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Nuclear Piwi/Piwi-interacting RNA complexes mediate co-transcriptional silencing of transposable elements by inducing local heterochromatin formation. In Drosophila, sumoylation plays an essential role in the assembly of the silencing complex; however, the molecular mechanism by which the sumoylation machinery is recruited to the transposon loci is poorly understood. Here, we show that the Drosophila E3 SUMO-ligase Su(var)2-10 directly binds to the Piwi protein. This interaction is mediated by the SUMO-interacting motif-like (SIM-like) structure in the C-terminal domain of Su(var)2-10. We demonstrated that the SIM-like structure binds to a special region found in the MID domain of the Piwi protein, the structure of which is highly similar to the SIM-binding pocket of SUMO proteins. Abrogation of the Su(var)2-10-binding surface of the Piwi protein resulted in transposon derepression in the ovary of adult flies. Based on our results, we propose a model in which the Piwi protein initiates local sumoylation in the silencing complex by recruiting Su(var)2-10 to the transposon loci., (© 2024 HUN‐REN Biological Research Centre and The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Growing evidence indicates the pronounced effects of physical activity on immune functions, which may largely depend on the type of exercise, intensity, and duration. However, limited information is available regarding the effects of low-impact exercises, especially on the level of adaptive immune system. Our study aimed to investigate and compare the changes in a broad spectrum of lymphocyte subtypes after 14 weeks of aerobic-type total-body-shaping workouts (TBSW) and Pilates workouts (PW) among healthy individuals. We determined the percentages of peripheral natural killer cells and different T and B lymphocyte subtypes with flow cytometry. At the end of the exercise program, significant changes in naïve and memory lymphocyte ratios were observed in TBSW group. Percentages of naïve cytotoxic T (Tc) cells elevated, frequencies of memory Tc and T-helper cell subsets decreased, and distribution of naïve and memory B cells rearranged. Proportions of activated T cells also showed significant changes. Nonetheless, percentages of anti-inflammatory interleukin (IL)-10-producing regulatory type 1 cells and immunosuppressive CD4 + CD127 lo/- CD25 bright T regulative cells decreased not only after TBSW but also after PW. Although weekly performed aerobic workouts may have a more pronounced impact on the adaptive immune system than low-impact exercises, both still affect immune regulation in healthy individuals.

Intraplaque hemorrhage frequently occurs in atherosclerotic plaques resulting in cell-free hemoglobin, which is oxidized to ferryl hemoglobin (FHb) in the highly oxidative environment. Osteoclast-like cells (OLCs) derived from macrophages signify a counterbalance mechanism for calcium deposition in atherosclerosis. Our aim was to investigate whether oxidized hemoglobin alters osteoclast formation, thereby affecting calcium removal from mineralized atherosclerotic lesions. RANKL- (receptor activator of nuclear factor kappa- Β ligand-) induced osteoclastogenic differentiation and osteoclast activity of RAW264.7 cells were studied in response to oxidized hemoglobin via assessing bone resorption activity, expression of osteoclast-specific genes, and the activation of signalization pathways. OLCs in diseased human carotid arteries were assessed by immunohistochemistry. FHb, but not ferrohemoglobin, decreased bone resorption activity and inhibited osteoclast-specific gene expression (tartrate-resistant acid phosphatase, calcitonin receptor, and dendritic cell-specific transmembrane protein) induced by RANKL. In addition, FHb inhibited osteoclastogenic signaling pathways downstream of RANK (receptor activator of nuclear factor kappa- Β ). It prevented the induction of TRAF6 (tumor necrosis factor (TNF) receptor-associated factor 6) and c-Fos, phosphorylation of p-38 and JNK (c-Jun N-terminal kinase), and nuclear translocation of NF κ B (nuclear factor kappa- Β ) and NFATc1 (nuclear factor of activated T-cells, cytoplasmic 1). These effects were independent of heme oxygenase-1 demonstrated by knocking down HO-1 gene in RAW264.7 cells and in mice. Importantly, FHb competed with RANK for RANKL binding suggesting possible mechanisms by which FHb impairs osteoclastic differentiation. In diseased human carotid arteries, OLCs were abundantly present in calcified plaques and colocalized with regions of calcium deposition, while the number of these cells were lower in hemorrhagic lesions exhibiting accumulation of FHb despite calcium deposition. We conclude that FHb inhibits RANKL-induced osteoclastic differentiation of macrophages and suggest that accumulation of FHb in a calcified area of atherosclerotic lesion with hemorrhage retards the formation of OLCs potentially impairing calcium resorption., Competing Interests: The authors confirm that there are no conflicts of interest., (Copyright © 2020 Erzsébet Zavaczki et al.)

