Release of an ~55kDa fragment containing the actin-binding domain of β-spectrin by caspase-8 during FND-induced apoptosis depends on the presence of protein 4.1

Arch Biochem Biophys. 2013 Jul 15;535(2):205-13. doi: 10.1016/ Epub 2013 Apr 8.


Analyses of the status of the membrane spectrin-based skeleton during fludarabine/mitoxantrone/dexamethasone-induced (FND-induced) apoptosis revealed proteolytic degradation of β-spectrin, with the prevalent appearance of a specific fragment with a molecular weight of ~55kDa, containing the actin-binding domain (ABD). Appearance of this fragment was dependent on induction of apoptosis. In silico proteolysis of spectrin identified caspase-8 as a candidate protease responsible for the generation of this ~55kDa ABD-containing fragment. Analyses of spectrin and procaspase-8 localization during early apoptosis indicated temporary (<30-120min) submembranous colocalization of both proteins. Proteolytic release of the N-terminal ~55kDa fragment of purified spectrin by recombinant caspase-8 does not occur in normal cells, but does occur in isolated membrane, such as red blood cell ghosts, or in vitro in the presence of apoptotic cell extracts. Surprisingly, proteolysis of purified spectrin by recombinant caspase-8 resulted in the generation of the ~55kDa fragment only in the presence of purified protein 4.1. This suggests that only the appropriate spatial arrangement of the spectrin-based membrane skeleton or the appropriate conformational state of spectrin, which are both known to be induced by 4.1, can sensitize β-spectrin to cleavage by caspase-8 at the N-terminal ABD-containing region.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism*
  • Amino Acid Sequence
  • Animals
  • Antineoplastic Agents / pharmacology*
  • Apoptosis*
  • Binding Sites
  • Brain / metabolism
  • Caspase 8 / metabolism*
  • Caspase Inhibitors / pharmacology
  • Cytoskeletal Proteins / metabolism*
  • Dexamethasone / pharmacology
  • Drug Interactions
  • Erythrocyte Membrane / metabolism
  • Humans
  • Jurkat Cells
  • Membrane Proteins / metabolism*
  • Mitoxantrone / pharmacology
  • Molecular Sequence Data
  • Protein Structure, Tertiary
  • Proteolysis
  • Spectrin / metabolism*
  • Swine
  • Vidarabine / analogs & derivatives
  • Vidarabine / pharmacology


  • Actins
  • Antineoplastic Agents
  • Caspase Inhibitors
  • Cytoskeletal Proteins
  • Membrane Proteins
  • erythrocyte membrane band 4.1 protein
  • Spectrin
  • Dexamethasone
  • Mitoxantrone
  • Caspase 8
  • Vidarabine
  • fludarabine