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  • The EMBO Journal (2002) 21, 1967 - 1977
  • doi:10.1093/emboj/21.8.1967

Caspase-6 gene disruption reveals a requirement for lamin A cleavage in apoptotic chromatin condensation

Sandrine Ruchaud1, Nadia Korfali1, Pascal Villa1,2, Timothy J. Kottke3, Colin Dingwall4, Scott H. Kaufmann3 and William C. Earnshaw1

  1. Wellcome Trust Centre for Cell Biology, ICMB, Swann Building, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK
  2. Present address: Trophos, Parc Scientific de Lumigny, Case 931, F-13288 Marseille cedex 9, France
  3. Division of Oncology Research, Mayo Clinic, 200 First Street, SW Rochester, MN 55905, USA
  4. Neurology CEDD, GlaxoSmithKline, New Frontiers Science Park (North), Third Avenue, Harlow, Essex CM19 5AW, UK

Correspondence to:

William C. Earnshaw, E-mail: bill.earnshaw@ed.ac.uk

Received 21 January 2002; Accepted 28 February 2002; Revised 28 February 2002

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.

  • Keywords:

    • apoptosis,
    • caspase-6,
    • chromatin condensation,
    • DT40,
    • lamins