Home About us Contact
|
Home About us Contact | ||
|
|
||
Spontaneous Apoptosis (spontaneous + apoptosi)
Selected AbstractsSpontaneous apoptosis in chronic lymphocytic leukemia and its relationship to clinical and cell kinetic parametersCYTOMETRY, Issue 6 2001Gislaine B. Oliveira Abstract Chronic lymphocytic leukemia (CLL) presents considerable variability in clinical presentation as well as in its evolution. In contrast to the inhibition of apoptosis in vivo, spontaneous apoptosis after short-term culture occurs. We studied the degree of this apoptosis in vitro, and its interactions with several clinical and laboratory parameters. Apoptosis was measured by the annexin V technique. Proliferation rate was evaluated by the AgNOR (nucleolar organizer regions) technique. There were inverse correlations between the percentage of annexin V-positive cells and peripheral lymphocyte count (r = - 0.49), Rai stage (r = - 0.40), Binet stage (r = - 0.50), TTM (total tumor mass score; r = - 0.51), and percentage of cells with one AgNOR cluster (r = - 0.45). Direct correlations were found with hemoglobin values ( r = 0.34) and platelet counts (r = 0.52). The number of CD8-positive cells showed a correlation with peripheral lymphocyte count (r = 0.49). When this variable was held constant, a correlation was detected between CD8-positive cells and staging (r = -0.47), TTM (r = - 0.42), and platelet count (r = 0.67). CD4-positive lymphocytes presented a correlation only with CD8-positive lymphocytes. In a cluster analysis, it was possible to create three groups of patients with different apoptosis rates using the TTM and AgNOR values. We conclude that, with the progression of the disease, together with the increase of tumor mass and proliferation rate, there is a decrease in the suceptibility to apoptosis. Cytometry (Comm. Clin. Cytometry) 46:329,335, 2001. © 2001 Wiley-Liss, Inc. [source] The antiapoptotic effects of blood constituents in patients with chronic lymphocytic leukemiaEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 5 2003Yonit Bomstein Abstract: Objective: Clonal B-lymphocytes of chronic lymphocytic leukemia (B-CLL) are characterized by decreased sensitivity to programmed cell death and, therefore, they accumulate in vivo. However, these malignant cells die rapidly in vitro. In the current study we concentrated on the contribution of autologous serum (AS) and lymphocyte subsets to the survival of the malignant cells in vitro. Methods: Mononuclear cells from the peripheral blood of 26 CLL patients and 24 controls were incubated overnight in the presence or absence of AS and heat-inactivated AS (HI-AS) or fetal calf serum (FCS). Also, isolated B cells were incubated at different concentrations in the presence of AS and/or isolated T cells. The level of apoptosis of CD19+ cells was measured by flow cytometry. Results: Spontaneous apoptosis of unfractionated B-CLL cells incubated with AS, FCS or without serum was significantly lower than the rate of B-cell death in the control group, in similar culture conditions. AS had an antiapoptotic effect on unfractionated B-CLL cells when compared with FCS. The rate of apoptosis of B-CLL cells was directly associated with stage. HI of AS had a variable effect, which was related to the stage of the disease. High concentrations of B cells and the addition of autologous T cells reduced the rate of apoptosis when incubated without serum. The antiapoptotic effect of T cells was most prominent in progressive stages. Conclusions: B-CLL cells exhibit decreased spontaneous apoptosis, which is partially prevented by humoral (AS) and cellular (T cells and B-CLL cells) factors. The equilibrium between apoptotic and antiapoptotic factors changes with disease progression. [source] Alterations in the expression of inhibitors of apoptosis during differentiation of prostate epithelial cellsBJU INTERNATIONAL, Issue 2 2007Ronan M. Long OBJECTIVE To investigate alterations in the apoptotic phenotype, specifically the inhibitors of apoptosis (IAP) family, in prostate epithelial cells after differentiation from an apoptotic-resistant basal cell to an apoptotic-susceptible secretory cell. MATERIALS AND METHODS Cells of the immortalized human prostate epithelial line HPr-1AR were cultured with and with no 5,-dihydrotestosterone (DHT) to drive differentiation. Western blotting and reverse transcription-polymerase chain reaction (RT-PCR) were used to determine changes in differentiation markers such as cytokeratins (CK) 14 and 18, and in XIAP, cIAP-1 and cIAP-2. Flow cytometry was used to assess viability and apoptosis, by propidium iodide DNA staining of the cells during differentiation. RESULTS Morphological changes and the increased CK-18 and decreased CK-14 expression confirmed differentiation of cells towards a secretory phenotype. Real-time PCR and Western blotting confirmed the expression of the IAPs in the HPr-1AR cells. There was a time-dependent decrease in the mRNA expression of XIAP, cIAP-1 and cIAP-2 after treatment with DHT. Differentiation also resulted in decreased cIAP-1 and XIAP protein expression, but cIAP-2 remained unchanged. Spontaneous apoptosis was significantly increased during cellular differentiation. CONCLUSION We show for the first time that differentiation of HPr-1AR prostate epithelial cells results in the development of a transient end-stage cell that might be explained by the loss of the IAP family of proteins. [source] JC-1, a sensitive probe for a simultaneous detection of P-glycoprotein activity and apoptosis in leukemic cellsCYTOMETRY, Issue 3 2006Driss Chaoui Abstract Background JC-1 probe has been successfully used for the analysis of either apoptosis or P-glycoprotein (P-gp) activity. Therefore, we wanted to see if JC-1 could also simultaneously assess both, P-gp activity and apoptosis, in acute myeloid leukemia (AML) cells. Methods P-gp activity was measured using JC-1 and compared to the results of the Rhodamine 123 (Rh 123) assay in P-gp negative and P-gp positive cell lines, and 12 AML samples. For apoptosis, spontaneous apoptosis, as well as, apoptosis induced by Cytosine Arabinosine and Homoharringtonine were analyzed. Both mitochondrial red fluorescence and cytoplasmic green fluorescence of JC-1 with and without a P-gp inhibitor (Cyclosporine A : CsA) were used for the identification of apoptotic cells, and this was compared to Annexin V/PI staining. Results (1) We found a good correlation between JC-1 and Rh 123 in viable cells. Even in a small population of viable cells, P-gp positive cells emitting low red fluorescence, gained on red fluorescence after P-gp inhibition with CsA permitting an evaluation of P-gp activity. (2) We found a good correlation between the Annexin V/PI staining and JC-1 (P < 0.0001) in the assessment of apoptotic cells. Most importantly, the apoptotic cells could be distinguished by the loss of red fluorescence and the increase of green fluorescence without any change after P-gp inhibition with CsA. Conclusions JC-1 can simultaneously evaluate two important parameters involved in drug resistance in AML cells, P-gp activity and apoptosis. © 2006 International Society for Analytical Cytology [source] Spontaneous apoptosis in chronic lymphocytic leukemia and its relationship to clinical and cell kinetic parametersCYTOMETRY, Issue 6 2001Gislaine B. Oliveira Abstract Chronic lymphocytic leukemia (CLL) presents considerable variability in clinical presentation as well as in its evolution. In contrast to the inhibition of apoptosis in vivo, spontaneous apoptosis after short-term culture occurs. We studied the degree of this apoptosis in vitro, and its interactions with several clinical and laboratory parameters. Apoptosis was measured by the annexin V technique. Proliferation rate was evaluated by the AgNOR (nucleolar organizer regions) technique. There were inverse correlations between the percentage of annexin V-positive cells and peripheral lymphocyte count (r = - 0.49), Rai stage (r = - 0.40), Binet stage (r = - 0.50), TTM (total tumor mass score; r = - 0.51), and percentage of cells with one AgNOR cluster (r = - 0.45). Direct correlations were found with hemoglobin values ( r = 0.34) and platelet counts (r = 0.52). The number of CD8-positive cells showed a correlation with peripheral lymphocyte count (r = 0.49). When this variable was held constant, a correlation was detected between CD8-positive cells and staging (r = -0.47), TTM (r = - 0.42), and platelet count (r = 0.67). CD4-positive lymphocytes presented a correlation only with CD8-positive lymphocytes. In a cluster analysis, it was possible to create