66 research outputs found
Overexpression of a Minimal Domain of Calpastatin Suppresses IL-6 Production and Th17 Development via Reduced NF-κB and Increased STAT5 Signals
Calpain, a calcium-dependent cysteine protease, is reportedly involved in the pathophysiology of autoimmune diseases such as rheumatoid arthritis (RA). In addition, autoantibodies against calpastatin, a natural and specific inhibitor of calpain, are widely observed in RA. We previously reported that E-64-d, a membrane-permeable cysteine protease inhibitor, is effective in treating experimental arthritis. However, the exact role of the calpastatin-calpain balance in primary inflammatory cells remains unclear. Here we investigated the effect of calpain-specific inhibition by overexpressing a minimal functional domain of calpastatin in primary helper T (Th) cells, primary fibroblasts from RA patients, and fibroblast cell lines. We found that the calpastatin-calpain balance varied during Th1, Th2, and Th17 development, and that overexpression of a minimal domain of calpastatin (by retroviral gene transduction) or the inhibition of calpain by E-64-d suppressed the production of IL-6 and IL-17 by Th cells and the production of IL-6 by fibroblasts. These suppressions were associated with reductions in RORγt expression and STAT3 phosphorylation. Furthermore, inhibiting calpain by silencing its small regulatory subunit (CPNS) suppressed Th17 development. We also confirmed that overexpressing a minimal domain of calpastatin suppressed IL-6 by reducing NF-κB signaling via the stabilization of IκBα, without affecting the upstream signal. Moreover, our findings indicated that calpastatin overexpression suppressed IL-17 production by Th cells by up-regulating the STAT5 signal. Finally, overexpression of a minimal domain of calpastatin suppressed IL-6 production efficiently in primary fibroblasts derived from the RA synovium. These findings suggest that inhibiting calpain by overexpressing a minimal domain of calpastatin could coordinately suppress proinflammatory activities, not only those of Th cells but also of synovial fibroblasts. Thus, this strategy may prove viable as a candidate treatment for inflammatory diseases such as RA
インテグリンα9の恒常的な活性化は関節リウマチ滑膜線維芽細胞の自発的な肥厚形成能及び炎症応答を増強する
京都大学0048新制・論文博士博士(医学)乙第13195号論医博第2159号新制||医||1030(附属図書館)(主査)教授 松田 秀一, 教授 三森 経世, 教授 妻木 範行学位規則第4条第2項該当Doctor of Medical ScienceKyoto UniversityDFA
Nuclear Smad7 Overexpressed in Mesenchymal Cells Acts as a Transcriptional Corepressor by Interacting with HDAC-1 and E2F to Regulate Cell Cycle
Summary
Smad family proteins are essential intracellular mediators that regulate transforming growth factor-β (TGF-β) ligand signaling. In response to diverse stimuli, Smad7 is rapidly expressed and acts as a cytoplasmic inhibitor that selectively interferes with signals elicited from TGF-β family receptors. In addition, earlier works have indicated that retrovirally transduced Smad7 induces long-lasting cell proliferation arrest in a variety of mesenchymal cells through down-regulation of G1 cyclins. However, the molecular mechanisms underlying the cytostatic effects of Smad7 remain unknown. We show here that Smad7 can form a complex with endogenous histone deacetylase proteins HDAC-1 and HDAC-3 in NIH 3T3 mouse fibroblast cells. By contrast, forced expression of a dominant-negative variant of HDAC-1 efficiently protected cells against Smad7 proliferation inhibition, suggesting that Smad7 depends on the deacetylase activity of its associated HDAC-1 to arrest the cell cycle. Furthermore, Smad7 caused HDAC-1 bind to E2F-1 to form a ternary complex on chromosomal DNA containing an E2F-binding motif and leading to repression in the activity of the E2F target genes. Smad7 mutations that prevented its binding to either HDAC-1 or E2F-1 resulted in a significant decrease in Smad7-mediated inhibition of cell proliferation. The present results strongly suggest that nuclear Smad7 is a transcriptional corepressor for E2F, providing a molecular basis for the Smad7-induced arrest of the cell cycle
Role of JAK-STAT signaling in the pathogenic behavior of fibroblast-like synoviocytes in rheumatoid arthritis: Effect of the novel JAK inhibitor peficitinib
Rheumatoid arthritis (RA) fibroblast-like synoviocytes (RA-FLS) play a crucial role in the pathogenesis of RA. RA-FLS display passive pro-inflammatory responses and self-directed aggressive responses, such as pro-inflammatory mediator production, reduced apoptosis and formation of a thickened synovial lining. Evidence suggests a role for Janus kinase (JAK)-signal transducer and transcriptional activator (STAT) signaling in the passive response but the aggressive behavior of RA-FLS is poorly understood. The pharmacologic effects of the novel JAK inhibitor, peficitinib, on cytokine-induced intracellular signaling and self-directed aggressive behavior of RA-FLS (e.g., increased expression of apoptosis-resistant genes and sodium nitroprusside-induced apoptosis) were investigated and compared with approved JAK inhibitors. RA-FLS assembly to form a lining-like structure and pro-inflammatory mediator production was investigated in three-dimensional (3D)-micromass culture. Peficitinib inhibited STAT3 phosphorylation in RA-FLS following induction by interferon (IFN)-α2b, IFN-γ, interleukin (IL)-6, oncostatin M, and leukemia inhibitory factor in a concentration-related manner, and was comparable to approved JAK inhibitors, tofacitinib and baricitinib. Peficitinib and tofacitinib suppressed autocrine phosphorylation of STAT3 and expression of apoptosis-resistant genes, and promoted cell death. In 3D-micromass culture, peficitinib reduced multi-layered RA-FLS cells to a thin monolayer, an effect less pronounced with tofacitinib. Both compounds attenuated production of vascular endothelial growth factor-A, matrix metalloproteinases, IL-6 and tumor necrosis factor superfamily-11. This study confirmed the pathogenic role of uncontrolled JAK-STAT signaling in the aggressive and passive responses of RA-FLS that are critical for RA progression. The novel JAK inhibitor peficitinib suppressed the pro-inflammatory behavior of RA-FLS, accelerated cell death and abrogated thickening of the synovium
Simulation of climate response to aerosol direct and indirect effects with aerosol transport‐radiation model
With a global aerosol transport‐radiation model coupled to a general circulation model, changes in the meteorological parameters of clouds, precipitation, and temperature caused by the direct and indirect effects of aerosols are simulated, and its radiative forcing are calculated. A microphysical parameterization diagnosing the cloud droplet number concentration based on the Köhler theory is introduced into the model, which depends not only on the aerosol particle number concentration but also on the updraft velocity, size distributions, and chemical properties of each aerosol species and saturation condition of the water vapor. The simulated cloud droplet effective radius, cloud radiative forcing, and precipitation rate, which relate to the aerosol indirect effect, are in reasonable agreement with satellite observations. The model results indicate that a decrease in the cloud droplet effective radius by anthropogenic aerosols occurs globally, while changes in the cloud water and precipitation are strongly affected by a variation of the dynamical hydrological cycle with a temperature change by the aerosol direct and first indirect effects rather than the second indirect effect itself. However, the cloud water can increase and the precipitation can simultaneously decrease in regions where a large amount of anthropogenic aerosols and cloud water exist, which is a strong signal of the second indirect effect. The global mean radiative forcings of the direct and indirect effects at the tropopause by anthropogenic aerosols are calculated to be −0.1 and −0.9 W m−2, respectively. It is suggested that aerosol particles approximately reduce 40% of the increase in the surface air temperature by anthropogenic greenhouse gases on the global mean
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