We analyzed the ultrastructure of apoptotic nuclear fragmentation in U937 cells treated with many different apoptogenic agents. We found that this characteristic apoptotic feature can be achieved through multiple alternative pathways, depending on the apoptogenic inducer, leading to slightly different final nuclear morphologies. In most instances, the irregularly shaped nucleus of U937 rounds up; then, chromatin condenses at the nuclear periphery. Condensed chromatin can form protruding patches, which eventually bud from the nucleus in sealed vesicles through a process which is actin-dependent, since it could be blocked by cytochalasins. Alternatively, chromatin condenses in tiny, nonprotruding crescents, and a cleavage in the nuclear sap forms, beginning from the inner nuclear membrane and growing inward, thus splitting the nucleus. In U937 induced to apoptosis by hydrogen peroxide in the presence of ADP-ribosylation inhibitors, the nuclei fragment in many vesicles before chromatin even begins to condense: chromatin condensation probably occurs as a consequence. While all the apoptotic morphologies described above evolve from interphase cells, a peculiar apoptotic morphology, possibly deriving from mitotic cells, is detected upon oxidative stress, recalling the formation of micronuclei by clastogenic treatments; it shows partially membrane-bound chromatin patches, which look midway between condensed chromosomes and apoptotic condensed chromatin. The existence of these multiple pathways for nuclear fragmentation may indicate an evolutionary convergence, suggesting that this event may play an important physiological role in apoptosis.

Dini, L., Coppola, S., Ruzittu, M., Ghibelli, L. (1996). Multiple pathways for apoptotic nuclear fragmentation. EXPERIMENTAL CELL RESEARCH, 223(2), 340-347 [10.1006/excr.1996.0089].

Multiple pathways for apoptotic nuclear fragmentation

DINI, LUCIANA;GHIBELLI, LINA
1996-01-01

Abstract

We analyzed the ultrastructure of apoptotic nuclear fragmentation in U937 cells treated with many different apoptogenic agents. We found that this characteristic apoptotic feature can be achieved through multiple alternative pathways, depending on the apoptogenic inducer, leading to slightly different final nuclear morphologies. In most instances, the irregularly shaped nucleus of U937 rounds up; then, chromatin condenses at the nuclear periphery. Condensed chromatin can form protruding patches, which eventually bud from the nucleus in sealed vesicles through a process which is actin-dependent, since it could be blocked by cytochalasins. Alternatively, chromatin condenses in tiny, nonprotruding crescents, and a cleavage in the nuclear sap forms, beginning from the inner nuclear membrane and growing inward, thus splitting the nucleus. In U937 induced to apoptosis by hydrogen peroxide in the presence of ADP-ribosylation inhibitors, the nuclei fragment in many vesicles before chromatin even begins to condense: chromatin condensation probably occurs as a consequence. While all the apoptotic morphologies described above evolve from interphase cells, a peculiar apoptotic morphology, possibly deriving from mitotic cells, is detected upon oxidative stress, recalling the formation of micronuclei by clastogenic treatments; it shows partially membrane-bound chromatin patches, which look midway between condensed chromosomes and apoptotic condensed chromatin. The existence of these multiple pathways for nuclear fragmentation may indicate an evolutionary convergence, suggesting that this event may play an important physiological role in apoptosis.
1996
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore BIO/13 - BIOLOGIA APPLICATA
English
Adenosine Diphosphate Ribose; Apoptosis; Cell Line; Cell Nucleus; Chromatin; DNA; Humans; Hydrogen Peroxide; Microscopy, Electron; Mitosis; Monocytes; Oxidative Stress; Protein Synthesis Inhibitors
Dini, L., Coppola, S., Ruzittu, M., Ghibelli, L. (1996). Multiple pathways for apoptotic nuclear fragmentation. EXPERIMENTAL CELL RESEARCH, 223(2), 340-347 [10.1006/excr.1996.0089].
Dini, L; Coppola, S; Ruzittu, M; Ghibelli, L
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/170691
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