scholarly journals Dominant negative FADD/MORT1 inhibits the development of intestinal intraepithelial lymphocytes with a marked defect on CD8αα+TCRγδ+ T cells

2018 ◽  
Author(s):  
Xuerui Zhang ◽  
Lina Huo ◽  
Lulu Song ◽  
Zhaoqing Hu ◽  
Xinran Wang ◽  
...  
Keyword(s):  
T Cells ◽  
Death Receptor ◽  
Adaptor Protein ◽  
Intraepithelial Lymphocytes ◽  
Protective Role ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Intestinal Intraepithelial Lymphocytes ◽  
Induced Apoptosis

AbstractIntestinal intraepithelial lymphocytes are considered to be distinct from thymus-derived cells and are thought to derive locally from cryptopatch (CP) precursors. Although the development and homing of IELs have been studied in some details, the factors controlling their homeostasis are incompletely understood. Here, we demonstrate that FADD, a classic adaptor protein required for death-receptor-induced apoptosis, is a critical regulator of the intestinal IEL development. The mice with a dominant negative mutant of FADD (FADD-DN) display a defective localized intestinal IELs with a marked defect on CD8αα+TCRγδ+ T cells. Since Lin- LPLs have been identified as precursors CP cells for CD8αα+ development, we analyzed lamina propria lymphocytes (LPLs) and found the massive accumulation of IL-7R-lin- LPLs in FADD-DN mice. IL-7 plays a differentiation inducing role in the development of intestinal IELs and its receptor IL-7R is a transcriptional target of Notch1. The level of Notch1 expression also showed very low in Lin- LPLs cells from FADD-DN mice compared with normal mice, indicating a possible molecular mechanism of FADD in the early IEL development. In addition, loss of γδ T-IELs induced by FADD-DN results in a worsening inflammation in murine DSS-induced colitis model, suggesting a protective role of FADD in the intestinal homeostasis.

scholarly journals RasGRP1 Sensitizes an Immature B Cell Line to Antigen Receptor-induced Apoptosis

2004 ◽  
Vol 279 (19) ◽  
pp. 19523-19530 ◽  
Author(s):  
Benoit Guilbault ◽  
Robert J. Kay
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Cell Line ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Wehi 231 ◽  
Induced Apoptosis

RasGRP1 is a guanine nucleotide exchange factor that activates Ras GTPases and is activated downstream of antigen receptors on both T and B lymphocytes. Ras-GRP1 provides signals to immature T cells that confer survival and proliferation, but RasGRP1 also promotes T cell receptor-mediated deletion of mature T cells. We used the WEHI-231 cell line as an experimental system to determine whether RasGRP1 can serve as a quantitative modifier of B cell receptor-induced deletion of immature B cells. A 2-fold elevation in RasGRP1 expression markedly increased apoptosis of WEHI-231 cells following B cell receptor ligation, whereas a dominant negative mutant of RasGRP1 suppressed B cell receptor-induced apoptosis. Activation of ERK1 or ERK2 kinases was not required for RasGRP1-mediated apoptosis. Instead, elevated RasGRP1 expression caused down-regulation of NF-κB and Bcl-xL, which provide survival signals counter-acting apoptosis induction by B cell receptor. Inhibition of NF-κB was sufficient to enhance B cell receptor-induced apoptosis of WEHI-231 cells, and ligation of co-stimulatory receptors that activate NF-κB suppressed the ability of RasGRP1 to promote B cell receptor-induced apoptosis. These experiments define a novel apoptosis-promoting pathway leading from B cell receptor to the inhibition of NF-κB and demonstrate that differential expression of RasGRP1 has the potential to modulate the sensitivities of B cells to negative selection following antigen encounter.

scholarly journals GATA4 protects granulosa cell tumors from TRAIL-induced apoptosis

2010 ◽  
Vol 17 (3) ◽  
pp. 709-717 ◽  
Author(s):  
Antti Kyrönlahti ◽  
Marjut Kauppinen ◽  
Essi Lind ◽  
Leila Unkila-Kallio ◽  
Ralf Butzow ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Granulosa Cell ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Granulosa Cell Tumors ◽  
Trail Receptors ◽  
Apoptotic Effect ◽  
Induced Apoptosis

