc. Source

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