three groups of patients with different apoptosis rates using the TTM and AgNOR values. We conclude that, with the progression of the disease, together with the increase of tumor mass and proliferation rate, there is a decrease in the suceptibility to apoptosis. Cytometry (Comm. Clin. Cytometry) 46:329,335, 2001. © 2001 Wiley-Liss, Inc. [source] The antiapoptotic effects of blood constituents in patients with chronic lymphocytic leukemiaEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 5 2003Yonit Bomstein Abstract: Objective: Clonal B-lymphocytes of chronic lymphocytic leukemia (B-CLL) are characterized by decreased sensitivity to programmed cell death and, therefore, they accumulate in vivo. However, these malignant cells die rapidly in vitro. In the current study we concentrated on the contribution of autologous serum (AS) and lymphocyte subsets to the survival of the malignant cells in vitro. Methods: Mononuclear cells from the peripheral blood of 26 CLL patients and 24 controls were incubated overnight in the presence or absence of AS and heat-inactivated AS (HI-AS) or fetal calf serum (FCS). Also, isolated B cells were incubated at different concentrations in the presence of AS and/or isolated T cells. The level of apoptosis of CD19+ cells was measured by flow cytometry. Results: Spontaneous apoptosis of unfractionated B-CLL cells incubated with AS, FCS or without serum was significantly lower than the rate of B-cell death in the control group, in similar culture conditions. AS had an antiapoptotic effect on unfractionated B-CLL cells when compared with FCS. The rate of apoptosis of B-CLL cells was directly associated with stage. HI of AS had a variable effect, which was related to the stage of the disease. High concentrations of B cells and the addition of autologous T cells reduced the rate of apoptosis when incubated without serum. The antiapoptotic effect of T cells was most prominent in progressive stages. Conclusions: B-CLL cells exhibit decreased spontaneous apoptosis, which is partially prevented by humoral (AS) and cellular (T cells and B-CLL cells) factors. The equilibrium between apoptotic and antiapoptotic factors changes with disease progression. [source] Progressive CD127 down-regulation correlates with increased apoptosis of CD8 T cells during chronic HIV-1 infectionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2009Shu-Ye Zhang Abstract Chronic HIV-1 infection can induce a significant decrease in CD127 expression on CD8 T cells, but the underlying mechanisms and immunological consequences are unclear. In this study, we investigated CD127 expression on CD8 T cells from a total of 51 HIV-1-infected subjects and 16 healthy individuals and analyzed the association between CD127 expression and CD8 T-cell apoptosis in these HIV-1-infected subjects. We found that CD127 expression on total CD8 T cells was significantly down-regulated, which was correlated with the increased CD8 T-cell apoptosis and disease progression of chronic HIV-1 infection. The in vitro addition of IL-7 efficiently rescued the spontaneous apoptosis of CD8 T cells from HIV-1-infected individuals. IL-7 stimulation also transiently down-regulated CD127 expression, whereas some of the CD127, CD8 T cells regained CD127 expression soon after IL-7 was retracted from the incubation medium. Thus, IL-7 stimulation reduced apoptosis of both CD127+ and CD127,CD8 T cells to some degree. These data indicate that CD127 loss might impair IL-7 signaling and increase CD8 T-cell apoptosis during HIV-1 infection. This study, therefore, will extend the notion that IL-7 could be a good candidate for immunotherapy in HIV-1-infected patients. [source] Murine thymic plasmacytoid dendritic cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 4 2003Tomoyuki Okada Abstract We report herein heterogeneous murine thymic cell subsets expressing CD11c and B220 (CD45R). The CD11c+B220+ subset expresses Ly6Chigh and MHC class IIlow in contrast with previously described thymic DC (CD11c+B220, cells). Freshly isolated thymic CD11c+B220+ cells show typical plasmacytoid morphology which differentiates to mature DC, in vitro with CpG oligodeoxynucleotides (ODN) 2216; we term this subset thymic plasmacytoid DC (pDC). These thymic pDC are highly sensitive to spontaneous apoptosis in vitro