@PhdThesis{duepublico_mods_00036782,
  author = 	{Unruhe Dr. rer. nat., Britta},
  title = 	{Relevance of survivin acetylation for its biological function},
  year = 	{2017},
  month = 	{Dec},
  day = 	{18},
  abstract = 	{Survivin belongs to the inhibitor of apoptosis protein family and is also a regulator of mitosis as it is a member of the chromosomal passenger complex (CPC). While it is not expressed in differentiated adult tissue (Adida et al., 1998), it was found to be upregulated
in virtually all types of human cancers (Ambrosini et al., 1997; Adida et al.,2000). Its overexpression is associated with resistance of tumors against chemo- and radiotherapy, frequent recurrences and decreased patient survival (Engels et al., 2007; Capalbo et al., 2007; Xu et al., 2014; Chen et al., 2014). Thus, Survivin is a potential target for cancer therapy. In order to develop strategies for the therapeutic inhibition of
Survivin, the mechanisms underlying its dual role have to be clarified in detail. While Survivin fulfills some of its cellular tasks as a homodimer (Pavlyukov et al., 2011), other functions require the monomer (Jeyaprakash et al., 2007). A further layer of complexity
is introduced by the fact that Survivin shuttles between the nucleus and the cytoplasm as it is able to passively diffuse into the nucleus and is actively exported by the solublereceptor CRM1 (Rodriguez et al., 2002; Knauer et al., 2006). The mechanisms regulating Survivin's functions, its localization as well as its dimerization state are still
not completely resolved and a matter of scientific disagreement. Recently, Wang et al. (2010b) reported that acetylation of Survivin at lysine 129 facilitates its dimerization, thus causing an accumulation of the protein in the nucleus as only the monomer is able to interact with CRM1 for nuclear export. As lysine acetylation has emerged as
a major post-translational modification capable of altering the functions and interactions of proteins, it is conceivable that Survivin's function might be regulated by the acetylation of any of its 16 lysine residues. Thus, as a preliminary work to our study, which aimed to identify further acetylation sites in Survivin and the effect of a potential acetylation on some of Survivin's functions,
we first set out to verify the findings obtained by Wang et al. (2010b). Accordingly, we cloned the four SurvK129 mutants investigated in their study and characterized them performing comprehensive molecular and structural analyses. Wang et al. (2010b)
reported a facilitated nuclear export and a reduced tendency to form dimers for the SurvK129E mutant, which they refered to as a mimicking mutant for Survivin unmodified at K129. They also claimed that this mutant was comparable to the SurvK129R
mutant bearing a lysine to arginine mutation typically introduced to mimic an unmodified lysine. In contrast to their results, we found that SurvK129E is unique among the analyzed SurvK129 mutants and not comparable to SurvK129R. Taken together, our results suggest that the effects observed for SurvK129E are not caused by the lack
of acetylation at K129, but might be due to the emergence of a potential high-affinity export signal by the exchange of a positively charged lysine with a negatively charged
glutamate at position 129. Moreover, our findings indicate that acetylation of Survivin at K129 impairs dimerization rather than facilitating it. Furthermore, we wanted to find out whether Survivin acetylated at K129 is involved in mitosis. Our analyses indeed indicate that acetylated Survivin might be incorporated into the CPC.
Finally, potential further acetylation sites within the Survivin protein were identified by in situ acetylation prediction. Fifteen Survivin mutants were cloned in which probably
acetylated lysine residues were either mutated to arginine or to glutamine in order to mimic an unmodified or an acetylated lysine residue. These mutants were analyzed accordingly to the SurvK129 mutants in order to reveal potential effects on Survivin's
cellular and mitotic localization as well as on its dimerization. However, the characterization of the mutants could not identify lysine residues potentially involved in Survivin regulation. Nevertheless, we could show that, although K90 is located within Survivin's
classical export signal, its acetylation is unlikely to affect the protein's dimerization.
In summary, our results indicate that further comprehensive studies are required in order to understand the complex regulation of Survivin's various functions and the role that lysine acetylation plays in it.},
  url = 	{https://duepublico2.uni-due.de/receive/duepublico_mods_00036782},
  file = 	{:https://duepublico2.uni-due.de/servlets/MCRFileNodeServlet/duepublico_derivate_00044495/Diss_Unruhe.pdf:PDF},
  language = 	{en}
}