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Early Apoptotic Reorganization of Spliceosomal Proteins Involves Caspases, CAD and Rearrangement of NuMA
Author(s) -
Dieker Jürgen,
IglesiasGuimarais Victoria,
Décossas Marion,
Stevenin James,
Vlag Johan,
Yuste Victor J.,
Muller Sylviane
Publication year - 2012
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2011.01307.x
Subject(s) - chromatin , biology , microbiology and biotechnology , caspase , apoptosis , fragmentation (computing) , nuclear matrix , caspase 2 , dna fragmentation , dna , programmed cell death , biochemistry , ecology
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 PP 1/ PP 2 A . 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 .