and induce low T cell allo-proliferation activity. Thymic pDC express low TLR2, TLR3 and TLR4 mRNA, normally found on human immature DC, and high TLR7 and TLR9 mRNA, normally found on human pDC. Thymic pDC also produce high amounts of IFN-, following culture with CpG ODN 2216 (TLR9 ligands) as compared with the previously defined thymic DC lineage which expresses low TLR9 mRNA and produce high IL-12 (p40) with CpG ODN 2216. These results indicate that thymic pDC are similar to IFN-producing cells as well as human pDC. The TLR and cytokine production profiles are consistent with a nomenclature of pDC. The repertoire of this cell lineage to TLR9 ligands demonstrate that such responses are determined not only by the quantity of expression, but also cell lineage. [source] Cell proliferation and apoptosis: dual-signal hypothesis tested in tuberculous pleuritis using mycobacterial antigensFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 1 2004Sulochana D. Das Abstract Antigens and mitogens have the innate ability to trigger cell proliferation and apoptosis thus exhibiting a dual-signal phenomenon. This dual-signal hypothesis was tested with mycobacterial antigens (PPD and heat killed Mycobacterium tuberculosis, MTB) in tuberculous pleuritis patients where the immune response is protective and compartmentalized. We compared and correlated the cell-cycle analysis and antigen-induced apoptosis in normal and patients' peripheral blood mononuclear cells (PBMCs) and patients' pleural fluid mononuclear cells (PFMCs). In cell-cycle analysis, PFMCs showed good mitotic response with PPD and MTB antigens where 10% and 7% of resting cells entered the S and G2/M phases of cell cycle, respectively. This antigen-induced proliferation of PFMCs correlated well with the lymphocyte transformation test (LTT) results. On the other hand, PFMCs also showed 21% of spontaneous apoptosis, which further increased to 43%, by induction with known apoptotic agent like Dexamethasone (DEX) and the mycobacterial antigens PPD and MTB. Further we demonstrated by anti-CD3 induction experiments that prior activation of cells is prerequisite for them to undergo apoptosis. Our results showed that PPD and MTB antigens induced both cell proliferation and apoptosis in PFMCs, which were pre-sensitized to mycobacterial antigens in vivo. Thus the dual-signal phenomenon was operative against these antigens in tuberculous pleuritis. We also demonstrated that the activated cells are more predisposed to apoptosis. [source] Prolonged exposure of naïve CD8+ T cells to interleukin-7 or interleukin-15 stimulates proliferation without differentiation or loss of telomere lengthIMMUNOLOGY, Issue 2 2006Diana L. Wallace Summary Interleukin (IL)-7 and IL-15 are cytokines implicated in homeostatic control of the peripheral CD8 T-cell pool. We compared the effects of IL-7 and IL-15 on survival and proliferation of purified human CD8+ T-cell subsets. Low concentrations of either cytokine reduced the spontaneous apoptosis of all subsets, and enhancement of survival corresponded to the extent of Bcl-2 up-regulation. Surprisingly, although minimal proliferation of naïve CD8+ T cells was observed during the first week of culture with cytokines, a marked expansion of these cells occurred at later time points, particularly in response to IL-15. This occurred largely without phenotypic change or acquisition of effector function, indicating a dissociation of differentiation from proliferation. Notably, progression of naïve CD8+ T cells through several cell divisions resulted in up-regulation of telomerase and the maintenance of telomere length. These data show that IL-7 and IL-15 induce cell proliferation and rescue from apoptosis in a concentration, time and subset-dependent manner, and have implications for the homeostatic expansion of the naïve CD8+ T-cell pool. [source] Induction of apoptosis in monocytes by Mycobacterium leprae in vitro: a possible role for tumour necrosis factor-,IMMUNOLOGY, Issue 1 2003M. O. Hernandez Summary A diverse range of infectious organisms, including mycobacteria, have been reported to induce cell death in vivo and in vitro. Although morphological features of apoptosis have been identified in leprosy lesions, it has not yet been determined whether Mycobacterium leprae modulates