Article

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.

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    • "This report presents a novel regulatory mechanism involving the action of Cdk1/cyclin B1 and Plk1 upon their common substrate procaspase-8. Previously, we could demonstrate that procaspase-8 is phosphorylated in mitotic cells by Cdk1/ cyclin B1 on S387, which is located at the N terminus of the catalytic subunit p10 (Matthess et al., 2010). Inhibition of Cdk1 activity by depletion of cyclin B1 or the use of the Cdk1 inhibitor RO-3306 enhanced the Fas-mediated activation and processing of procaspase-8 in mitotic cells suggesting the possibility that Cdk1/cyclin B1 alone exerts the anti-apoptotic effect in mitotic cells. "
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    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.
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    • "Over the years, different groups have been able to identify a handful of kinases that can carry out such phosphorylation. The p38 MAPK can phosphorylate pro-Caspase-8 at Ser364 (Alvarado-Kristensson et al., 2004), the Src kinase at Tyr380 (Cursi et al., 2006), CDK1 at Ser387 (Matthess et al., 2010) and finally RSK2 at Thr263 (Peng et al., 2011). Active ERK 1/2 have also been reported to protect cancer cells from undergoing apoptosis in the presence of cytotoxic agents like Trail, FasL or TNFa and we intended to determine the mechanism(s) behind this anti-apoptotic function of pERK 1/2 (Holmstrom et al., 1998, 2000; Lee et al., 2005; Liu et al., 2004; Pucci et al., 2009; Tran et al., 2001; Zhang et al., 2003). "
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    • "Cdc2 activity is frequently upregulated in G 2 /M phase arrest-associated apoptosis induced by paclitaxel, vincristine (Stewart et al., 1999), or death receptor mediated apoptosis (Zhou et al., 1998). Cdk1/cyclin B1 activity shields human cells against extrinsic death stimuli (Matthess et al., 2010). Cdk2 activation is mainly detected in apoptotic cells that exhibit G 1 /S phase arrest, as observed in ultraviolet irradiation-treated mesangial cells (Hiromura et al., 2002), etoposide-induced human leukemic cells (Choi et al., 2007; Bastin-Coyette et al., 2011), growth factor-deprived HUVEC cells (Levkau et al., 1998), G-Rh2-induced human hepatoma cells (Jin et al., 2000), panaxadiol-induced SK-HEP-1 cells (Jin et al., 2003). "
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