Disturbances in granulosa cell apoptosis have been implicated in the pathogenesis of human granulosa cell tumors (GCTs). Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent cytokine that induces apoptosis in a variety of malignancies without toxic effects on benign cells. The aim of this study was to investigate the expression and functionality of the TRAIL receptors DR4 and DR5 in human GCTs. Additionally, we examined the role of GATA4, a transcription factor expressed in normal and malignant granulosa cells, in TRAIL-induced GCT apoptosis. For this purpose, a tissue microarray of 80 primary and 12 recurrent GCTs was subjected to immunohistochemistry for DR4 and DR5, and freshly isolated primary GCT cultures were utilized to evaluate the functional effects of TRAIL on GCT cells. To clarify the role of GATA4 in the regulation of TRAIL-induced apoptosis, a human GCT-derived cell line (KGN) was transduced with lentiviral vectors expressing small hairpin RNAs targeting GATA4 or transfected with adenovirus expressing either wild-type or dominant negative mutant GATA4. We found that receptors DR4 and DR5 are expressed in a vast majority of GCTs as well as in primary GCT cultures, and that TRAIL induces apoptosis in the primary GCT cultures. Moreover, we showed that overexpressing GATA4 protects GCTs from TRAIL-induced apoptosis in vitro, whereas disrupting GATA4 function induces apoptosis and potentiates the apoptotic effect of TRAIL administration. Our results demonstrate that the TRAIL pathway is functional in GCT cells, and suggest that transcription factor GATA4 may function as a survival factor in this ovarian malignancy.

scholarly journals Tyrosine Phosphorylation of Protein Kinase Cδ Is Essential for Its Apoptotic Effect in Response to Etoposide

2002 ◽  
Vol 22 (1) ◽  
pp. 182-195 ◽  
Author(s):  
Michal Blass ◽  
Ilana Kronfeld ◽  
Gila Kazimirsky ◽  
Peter M. Blumberg ◽  
Chaya Brodie
Keyword(s):  
Protein Kinase ◽  
Tyrosine Phosphorylation ◽  
Dominant Negative ◽  
C6 Glioma Cells ◽  
Dominant Negative Mutant ◽  
Tyrosine Residues ◽  
Apoptotic Effect ◽  
Induced Apoptosis ◽  
Protein Kinase Cδ

ABSTRACT Protein kinase Cδ (PKCδ) is involved in the apoptosis of various cells in response to diverse stimuli. In this study, we characterized the role of PKCδ in the apoptosis of C6 glioma cells in response to etoposide. We found that etoposide induced apoptosis in the C6 cells within 24 to 48 h and arrested the cells in the G1/S phase of the cell cycle. Overexpression of PKCδ increased the apoptotic effect induced by etoposide, whereas the PKCδ selective inhibitor rottlerin and the PKCδ dominant-negative mutant K376R reduced this effect compared to control cells. Etoposide-induced tyrosine phosphorylation of PKCδ and its translocation to the nucleus within 3 h was followed by caspase-dependent cleavage of the enzyme. Using PKC chimeras, we found that both the regulatory and catalytic domains of PKCδ were necessary for its apoptotic effect. The role of tyrosine phosphorylation of PKCδ in the effects of etoposide was examined using cells overexpressing a PKCδ mutant in which five tyrosine residues were mutated to phenylalanine (PKCδ5). These cells exhibited decreased apoptosis in response to etoposide compared to cells overexpressing PKCδ. Likewise, activation of caspase 3 and the cleavage of the PKCδ5 mutant were significantly lower in cells overexpressing PKCδ5. Using mutants of PKCδ altered at individual tyrosine residues, we identified tyrosine 64 and tyrosine 187 as important phosphorylation sites in the apoptotic effect induced by etoposide. Our results suggest a role of PKCδ in the apoptosis induced by etoposide and implicate tyrosine phosphorylation of PKCδ as an important regulator of this effect.

Akt Regulates the Activation-Induced Apoptosis of T Cells Mediated by HIV-1 gp120.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3109-3109
Author(s):  
Appakkudal R. Anand ◽  
Ramesh K. Ganju
Keyword(s):  
T Cells ◽  
Cell Death ◽  
T Cell ◽  
Vector Control ◽  
Dominant Negative ◽  
Wild Type ◽  
Jurkat T Cells ◽  
Induced Apoptosis ◽  
Hiv 1