programmed cell death. For that purpose, peripheral blood mononuclear cells obtained from leprosy patients were stimulated with different concentrations of this pathogen. Following analysis by flow cytometry on 7AAD/CD14+ cells, it was observed that M. leprae induced apoptosis of monocyte-derived macrophages in a dose-dependent manner in both leprosy patients and healthy individuals, but still with lower efficiency as compared to M. tuberculosis. Expression of tumour necrosis factor-, (TNF-,), Bax-,, Bak mRNA and TNF-, protein was also detected in these cultures; in addition, an enhancement in the rate of apoptotic cells (and of TNF-, release) was noted when interferon-, was added to the wells. On the other hand, incubation of the cells with pentoxifylline impaired mycobacterium-induced cell death, the secretion of TNF-,, and gene expression in vitro. In addition, diminished bacterial entry decreased both TNF-, levels and the death of CD14+ cells, albeit to a different extent. When investigating leprosy reactions, an enhanced rate of spontaneous apoptosis was detected as compared to the unreactive lepromatous patients. The results demonstrated that M. leprae can lead to apoptosis of macrophages through a mechanism that could be at least partially related to the expression of pro-apoptotic members of the Bcl-2 protein family and of TNF-,. Moreover, while phagocytosis may be necessary, it seems not to be crucial to the induction of cell death by the mycobacteria. [source] Absence of acute apoptotic response to genotoxic carcinogens in p53 -deficient mice is associated with increased susceptibility to azoxymethane-induced colon tumoursINTERNATIONAL JOURNAL OF CANCER, Issue 4 2005Ying Hu Abstract Acute apoptotic response to genotoxic carcinogens (AARGC) might be important for controlling the consequences of mutational load in the colon. It has been shown to occur in parallel with activation of DNA repair mechanisms. Inadequate AARGC might allow development of mutated clones with the potential to progress to cancer. In this study, we tested if p53 levels were important for AARGC in the colon and whether defective AARGC was associated with increased risk for colorectal oncogenesis. Apoptosis was measured in colonic epithelium of mice from each p53 genotype (p53,/,, p53+/,, wild-type) without and 8 hr following a single injection of azoxymethane (AOM). To determine risk for carcinogen-induced colorectal cancer (CRC), groups of mice from each p53 genotype received 3 weekly injections of AOM and colons were examined for tumour 20 weeks later. Rates of spontaneous apoptosis in colon were not affected by p53 level. However, AARGC was absent in p53,/, mice and reduced by 50% in p53+/, mice (both p < 0.01) compared to wild-type mice. AOM induced tumours in 30% of wild-type mice (average multiplicity 1.0 tumours/mouse) compared to 72% of p53+/, mice (2.0 tumours/mouse, p < 0.01) and 100% of p53,/, mice (2.8 tumours/mouse, p < 0.01). Without AOM, significantly fewer mice in all groups had tumours. Rates of apoptosis in tumours were independent of p53 status. p53 dysfunction puts intestinal epithelia at increased risk of genotoxin-induced oncogenesis due to impairment of apoptotic response mechanisms. p53 levels do not appear, however, to be important for spontaneous apoptosis in normal epithelium or apoptosis in tumours. Subsequent studies are now warranted to test the converse, namely, that enhanced apoptotic response to carcinogen reduces risk for colorectal oncogenesis. © 2005 Wiley-Liss, Inc. [source] Aberrant expression of TRAIL in B chronic lymphocytic leukemia (B-CLL) cellsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2005Paola Secchiero Analysis of peripheral blood (>85% CD19+/CD5+ B) lymphocytes, obtained from 44 patients affected by B chronic lymphoid leukemia (B-CLL), showed that surface TNF-related apoptosis inducing ligand (TRAIL) was expressed in all samples and at higher levels with respect to unfractionated lymphocytes and purified CD19+ B cells, obtained from 15 normal blood donors. Of note, in a subset of B-CLL samples, the addition to B-CLL cultures of a TRAIL-R1-Fc chimera, which binds at high affinity to surface TRAIL, significantly decreased the percentage of viable cells with respect to untreated control B-CLL cells, suggesting that surface