Targeting c-FLIP in the CD95 signaling network.

Bollmann, M. (2015) Targeting c-FLIP in the CD95 signaling network. Master's Thesis / Essay, Biology.

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Abstract

Apoptosis is a type of a programmed cell death which can be found in all multicellular organisms. The induction of apoptosis can be triggered by two different ways: the intrinsic pathway, which is initiated via mitochondria, and the extrinsic pathway; which is activated via a family of death receptors (DRs). CD95 (APO-1/Fas) is one of the best studied DR family members. CD95 stimulation induces the formation of the death-inducing signaling complex (DISC), activation of caspases and finally apoptosis. On contrary, CD95 stimulation can also lead to the activation of the transcription factor (TF) NF-κB. In the canonical NF-κB signaling pathway heterodimers p65/p50 are translocated into the nucleus, which leads to the expression of target genes. NF-κB induction is mediated by the activation of the IKK complex. The c-FLIP (cellular FLICE inhibitory proteins) proteins are key inhibitors of apoptosis. In addition, the c-FLIPL cleavage product p43-FLIP has been reported to mediate the activation of the IKK complex and a direct interaction between p43-FLIP and Nemo has been proposed. In this study the role of c-FLIP in CD95-mediated NF-κB activation has been analyzed by using a specific inhibitor of the presumed interaction between c-FLIP and Nemo. The peptide was constructed similar to the part of Nemo that has been reported before to form a complex with viral FLIP (v-FLIP). Further, Bcl10, a new interaction partner of c-FLIP and Nemo, which has been found in a previous proteomic screening, has been analyzed. It has been demonstrated that the peptide, which inhibits the proposed p43-FLIP-Nemo interaction, decreases IκBα phosphorylation but not p65 translocation into the nucleus. The results obtained in this project prove that an interaction between p43-FLIP and Nemo might take place, but that this interaction has to be further investigated. The knockdown of Bcl10 led to the decreased phosphorylation of IκBα and p65 translocation. The obtained results suggest that Bcl10 promotes the activation of IKK in CD95-induced NF-κB activation, but plays a rather minor role, as its downregulation does not inhibit NF-κB activation drastically. Taken together, this work allowed to demonstrate new insights into CD95-mediated NF-κB activation via c-FLIP proteins.

Item Type:	Thesis (Master's Thesis / Essay)
Degree programme:	Biology
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	15 Feb 2018 08:09
Last Modified:	15 Feb 2018 08:09
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/13423

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