Abstract Multiple mechanisms contribute to the loss of CD4+ T cells in HIV-1 infected individuals. Activation-induced apoptosis of bystander T cells mediated by HIV-1 gp120 is one of the critical mechanisms leading to T cell loss in AIDS. Clinical studies have shown that T cells in the lymph nodes of HIV-1 infected individuals undergo activation-induced apoptosis. In the present study, we used a model where T cells undergo apoptosis after HIV-1 gp120/CD4 cross-linking in conjunction with CD3/T cell antigen receptor activation. We have shown that treatment with HIV-1 gp120 (10 nM) and anti-gp120 MoAb induces approximately 20–25% apoptosis in Jurkat T cells in the presence of immobilized anti-CD3 antibody. However, the molecular mechanism by which HIV-1 gp120 mediates the apoptosis of T cells is still unclear. We have also examined the role of Akt/Protein kinase B in HIV-1 gp120-induced apoptosis. Akt is a cell survival molecule that has been shown to block cell death. We observed a decrease in Akt phosphorylation upon gp120 treatment of Jurkat T cells and peripheral blood mononuclear cells (PBMCs). In contrast, only CD3 stimulation was shown to increase the phosphorylation of Akt. To further confirm the role of Akt in gp120-induced apoptosis, Jurkat T cells were transfected with HA epitope-tagged wild type Akt, dominant-negative Akt that lacks kinase activity, or with a control vector. The transfected cells were treated with gp120 and apoptosis was evaluated by Annexin-PI staining. The T cells expressing wild type Akt showed reduced gp120 apoptosis as compared to the vector control-expressing cells. Conversely, expression of a dominant-negative mutant of Akt accelerated cell death as compared to the vector control. We then further assessed the role of upstream regulators of Akt, such as PI-3 kinase. In this regard, we have shown that inhibition of PI-3 kinase leads to enhanced gp120-induced apoptosis. At present, we are elucidating downstream effectors of the Akt pathway. Taken together, these studies suggest that Akt plays a key role in HIV-1 gp120-induced apoptosis, and that identification of Akt-mediated signaling pathways may provide novel therapeutic targets to combat immune deficiency in AIDS.

scholarly journals Trafficking of the Menkes copper transporter ATP7A is regulated by clathrin-, AP-2–, AP-1–, and Rab22-dependent steps

2013 ◽  
Vol 24 (11) ◽  
pp. 1735-1748 ◽  
Author(s):  
Zoe G. Holloway ◽  
Antonio Velayos-Baeza ◽  
Gareth J. Howell ◽  
Clotilde Levecque ◽  
Sreenivasan Ponnambalam ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Adaptor Protein ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Copper Transporter ◽  
Caveolin 1 ◽  
Clathrin Adaptor ◽  
Partial Overlap ◽  
Golgi Network

The transporter ATP7A mediates systemic copper absorption and provides cuproenzymes in the trans-Golgi network (TGN) with copper. To regulate metal homeostasis, ATP7A constitutively cycles between the TGN and plasma membrane (PM). ATP7A trafficking to the PM is elevated in response to increased copper load and is reversed when copper concentrations are lowered. Molecular mechanisms underlying this trafficking are poorly understood. We assess the role of clathrin, adaptor complexes, lipid rafts, and Rab22a in an attempt to decipher the regulatory proteins involved in ATP7A cycling. While RNA interference (RNAi)–mediated depletion of caveolin 1/2 or flotillin had no effect on ATP7A localization, clathrin heavy chain depletion or expression of AP180 dominant-negative mutant not only disrupted clathrin-regulated pathways, but also blocked PM-to-TGN internalization of ATP7A. Depletion of the μ subunits of either adaptor protein-2 (AP-2) or AP-1 using RNAi further provides evidence that both clathrin adaptors are important for trafficking of ATP7A from the PM to the TGN. Expression of the GTP-locked Rab22aQ64L mutant caused fragmentation of TGN membrane domains enriched for ATP7A. These appear to be a subdomain of the mammalian TGN, showing only partial overlap with the TGN marker golgin-97. Of importance, ATP7A remained in the Rab22aQ64L-generated structures after copper treatment and washout, suggesting that forward trafficking out of this compartment was blocked. This study provides evidence that multiple membrane-associated factors, including clathrin, AP-2, AP-1, and Rab22, are regulators of ATP7A trafficking.

The role of cbl family of ubiquitin ligases in gastric cancer exosome-induced apoptosis of Jurkat T cells

2009 ◽  
pp. 1-8
Author(s):  
Jing-Lei Qu ◽  
Xiu-Juan Qu ◽  
Ming-Fang Zhao ◽  
Yue-E Teng ◽  
Ye Zhang ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
T Cells ◽  
Ubiquitin Ligases ◽  
Jurkat T Cells ◽  
Induced Apoptosis

Interleukin 35 protects cardiomyocytes following ischemia/reperfusion-induced apoptosis via activation of mitochondrial STAT3