TRAIL may play an unexpected role in promoting B-CLL cell survival. In spite of the majority of B-CLL lymphocytes expressed variable surface levels of "death receptors" TRAIL-R1 and TRAIL-R2, the addition in culture of recombinant TRAIL increased (>20% vs. controls) the degree of spontaneous apoptosis in only 11/44 of the B-CLL samples, had no effect in 19/44, while it significantly increased leukemic cell survival in 14/44. Taken together, these findings suggest that an aberrant expression of TRAIL might contribute to the pathogenesis of B-CLL by promoting the survival in a subset of B-CLL cells. © 2005 Wiley-Liss, Inc. [source] Recently identified a novel neuropeptide manserin colocalize with the TUNEL-positive cells in the top villi of the rat duodenumJOURNAL OF PEPTIDE SCIENCE, Issue 6 2008Aika Yajima Abstract We recently isolated a novel 40 amino acid neuropeptide designated manserin from the rat brain. Manserin is derived from secretogranin II, a member of granin acidic secretory protein family by proteolytic processing, as previously reported secretoneurin and EM66. Manserin peptide are localized in the endocrine cells of the pituitary. In this study, we further investigated the manserin localization in the digestive system by immunohistochemical analysis using antimanserin antibody. In the duodenum, manserin immunostaining was exclusively observed in the nuclei of top villi instead of cytosol as observed in neurons in our previous study. Interestingly, manserin-positive cells in the duodenum are colocalized with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) positive cells, the cells whose DNA was damaged. Since the top villi of duodenum epithelial cells are known to undergo spontaneous apoptosis during epithelial cell turn over, and since other peptides such as secretoneurin and EM66 derived from SgII have been reported to be cancer-related, these results indicated that manserin peptide may have a role in apoptosis and/or cancer pathogenesis in the digestive organ. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd. [source] Mesenchymal cells in the liver , one cell type or two?LIVER INTERNATIONAL, Issue 4 2002G. Ramadori Abstract: The wall of the liver sinusoid is made of highly specialized cells, the hepatic stellate cells (HSC) which together with the sinusoidal endothelial cells represent a loose barrier to the corpusculate part of the blood flowing through the liver. Quiescent stellate cells (quiescent HSC) store Vitamin A; "activated" stellate cells become involved in the reaction to acute or chronic noxae damaging the liver parenchyma. Activated HSC show increased protein synthesis capacity, increased DNA-synthesis and acquire a myofibroblast-like phenotype. Under similar conditions liver myofibroblasts (MF) of the portal field and of the pericentral area may also become "activated" by increasing protein synthesis, DNA synthesis and cell division. They express the fibulin-2 gene and produce large amounts of IL-6. In contrast to "activated" HSC they do not undergo spontaneous apoptosis in vitro and do not express the CD95-ligand gene. So far no definite prove has been found for a "transdifferentiation" of HSC to myofibroblasts. On the contrary an increasing amount of data support the conviction that HSC and MF represent two similar but not identical cell populations the latter being comparable to those of other organs. [source] The small ubiquitin-like modifier mediates the resistance of prosthesis-loosening fibroblast-like synoviocytes against fas-induced apoptosisARTHRITIS & RHEUMATISM, Issue 7 2009Ingmar Meinecke Objective To study the expression of small ubiquitin-like modifier 1 (SUMO-1) in aseptic loosening of prosthesis implants and to investigate its role in regulating the susceptibility of prosthesis-loosening fibroblast-like synoviocytes (FLS) to Fas-induced apoptosis. Methods Specimens of aseptically loosened tissue were obtained at revision surgery, and the expression of SUMO-1 was analyzed by in situ hybridization. SUMO-1 levels in FLS were determined by quantitative polymerase chain reaction and Western blot analysis. Immunohistochemistry and confocal microscopy were used to study the subcellular localization of SUMO-1. The functional role of SUMO-1 in Fas-induced apoptosis of prosthesis-loosening FLS was