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Neutral sphingomyelinase 2

Yohei Iguchi, Lara Eid, Martin Parent, Geneviève Soucy, Christine Bareil, Yuichi Riku, Kaori Kawai, Shinnosuke Takagi, Mari Yoshida, Masahisa Katsuno, Gen Sobue, Jean-Pierre Julien
Cytoplasmic TDP-43 aggregation is a pathological hallmark of amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Here we investigated the role of exosomes in the secretion and propagation of TDP-43 aggregates. TDP-43 was detected in secreted exosomes from Neuro2a cells and primary neurons but not from astrocytes or microglia. Evidence is presented that protein aggregation and autophagy inhibition are factors that promote exosomal secretion of TDP-43. We also report that levels of exosomal TDP-43 full length and C-terminal fragment species are upregulated in human amyotrophic lateral sclerosis brains...
September 27, 2016: Brain: a Journal of Neurology
Simon R Lea, Hannah J Metcalfe, Jonathan Plumb, Christian Beerli, Chris Poll, Dave Singh, Katharine H Abbott-Banner
BACKGROUND: Increased pulmonary ceramide levels are suggested to play a causative role in lung diseases including COPD. Neutral sphingomyelinase-2 (nSMase-2) and acid SMase (aSMase), which hydrolyze sphingomyelin to produce ceramide, are activated by a range of cellular stresses, including inflammatory cytokines and pathogens, but notably cigarette smoke appears to only activate nSMase-2. Our primary objective was to investigate nSMase-2 and aSMase protein localization and quantification in lung tissue from nonsmokers (NS), smokers (S), and COPD patients...
2016: International Journal of Chronic Obstructive Pulmonary Disease
Antje Scholl, Igor Ivanov, Burkhard Hinz
The role of cannabinoids in thrombosis remains controversial. In view of the primary importance of tissue factor (TF) in blood coagulation and its involvement in the pathology of several cardiovascular, inflammatory and neoplastic diseases, a regulation of this initial procoagulant signal seems to be of particular interest. Using human umbilical vein endothelial cells (HUVEC) the present study investigated the impact of the synthetic cannabinoid WIN 55,212-2 on interleukin (IL)-1β-induced TF expression and activity...
August 18, 2016: Oncotarget
Michael B Dinkins, John Enasko, Caterina Hernandez, Guanghu Wang, Jina Kong, Inas Helwa, Yutao Liu, Alvin V Terry, Erhard Bieberich
UNLABELLED: Recent evidence implicates exosomes in the aggregation of Aβ and spreading of tau in Alzheimer's disease. In neural cells, exosome formation can be blocked by inhibition or silencing of neutral sphingomyelinase-2 (nSMase2). We generated genetically nSMase2-deficient 5XFAD mice (fro;5XFAD) to assess AD-related pathology in a mouse model with consistently reduced ceramide generation. We conducted in vitro assays to assess Aβ42 aggregation and glial clearance with and without exosomes isolated by ultracentrifugation and determined exosome-induced amyloid aggregation by particle counting...
August 17, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Justyna Sosna, Stephan Philipp, Johaiber Fuchslocher Chico, Carina Saggau, Jürgen Fritsch, Alexandra Föll, Johannes Plenge, Christoph Arenz, Thomas Pinkert, Holger Kalthoff, Anna Trauzold, Ingo Schmitz, Stefan Schütze, Dieter Adam
Recently, a type of regulated necrosis (RN) called necroptosis was identified to be involved in many pathophysiological processes and emerged as an alternative method to eliminate cancer cells. However, only a few studies have elucidated components of TRAIL-mediated necroptosis useful for anticancer therapy. Therefore, we have compared this type of cell death to tumor necrosis factor (TNF)-mediated necroptosis and found similar signaling through acid and neutral sphingomyelinases, the mitochondrial serine protease HtrA2/Omi, Atg5, and vacuolar H(+)-ATPase...
