Plasma membrane and nuclear envelope integrity during the blebbing stage of apoptosis: a time-lapse study.
BACKGROUND
The execution phase of apoptosis is characterized by extensive blebbing of the plasma membrane, which usually results in secondary lysis in vitro. To analyse the permeability of cellular membranes during this process, we induced apoptosis in human melanoma A375 cells that had been transfected with fluorescently tagged proteins which were targeted to different subcellular locations.


RESULTS
The dual treatment of resveratrol and butyrate produced a synergistic induction of apoptosis by blocking different phases of the cell cycle. Changes in the plasma membrane, nuclear envelope and nucleoli were monitored by time-lapse confocal microscopy. Fluorescently labelled proteins were not mis-localized from their original locations in any of the cells undergoing blebbing for several hours. Thus the maintenance of karyophilic and nucleolar proteins within the nucleus during the blebbing stage and the accessibility of vital selective chromatin dyes confirmed a functional preservation of the nuclear compartment until the final necrotic blister. The translocation of phosphatidylserine to the outer leaflet of the plasma membrane was not detected during the blebbing period.


CONCLUSIONS
These results show that the functional integrity of the nuclear envelope and plasma membrane may be conserved until the end of the execution phase of apoptosis.
Andrade
Ricardo
R
Biomedical Analytical and High Resolution Microscopy Facility, University of the Basque Country, Leioa, Vizcaya, Spain.
Crisol
Lorena
L
Prado
Roberto
R
Boyano
María Dolores
MD
Arluzea
Jon
J
Aréchaga
Juan
J
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002087:Butyrates / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002466:Cell Nucleolus / Q000187:drug effects / Q000378:metabolism; D005456:Fluorescent Dyes / Q000494:pharmacology; D006801:Humans; D008856:Microscopy, Fluorescence; D009685:Nuclear Envelope / Q000187:drug effects / Q000378:metabolism*; D010718:Phosphatidylserines / Q000494:pharmacology; D000077185:Resveratrol; D013267:Stilbenes / Q000494:pharmacology; D013997:Time Factors
D000970:Antineoplastic Agents; D002087:Butyrates; D005456:Fluorescent Dyes; D010718:Phosphatidylserines; D013267:Stilbenes; D000077185:Resveratrol