Search results for "FLOW CYTOMETRY"
showing 10 items of 814 documents
Topotecan triggers apoptosis in p53-deficient cells by forcing degradation of XIAP and survivin thereby activating caspase-3-mediated Bid cleavage.
2009
The topoisomerase I inhibitor topotecan (TPT) is used in the therapy of different tumors including high-grade gliomas. We previously showed that TPT-induced apoptosis depends on p53 with p53 wild-type (wt) cells being more resistant because of p53-controlled degradation of topoisomerase I. Here, we show that p53-deficient (p53(-/-)) fibroblasts undergo excessive mitochondrial apoptosis featuring H2AX phosphorylation, Bcl-x(L) decline, cytochrome c release, caspase-9/-3/-2 activation, and cleavage of Bid. In wt and apaf-1(-/-) cells, caspase-2 did not become activated and Bid was not cleaved. In addition, p53(-/-) cells cotreated with TPT and caspase-3 inhibitor showed neither caspase-2 acti…
Translocation Biosensors – Cellular System Integrators to Dissect CRM1-Dependent Nuclear Export by Chemicogenomics
2009
Fluorescent protein biosensors are powerful cellular systems biology tools for dissecting the complexity of cellular processes with high spatial and temporal resolution. As regulated nucleo-cytoplasmic transport is crucial for the modulation of numerous (patho)physiological cellular responses, a detailed understanding of its molecular mechanism would open up novel options for a rational manipulation of the cell. In contrast to genetic approaches, we here established and employed high-content cellular translocation biosensors applicable for dissecting nuclear export by chemicogenomics. A431 cell lines, stably expressing a translocation biosensor composed of glutathione S-transferase, GFP and…
Neuronal nitric oxide synthase modulates maturation of human dendritic cells.
2010
AbstractDendritic cells (DCs) are the most potent APCs of the immune system. Understanding the intercellular and intracellular signaling processes that lead to DC maturation is critical for determining how these cells initiate T cell-mediated immune processes. NO synthesized by the inducible NO synthase (iNOS) is important for the function of murine DCs. In our study, we investigated the regulation of the arginine/NO-system in human monocyte-derived DCs. Maturation of DCs induced by inflammatory cytokines (IL-1β, TNF, IL-6, and PGE2) resulted in a pronounced expression of neuronal NOS (nNOS) but only minimal levels of iNOS and endothelial NOS were detected in human mature DCs. In addition, …
Definition of the HLA-A2 restricted peptides recognized by human CD8+ effector T cells by flow-assisted sorting of the CD8+ CD45RA+ CD28– T cell subp…
2003
SUMMARY In response to antigenic stimulation, naive MHC-class I restricted and antigen-specific CD8+ CD45RA+ CD28+ T cells undergo clonal expansion, differentiate into CD8+ CD45RO+ memory T cells and convert to CD8+ CD45RA+ CD28− T cells displaying potent immune effector functions upon re-encounter with the nominal antigen. We show that the effector CD8+ CD45RA+ CD28– T cell subset is expanded in peripheral blood lymphocytes (PBL) from patients with human papilloma virus (HPV)+ cervical lesions as well as in PBL from patients with pulmonary tuberculosis. Flow-cytometric cell sorted CD8+ CD45RA+ CD28– and CD8+ CD45RA+ CD28– T cells were tested for recognition of HLA-A2 restricted peptides de…
The mitochondrial protein TCAIM regulates activation of T cells and thereby promotes tolerance induction of allogeneic transplants.
2013
Primary T cell activation and effector cell differentiation is required for rejection of allogeneic grafts in naive recipients. It has become evident, that mitochondria play an important role for T cell activation. Expression of several mitochondrial proteins such as TCAIM (T cell activation inhibitor, mitochondrial) is down-regulated upon T cell receptor triggering. Here we report that TCAIM inhibited spontaneous development of memory and effector T cells. CD4(+) T cells from Tcaim knock-in (KI) mice showed reduced activation, cytokine secretion and proliferation in vitro. Tcaim KI T cells tolerated allogeneic skin grafts upon transfer into Rag-1 KO mice. CD4(+) and CD8(+) T cells from the…
Macrophages are dispensable for superantigen-mediated stimulation and anergy induction of peripheral T cells in vivo.
