Caspase-6 gene disruption reveals a requirement for lamin A cleavage in apoptotic chromatin condensation.
To study the role of caspase-6 during nuclear disassembly, we generated a chicken DT40 cell line in which both alleles of the caspase-6 gene were disrupted. No obvious morphological differences were observed in the apoptotic process in caspase-6- deficient cells compared with the wild type. However, examination of apoptosis in a cell-free system revealed a block in chromatin condensation and apoptotic body formation when nuclei from HeLa cells expressing lamin A or lamin A-transfected Jurkat cells were incubated in caspase-6-deficient apoptotic extracts. Transfection of exogenous caspase-6 into the clone reversed this phenotype. Lamins A and C, which are caspase-6-only substrates, were cleaved by the wild-type and heterozygous apoptotic extracts but not by the extracts lacking caspase-6. Furthermore, the caspase-6 inhibitor z-VEID-fmk mimicked the effects of caspase-6 deficiency and prevented the cleavage of lamin A. Taken together, these observations indicate that caspase-6 activity is essential for lamin A cleavage and that when lamin A is present it must be cleaved in order for the chromosomal DNA to undergo complete condensation during apoptotic execution.
Ruchaud
Sandrine
S
Wellcome Trust Centre for Cell Biology, ICMB, Swann Building, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK.
Korfali
Nadia
N
Villa
Pascal
P
Kottke
Timothy J
TJ
Dingwall
Colin
C
Kaufmann
Scott H
SH
Earnshaw
William C
WC
D000818:Animals; D017209:Apoptosis; D053178:Caspase 6; D020169:Caspases / Q000235:genetics / Q000502:physiology*; D002467:Cell Nucleus / Q000502:physiology; D002645:Chickens; D002843:Chromatin / Q000502:physiology*; D018390:Gene Targeting; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins / Q000378:metabolism*; D010641:Phenotype; D014407:Tumor Cells, Cultured
D002843:Chromatin; D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins; C505514:CASP6 protein, human; D053178:Caspase 6; D020169:Caspases