Cdk1/cyclin B1 controls Fas-mediated apoptosis by regulating caspase-8 activity.

Department of Obstetrics and Gynecology, School of Medicine, J W Goethe University, Frankfurt, Germany.
Molecular and Cellular Biology (Impact Factor: 5.04). 10/2010; 30(24):5726-40. DOI: 10.1128/MCB.00731-10
Source: PubMed

ABSTRACT Caspase activation is a hallmark of apoptosis. However, the molecular mechanisms underlying the regulation of caspase-8 activation within the extrinsic death pathway are not well understood. In this study, we demonstrate that procaspase-8 is phosphorylated in mitotic cells by Cdk1/cyclin B1 on Ser-387, which is located at the N terminus of the catalytic subunit p10. This phosphorylation of procaspase-8 on Ser-387 occurs in cancer cell lines, as well as in primary breast tissues and lymphocytes. Furthermore, RNA interference-mediated silencing of cyclin B1 or treatment with the Cdk1 inhibitor RO-3306 enhances the Fas-mediated activation and processing of procaspase-8 in mitotic cells. A nonphosphorylatable procaspase-8 (S387A) facilitates Fas-induced apoptosis during mitosis. Our findings suggest that Cdk1/cyclin B1 activity shields human cells against extrinsic death stimuli and unravel the molecular details of the cross talk between cell cycle and extrinsic apoptotic pathways. Finally, this new mechanism may also contribute to tumorigenesis.

Download full-text


Available from: Klaus Strebhardt, Jun 24, 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Caspase-8 is crucial for cell death induction, especially via the death receptor pathway. The dysregulated expression or function of caspase-8 can promote tumor formation, progression and treatment resistance in different human cancers. Here, we show procaspase-8 is regulated during the cell cycle through the concerted inhibitory action of Cdk1/cyclin B1 and polo-like kinase 1 (Plk1). By phosphorylating S387 in procaspase-8 Cdk1/cyclin B1 generates a phospho-epitope for the binding of the PBD of Plk1. Subsequently, S305 in procaspase-8 is phosphorylated by Plk1 during mitosis. Using an RNAi-based strategy we could demonstrate that the extrinsic cell death is increased upon Fas-stimulation when endogenous caspase-8 is replaced by a mutant (S305A) mimicking the non-phosphorylated form. Together, our data show that sequential phosphorylation by Cdk1/cyclin B1 and Plk1 decreases the sensitivity of cells toward stimuli of the extrinsic pathway during mitosis. Thus, the clinical Plk1 inhibitor BI 2536 decreases the threshold of different cancer cell types toward Fas-induced cell death.
    Molecular oncology 05/2014; DOI:10.1016/j.molonc.2013.12.013 · 5.94 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: ERK 1/2 are found to be hyperactive in many cancers. Active ERK 1/2 (pERK 1/2) are known to protect cancer cells from undergoing death receptor-mediated apoptosis, although the mechanism(s) behind this is poorly understood. Through in vitro kinase assays and mass-spectrometry we demonstrate that pERK 1/2 can phosphorylate pro-Caspase-8 at S387. Also, in EGFR-overexpressing Type I and II ovarian and breast cancer cell lines respectively, ERK 1/2 remain active only during the interphase. During this period, pERK 1/2 could inhibit Trail-induced apoptosis, most effectively during the G1/S phase. By knocking-down the endogenous pro-Caspase-8 using RNAi and replacing it with its non-phosphorylatable counterpart (S387A), a significant increase in Caspase-8 activity upon Trail stimulation was observed, even in the presence of pERK 1/2. Taken together, we propose that a combination of Trail and an inhibitor of ERK 1/2 activities could potentially enhance of Trail’s effectiveness as an anti-cancer agent in ERK 1/2 hyperactive cancer cells.
    Molecular oncology 01/2013; 8(2). DOI:10.1016/j.molonc.2013.11.003 · 5.94 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Biochemical studies suggest that caspase activity is required for a functional mitotic checkpoint (MC) and mitotic slippage. To test this directly, we followed nontransformed human telomerase immortalized human retinal pigment epithelia (RPE-1) cells through mitosis after inhibiting or depleting selected caspases. We found that inhibiting caspases individually, in combination, or in toto did not affect the duration or fidelity of mitosis in otherwise untreated cells. When satisfaction of the MC was prevented with 500 nM nocodazole or 2.5 μM dimethylenastron (an Eg5 inhibitor), 92-100% of RPE-1 cells slipped from mitosis in the presence of pan-caspase inhibitors or after simultaneously depleting caspase-3 and -9, and they did so with the same kinetics (~21-22 h) as after treatment with nocodazole or Eg5 inhibitors alone. Surprisingly, inhibiting or depleting caspase-9 alone doubled the number of nocodazole-treated, but not Eg5-inhibited, cells that died in mitosis. In addition, inhibiting or depleting caspase-9 and -3 together accelerated the rate of slippage ~40% (to ~13-15 h). Finally, nocodazole-treated cells that recently slipped through mitosis in the presence or absence of pan-caspase inhibitors contained numerous BubR1 foci in their nuclei. From these data, we conclude that caspase activity is not required for a functional MC or for mitotic slippage.
    Molecular biology of the cell 05/2011; 22(14):2470-9. DOI:10.1091/mbc.E11-03-0228 · 5.98 Impact Factor