1994
Bacterial superantigens provoke T lymphocyte activation by cross-linking the variable part of the T cell receptor (TCR) beta-chain with MHC class II molecules on antigen-presenting cells. Although the molecular mechanisms of this interaction are well characterized, the in vivo accessory cell requirements for this stimulation of T lymphocytes by bacterial superantigens remain unknown. In the present study we have addressed the role of splenic macrophages in the activation of V beta 8+ peripheral T cells by staphylococcal enterotoxin B (SEB) in BALB/c mice. SEB-triggered clonal expansion and subsequent induction of unresponsiveness of both CD4+ and CD8+ T cells were investigated in naive anim…
Intrahepatic myeloid-cell aggregates enable local proliferation of CD8+T cells and successful immunotherapy against chronic viral liver infection
2013
Chronic infection is difficult to overcome because of exhaustion or depletion of cytotoxic effector CD8(+) T cells (cytotoxic T lymphoytes (CTLs)). Here we report that signaling via Toll-like receptors (TLRs) induced intrahepatic aggregates of myeloid cells that enabled the population expansion of CTLs (iMATEs: 'intrahepatic myeloid-cell aggregates for T cell population expansion') without causing immunopathology. In the liver, CTL proliferation was restricted to iMATEs that were composed of inflammatory monocyte-derived CD11b(+) cells. Signaling via tumor-necrosis factor (TNF) caused iMATE formation that facilitated costimulation dependent on the receptor OX40 for expansion of the CTL popu…
Association between Serum Heat Shock Proteins and Gamma-Delta T Cells—An Outdated Clue or a New Direction in Searching for an Anticancer Strategy? A …
2021
HSPs demonstrate a strong association with gamma-delta (γδ) T cells. Most of the studies regarding interactions between the parameters were conducted in the 1990s. Despite promising results, the concept of targeting γδ T cells by HSPs seems to be a forgotten direction due to potent non-peptidic phosphoantigens rather than HSPs have been found to be the essential stimulatory components for human γδ cells. Currently, with greater knowledge of lymphocyte diversity, and more accurate diagnostic methods, we decided to study the correlation once again in the neoplastic condition. Twenty-one children with newly diagnosed acute lymphoblastic leukaemia (ALL) were enrolled on the study. Serum HSP90 c…
Glutathione regulates telomerase activity in 3T3 fibroblasts.
2004
Changes in telomerase activity have been associated either with cancer, when activity is increased, or with cell cycle arrest when it is decreased. We report that glutathione, a physiological antioxidant present at high intracellular concentrations, regulates telomerase activity in cells in culture. Telomerase activity increases in 3T3 fibroblasts before exponential cell growth. The peak of telomerase activity takes place 24 h after plating and coincides with the maximum levels of glutathione in the cells. When cells are treated with buthionine sulfoximine, which decreases glutathione levels in cells, telomerase activity decreases by 60%, and cell growth is delayed. Glutathione depletion in…
pRb suppresses camptothecin-induced apoptosis in human osteosarcoma Saos-2 cells by inhibiting c-Jun N-terminal kinase
2001
AbstractThis paper studies the cytotoxic effect induced by the topoisomerase I inhibitor camptothecin in human osteosarcoma Saos-2 cells, which lack p53 and contain a non-functional form of the product of the retinoblastoma gene, pRb. Cytotoxicity induced by camptothecin was dose- and time-dependent; the treatment with 100 nM camptothecin reduced cell viability by 50% at 32 h and by 75% at 72 h of exposure. The cytotoxic effect was caused by apoptosis, as ascertained by morphological evidence, acridine orange-ethidium bromide staining and flow cytometric analysis. Apoptosis was accompanied by both the activation of caspase-3 and the fragmentation of poly(ADP-ribose) polymerase. Treatment wi…