References of "Ramirez, Alfredo"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailGenetic meta-analysis of diagnosed Alzheimer's disease identifies new risk loci and implicates Aβ, tau, immunity and lipid processing
Kunkle, Brian W.; Grenier-Boley, Benjamin; Sims, Rebecca et al

in Nature Genetics (2019), 51(3), 414

Risk for late-onset Alzheimer's disease (LOAD), the most prevalent dementia, is partially driven by genetics. To identify LOAD risk loci, we performed a large genome-wide association meta-analysis of ... [more ▼]

Risk for late-onset Alzheimer's disease (LOAD), the most prevalent dementia, is partially driven by genetics. To identify LOAD risk loci, we performed a large genome-wide association meta-analysis of clinically diagnosed LOAD (94,437 individuals). We confirm 20 previous LOAD risk loci and identify five new genome-wide loci (IQCK, ACE, ADAM10, ADAMTS1, and WWOX), two of which (ADAM10, ACE) were identified in a recent genome-wide association (GWAS)-by-familial-proxy of Alzheimer's or dementia. Fine-mapping of the human leukocyte antigen (HLA) region confirms the neurological and immune-mediated disease haplotype HLA-DR15 as a risk factor for LOAD. Pathway analysis implicates immunity, lipid metabolism, tau binding proteins, and amyloid precursor protein (APP) metabolism, showing that genetic variants affecting APP and A$\beta$ processing are associated not only with early-onset autosomal dominant Alzheimer's disease but also with LOAD. Analyses of risk genes and pathways show enrichment for rare variants (P = 1.32 × 10−7), indicating that additional rare variants remain to be identified. We also identify important genetic correlations between LOAD and traits such as family history of dementia and education. [less ▲]

Detailed reference viewed: 113 (8 UL)
Full Text
Peer Reviewed
See detailRare coding variants in PLCG2, ABI3, and TREM2 implicate microglial-mediated innate immunity in Alzheimer's disease
Sims, Rebecca; van der Lee, Sven J.; Naj, Adam C. et al

in Nature Genetics (2017), 49

Detailed reference viewed: 122 (9 UL)
Full Text
Peer Reviewed
See detailGene-wide analysis detects two new susceptibility genes for Alzheimer's disease.
Escott-Price, Valentina; Bellenguez, Celine; Wang, Li-San et al

in PloS one (2014), 9(6), 94661

BACKGROUND: Alzheimer's disease is a common debilitating dementia with known heritability, for which 20 late onset susceptibility loci have been identified, but more remain to be discovered. This study ... [more ▼]

BACKGROUND: Alzheimer's disease is a common debilitating dementia with known heritability, for which 20 late onset susceptibility loci have been identified, but more remain to be discovered. This study sought to identify new susceptibility genes, using an alternative gene-wide analytical approach which tests for patterns of association within genes, in the powerful genome-wide association dataset of the International Genomics of Alzheimer's Project Consortium, comprising over 7 m genotypes from 25,580 Alzheimer's cases and 48,466 controls. PRINCIPAL FINDINGS: In addition to earlier reported genes, we detected genome-wide significant loci on chromosomes 8 (TP53INP1, p = 1.4x10-6) and 14 (IGHV1-67 p = 7.9x10-8) which indexed novel susceptibility loci. SIGNIFICANCE: The additional genes identified in this study, have an array of functions previously implicated in Alzheimer's disease, including aspects of energy metabolism, protein degradation and the immune system and add further weight to these pathways as potential therapeutic targets in Alzheimer's disease. [less ▲]

Detailed reference viewed: 90 (8 UL)
Full Text
Peer Reviewed
See detailMeta-analysis of 74,046 individuals identifies 11 new susceptibility loci for Alzheimer's disease
Lambert, Jean-Charles; Ibrahim-Verbaas, Carla A.; Harold, Denise et al

in Nature Genetics (2013), 45

Detailed reference viewed: 129 (10 UL)
Peer Reviewed
See detailATP13A2 mutations impair mitochondrial function in fibroblasts from patients with Kufor-Rakeb syndrome.
Grünewald, Anne UL; Arns, Bjorn; Seibler, Philip et al

in Neurobiology of aging (2012), 33(8), 18431-7

Mutations in ATP13A2 cause autosomal-recessive parkinsonism (Kufor-Rakeb syndrome; KRS). Because several other parkinsonism-associated proteins have been connected to mitochondrial function and mitophagy ... [more ▼]

Mutations in ATP13A2 cause autosomal-recessive parkinsonism (Kufor-Rakeb syndrome; KRS). Because several other parkinsonism-associated proteins have been connected to mitochondrial function and mitophagy, we studied the impact of endogenous mutations in ATPase type 13A2 (ATP13A2) on mitochondria in fibroblasts from KRS patients compared with controls. In patients, we detected decreased adenosine triphosphate (ATP) synthesis rates, increased mitochondrial DNA levels, a higher frequency of mitochondrial DNA lesions, increased oxygen consumption rates, and increased fragmentation of the mitochondrial network. Importantly, overexpression of wild-type ATP13A2 rescued the respiration phenotype. These findings collectively suggest that ATP13A2 contributes to the maintenance of a healthy mitochondrial pool, supporting the hypothesis that impaired mitochondrial clearance represents an important pathogenic mechanism underlying KRS. [less ▲]

Detailed reference viewed: 63 (3 UL)
Peer Reviewed
See detailAn unusual neurological syndrome of crawling gait, dystonia, pyramidal signs, and limited speech.
Arif, Beenish; Grünewald, Anne UL; Fatima, Amara et al

in Movement disorders : official journal of the Movement Disorder Society (2011), 26(12), 2279-83

