scholarly journals Thy-1 triggers mouse thymocyte apoptosis through a bcl-2-resistant mechanism.

1994 ◽  
Vol 179 (3) ◽  
pp. 785-796 ◽  
Author(s):  
A O Hueber ◽  
G Raposo ◽  
M Pierres ◽  
H T He
Keyword(s):  
Cell Death ◽  
Protein Synthesis ◽  
Structural Domain ◽  
Protein Synthesis Inhibitors ◽  
Thymocyte Development ◽  
Dot Blot ◽  
Double Positive ◽  
Mouse Thymocyte ◽  
Major Interest ◽  
Thymocyte Apoptosis

Programmed cell death plays an important role during thymocyte development, since a vast majority (97%) of mouse cortical thymocytes die in thymus, whereas only 3% of these cells are rescued from cell death and positively selected. Although it seems well established that thymocyte fate depends upon appropriate surface-expressed T cell receptor, little is known about the molecular mechanism(s) responsible for the massive thymocyte elimination that occurs in the thymus. We report here that Thy-1 is capable of triggering mouse thymocyte death in vitro through a bcl-2-resistant mechanism. We have previously shown that Thy-1 is involved in mouse thymocyte adhesion to thymic stroma through interaction with an epithelial cell ligand. To examine the Thy-1 signaling function in thymocytes, we have mimicked its interaction with stromal cells by culturing mouse thymocytes onto tissue culture plates coated with monoclonal antibodies (mAb) directed at distinct Thy-1 epitope regions. mAb recognizing determinants in a defined Thy-1 structural domain, but not others, were found to induce marked thymocyte apoptosis as evidenced by morphological and biochemical data. Use of a quantitative DNA dot blot assay indicated that Thy-1-mediated thymocyte apoptosis was not blocked by RNA or protein synthesis inhibitors, EGTA, or by cyclosporin A, and differed, therefore, from "activation-driven cell death". Moreover, Thy-1(+)-transfected, but not wild-type AKR1 (Thy-1-d) thymoma cells underwent apoptosis after ligation with apoptosis-inducing, Thy-1-specific mAb. In contrast to thymocytes, the latter event was inhibitable by RNA and protein synthesis inhibitors, an indication that thymocytes, but not thymoma cells, contain the molecular components necessary for Thy-1-driven apoptosis. We further showed that Thy-1-triggered thymocyte death is a developmentally regulated process operative in fetal thymocytes from day 17 of gestation, but not in peripheral T cells. Indeed, the target of apoptosis by anti-Thy-1 was found to reside mainly within the CD4+8+3- and CD4+8+3lo double positive immature thymocyte subsets. Finally, it is of major interest that Thy-1-mediated apoptosis, which was found to be readily detectable in thymocytes from bcl-2-transgenic mice, represents a thus far unique experimental system for studying bcl-2-resistant thymocyte death mechanism(s).

scholarly journals Critical role of WNK1 in MYC-dependent early mouse thymocyte development

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Robert Köchl ◽  
Lesley Vanes ◽  
Miriam Llorian Sopena ◽  
Probir Chakravarty ◽  
Harald Hartweger ◽  
...  
Keyword(s):  
Critical Role ◽  
Ion Homeostasis ◽  
Thymocyte Development ◽  
Double Positive ◽  
Mouse Thymocyte ◽  
Proliferation And Differentiation ◽  
Tcr Signals ◽  
And Migration ◽  
Early Mouse

WNK1, a kinase that controls kidney salt homeostasis, also regulates adhesion and migration in CD4+ T cells. Wnk1 is highly expressed in thymocytes, and since migration is important for thymocyte maturation, we investigated a role for WNK1 in mouse thymocyte development. We find that WNK1 is required for the transition of double negative (DN) thymocytes through the β-selection checkpoint and subsequent proliferation and differentiation into double positive (DP) thymocytes. Furthermore, we show that WNK1 negatively regulates LFA1-mediated adhesion and positively regulates CXCL12-induced migration in DN thymocytes. Despite this, migration defects of WNK1-deficient thymocytes do not account for the developmental arrest. Instead, we show that in DN thymocytes WNK1 transduces pre-TCR signals via OXSR1 and STK39 kinases, and the SLC12A2 ion co-transporter that are required for post-transcriptional upregulation of MYC and subsequent proliferation and differentiation into DP thymocytes. Thus, a pathway regulating ion homeostasis is a critical regulator of thymocyte development.

