Caspase activation during phorbol ester-induced apoptosis requires ROCK-dependent myosin-mediated contraction

Jin Mei Lai, Chia Ling Hsieh, Zee Fen Chang

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Abstract

Treatment of cells with phorbol ester, phorbol-12-myristate-13-acetate (PMA), triggers differentiation or apoptosis, depending on the cell type. In this study, we used an erythroblastic cell line, TF-1, to investigate the molecular mechanism that determines the cell fate in response to PMA exposure. Upon PMA treatment in the presence of serum or lysophosphatidic acid (LPA), TF-1 cells exhibited contraction followed by apoptosis. By contrast, under serum-free conditions, cells became adherent and survived after PMA treatment. Here, we show that the pathway of Rho kinase (ROCK)/myosin light chain (MLC) phosphorylation/myosin-mediated contraction was activated in PMA-induced apoptotic cells in serum-containing medium, but not in the adherent and survived cells. Pretreatment of cells with a specific ROCK inhibitor, Y27632, not only abrogated MLC phosphorylation and membrane contraction, but also prevented PMA-induced activation of caspase-3 and subsequent cell death, indicating that ROCK-dependent myosin-mediated contraction elicits an upstream signal required for caspase-3 activation in PMA-induced apoptosis. Interestingly, we further found that caspases-8 and -10 are the initiator caspases in PMA-induced apoptosis and a ROCK-dependent enhancement of specific complex formation between the Fas-associated death domain (FADD) and pro-caspase-10 in pro-apoptotic cells. In summary, these results revealed that, following PMA treatment, the upregulation of the RhoA/ROCK pathway contributes to a cellular context that switches-on myosin-mediated contraction, which provides a mechanism for triggering apoptotic induction mediated by caspase-8 and -10.

Original languageEnglish
Pages (from-to)3491-3501
Number of pages11
JournalJournal of Cell Science
Volume116
Issue number17
DOIs
Publication statusPublished - Sep 1 2003
Externally publishedYes

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Keywords

  • Apoptosis
  • Caspase
  • Myosin light chain
  • Phosphorylation
  • Rho kinase

ASJC Scopus subject areas

  • Cell Biology

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