A Novel Sphingomyelin Synthase Gene, SMS1-Regulated Sphingomyelin/Ceramide-Rich Microdomain Plays a Crucial Role in Fas-Mediated Apoptosis.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1266-1266
Author(s):  
Michihiko Miyaji ◽  
Shohei Yamaoka ◽  
Jin Zhe Xiong ◽  
Ryuichi Amakawa ◽  
Tsuneyo Mimori ◽  
...  
Keyword(s):  
Cell Death ◽  
Crucial Role ◽  
Apoptotic Cell ◽  
Cholesterol Content ◽  
Sphingomyelin Synthase ◽  
Microscopy Analysis ◽  
Induced Apoptosis ◽  
Lipid Microdomain ◽  
First Time

Abstract Lipid microdomain consisting of sphingolipids, glycosphingolipids and cholesterol plays an important role in mediating cell death signals. Although functional analysis of lipid microdomain is conventionally performed by exclusion of cholesterol tightly binding with sphingomyein (SM), the exact role of SM in microdomain in signal transduction remains to be cleared. Since we for the first time obtained cDNA (SMS1) responsible for SM synthesis, it became possible to investigate the role of SM in the membrane without affecting cholesterol content. We here examine the role of SM/ceramide-rich microdomain in Fas-induced apoptosis using the SM-deficient cells and its revertant cells by transfection with SMS1. SM synthase-defective WR19L cells transfected with human-Fas gene (WR/Fas-SM(-)), and its functional revertant cells by transfection with SMS1 (WR/Fas-SMS1) were established. Both SMS1 cells and SM(-) cells expressed similar levels of CD44, CD90, CD95 (Human) and LFA-1 by FACS analysis. Although the levels of cholesterol and GM1-ganglioside on the surface of the membrane were similar in both cells, SM was detected only on the surface of SMS1 cells by FACS and confocal microscopy analysis. Fas crosslinking induced not only higher rate of apoptotic cell death, but also translocation of Fas into TritonX-100-insoluble fractions with a significant increase of ceramide in SMS1 cells as compared with SM(-) cells. After increase of SM and ceramide in microdomain, more efficient aggregation of Fas was detected with increase of DISC formation, resulting in activation of caspase-8 and 3 and decrease of mitochondrial membrane potential in SMS-1 cells than SM(-) cells. Our results clearly demonstrate that SM and ceramide in microdomain of plasma membrane plays a crucial role in Fas clustering and aggregation requires for activation of apoptosis-inducing signals.

scholarly journals JNK1/2 regulates ER–mitochondrial Ca2+ cross-talk during IL-1β–mediated cell death in RINm5F and human primary β-cells

2013 ◽  
Vol 24 (12) ◽  
pp. 2058-2071 ◽  
Author(s):  
Gaurav Verma ◽  
Himanshi Bhatia ◽  
Malabika Datta
Keyword(s):  
Cell Death ◽  
Er Stress ◽  
Mitochondrial Permeability Transition ◽  
Apoptotic Cell ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Β Cells ◽  
Mediating Role ◽  
Induced Apoptosis

Elevated interleukin-1β (IL-1β) induces apoptosis in pancreatic β-cells through endoplasmic reticulum (ER) stress induction and subsequent c-jun-N-terminal kinase 1/2 (JNK1/2) activation. In earlier work we showed that JNK1/2 activation is initiated before ER stress and apoptotic induction in response to IL-1β. However, the detailed regulatory mechanisms are not completely understood. Because the ER is the organelle responsible for Ca2+ handling and storage, here we examine the effects of IL-1β on cellular Ca2+ movement and mitochondrial dysfunction and evaluate the role of JNK1/2. Our results show that in RINm5F cells and human primary β-cells, IL-1β alters mitochondrial membrane potential, mitochondrial permeability transition pore opening, ATP content, and reactive oxygen species production and these alterations are preceded by ER Ca2+ release via IP3R channels and mitochondrial Ca2+ uptake. All these events are prevented by JNK1/2 small interfering RNA (siRNA), indicating the mediating role of JNK1/2 in IL-1β–induced cellular alteration. This is accompanied by IL-1β–induced apoptosis, which is prevented by JNK1/2 siRNA and the IP3R inhibitor xestospongin C. This suggests a regulatory role of JNK1/2 in modulating the ER-mitochondrial-Ca2+ axis by IL-1β in apoptotic cell death.

scholarly journals Bcl-3 Expression Promotes Cell Survival following Interleukin-4 Deprivation and Is Controlled by AP1 and AP1-Like Transcription Factors

2000 ◽  
Vol 20 (10) ◽  
pp. 3407-3416 ◽  
Author(s):  
Angelita Rebollo ◽  
Laure Dumoutier ◽  
Jean-Christophe Renauld ◽  
Angel Zaballos ◽  
Verónica Ayllón ◽  
...  
Keyword(s):  
Cell Death ◽  
Transcription Factors ◽  
Cell Survival ◽  
Binding Sites ◽  
Apoptotic Cell ◽  
Binding Activity ◽  
Interleukin 4 ◽  
Survival Factor ◽  
Induced Apoptosis