Background: Bronchoalveolar mesenchymal stem cells (MSCs) play an important role in the maintenance of lung integrity. Therapeutic application of bone marrow-derived MSCs reduced chronic bronchial inflammation in idiopathic pulmonary fibrosis, and improved the ratio of survivors in sepsis with pneumonia. This study investigated the effect of MSCs from bronchoalveolar lavage fluid (BALF) of hypersensitivity pneumonitis (HP) on T-cell function under in vitro conditions., Methods: Bronchoalveolar MSCs were obtained via bronchoscopy with BAL from children with severe subacute HP. As control, BALF MSCs were assessed from children without any inflammatory lung disease. Isolated MSCs were characterized via immunophenotyping by flow cytometry and confocal laser scanning microscopy. HP-derived and healthy separated peripheral blood mononuclear cells (PBMCs) were stimulated by 5 µg/mL phytohemagglutinin in the presence of HP-derived or control MSCs in 5-day cultures. Proliferation and activation of T-cells were characterized by the mean fluorescence intensity (MFI) of 5,6-carboxyfluorescein-diacetat succinimidyl ester (CFSE) and CD25, CD69 as well as HLA-DR surface positivities, respectively., Results: HP-derived MSCs showed significantly lower level of CD73, CD90, and CD105 expression compared to control MSCs in both flow cytometric and confocal microscopic experiments. MSCs from HP did not reduce T-cell proliferation based on CFSE MFI values, while the level of CD25 expression on both control and HP-derived CD4+ and CD8+ T-cells was significantly reduced by normal MSCs, while HP-derived MSCs did not have any significant effect. The level of other activation markers was not markedly modulated by MSCs., Conclusions: BALF MSCs from HP are unable to downregulate the proliferation and activation of T-cells that may support the development of recurrent intrapulmonary inflammation in HP. © 2016 International Clinical Cytometry Society., (© 2016 International Clinical Cytometry Society.)

The infiltration of red blood cells into atheromatous plaques is implicated in atherogenesis. Inside the lesion, hemoglobin (Hb) is oxidized to ferri- and ferrylHb which exhibit prooxidant and proinflammatory activities. Cystathione gamma-lyase- (CSE-) derived H 2 S has been suggested to possess various antiatherogenic actions. Expression of CSE was upregulated predominantly in macrophages, foam cells, and myofibroblasts of human atherosclerotic lesions derived from carotid artery specimens of patients. A similar pattern was observed in aortic lesions of apolipoprotein E-deficient mice on high-fat diet. We identified several triggers for inducing CSE expression in macrophages and vascular smooth muscle cells including heme, ferrylHb, plaque lipids, oxidized low-density lipoprotein, tumor necrosis factor- α , and interleukin-1 β . In the interplay between hemoglobin and atheroma lipids, H 2 S significantly mitigated oxidation of Hb preventing the formation of ferrylHb derivatives, therefore providing a novel function as a heme-redox-intermediate-scavenging antioxidant. By inhibiting Hb-lipid interactions, sulfide lowered oxidized Hb-mediated induction of adhesion molecules in endothelium and disruption of endothelial integrity. Exogenous H 2 S inhibited heme and Hb-mediated lipid oxidation of human atheroma-derived lipid and human complicated lesion. Our study suggests that the CSE/H 2 S system represents an atheroprotective pathway for removing or limiting the formation of oxidized Hb and lipid derivatives in the atherosclerotic plaque.