Publikationsserver der RWTH Aachen University
Charakterisierung kernständiger Funktionen der NAD+-abhängigen Deacetylase SIRT2
Abstract
dc:descriptionThe human Sirtuin SIRT2 is a deacetylase predominantly found in the cytoplasm during the cell cycle, which co-localizes with the chromatin at the G2/M transition. During this transition SIRT2 was described) to deacetylate lysine-16 of histone 4. Due to the sufficient nuclear export of SIRT2 its function inside the nucleus was difficult to elucidate. The aim of this study was to describe nuclear functions of SIRT2 without using agents to block nuclear export. Therefore a SIRT 2 mutant was generated which remains inside the nucleus. This was achieved by combining an additional nuclear localisation signal with the mutation of the nuclear export signal of SIRT2. Additionally a catalytic inactive mutant of the nuclear SIRT2 was cloned. From this it was possible to investigate the dependence of the visible effects from the deacetylase activity. These SIRT2 mutants enable to examine the influence of nuclear SIRT2 on the acetylation of lysine K-16 and additional lysines of histone H4. Furthermore the nuclear-morphology and their effect on cell proliferation were investigated. By over-expression of the nuclear SIRT2 mutant a reduction in the level K16 acetylation on histone H4 was observed. Overexpression of either wildtype SIRT2 or the catalytic inactive mutant did not effect the acetylation on H4K16 in a similar way. Remarkably nuclear SIRT2 was more highly phosphorylated compared to wildtype SIRT2 and its catalytic inactive mutant. The inhibition of this phosphorylation with the CDK inhibitor roscovitine correlated with an increase in H4K16 deacetylation. Overexpression of nuclear SIRT2 had no significant effect on the acetylation of other lysines on histone H4, which suggests a specific deacetylation of H4K16 by SIRT2 in vivo. In HeLa cells expression of nuclear SIRT2 correlates with an increase in polylobular nuclei. This phenotype resembles the one shown during the decrease of the histone acetyl transferase MOF. Striking was the fact of increased cell proliferation at over-expression of nuclear SIRT2, even though the deacetylation of H4K16 has been shown to inhibit cell proliferation.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2010
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Waibel, Susanne
- Contributors dc:contributor
-
- Lüscher, Bernhard
Subjects
dc:subject × 8Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger