Browsing by Author "Segal, Anthony W."

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    Functional variants in the LRRK2 gene confer shared effects on risk for Crohn's disease and Parkinson's disease
    (American Association for the Advancement of Science, 2018-01-10) Hui, Ken Y.; Fernandez-Hernandez, Heriberto; Hu, Jianzhong; Schaffner, Adam; Pankratz, Nathan; Hsu, Nai-Yun; Chuang, Ling-Shiang; Carmi, Shai; Villaverde, Nicole; Li, Xianting; Rivas, Manual; Levine, Adam P.; Bao, Xiuliang; Labrias, Philippe R.; Haritunians, Talin; Ruane, Darren; Gettler, Kyle; Chen, Ernie; Li, Dalin; Schiff, Elena R.; Pontikos, Nikolas; Barzilai, Nir; Brant, Steven R.; Bressman, Susan; Cheifetz, Adam S.; Clark, Lorraine N.; Daly, Mark J.; Desnick, Robert J.; Duerr, Richard H.; Katz, Seymour; Lencz, Todd; Myers, Richard H.; Ostrer, Harry; Ozelius, Laurie; Payami, Haydeh; Peter, Yakov; Rioux, John D.; Segal, Anthony W.; Scott, William K.; Silverberg, Mark S.; Vance, Jeffery M.; Ubarretxena-Belandia, Iban; Foroud, Tatiana; Atzmon, Gil; Pe’er, Itsik; Ioannou, Yiannis; McGovern, Dermot P.B.; Yue, Zhenyu; Schadt, Eric E.; Cho, Judy H.; Peter, Inga; Medical and Molecular Genetics, School of Medicine
    Crohn's disease (CD), a form of inflammatory bowel disease, has a higher prevalence in Ashkenazi Jewish than in non-Jewish European populations. To define the role of nonsynonymous mutations, we performed exome sequencing of Ashkenazi Jewish patients with CD, followed by array-based genotyping and association analysis in 2066 CD cases and 3633 healthy controls. We detected association signals in the LRRK2 gene that conferred risk for CD (N2081D variant, P = 9.5 × 10-10) or protection from CD (N551K variant, tagging R1398H-associated haplotype, P = 3.3 × 10-8). These variants affected CD age of onset, disease location, LRRK2 activity, and autophagy. Bayesian network analysis of CD patient intestinal tissue further implicated LRRK2 in CD pathogenesis. Analysis of the extended LRRK2 locus in 24,570 CD cases, patients with Parkinson's disease (PD), and healthy controls revealed extensive pleiotropy, with shared genetic effects between CD and PD in both Ashkenazi Jewish and non-Jewish cohorts. The LRRK2 N2081D CD risk allele is located in the same kinase domain as G2019S, a mutation that is the major genetic cause of familial and sporadic PD. Like the G2019S mutation, the N2081D variant was associated with increased kinase activity, whereas neither N551K nor R1398H variants on the protective haplotype altered kinase activity. We also confirmed that R1398H, but not N551K, increased guanosine triphosphate binding and hydrolyzing enzyme (GTPase) activity, thereby deactivating LRRK2. The presence of shared LRRK2 alleles in CD and PD provides refined insight into disease mechanisms and may have major implications for the treatment of these two seemingly unrelated diseases.
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    Two CGD Families with a Hypomorphic Mutation in the Activation Domain of p67(phox)
    (OMICS Publishing Group, 2014-06-30) Roos, Dirk; van Buul, Jaap D.; Tool, Anton TJ; Matute, Juan D.; Marchal, Christophe M.; Hayee, Bu’Hussain; Köker, M. Yavuz; de Boer, Martin; van Leeuwen, Karin; Segal, Anthony W.; Pick, Edgar; Dinauer, Mary C.; Department of Pediatrics, IU School of Medicine
    STUDY BACKGROUND: Chronic granulomatous Disease (CGD) is a rare immunodeficiency caused by a defect in the leukocyte NADPH oxidase. This enzyme generates superoxide, which is needed for the killing of bacteria and fungi by phagocytic leukocytes. Most CGD patients have mutations in CYBB, the X-linked gene that encodes gp91(phox), the catalytic subunit of the leukocyte NADPH oxidase. We report here three autosomal recessive CGD patients from two families with a homozygous mutation in NCF2, the gene that encodes p67(phox), the activator subunit of the NADPH oxidase. METHODS: Leukocyte NADPH oxidase activity, expression of oxidase components and gene sequences were measured with standard methods. The mutation found in the patients' NCF2 gene was expressed as Ala202Val-p67(phox) in K562 cells to measure its effect on NADPH oxidase activity. Translocation of the mutated p67(phox) from the cytosol of the patients' neutrophils to the plasma membrane was measured by confocal microscopy and by Western blotting after membrane purification. RESULTS: The exceptional feature of the A67 CGD patients reported here is that the p.Ala202Val mutation in the activation domain of p67(phox) was clearly hypomorphic: substantial expression of p67(phox) protein was noted and the NADPH oxidase activity in the neutrophils of the patients was 20-70% of normal, dependent on the stimulus used to activate the cells. The extent of Ala202Val-p67(phox) translocation to the plasma membrane during cell activation was also stimulus dependent. Ala202Val-p67(phox) in K562 cells mediated only about 3% of normal oxidase activity compared to cells transfected with the wild-type p67(phox). CONCLUSION: The mutation found in NCF2 is the cause of the decreased NADPH oxidase activity and the (mild) clinical problems of the patients. We propose that the p.Ala202Val mutation has changed the conformation of the activation domain of p67(phox), resulting in reduced activation of gp91(phox).