Biochemische und molekularbiologische Charakterisierung von Spike, einem neuen BH3-Domänen Protein

During my PhD thesis I was working on the identification of novel apoptosis-inducing genes by using a novel genetic expression screen (Grimm and Leder, 1997). One of the identified genes turned out to be a evolutionary conserved cDNA that codes for a novel BH3-only protein of 219 amino acid residues which was named Spike, for Small protein with inherent killing effect. Spike was then in the course of my PhD thesis extensively characterised, molecularly and biochemically. In summary, upon overexpression in mammalian cells Spike efficiently leads to all features of apoptosis, such as phenotypic alterations, cytochrome c release, caspase activation and DNA degradation. It was shown that Spike localised to the endoplasmic reticulum, where it interacts with a recently identified apoptosis regulating protein complex, consisting of Bap31, Bcl-2, Bcl-XL and an ER-specific isoform of caspase-8: pro-caspase 8L (Breckenridge et al. 2002). Although no direct interaction with anti-apoptotic members of the Bcl2-family could be observed, the importance of the BH3-like sequence for the apoptosis-inducing activity of Spike was demonstrated by using point mutations of conserved amino acid residues of this motif (Mund et al. 2003). Instead of directly interacting with anti-apoptotic members of the Bcl-2 family Spike is able to interfere with the complex formation between Bap31 and Bcl-XL. Based on these data I proposed a model according to which the complex on Bap31 is controlled by Bcl-2/Bcl-XL as long as they are associated. Displacement of Bcl-2/Bcl-XL from Bap31 by Spike leads to the formation of a pro-apoptotic complex. In addition, Spike appears to be implicated in the cell death signal of the Fas receptor. I observed that a dominant-negative version of Spike and a highly effective anti-sense oligonucleotide significantly reduced Fas-mediated DNA fragmentation whereas no reduction was detected in TNFa-induced cell death (Mund et al. 2003).

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Ludwig-Maximilians-Universität

Year

2003

Author dc:creator

• Mund, Thomas

Repository record source_url

https://edoc.ub.uni-muenchen.de/1445/

OAI identifier oai:identifier

oai:edoc.ub.uni-muenchen.de:1445