October 15, 2016: Molecular and Cellular Biology
N I Hanafi, A S Mohamed, J Md Noor, N Abdu, Hamid Hasani, R Siran, N J Osman, S Ab Rahim, S H Sheikh Abdul Kadir
Ursodeoxycholic acid (UDCA) is used to treat liver diseases and demonstrates cardioprotective effects. Accumulation of the plasma membrane sphingolipid sphingomyelin in the heart can lead to atherosclerosis and coronary artery disease. Sphingomyelinases (SMases) break down sphingomyelin, producing ceramide, and inhibition of SMases activity can promote cell survival. We hypothesized that UDCA regulates activation of ERK and Akt survival signaling pathways and SMases in protecting cardiac cells against hypoxia...
2016: Genetics and Molecular Research: GMR
Yingping Xu, Yi Liu, Chunqing Yang, Li Kang, Meixiang Wang, Jingxia Hu, Hao He, Wengang Song, Hua Tang
Defects in rapid clearance of apoptotic cells lead to an accumulation of dead cells (late apoptotic or secondary necrotic cells), which results in an aberrant immune response. However, little is known about whether and how macrophages (Mφs) cooperate with dendritic cells (DCs) in the presentation of dead-cell-associated antigens in this process. By transferring high numbers of dead cells to mimic a failure of apoptotic cell clearance in vivo, we found that Mφs and neutrophils were the predominant phagocytes in the uptake of dead cells in the spleen...
October 2016: Immunology
Hiroshi Watanabe, Kyohei Okahara, Yuko Naito-Matsui, Mitsuhiro Abe, Shinji Go, Jinichi Inokuchi, Toshiro Okazaki, Toshihide Kobayashi, Yasunori Kozutsumi, Shogo Oka, Hiromu Takematsu
Endomitosis is a special type of mitosis in which only cytokinesis-the final step of the cell division cycle-is defective, resulting in polyploid cells. Although endomitosis is biologically important, its regulatory aspects remain elusive. Psychosine, a lysogalactosylceramide, prevents proper cytokinesis when supplemented to proliferating cells. Cytokinetic inhibition by psychosine does not inhibit genome duplication. Consequently cells undergo multiple rounds of endomitotic cell cycles, resulting in the formation of giant multiploid cells...
July 1, 2016: Molecular Biology of the Cell
Betul Unal, Filiz Ozcan, Hazal Tuzcu, Ebru Kırac, Gulsum O Elpek, Mutay Aslan
Oxidative stress and excessive nitric oxide production via induction of inducible nitric oxide synthase (NOS)-2 have been shown in the pathogenesis of liver ischemia-reperfusion (IR) injury. Neutral sphingomyelinase (N-SMase)/ceramide pathway can regulate NOS2 expression therefore this study determined the role of selective N-SMase inhibition on nitrative and oxidative stress markers following liver IR injury. Selective N-SMase inhibitor was administered via intraperitoneal injections. Liver IR injury was created by clamping blood vessels supplying the median and left lateral hepatic lobes for 60 min, followed by 60 min reperfusion...
March 24, 2016: Redox Report: Communications in Free Radical Research
Juan Liao, Ran Liu, Ya-Juan Shi, Li-Hong Yin, Yue-Pu Pu
Recent evidence indicates that exosomes can mediate certain microRNAs (miRNAs) involved in a series of biological functions in tumor occurrence and development. Our previous studies showed that microRNA-21 (miR-21) was abundant in both esophageal cancer cells and their corresponding exosomes. The present study explored the function of exosome-shuttling miR-21 involved in esophageal cancer progression. We found that exosomes could be internalized from the extracellular space to the cytoplasm. The exosome-derived Cy3-labeled miR-21 mimics could be transported into recipient cells in a neutral sphingomyelinase 2 (nSMase2)-dependent manner...
