Browsing by Subject "MVNP"

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    Increased IL-6 expression in osteoclasts is necessary but not sufficient for the development of Paget's disease of bone
    (Wiley, 2014-06) Teramachi, Jumpei; Zhou, Hua; Subler, Mark A.; Kitagawa, Yukiko; Galson, Deborah L.; Dempster, David W.; Windle, Jolene J.; Kurihara, Noriyoshi; Roodman, G. David; Department of Medicine, IU School of Medicine
    Measles virus nucleocapsid protein (MVNP) expression in osteoclasts (OCLs) and mutation of the SQSTM1 (p62) gene contribute to the increased OCL activity in Paget's disease (PD). OCLs expressing MVNP display many of the features of PD OCLs. Interleukin-6 (IL-6) production is essential for the pagetic phenotype, because transgenic mice with MVNP targeted to OCLs develop pagetic OCLs and lesions, but this phenotype is absent when MVNP mice are bred to IL-6(-/-) mice. In contrast, mutant p62 expression in OCL precursors promotes receptor activator of NF-κB ligand (RANKL) hyperresponsivity and increased OCL production, but OCLs that form have normal morphology, are not hyperresponsive to 1,25-dihydroxyvitamin D3 (1,25-(OH)2 D3 ), nor produce elevated levels of IL-6. We previously generated p62(P394L) knock-in mice (p62KI) and found that although OCL numbers were increased, the mice did not develop pagetic lesions. However, mice expressing both MVNP and p62KI developed more exuberant pagetic lesions than mice expressing MVNP alone. To examine the role of elevated IL-6 in PD and determine if MVNP mediates its effects primarily through elevation of IL-6, we generated transgenic mice that overexpress IL-6 driven by the tartrate-resistant acid phosphatase (TRAP) promoter (TIL-6 mice) and produce IL-6 at levels comparable to MVNP mice. These were crossed with p62KI mice to determine whether IL-6 overexpression cooperates with mutant p62 to produce pagetic lesions. OCL precursors from p62KI/TIL-6 mice formed greater numbers of OCLs than either p62KI or TIL-6 OCL precursors in response to 1,25-(OH)2 D3 . Histomorphometric analysis of bones from p62KI/TIL-6 mice revealed increased OCL numbers per bone surface area compared to wild-type (WT) mice. However, micro-quantitative CT (µQCT) analysis did not reveal significant differences between p62KI/TIL-6 and WT mice, and no pagetic OCLs or lesions were detected in vivo. Thus, increased IL-6 expression in OCLs from p62KI mice contributes to increased responsivity to 1,25-(OH)2 D3 and increased OCL numbers, but is not sufficient to induce Paget's-like OCLs or bone lesions in vivo.
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    Measles virus nucleocapsid protein, a key contributor to Paget’s disease, increases IL-6 expression via down-regulation of FoxO3/Sirt1 signaling
    (Elsevier, 2013) Wang, Feng-Ming; Sarmasik, Aliye; Hiruma, Yuko; Sun, Quanhong; Sammut, Benedicte; Windle, Jolene J.; Roodman, G. David; Galson, Deborah L.; Medicine, School of Medicine
    Measles virus plays an important role as an environmental factor in the pathogenesis of Paget's disease (PD). Previous studies have shown that IL-6 is increased in the bone marrow of Paget's patients and that measles virus nucleocapsid protein (MVNP) induces IL-6 secretion by pagetic osteoclasts. Further, IL-6 plays a critical role in the development of pagetic osteoclasts and bone lesions induced by PD, but the mechanisms regulating IL-6 production by MVNP remain unclear. Our current studies revealed that MVNP expression in osteoclast precursors down-regulated Sirt1 mRNA and protein, a negative regulator of NF-κB activity, which is a key factor for IL-6 expression. MVNP expression in NIH3T3 cells also elevated Il-6 transcription and impaired the expression of Sirt1 mRNA both under basal conditions and upon activation of the Sirt1 upstream regulator FoxO3 by LY294002 (a PI3K/AKT inhibitor). Luciferase activity assays showed that constitutively active FoxO3 abolished the repressive effect of MVNP on reporters driven by either FoxO3 response elements or the Sirt1 promoter. Further, protein stability assays revealed that FoxO3 was degraded more rapidly in MVNP-expressing cells than in control cells following the addition of cycloheximide. Similarly, co-transfection of MVNP and FoxO3 into HEK293 cells demonstrated that MVNP decreased the protein levels of over-expressed FoxO3 in a dose-dependent manner. Treatment with the proteasome inhibitor, MG132, blocked the MVNP-triggered decrease of FoxO3, and the treatment with the serine/threonine phosphatase inhibitor, calyculin A, revealed that MVNP increased phosphorylation of FoxO3. Further, over-expression of Sirt1 or treatment with the Sirt1 activator resveratrol blocked the increase in Il-6 transcription by MVNP. Finally, resveratrol reduced the numbers of TRAP positive multi-nuclear cells in bone marrow cultures from TRAP-MVNP transgenic mice to wild type levels. These results indicate that MVNP decreases FoxO3/Sirt1 signaling to enhance the levels of IL-6, which in part mediate MVNP's contribution to the development of Paget's disease.