investigated by small interfering RNA,mediated knockdown of SUMO-1 and by gene transfer of the nuclear SUMO-specific protease SENP1. Results SUMO-1 was expressed strongly in aseptically loosened tissue and was found prominently at sites adjacent to bone. Prosthesis-loosening FLS expressed levels of SUMO-1 similar to the levels expressed by rheumatoid arthritis (RA) FLS, with SUMO-1 being found mainly in promyelocytic leukemia protein nuclear bodies. Knockdown of SUMO-1 had no effect on spontaneous apoptosis but significantly increased the susceptibility of prosthesis-loosening FLS to Fas-induced apoptosis. Gene transfer of the nuclear SUMO-specific protease SENP1 reverted the apoptosis-inhibiting effects of SUMO-1. Conclusion These data suggest that SUMO-1 is involved in the activation of both RA FLS and prosthesis-loosening FLS by preventing these cells from undergoing apoptosis. Modification of nuclear proteins by SUMO-1 contributes to the antiapoptotic effects of SUMO-1 in prosthesis-loosening FLS, providing evidence for the specific activation of sumoylation during their differentiation. Therefore, SUMO-1 may be an interesting target for novel strategies to prevent aseptic prosthesis loosening. [source] Inhibition of caspase-dependent spontaneous apoptosis via a cAMP-protein kinase A dependent pathway in neutrophils from sickle cell disease patientsBRITISH JOURNAL OF HAEMATOLOGY, Issue 1 2007Nicola Conran Summary Sickle cell disease (SCD) is a chronic inflammatory condition characterized by high leucocyte counts, altered cytokine levels and endothelial cell injury. As the removal of inflammatory cells by apoptosis is fundamental for the resolution of inflammation, we aimed to determine whether the leucocyte apoptotic process is altered in SCD. Neutrophils from SCD individuals showed an inhibition of spontaneous apoptosis when cultured in vitro, in the presence of autologous serum for 20 h. Intracellular cyclic adenosine monophosphate (cAMP) levels were approximately twofold increased in SCD neutrophils; possible cAMP-upregulating factors present in SCD serum include interleukin-8, granulocyte-macrophage colony-stimulating factor and prostaglandin. Accordingly, co-incubation of SCD neutrophils with KT5720, a cAMP-dependent protein kinase (PKA) inhibitor, abrogated increased SCD neutrophil survival. Caspase-3 activity was also significantly diminished in SCD neutrophils cultured for 16 h and this activity was restored when cells were co-incubated with KT5720. BIRC2 (encoding cellular inhibitor of apoptosis protein 1, cIAP1), MCL1 and BAX expression were unaltered in SCD neutrophils; however, BIRC3 (encoding the caspase inhibitor, cIAP2), was expressed at significantly higher levels. Thus, we report an inhibition of spontaneous SCD neutrophil apoptosis that appears to be mediated by upregulated cAMP-PKA signalling and decreased caspase activity. Increased neutrophil survival may have significant consequences in SCD; contributing to leucocytosis, tissue damage and exacerbation of the chronic inflammatory state. [source] Inhibition of NF-,B activation by the histone deacetylase inhibitor 4-Me2N-BAVAH induces an early G1 cell cycle arrest in primary hepatocytesCELL PROLIFERATION, Issue 5 2007P. Papeleu 4-Me2N-BAVAH has been shown to induce histone hyperacetylation and to inhibit proliferation in Friend erythroleukaemia cells in vitro. However, the molecular mechanisms have remained unidentified. Materials and Methods:,In this study, we evaluated the effects of 4-Me2N-BAVAH on proliferation in non-malignant cells, namely epidermal growth factor-stimulated primary rat hepatocytes. Results and Conclusion:,We have found that 4-Me2N-BAVAH inhibits HDAC activity at non-cytotoxic concentrations and prevents cells from responding to the mitogenic stimuli of epidermal growth factor. This results in an early G1 cell cycle arrest that is independent of p21 activity, but instead can be attributed to inhibition of cyclin D1 transcription through a mechanism involving inhibition of nuclear factor-kappaB activation. In addition, 4-Me2N-BAVAH delays the onset of spontaneous apoptosis in primary rat hepatocyte cultures as evidenced by down-regulation of the pro-apoptotic proteins Bid and Bax, and inhibition of caspase-3 activation. [source] | ||||||||||||||||||||||