The ubiquitin ligase G2E3 modulates cell proliferation, survival and the DNA damage response

by Franziska Schmidt
Doctoral thesis
Date of Examination:2013-08-30
Date of issue:2014-07-28
Advisor:Prof. Dr. Matthias Dobbelstein
Referee:Prof. Dr. Holger Reichardt
Referee:Prof. Dr. Felix Hermann Brembeck
Persistent Address: http://dx.doi.org/10.53846/goediss-4625

 

 

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Abstract

English

The chemotherapeutic cisplatin is widely used to treat various tumors. By inducing crosslinking of DNA, signaling and repair pathways are activated which are referred to as the DNA damage response (DDR). However, the cellular and molecular mechanisms of cisplatin treatment are incompletely understood. We set up a study to find new regulators in the DDR to cisplatin. Since ubiquitination plays a major role in the DDR, we applied a high-content siRNA screen targeting 327 human ubiquitin ligases and 92 deubiquitinating enzymes in U2OS cells. We detected phosphorylation of the histone variant H2AX (yielding γH2AX), a marker for DNA damage. Knockdown of one of the candidates, the ubiquitin ligase G2E3, led to decrease in γH2AX levels. G2E3 had previously been proposed to play a role in the DDR and in cell survival. However, little was known about the underlying mechanisms. In the work presented here, we show that G2E3 is a DNA damage-responsive, cell cycle-dependent survival factor.
Keywords: chemotherapeutic; cisplatin; DNA damage response; ubiquitination; γH2AX; siRNA high-content screen
 
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