scholarly journals Survivin Loss in Thymocytes Triggers p53-mediated Growth Arrest and p53-independent Cell Death

2004 ◽  
Vol 199 (3) ◽  
pp. 399-410 ◽  
Author(s):  
Hitoshi Okada ◽  
Chris Bakal ◽  
Arda Shahinian ◽  
Andrew Elia ◽  
Andrew Wakeham ◽  
...  
Keyword(s):  
Cell Death ◽  
Critical Role ◽  
Cell Receptor ◽  
Thymocyte Development ◽  
Double Positive ◽  
Developmental Defects ◽  
Cycle Arrest ◽  
Tightly Coupled ◽  
Early Embryonic Stage ◽  
P53 Inactivation

Because survivin-null embryos die at an early embryonic stage, the role of survivin in thymocyte development is unknown. We have investigated the role by deleting the survivin gene only in the T lineage and show here that loss of survivin blocks the transition from CD4− CD8− double negative (DN) thymocytes to CD4+ CD8+ double positive cells. Although the pre–T cell receptor signaling pathway is intact in survivin-deficient thymocytes, the cells cannot respond to its signals. In response to proliferative stimuli, cycling survivin-deficient DN cells exhibit cell cycle arrest, a spindle formation defect, and increased cell death. Strikingly, loss of survivin activates the tumor suppressor p53. However, the developmental defects caused by survivin deficiency cannot be rescued by p53 inactivation or introduction of Bcl-2. These lines of evidence indicate that developing thymocytes depend on the cytoprotective function of survivin and that this function is tightly coupled to cell proliferation but independent of p53 and Bcl-2. Thus, survivin plays a critical role in early thymocyte development.

Changes in heat shock protein synthesis and heat sensitivity during mouse thymocyte development

1993 ◽  
Vol 14 (2) ◽  
pp. 148-158 ◽  
Author(s):  
Dick D. Mosser ◽  
Jean Duchaine ◽  
Lucie Bourget ◽  
Luis H. Martin
Keyword(s):  
Protein Synthesis ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Heat Sensitivity ◽  
Thymocyte Development ◽  
Mouse Thymocyte

scholarly journals Normal Immune Development and Glucocorticoid-Induced Thymocyte Apoptosis in Mice Deficient for the T-Cell Death-Associated Gene 8 Receptor

2006 ◽  
Vol 26 (2) ◽  
pp. 668-677 ◽  
Author(s):  
Caius G. Radu ◽  
Donghui Cheng ◽  
Amar Nijagal ◽  
Mireille Riedinger ◽  
Jami McLaughlin ◽  
...  
Keyword(s):  
Cell Death ◽  
T Cell ◽  
Fluorescent Protein ◽  
Critical Role ◽  
Immune Functions ◽  
Thymocyte Development ◽  
Double Positive ◽  
Immune Development ◽  
Induced Apoptosis