ABSTRACT We have analyzed the interleukin-4 (IL-4)-triggered mechanisms implicated in cell survival and show here that IL-4 deprivation induces apoptotic cell death but does not modulate Bcl-2 or Bcl-x expression. Since Bcl-x expression is insufficient to ensure cell survival in the absence of IL-4, we speculate that additional molecules replace the antiapoptotic role of Bcl-2 and Bcl-x in an alternative IL-4-triggered pathway. Cell death is associated with Bcl-3 downregulation and Bcl-3 expression blocks IL-4 deprivation-induced apoptosis, suggesting that Bcl-3 acts as a survival factor in the absence of growth factor. To characterize the IL-4-induced regulation of murine Bcl-3 expression, we cloned the promoter of this gene. Sequencing of the promoter showed no TATA box element but did reveal binding sites for AP1, AP1-like, and SP1 transcription factors. Retardation gels showed that IL-4 specifically induces AP1 and AP1-like binding activity and that mutation of these binding sites abolishes the IL-4-induced Bcl-3 promoter activity, suggesting that these transcription factors are important in Bcl-3 promoter transactivation. IL-4 deprivation induces downregulation of Jun expression and upregulation of Fos expression, both of which are proteins involved in the formation of AP1 and AP1-like transcription factors. Overexpression of Jun family proteins transactivates the promoter and restores Bcl-3 expression in the absence of IL-4 stimulation. Taken together, these data describe a new biological role for Bcl-3 and define the regulatory pathway implicated in Bcl-3 expression.

scholarly journals Receptor-Mediated Mitophagy Rescues Cancer Cells under Hypoxic Conditions

Cancers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 4027
Author(s):  
Alibek Abdrakhmanov ◽  
Maria A. Yapryntseva ◽  
Vitaliy O. Kaminskyy ◽  
Boris Zhivotovsky ◽  
Vladimir Gogvadze
Keyword(s):  
Cell Death ◽  
Apoptotic Cell ◽  
A549 Cells ◽  
Inhibitory Effect ◽  
Protective Role ◽  
Hypoxic Conditions ◽  
Key Enzyme ◽  
Induced Apoptosis ◽  
Key Participants

Targeting mitochondria with thenoyltrifluoroacetone (TTFA), an inhibitor of Complex II in the respiratory chain, stimulated cisplatin-induced apoptosis in various cell lines in normoxia but not in hypoxia. This can be explained by the elimination of mitochondria involved in triggering apoptotic cell death by mitophagy, either Parkin-dependent or receptor-mediated. Treatment with TTFA alone or in combination with cisplatin did not cause accumulation of PINK1, meaning that under hypoxic conditions cells survive through activation of a receptor-mediated pathway. Hypoxia triggers the accumulation of BNIP3 and BNIP3L (also known as NIX), key participants in receptor-mediated mitophagy. Under hypoxic conditions, stimulation of autophagy, as assessed by the accumulation of lipidated form of LC3 (LC3II), was observed. To exclude the contribution of canonical macroautophagy in LC3II accumulation, experiments were performed using U1810 cells lacking ATG13, a key enzyme of macroautophagy. Despite the absence of ATG13, hypoxia-mediated accumulation of LC3II was not affected, underlying the importance of the receptor-mediated pathway. In order to prove the protective role of BNIP3 against cisplatin-induced apoptosis, BNIP3-deficient A549 cells were used. Surprisingly, a BNIP3 knockout did not abolish hypoxia-induced protection; however, in cells lacking BNIP3, a compensatory upregulation of BNIP3L was detected. Thus, in the absence of BNIP3, mitophagy could be maintained by BNIP3L and lead to cell death suppression due to the elimination of proapoptotic mitochondria. When both BNIP3 and BNIP3L were knocked out, the inhibitory effect of hypoxia on apoptosis was diminished, although not abolished completely. Undoubtedly, receptor-mediated mitophagy is likely to be one of the mechanisms responsible for cell death suppression under hypoxic conditions.

Modulation of LPS-induced Cell Death by 5,6,7,8-Tetrahydrobiopterin

Pteridines ◽  
1999 ◽  
Vol 10 (4) ◽  
pp. 202-206
Author(s):  
Hiroyuki Iizuka ◽  
Hirofumi Sagara ◽  
Shuji Kojima
Keyword(s):  
Cell Death ◽  
Antioxidative Activity ◽  
Apoptotic Cell ◽  
Apoptotic Cell Death ◽  
Nitrate Content ◽  
Oxygen Species ◽  
No Donor ◽  
Induced Apoptosis ◽  
Raw 264.7 Cell Line