BACKGROUND: The purpose of the study was to identify and molecularly characterize a neurological syndrome in a consanguineous Pakistani family. METHODS: Five patients, their 2 siblings, and their parents ... [more ▼]

BACKGROUND: The purpose of the study was to identify and molecularly characterize a neurological syndrome in a consanguineous Pakistani family. METHODS: Five patients, their 2 siblings, and their parents were clinically examined. DNA from all 7 siblings was genotyped with Affymetrix SNP arrays and sequencing of selected candidate genes. RESULTS: An unusual neurological syndrome of crawling gait, predominant leg dystonia, pyramidal signs, microcephaly, and suspected deafness segregated in the family. Three patients ambulated on hands and knees, either by hopping and crossing their legs, or by dragging the legs behind them. Two patients have acquired the ability to walk bipedally with a dystonic gait. Unexpectedly, no chromosomal region was homozygous in patients only. Under different disease models, we localized 7 chromosomal regions in the genome common to all patients. No pathogenic mutations were identified in selected candidate genes or the mitochondrial genome. CONCLUSION: We describe an unusual movement disorder syndrome reminiscent of but distinct from Uner Tan syndrome. [less ▲]

Detailed reference viewed: 50 (1 UL)
Peer Reviewed
See detailEffect of endogenous mutant and wild-type PINK1 on Parkin in fibroblasts from Parkinson disease patients.
Rakovic, Aleksandar; Grünewald, Anne UL; Seibler, Philip et al

in Human molecular genetics (2010), 19(16), 3124-37

Mutations in the PTEN-induced putative kinase 1 (PINK1), a mitochondrial serine-threonine kinase, and Parkin, an E3 ubiquitin ligase, are associated with autosomal-recessive forms of Parkinson disease (PD ... [more ▼]

Mutations in the PTEN-induced putative kinase 1 (PINK1), a mitochondrial serine-threonine kinase, and Parkin, an E3 ubiquitin ligase, are associated with autosomal-recessive forms of Parkinson disease (PD). Both are involved in the maintenance of mitochondrial integrity and protection from multiple stressors. Recently, Parkin was demonstrated to be recruited to impaired mitochondria in a PINK1-dependent manner, where it triggers mitophagy. Using primary human dermal fibroblasts originating from PD patients with various PINK1 mutations, we showed at the endogenous level that (i) PINK1 regulates the stress-induced decrease of endogenous Parkin; (ii) mitochondrially localized PINK1 mediates the stress-induced mitochondrial translocation of Parkin; (iii) endogenous PINK1 is stabilized on depolarized mitochondria; and (iv) mitochondrial accumulation of full-length PINK1 is sufficient but not necessary for the stress-induced loss of Parkin signal and its mitochondrial translocation. Furthermore, we showed that different stressors, depolarizing or non-depolarizing, led to the same effect on detectable Parkin levels and its mitochondrial targeting. Although this effect on Parkin was independent of the mitochondrial membrane potential, we demonstrate a differential effect of depolarizing versus non-depolarizing stressors on endogenous levels of PINK1. Our study shows the necessity to introduce an environmental factor, i.e. stress, to visualize the differences in the interaction of PINK1 and Parkin in mutants versus controls. Establishing human fibroblasts as a suitable model for studying this interaction, we extend data from animal and other cellular models and provide experimental evidence for the generally held notion of PD as a condition with a combined genetic and environmental etiology. [less ▲]

Detailed reference viewed: 26 (2 UL)
Peer Reviewed
See detailMutant Parkin impairs mitochondrial function and morphology in human fibroblasts.
Grünewald, Anne UL; Voges, Lisa; Rakovic, Aleksandar et al

in PloS one (2010), 5(9), 12962

BACKGROUND: Mutations in Parkin are the most common cause of autosomal recessive Parkinson disease (PD). The mitochondrially localized E3 ubiquitin-protein ligase Parkin has been reported to be involved ... [more ▼]

BACKGROUND: Mutations in Parkin are the most common cause of autosomal recessive Parkinson disease (PD). The mitochondrially localized E3 ubiquitin-protein ligase Parkin has been reported to be involved in respiratory chain function and mitochondrial dynamics. More recent publications also described a link between Parkin and mitophagy. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we investigated the impact of Parkin mutations on mitochondrial function and morphology in a human cellular model. Fibroblasts were obtained from three members of an Italian PD family with two mutations in Parkin (homozygous c.1072delT, homozygous delEx7, compound-heterozygous c.1072delT/delEx7), as well as from two relatives without mutations. Furthermore, three unrelated compound-heterozygous patients (delEx3-4/duplEx7-12, delEx4/c.924C>T and delEx1/c.924C>T) and three unrelated age-matched controls were included. Fibroblasts were cultured under basal or paraquat-induced oxidative stress conditions. ATP synthesis rates and cellular levels were detected luminometrically. Activities of complexes I-IV and citrate synthase were measured spectrophotometrically in mitochondrial preparations or cell lysates. The mitochondrial membrane potential was measured with 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide. Oxidative stress levels were investigated with the OxyBlot technique. The mitochondrial network was investigated immunocytochemically and the degree of branching was determined with image processing methods. We observed a decrease in the production and overall concentration of ATP coinciding with increased mitochondrial mass in Parkin-mutant fibroblasts. After an oxidative insult, the membrane potential decreased in patient cells but not in controls. We further determined higher levels of oxidized proteins in the mutants both under basal and stress conditions. The degree of mitochondrial network branching was comparable in mutants and controls under basal conditions and decreased to a similar extent under paraquat-induced stress. CONCLUSIONS: Our results indicate that Parkin mutations cause abnormal mitochondrial function and morphology in non-neuronal human cells. [less ▲]

Detailed reference viewed: 59 (2 UL)