ABSTRACT T-cell death-associated gene 8 (TDAG8) is a G-protein-coupled receptor transcriptionally upregulated by glucocorticoids (GCs) and implicated by overexpression studies in psychosine-mediated inhibition of cytokinesis and in GC-induced apoptosis. To examine the physiological function of TDAG8, we generated knockout (KO) mice by homologous recombination. An enhanced green fluorescent protein reporter was knocked into the disrupted tdag8 locus to allow the analysis of TDAG8 expression in living cells. Interestingly, we found that during thymocyte development, TDAG8 expression resembled the dynamic regulation described for known modulators of GC-induced apoptosis, including Bcl-2, Notch1, and GC receptor. TDAG8 was expressed in double-negative cells, was downregulated at the double-positive transition, and was upregulated in single-positive thymocytes. However, despite this striking expression pattern, maturation and selection of thymocytes, as well as major immune functions, were not affected in TDAG8 KO mice. In contrast to previous overexpression results, TDAG8 was dispensable for psychosine-induced formation of multinucleated cells. Furthermore, TDAG8 KO thymocytes showed normal apoptosis following in vivo and in vitro GC treatment. These results, while establishing a useful reporter strain to study T-lymphocyte maturation, argue against a critical role for TDAG8 in immune development, psychosine-mediated inhibition of cytokinesis, and GC-induced cell death.

Apoptosis of Dedifferentiated Hepatoma Cells is Independent of NF-κB Activation in Response to LPS

2007 ◽  
Vol 27 (4-5) ◽  
pp. 235-246
Author(s):  
M. Ryan Reidy ◽  
Janette Ellis ◽  
Erin A. Schmitz ◽  
David M. Kraus ◽  
Gary A. Bulla
Keyword(s):  
Gene Expression ◽  
Cell Death ◽  
Protein Synthesis ◽  
Cell Survival ◽  
Cell Types ◽  
Hepatoma Cells ◽  
Protein Synthesis Inhibitor ◽  
Protein Synthesis Inhibitors ◽  
Synthesis Inhibitor ◽  
Dedifferentiated Hepatoma

Dedifferentiated hepatoma cells, in contrast to most other cell types including hepatoma cells, undergo apoptosis when treated with lipopolysaccharide (LPS) plus the protein synthesis inhibitor cycloheximide (CHx). We recently reported that the dedifferentiated hepatoma cells also exhibit a strong and prolonged NF-κB induction phenotype upon exposure to LPS, suggesting that NF-κB signaling may play a pro-survival role, as reported in several other cell systems. To test the role of NF-κB in preventing LPS-mediated apoptosis, we examined the dedifferentiated cell line M38. Results show that antioxidants strongly inhibited LPS + CHx-mediated cell death in the M38 cells, yet only modestly inhibited NF-κB induction. In addition, inhibition of NF-κB translocation by infection of the M38 cells with an adenoviral vector expressing an IκBα super-repressor did not result in LPS-mediated cell death. These results suggest that unlike TNFα induction, the cell survival pathway activated in response to LPS is independent of NF-κB translocation in the dedifferentiated cells. Addition of inhibitors of JNK, p38 and ERK pathways also failed to elicit LPS-mediated apoptosis similar to that observed when protein synthesis is prevented. Thus, cell survival pathways other than those involving NF-κB inducible gene expression or other well-known pathways appear to be involved in protecting the dedifferentiated hepatoma variant cells from LPS-mediated apoptosis. Importantly, this pro-apoptotic function of LPS appears to be a function of loss of hepatic gene expression, as the parental hepatoma cells resist LPS-mediated apoptosis in the presence of protein synthesis inhibitors.

Activation of bovine oocytes by protein synthesis inhibitors: new findings on the role of MPF/MAPKs†

2021 ◽  
Author(s):  
Cecilia Valencia ◽  
Felipe Alonso Pérez ◽  
Carola Matus ◽  
Ricardo Felmer ◽  
María Elena Arias
Keyword(s):  
Protein Synthesis ◽  
Kinase Activity ◽  
Cyclin B1 ◽  
Protein Synthesis Inhibitors ◽  
Vitro Fertilization ◽  
New Findings ◽  
Bovine Oocytes ◽  
Dependent Pathway