SummaryIt has been previously reported that 5,6,7,S-tetrahydrobiopterin (BH4) modulates HL-60 cell death induced by a nitric oxide (NO) donor, S-nitroso-N-acetyl-D, L-penicillamine (SNAP). In this study, the role of endogenous BH4 was investigated in lipopolysaccharide (LPS)-induced apoptotic cell death. LPS induced an increase of DNA fragmentation and of nitrite and nitrate content (NOx content) in the macrophage- like RAW 264.7 cell line. 2,4-Diamino-6-hydroxypyrimidine (DAHP) , an inhibitor of BH4 synthesis, suppressed both of them. The NOx content of cells treated with LPS and interferon-y was much higher than that of cells treated with LPS alone. However, the degree of apoptotic cell death induced by LPS and interferon-y did not differ significantly from that induced by LPS alone. Further investigation revealed that LPS-induced cell death of RAW264.7 cells was mainly mediated by reactive oxygen species, such as hydrogen peroxide (H2O2). From these data, it was speculated that BH4 might be a modulator in NO-induced apoptosis, in which BH4 involves LPS-induced cell death by its function asa cofactor of inducible NO synthase and it suppresses the cell death mediated by NO and/or H2O2 via an antioxidative activity.

scholarly journals Tumor Suppressive Role of miR-342-5p in Human Chondrosarcoma Cells and 3D Organoids

2021 ◽  
Vol 22 (11) ◽  
pp. 5590
Author(s):  
Clément Veys ◽  
Abderrahim Benmoussa ◽  
Romain Contentin ◽  
Amandine Duchemin ◽  
Emilie Brotin ◽  
...  
Keyword(s):  
Luciferase Reporter ◽  
Functional Screening ◽  
Western Blots ◽  
Egfr Expression ◽  
Reporter Assays ◽  
Direct Target ◽  
Induced Apoptosis ◽  
First Time

Chondrosarcomas are malignant bone tumors. Their abundant cartilage-like extracellular matrix and their hypoxic microenvironment contribute to their resistance to chemotherapy and radiotherapy, and no effective therapy is currently available. MicroRNAs (miRNAs) may be an interesting alternative in the development of therapeutic options. Here, for the first time in chondrosarcoma cells, we carried out high-throughput functional screening using impedancemetry, and identified five miRNAs with potential antiproliferative or chemosensitive effects on SW1353 chondrosarcoma cells. The cytotoxic effects of miR-342-5p and miR-491-5p were confirmed on three chondrosarcoma cell lines, using functional validation under normoxia and hypoxia. Both miRNAs induced apoptosis and miR-342-5p also induced autophagy. Western blots and luciferase reporter assays identified for the first time Bcl-2 as a direct target of miR-342-5p, and also Bcl-xL as a direct target of both miR-342-5p and miR-491-5p in chondrosarcoma cells. MiR-491-5p also inhibited EGFR expression. Finally, only miR-342-5p induced cell death on a relevant 3D chondrosarcoma organoid model under hypoxia that mimics the in vivo microenvironment. Altogether, our results revealed the tumor suppressive activity of miR-342-5p, and to a lesser extent of miR-491-5p, on chondrosarcoma lines. Through this study, we also confirmed the potential of Bcl-2 family members as therapeutic targets in chondrosarcomas.

scholarly journals Inhibition of Autophagy Enhances the Antitumor Effect of Thioridazine in Acute Lymphoblastic Leukemia Cells

Life ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 365
Author(s):  
Carina Colturato-Kido ◽  
Rayssa M. Lopes ◽  
Hyllana C. D. Medeiros ◽  
Claudia A. Costa ◽  
Laura F. L. Prado-Souza ◽  
...  
Keyword(s):  
Cell Death ◽  
Acute Lymphoblastic Leukemia ◽  
Lymphoblastic Leukemia ◽  
Clinical Problem ◽  
Jurkat Cells ◽  
Leukemia Cells ◽  
Peripheral Mononuclear Blood ◽  
Induced Apoptosis ◽  
Cure Rates

Acute lymphoblastic leukemia (ALL) is an aggressive malignant disorder of lymphoid progenitor cells that affects children and adults. Despite the high cure rates, drug resistance still remains a significant clinical problem, which stimulates the development of new therapeutic strategies and drugs to improve the disease outcome. Antipsychotic phenothiazines have emerged as potential candidates to be repositioned as antitumor drugs. It was previously shown that the anti-histaminic phenothiazine derivative promethazine induced autophagy-associated cell death in chronic myeloid leukemia cells, although autophagy can act as a “double-edged sword” contributing to cell survival or cell death. Here we evaluated the role of autophagy in thioridazine (TR)-induced cell death in the human ALL model. TR induced apoptosis in ALL Jurkat cells and it was not cytotoxic to normal peripheral mononuclear blood cells. TR promoted the activation of caspase-8 and -3, which was associated with increased NOXA/MCL-1 ratio and autophagy triggering. AMPK/PI3K/AKT/mTOR and MAPK/ERK pathways are involved in TR-induced cell death. The inhibition of the autophagic process enhanced the cytotoxicity of TR in Jurkat cells, highlighting autophagy as a targetable process for drug development purposes in ALL.

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