2021 ◽  
Author(s):  
Fengyun Zhou ◽  
Ting Feng ◽  
Xiangqi Lu ◽  
Huicheng Wang ◽  
Yangping Chen ◽  
...  
Keyword(s):  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Protective Role ◽  
Cytochrome C Release ◽  
Neonatal Cardiomyocytes ◽  
Myocardial Ischemia Reperfusion Injury ◽  
Myocardial Ischemia Reperfusion ◽  
Underlying Mechanisms ◽  
Induced Apoptosis

Abstract Mitochondrial reactive oxygen species (mtROS)-induced apoptosis has been suggested to contribute to myocardial ischemia/reperfusion injury. Interleukin 35 (IL-35), a novel anti-inflammatory cytokine, has been shown to protect the myocardium and inhibit mtROS production. However, its effect on cardiomyocytes upon exposure to hypoxia/reoxygenation (H/R) damage has not yet been elucidated. The present study aimed to investigate the potential protective role and underlying mechanisms of IL-35 in H/R-induced mouse neonatal cardiomyocyte injury. Mouse neonatal cardiomyocytes were challenged to H/R in the presence of IL-35, and we found that IL-35 dose dependently promotes cell viability, diminishes mtROS, maintains mitochondrial membrane potential, and decreases the number of apoptotic cardiomyocytes. Meanwhile, IL-35 remarkably activates mitochondrial STAT3 (mitoSTAT3) signaling, inhibits cytochrome c release, and reduces apoptosis signaling. Furthermore, co-treatment of the cardiomyocytes with the STAT3 inhibitor AG490 abrogates the IL-35-induced cardioprotective effects. Our study identified the protective role of IL-35 in cardiomyocytes following H/R damage and revealed that IL-35 protects cardiomyocytes against mtROS-induced apoptosis through the mitoSTAT3 signaling pathway during H/R.

scholarly journals The role of unconventional T cells in COVID-19

2021 ◽  
Author(s):  
Kristen Orumaa ◽  
Margaret R. Dunne
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Treatment Strategies ◽  
Γδ T Cells ◽  
Protective Role ◽  
T Cell Subsets ◽  
Viral Immunity ◽  
Mait Cells

AbstractCOVID-19 is a respiratory disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It was first documented in late 2019, but within months, a worldwide pandemic was declared due to the easily transmissible nature of the virus. Research to date on the immune response to SARS-CoV-2 has focused largely on conventional B and T lymphocytes. This review examines the emerging role of unconventional T cell subsets, including γδ T cells, invariant natural killer T (iNKT) cells and mucosal associated invariant T (MAIT) cells in human SARS-CoV-2 infection.Some of these T cell subsets have been shown to play protective roles in anti-viral immunity by suppressing viral replication and opsonising virions of SARS-CoV. Here, we explore whether unconventional T cells play a protective role in SARS-CoV-2 infection as well. Unconventional T cells are already under investigation as cell-based immunotherapies for cancer. We discuss the potential use of these cells as therapeutic agents in the COVID-19 setting. Due to the rapidly evolving situation presented by COVID-19, there is an urgent need to understand the pathogenesis of this disease and the mechanisms underlying its immune response. Through this, we may be able to better help those with severe cases and lower the mortality rate by devising more effective vaccines and novel treatment strategies.

scholarly journals The critical role of T cells in glucocorticoid-induced osteoporosis

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Lin Song ◽  
Lijuan Cao ◽  
Rui Liu ◽  
Hui Ma ◽  
Yanan Li ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Steady State ◽  
Side Effects ◽  
Critical Role ◽  
Wild Type ◽  
Receptor Activator ◽  
Steady State Levels ◽  
Induced Apoptosis

AbstractGlucocorticoids (GC) are widely used clinically, despite the presence of significant side effects, including glucocorticoid-induced osteoporosis (GIOP). While GC are believed to act directly on osteoblasts and osteoclasts to promote osteoporosis, the detailed underlying molecular mechanism of GC-induced osteoporosis is still not fully elucidated. Here, we show that lymphocytes play a pivotal role in regulating GC-induced osteoporosis. We show that GIOP could not be induced in SCID mice that lack T cells, but it could be re-established by adoptive transfer of splenic T cells from wild-type mice. As expected, T cells in the periphery are greatly reduced by GC; instead, they accumulate in the bone marrow where they are protected from GC-induced apoptosis. These bone marrow T cells in GC-treated mice express high steady-state levels of NF-κB receptor activator ligand (RANKL), which promotes the formation and maturation of osteoclasts and induces osteoporosis. Taken together, these findings reveal a critical role for T cells in GIOP.

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