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Regulation of apoptosis in myeloid cells by interferon consensus sequence-binding protein.

Gabriele L, Phung J, Fukumoto J, Segal D, Wang IM, Giannakakou P, Giese NA, Ozato K, Morse HC - J. Exp. Med. (1999)

Bottom Line: One important feature of CML is decreased responsiveness of myeloid cells to apoptotic stimuli.In addition, analyses of antiapoptotic genes showed that overexpression of ICSBP results in decreased expression of Bcl-X(L).These data suggest that ICSBP modulates survival of myeloid cells by regulating expression of apoptosis-related genes.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Immunopathology, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892-0760, USA. lgabriele@atlas.niaid.nih.gov

ABSTRACT
Mice with a mutation of the gene encoding interferon consensus sequence-binding protein (ICSBP) develop a disease with marked expansion of granulocytes and macrophages that frequently progresses to a fatal blast crisis, thus resembling human chronic myelogenous leukemia (CML). One important feature of CML is decreased responsiveness of myeloid cells to apoptotic stimuli. Here we show that myeloid cells from mice deficient in ICSBP exhibit reduced spontaneous apoptosis and a significant decrease in sensitivity to apoptosis induced by DNA damage. In contrast, apoptosis in thymocytes from ICSBP-deficient mice is unaffected. We also show that overexpression of ICSBP in the human U937 monocytic cell line enhances the rate of spontaneous apoptosis and the sensitivity to apoptosis induced by etoposide, lipopolysaccharide plus ATP, or rapamycin. Programmed cell death induced by etoposide was specifically blocked by peptides inhibitory for the caspase-1 or caspase-3 subfamilies of caspases. Studies of proapoptotic genes showed that cells overexpressing ICSBP have enhanced expression of caspase-3 precursor protein. In addition, analyses of antiapoptotic genes showed that overexpression of ICSBP results in decreased expression of Bcl-X(L). These data suggest that ICSBP modulates survival of myeloid cells by regulating expression of apoptosis-related genes.

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Caspase inhibitors block apoptosis in cells overexpressing ICSBP. Cells were incubated with caspase inhibitors ZVAD-FMK and BD-FMK and the inactive reagent ZFA-FMK for 1 h before addition of etoposide. TUNEL assays were performed 16 h later. Data are representative of three experiments.
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Figure 5: Caspase inhibitors block apoptosis in cells overexpressing ICSBP. Cells were incubated with caspase inhibitors ZVAD-FMK and BD-FMK and the inactive reagent ZFA-FMK for 1 h before addition of etoposide. TUNEL assays were performed 16 h later. Data are representative of three experiments.

Mentions: We next examined the role of caspases in programmed cell death of U937+ cells. It is evident that caspases are important effector molecules of apoptosis 2631. To determine whether specific caspase subfamilies contribute to apoptosis in U937+ cells treated with etoposide, we tested the activity of two cell-permeable peptide FMK inhibitors of caspase-1 (IL-1β converting enzyme-family) proteases 32. ZVAD-FMK specifically blocks the caspase-1–like subfamily, and BD-FMK preferentially inhibits caspase-3–like proteases. ZFA-FMK, which lacks inhibitory activity for caspases, was used as a negative control. Both ZVAD-FMK and BD-FMK inhibited apoptotic death induced by etoposide in U937+ (Fig. 5) and U937− cells (data not shown). These results suggest that ICSBP enhances the sensitivity of U937 monocytic cells to apoptosis induced by etoposide and that the apoptotic process involves the activity of members of the caspase-1 and caspase-3 subfamilies.


Regulation of apoptosis in myeloid cells by interferon consensus sequence-binding protein.

Gabriele L, Phung J, Fukumoto J, Segal D, Wang IM, Giannakakou P, Giese NA, Ozato K, Morse HC - J. Exp. Med. (1999)

Caspase inhibitors block apoptosis in cells overexpressing ICSBP. Cells were incubated with caspase inhibitors ZVAD-FMK and BD-FMK and the inactive reagent ZFA-FMK for 1 h before addition of etoposide. TUNEL assays were performed 16 h later. Data are representative of three experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2195590&req=5

Figure 5: Caspase inhibitors block apoptosis in cells overexpressing ICSBP. Cells were incubated with caspase inhibitors ZVAD-FMK and BD-FMK and the inactive reagent ZFA-FMK for 1 h before addition of etoposide. TUNEL assays were performed 16 h later. Data are representative of three experiments.
Mentions: We next examined the role of caspases in programmed cell death of U937+ cells. It is evident that caspases are important effector molecules of apoptosis 2631. To determine whether specific caspase subfamilies contribute to apoptosis in U937+ cells treated with etoposide, we tested the activity of two cell-permeable peptide FMK inhibitors of caspase-1 (IL-1β converting enzyme-family) proteases 32. ZVAD-FMK specifically blocks the caspase-1–like subfamily, and BD-FMK preferentially inhibits caspase-3–like proteases. ZFA-FMK, which lacks inhibitory activity for caspases, was used as a negative control. Both ZVAD-FMK and BD-FMK inhibited apoptotic death induced by etoposide in U937+ (Fig. 5) and U937− cells (data not shown). These results suggest that ICSBP enhances the sensitivity of U937 monocytic cells to apoptosis induced by etoposide and that the apoptotic process involves the activity of members of the caspase-1 and caspase-3 subfamilies.

Bottom Line: One important feature of CML is decreased responsiveness of myeloid cells to apoptotic stimuli.In addition, analyses of antiapoptotic genes showed that overexpression of ICSBP results in decreased expression of Bcl-X(L).These data suggest that ICSBP modulates survival of myeloid cells by regulating expression of apoptosis-related genes.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Immunopathology, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892-0760, USA. lgabriele@atlas.niaid.nih.gov

ABSTRACT
Mice with a mutation of the gene encoding interferon consensus sequence-binding protein (ICSBP) develop a disease with marked expansion of granulocytes and macrophages that frequently progresses to a fatal blast crisis, thus resembling human chronic myelogenous leukemia (CML). One important feature of CML is decreased responsiveness of myeloid cells to apoptotic stimuli. Here we show that myeloid cells from mice deficient in ICSBP exhibit reduced spontaneous apoptosis and a significant decrease in sensitivity to apoptosis induced by DNA damage. In contrast, apoptosis in thymocytes from ICSBP-deficient mice is unaffected. We also show that overexpression of ICSBP in the human U937 monocytic cell line enhances the rate of spontaneous apoptosis and the sensitivity to apoptosis induced by etoposide, lipopolysaccharide plus ATP, or rapamycin. Programmed cell death induced by etoposide was specifically blocked by peptides inhibitory for the caspase-1 or caspase-3 subfamilies of caspases. Studies of proapoptotic genes showed that cells overexpressing ICSBP have enhanced expression of caspase-3 precursor protein. In addition, analyses of antiapoptotic genes showed that overexpression of ICSBP results in decreased expression of Bcl-X(L). These data suggest that ICSBP modulates survival of myeloid cells by regulating expression of apoptosis-related genes.

Show MeSH
Related in: MedlinePlus