June 2016: International Journal of Oncology
Christopher J Clarke, Achraf A Shamseddine, Joseph J Jacob, Gabrielle Khalife, Tara A Burns, Yusuf A Hannun
Neutral sphingomyelinase-2 (nSMase2) is a key ceramide-producing enzyme in cellular stress responses. While many posttranslational regulators of nSMase2 are known, emerging evidence suggests a more protracted regulation of nSMase2 at the transcriptional level. Previously, we reported that nSMase2 is induced by all-trans retinoic acid (ATRA) in MCF7 cells and implicated nSMase2 in ATRA-induced growth arrest. Here, we further investigated how ATRA regulates nSMase2. We find that ATRA regulates nSMase2 transcriptionally through the retinoic acid receptor-α, but this is independent of previously identified transcriptional regulators of nSMase2 (Sp1, Sp3, Runx2) and is not through increased promoter activity...
May 2016: Journal of Lipid Research
Caroline Camaré, Nathalie Augé, Mélanie Pucelle, Bertrand Saint-Lebes, Marie-Hélène Grazide, Anne Nègre-Salvayre, Robert Salvayre
Capillaries of the external part of the normal arterial wall constitute the vasa vasorum network. In atherosclerotic lesions, neovascularization occurs in areas of intimal hyperplasia where it may promote plaque expansion, and intraplaque hemorrhage. Oxidized LDL that are present in atherosclerotic areas activate various angiogenic signaling pathways, including reactive oxygen species and the sphingosine kinase/sphingosine-1-phosphate pathway. We aimed to investigate whether oxidized LDL-induced angiogenesis requires neutral sphingomyelinase-2 activation and the neutral sphingomyelinase-2/sphingosine kinase-1 pathway...
April 2016: Free Radical Biology & Medicine
Biswarup Ghosh, Matthew V Green, Kelly A Krogh, Stanley A Thayer
The plasma membrane Ca(2+) ATPase (PMCA) plays a major role in clearing Ca(2+) from the neuronal cytoplasm. The cytoplasmic Ca(2+) clearance rate affects neuronal excitability, synaptic plasticity, and neurotransmission. Here, we examined the modulation of PMCA activity by PTKs in hippocampal neurons. PMCA-mediated Ca(2+) clearance slowed in the presence of pyrazolopyrimidine 2, an inhibitor of Src family kinases (SFKs), and accelerated in the presence of C2-ceramide, an activator of PTKs. Ca(2+) clearance kinetics were attenuated in cells expressing a dominant-negative Src mutant, suggesting that the pump is tonically stimulated by a PTK...
April 2016: Journal of Neurophysiology
A A Shamseddine, C J Clarke, B Carroll, M V Airola, S Mohammed, A Rella, L M Obeid, Y A Hannun
Neutral sphingomyelinase-2 (nSMase2) is a ceramide-generating enzyme that has been implicated in growth arrest, apoptosis and exosome secretion. Although previous studies have reported transcriptional upregulation of nSMase2 in response to daunorubicin, through Sp1 and Sp3 transcription factors, the role of the DNA damage pathway in regulating nSMase2 remains unclear. In this study, we show that doxorubicin induces a dose-dependent induction of nSMase2 mRNA and protein with concomitant increases in nSMase activity and ceramide levels...
October 29, 2015: Cell Death & Disease
Ying Chen, Shu-Chang Xu, Rui-Dong Duan
BACKGROUND: Sphingomyelin (SM) and cholesterol are two types of lipid closely related biophysically. Treating the cells with exogenous sphingomyelinase (SMase) induces trafficking of cholesterol from membrane to intracellular pools and inhibition of cholesterol synthesis. In the present work, we address a question whether increased cholesterol synthesis affects hydrolysis of SM by endogenous SMases. METHODS: Both HepG2 and Caco-2 cells were incubated with mevalonate...
