Behavior of nucleolar proteins during the course of apoptosis in camptothecin-treated HL60 cells.
By means of immunofluorescence and immunoelectron microscopy we have studied the fate of different nucleolar components during the apoptotic process in camptothecin-treated HL60 cells. We have found that RNA polymerase I disappeared while UBF was associated with previously described fibrogranular threaded bodies. In contrast, fibrillarin, C23/nucleolin, and B23/nucleophosmin remained detectable in granular material present amid micronuclei of late apoptotic cells. Double immunolabeling experiments showed colocalization of both C23 and B23 with fibrillarin. Immunoblotting analysis showed that UBF was proteolytically degraded, whereas fibrillarin, C23/nucleolin, and B23/nucleophosmin were not. These results may help explain the presence of anti-nucleolar antibodies seen in various pathological disorders.
Martelli
A M
AM
Dipartimento di Morfologia Umana Normale, Università di Trieste, 34138 Trieste, Italy. martelli@univ.trieste.it
Robuffo
I
I
Bortul
R
R
Ochs
R L
RL
Luchetti
F
F
Cocco
L
L
Zweyer
M
M
Bareggi
R
R
Falcieri
E
E
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology*; D002166:Camptothecin / Q000494:pharmacology*; D002466:Cell Nucleolus / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D009687:Nuclear Proteins / Q000378:metabolism*; D000090243:Nucleophosmin; D010750:Phosphoproteins / Q000378:metabolism; D035463:Pol1 Transcription Initiation Complex Proteins; D012318:RNA Polymerase I / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D010750:Phosphoproteins; D035463:Pol1 Transcription Initiation Complex Proteins; D014157:Transcription Factors; C047458:fibrillarin; C036825:phosphoprotein C23; C063844:transcription factor UBF; D000090243:Nucleophosmin; D012318:RNA Polymerase I; D002166:Camptothecin