Browsing by Author "Ikezu, Tsuneya"

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    PLXNA4 is associated with Alzheimer disease and modulates tau phosphorylation
    (Wiley Blackwell (John Wiley & Sons), 2014-09) Jun, Gyungah; Asai, Hirohide; Zeldich, Ella; Drapeau, Elodie; Chen, CiDi; Chung, Jaeyoon; Park, Jong-Ho; Kim, Sehwa; Haroutunian, Vahram; Foroud, Tatiana; Kuwano, Ryozo; Haines, Jonathan L.; Pericak-Vance, Margaret A.; Schellenberg, Gerard D.; Lunetta, Kathryn L.; Kim, Jong-Won; Buxbaum, Joseph D.; Mayeux, Richard; Ikezu, Tsuneya; Abraham, Carmela R.; Farrer, Lindsay A.; Department of Medical & Molecular Genetics, IU School of Medicine
    OBJECTIVE: Much of the genetic basis for Alzheimer disease (AD) is unexplained. We sought to identify novel AD loci using a unique family-based approach that can detect robust associations with infrequent variants (minor allele frequency < 0.10). METHODS: We conducted a genome-wide association study in the Framingham Heart Study (discovery) and NIA-LOAD (National Institute on Aging-Late-Onset Alzheimer Disease) Study (replication) family-based cohorts using an approach that accounts for family structure and calculates a risk score for AD as the outcome. Links between the most promising gene candidate and AD pathogenesis were explored in silico as well as experimentally in cell-based models and in human brain. RESULTS: Genome-wide significant association was identified with a PLXNA4 single nucleotide polymorphism (rs277470) located in a region encoding the semaphorin-3A (SEMA3A) binding domain (meta-analysis p value [meta-P] = 4.1 × 10(-8) ). A test for association with the entire region was also significant (meta-P = 3.2 × 10(-4) ). Transfection of SH-SY5Y cells or primary rat neurons with full-length PLXNA4 (TS1) increased tau phosphorylation with stimulated by SEMA3A. The opposite effect was observed when cells were transfected with shorter isoforms (TS2 and TS3). However, transfection of any isoform into HEK293 cells stably expressing amyloid β (Aβ) precursor protein (APP) did not result in differential effects on APP processing or Aβ production. Late stage AD cases (n = 9) compared to controls (n = 5) had 1.9-fold increased expression of TS1 in cortical brain tissue (p = 1.6 × 10(-4) ). Expression of TS1 was significantly correlated with the Clinical Dementia Rating score (ρ = 0.75, p = 2.2 × 10(-4) ), plaque density (ρ = 0.56, p = 0.01), and Braak stage (ρ = 0.54, p = 0.02). INTERPRETATION: Our results indicate that PLXNA4 has a role in AD pathogenesis through isoform-specific effects on tau phosphorylation.
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    Protein phosphatase 2A and complement component 4 are linked to the protective effect of APOE ɛ2 for Alzheimer's disease
    (Wiley, 2022) Jun, Gyungah R.; You, Yang; Zhu, Congcong; Meng, Gaoyuan; Chung, Jaeyoon; Panitch, Rebecca; Hu, Junming; Xia, Weiming; The Alzheimer’s Disease Genetics Consortium; Bennett, David A.; Foroud, Tatiana M.; Wang, Li-San; Haines, Jonathan L.; Mayeux, Richard; Pericak-Vance, Margaret A.; Schellenberg, Gerard D.; Au, Rhoda; Lunetta, Kathryn L.; Ikezu, Tsuneya; Stein, Thor D.; Farrer, Lindsay A.; Medical and Molecular Genetics, School of Medicine
    Introduction: The apolipoprotein E (APOE) ɛ2 allele reduces risk against Alzheimer's disease (AD) but mechanisms underlying this effect are largely unknown. Methods: We conducted a genome-wide association study for AD among 2096 ɛ2 carriers. The potential role of the top-ranked gene and complement 4 (C4) proteins, which were previously linked to AD in ɛ2 carriers, was investigated using human isogenic APOE allele-specific induced pluripotent stem cell (iPSC)-derived neurons and astrocytes and in 224 neuropathologically examined human brains. Results: PPP2CB rs117296832 was the second most significantly associated single nucleotide polymorphism among ɛ2 carriers (P = 1.1 × 10-7 ) and the AD risk allele increased PPP2CB expression in blood (P = 6.6 × 10-27 ). PPP2CB expression was correlated with phosphorylated tau231/total tau ratio (P = .01) and expression of C4 protein subunits C4A/B (P = 2.0 × 10-4 ) in the iPSCs. PPP2CB (subunit of protein phosphatase 2A) and C4b protein levels were correlated in brain (P = 3.3 × 10-7 ). Discussion: PP2A may be linked to classical complement activation leading to AD-related tau pathology.
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    Protein phosphatase 2A and complement component 4 are linked to the protective effect of APOE ɛ2 for Alzheimer's disease
    (Wiley, 2022-11) Jun, Gyungah R.; You, Yang; Zhu, Congcong; Meng, Gaoyuan; Chung, Jaeyoon; Panitch, Rebecca; Hu, Junming; Xia, Weiming; The Alzheimer's Disease Genetics Consortium; Bennett, David A.; Foroud, Tatiana M.; Wang, Li-San; Haines, Jonathan L.; Mayeux, Richard; Pericak-Vance, Margaret A.; Schellenberg, Gerard D.; Au, Rhoda; Lunetta, Kathryn L.; Ikezu, Tsuneya; Stein, Thor D.; Farrer, Lindsay A.; Medical and Molecular Genetics, School of Medicine
    Introduction The apolipoprotein E (APOE) ɛ2 allele reduces risk against Alzheimer's disease (AD) but mechanisms underlying this effect are largely unknown. Methods We conducted a genome‐wide association study for AD among 2096 ɛ2 carriers. The potential role of the top‐ranked gene and complement 4 (C4) proteins, which were previously linked to AD in ɛ2 carriers, was investigated using human isogenic APOE allele‐specific induced pluripotent stem cell (iPSC)–derived neurons and astrocytes and in 224 neuropathologically examined human brains. Results PPP2CB rs117296832 was the second most significantly associated single nucleotide polymorphism among ɛ2 carriers (P = 1.1 × 10−7) and the AD risk allele increased PPP2CB expression in blood (P = 6.6 × 10−27). PPP2CB expression was correlated with phosphorylated tau231/total tau ratio (P = .01) and expression of C4 protein subunits C4A/B (P = 2.0 × 10−4) in the iPSCs. PPP2CB (subunit of protein phosphatase 2A) and C4b protein levels were correlated in brain (P = 3.3 × 10−7). Discussion PP2A may be linked to classical complement activation leading to AD‐related tau pathology.