2015: Lipids in Health and Disease
Vitor Teixeira, Tânia C Medeiros, Rita Vilaça, João Ferreira, Pedro Moradas-Ferreira, Vítor Costa
The vacuoles play important roles in cellular homeostasis and their functions include the digestion of cytoplasmic material and organelles derived from autophagy. Conserved nutrient signaling pathways regulate vacuolar function and autophagy, ensuring normal cell and organismal development and aging. Recent evidence implicates sphingolipids in the modulation of these processes, but the impact of ceramide signaling on vacuolar dynamics and autophagy remains largely unknown. Here, we show that yeast cells lacking Isc1p, an orthologue of mammalian neutral sphingomyelinase type 2, exhibit vacuolar fragmentation and dysfunctions, namely decreased Pep4p-mediated proteolysis and V-ATPase activity, which impairs vacuolar acidification...
January 2016: Biochimica et Biophysica Acta
Abo Bakr Abdel Shakor, Mona Atia, Ali Saleh Alshehri, Andrzej Sobota, Katarzyna Kwiatkowska
Curcumin exhibits anti-cancer properties manifested by activation of pro-apoptotic signaling. We have demonstrated earlier that apoptosis of HL-60 human leukemia cells induced by curcumin is controlled by ceramide generated by neutral sphingomyelinase (nSMase) which contributes to sphingomyelin synthase (SMS) inhibition favoring accumulation of ceramide in cells. Here we report that the activity of nSMase, ceramide accumulation and death of HL-60 cells are inhibited by overexpression of Bcl-xL or Bcl-2 proteins, while down-regulation of nSMase interferes with degradation of Bcl-2 but not Bcl-xL...
November 2015: Cellular Signalling
Nehman Makdissy, Katia Haddad, Charbel Mouawad, Iuliana Popa, Mohamed Younsi, Philippe Valet, Laurent Brunaud, Olivier Ziegler, Didier Quilliot
Sterol response element binding protein (SREBP) is a key transcription factor in insulin and glucose metabolism. We previously demonstrated that elevated levels of membrane sphingomyelin (SM) were related to peroxisome proliferator-activated receptor-γ (PPARγ), which is a known target gene of SREBP-1 in adipocytes. However, the role of SM in SREBP expression in adipocytes remains unknown. In human abdominal adipose tissue from obese women with various concentrations of fasting plasma insulin, SREBP-1 proteins decreased in parallel with increases in membrane SM levels...
2015: PloS One
Gerald S Supinski, Alexander P Alimov, Lin Wang, Xiao-Hong Song, Leigh A Callahan
Calpain contributes to infection-induced diaphragm dysfunction but the upstream mechanism(s) responsible for calpain activation are poorly understood. It is known, however, that cytokines activate neutral sphingomyelinase (nSMase) and nSMase has downstream effects with the potential to increase calpain activity. We tested the hypothesis that infection-induced skeletal muscle calpain activation is a consequence of nSMase activation. We administered cytomix (20 ng/ml TNF-α, 50 U/ml IL-1β, 100 U/ml IFN-γ, 10 μg/ml LPS) to C2C12 muscle cells to simulate the effects of infection in vitro and studied mice undergoing cecal ligation puncture (CLP) as an in vivo model of infection...
September 15, 2015: American Journal of Physiology. Lung Cellular and Molecular Physiology
Vitor Teixeira, Tânia C Medeiros, Rita Vilaça, Andreia T Pereira, Susana R Chaves, Manuela Côrte-Real, Pedro Moradas-Ferreira, Vítor Costa
Mitochondria function as the powerhouses of the cell for energy conversion through the oxidative phosphorylation process. Accumulation of dysfunctional mitochondria promotes a bioenergetic crisis and cell death by apoptosis. Yeast cells lacking Isc1p, an orthologue of mammalian neutral sphingomyelinase type 2, exhibit mitochondrial dysfunction and shortened lifespan associated with the accumulation of specific ceramide species and activation of the PP2A-like protein phosphatase Sit4p and of the Hog1p kinase...
September 2015: Cellular Signalling
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