Early apoptotic reorganization of spliceosomal proteins involves caspases, CAD and rearrangement of NuMA.
The reorganization of nuclear structures is an important early feature of apoptosis and involves the activity of specific proteases and nucleases. Well-known is the condensation and fragmentation of chromatin; however, much less is understood about the mechanisms involved in the reorganization of structures from the interchromatin space, such as interchromatin granule clusters (IGCs). In this study, we show that the initial enlargement and rounding-up of IGCs correlate with a decrease in mRNA transcription and are caspase-independent, but involve protein phosphatases PP1/PP2A. Subsequently, multiple enlarged IGCs dissociate from chromatin and fuse into a single structure. The dissociation requires caspase activity and involves caspase-activated DNase (CAD). Apoptotic IMR-5 cells, lacking a proper processing of CAD, show multiple enlarged IGCs that remain linked with chromatin. Overexpression of CAD in IMR-5 cells results in the dissociation of IGCs from chromatin, but the fusion into a single structure remains disturbed. Nuclear matrix protein NuMA is reorganized in a caspase-dependent way around fused IGCs. In conclusion, we show here that the apoptotic rearrangement of IGCs, the nuclear matrix and chromatin are closely associated, occur in defined stages and depend on the activity of protein phosphatases, caspases and CAD.
Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France.
Jürgen
J
Dieker
Victoria
V
Iglesias-Guimarais
Marion
M
Décossas
James
J
Stevenin
Johan
J
van der Vlag
Victor J
VJ
Yuste
Sylviane
S
Muller
D000818:Animals; D034961:Antigens, Nuclear / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D002843:Chromatin / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D003851:Deoxyribonucleases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D042581:Intranuclear Space / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D051379:Mice; D008807:Mice, Inbred BALB C; D008954:Models, Biological; D034521:Nuclear Matrix-Associated Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D000090243:Nucleophosmin; D010766:Phosphorylation / Q000187:drug effects; D000075223:Poly-ADP-Ribose Binding Proteins; D054645:Protein Phosphatase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D000068103:Serine-Arginine Splicing Factors; D017381:Spliceosomes / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D014162:Transfection; D055517:snRNP Core Proteins / Q000378:metabolism
D034961:Antigens, Nuclear; D061945:Caspase Inhibitors; D018797:Cell Cycle Proteins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; C050045:NUMA1 protein, human; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins; C478629:P105 antigen, human; D000075223:Poly-ADP-Ribose Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; D012261:Ribonucleoproteins; C490688:SNRNP70 protein, human; C526408:SNRPB2 protein, human; D055517:snRNP Core Proteins; D000090243:Nucleophosmin; C073288:SRSF2 protein, human; D000068103:Serine-Arginine Splicing Factors; C113696:DFFB protein, human; D003851:Deoxyribonucleases; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2; C505530:CASP8 protein, human; D053148:Caspase 3; D053179:Caspase 7; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D019311:Staurosporine