Abstract The present study evaluated the mechanism by which protein synthesis inhibitors activate bovine oocytes. The aim was to analyze the dynamics of MPF and MAPKs. MII oocytes were activated with ionomycin (Io), ionomycin+anisomycin (ANY) and ionomycin+cycloheximide (CHX) and by in vitro fertilization (IVF). The expression of cyclin B1, p-CDK1, p-ERK1/2, p-JNK, and p-P38 were evaluated by immunodetection and the kinase activity of ERK1/2 was measured by enzyme assay. Evaluations at 1, 4, and 15 hours postactivation (hpa) showed that the expression of cyclin B1 was not modified by the treatments. ANY inactivated MPF by p-CDK1Thr14-Tyr15 at 4 hpa (P < 0.05), CHX increased pre-MPF (p-CDK1Thr161 and p-CDK1Thr14-Tyr15) at 1 hpa and IVF increased p-CDK1Thr14-Tyr15 at 17 hours postfertilization (hpf) (P < 0.05). ANY and CHX reduced the levels of p-ERK1/2 at 4 hpa (P < 0.05) and its activity at 4 and 1 hpa, respectively (P < 0.05). Meanwhile, IVF increased p-ERK1/2 at 6 hpf (P < 0.05); however, its kinase activity decreased at 6 hpf (P < 0.05). p-JNK in ANY, CHX, and IVF oocytes decreased at 4 hpa (P < 0.05). p-P38 was only observed at 1 hpa, with no differences between treatments. In conclusion, activation of bovine oocytes by ANY, CHX, and IVF inactivates MPF by CDK1-dependent specific phosphorylation without cyclin B1 degradation. ANY or CHX promoted this inactivation, which seemed to be more delayed in the physiological activation (IVF). Both inhibitors modulated MPF activity via an ERK1/2-independent pathway, whereas IVF activated the bovine oocytes via an ERK1/2-dependent pathway. Finally, ANY does not activate the JNK and P38 kinase pathways.

scholarly journals CD45-null transgenic mice reveal a positive regulatory role for CD45 in early thymocyte development, in the selection of CD4+CD8+ thymocytes, and B cell maturation.

1996 ◽  
Vol 183 (4) ◽  
pp. 1707-1718 ◽  
Author(s):  
K F Byth ◽  
L A Conroy ◽  
S Howlett ◽  
A J Smith ◽  
J May ◽  
...  
Keyword(s):  
Signal Transduction ◽  
T Cell ◽  
B Cells ◽  
Transgenic Mice ◽  
B Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Cross Linking ◽  
Thymocyte Development ◽  
Double Positive

The CD45 transmembrane glycoprotein has been shown to be a protein phosphotyrosine phosphatase and to be important in signal transduction in T and B lymphocytes. We have employed gene targeting to create a strain of transgenic mice that completely lacks expression of all isoforms of CD45. The spleens from CD45-null mice contain approximately twice the number of B cells and one fifth the number of T cells found in normal controls. The increase in B cell numbers is due to the specific expansion of two B cell subpopulations that express high levels of immunoglobulin (IgM) staining. T cell development is significantly inhibited in CD45-null animals at two distinct stages. The efficiency of the development of CD4-CD8- thymocytes into CD4+ CD8+ thymocytes is reduced by twofold, subsequently the frequency of successful maturation of the double positive population into mature, single positive thymocytes is reduced by a further four- to fivefold. In addition, we demonstrate that CD45-null thymocytes are severely impaired in their apoptotic response to cross-linking signals via T cell receptor (TCR) in fetal thymic organ culture. In contrast, apoptosis can be induced normally in CD45-null thymocytes by non-TCR-mediated signals. Since both positive and negative selection require signals through the TCR complex, these findings suggest that CD45 is an important regulator of signal transduction via the TCR complex at multiple stages of T cell development. CD45 is absolutely required for the transmission of mitogenic signals via IgM and IgD. By contrast, CD45-null B cells proliferate as well as wild-type cells to CD40-mediated signals. The proliferation of B cells in response to CD38 cross-linking is significantly reduced but not abolished by the CD45-null mutation. We conclude that CD45 is not required at any stage during the generation of mature peripheral B cells, however its loss reveals a previously unrecognized role for CD45 in the regulation of certain subpopulations of B cells.

Sign in / Sign up

Export Citation Format

Share Document