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  1. Article ; Online: Contribution of NADPH oxidase to membrane CD38 internalization and activation in coronary arterial myocytes.

    Ming Xu / Xiao-Xue Li / Joseph K Ritter / Justine M Abais / Yang Zhang / Pin-Lan Li

    PLoS ONE, Vol 8, Iss 8, p e

    2013  Volume 71212

    Abstract: The CD38-ADP-ribosylcyclase-mediated Ca(2+) signaling pathway importantly contributes to the vasomotor response in different arteries. Although there is evidence indicating that the activation of CD38-ADP-ribosylcyclase is associated with CD38 ... ...

    Abstract The CD38-ADP-ribosylcyclase-mediated Ca(2+) signaling pathway importantly contributes to the vasomotor response in different arteries. Although there is evidence indicating that the activation of CD38-ADP-ribosylcyclase is associated with CD38 internalization, the molecular mechanism mediating CD38 internalization and consequent activation in response to a variety of physiological and pathological stimuli remains poorly understood. Recent studies have shown that CD38 may sense redox signals and is thereby activated to produce cellular response and that the NADPH oxidase isoform, NOX1, is a major resource to produce superoxide (O2·-)) in coronary arterial myocytes (CAMs) in response to muscarinic receptor agonist, which uses CD38-ADP-ribosylcyclase signaling pathway to exert its action in these CAMs. These findings led us hypothesize that NOX1-derived O2·- serves in an autocrine fashion to enhance CD38 internalization, leading to redox activation of CD38-ADP-ribosylcyclase activity in mouse CAMs. To test this hypothesis, confocal microscopy, flow cytometry and a membrane protein biotinylation assay were used in the present study. We first demonstrated that CD38 internalization induced by endothelin-1 (ET-1) was inhibited by silencing of NOX1 gene, but not NOX4 gene. Correspondingly, NOX1 gene silencing abolished ET-1-induced O2·- production and increased CD38-ADP-ribosylcyclase activity in CAMs, while activation of NOX1 by overexpression of Rac1 or Vav2 or administration of exogenous O2·- significantly increased CD38 internalization in CAMs. Lastly, ET-1 was found to markedly increase membrane raft clustering as shown by increased colocalization of cholera toxin-B with CD38 and NOX1. Taken together, these results provide direct evidence that Rac1-NOX1-dependent O2·- production mediates CD38 internalization in CAMs, which may represent an important mechanism linking receptor activation with CD38 activity in these cells.
    Keywords Medicine ; R ; Science ; Q
    Subject code 572
    Language English
    Publishing date 2013-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Acid sphingomyelinase gene knockout ameliorates hyperhomocysteinemic glomerular injury in mice lacking cystathionine-β-synthase.

    Krishna M Boini / Min Xia / Justine M Abais / Ming Xu / Cai-xia Li / Pin-Lan Li

    PLoS ONE, Vol 7, Iss 9, p e

    2012  Volume 45020

    Abstract: Acid sphingomyelinase (ASM) has been implicated in the development of hyperhomocysteinemia (hHcys)-induced glomerular oxidative stress and injury. However, it remains unknown whether genetically engineering of ASM gene produces beneficial or detrimental ... ...

    Abstract Acid sphingomyelinase (ASM) has been implicated in the development of hyperhomocysteinemia (hHcys)-induced glomerular oxidative stress and injury. However, it remains unknown whether genetically engineering of ASM gene produces beneficial or detrimental action on hHcys-induced glomerular injury. The present study generated and characterized the mice lacking cystathionine β-synthase (Cbs) and Asm mouse gene by cross breeding Cbs(+/-) and Asm(+/-) mice. Given that the homozygotes of Cbs(-/-/)Asm(-/-) mice could not survive for 3 weeks. Cbs(+/-/)Asm(+/+), Cbs(+/-/)Asm(+/-) and Cbs(+/-/)Asm(-/-) as well as their Cbs wild type littermates were used to study the role of Asm(-/-) under a background of Cbs(+/-) with hHcys. HPLC analysis revealed that plasma Hcys level was significantly elevated in Cbs heterozygous (Cbs(+/-)) mice with different copies of Asm gene compared to Cbs(+/+) mice with different Asm gene copies. Cbs(+/-/)Asm(+/+) mice had significantly increased renal Asm activity, ceramide production and O(2.)(-) level compared to Cbs(+/+)/Asm(+/+), while Cbs(+/-/)Asm(-/-) mice showed significantly reduced renal Asm activity, ceramide production and O(2.)(-) level due to increased plasma Hcys levels. Confocal microscopy demonstrated that colocalization of podocin with ceramide was much lower in Cbs(+/-/)Asm(-/-) mice compared to Cbs(+/-/)Asm(+/+) mice, which was accompanied by a reduced glomerular damage index, albuminuria and proteinuria in Cbs(+/-/)Asm(-/-) mice. Immunofluorescent analyses of the podocin, nephrin and desmin expression also illustrated less podocyte damages in the glomeruli from Cbs(+/-/)Asm(-/-) mice compared to Cbs(+/-/)Asm(+/+) mice. In in vitro studies of podocytes, hHcys-enhanced O(2.)(-) production, desmin expression, and ceramide production as well as decreases in VEGF level and podocin expression in podocytes were substantially attenuated by prior treatment with amitriptyline, an Asm inhibitor. In conclusion, Asm gene knockout or corresponding enzyme inhibition protects the podocytes ...
    Keywords Medicine ; R ; Science ; Q
    Subject code 572
    Language English
    Publishing date 2012-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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