NF-κB in the Mammalian Cellular Response to Exposure with Ionising Radiation
Ruscher, Roland (2008) NF-κB in the Mammalian Cellular Response to Exposure with Ionising Radiation. Diploma, Universität Köln.
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During space missions, astronauts are exposed not only to greater amounts of radiation than on Earth but also to different radiation qualities, which can result in immediate and long-term risks. Activation of the Nuclear Factor κB (NF-κB) pathway resulting in increased survival of irradiated cells might contribute to cancer risk after space radiation exposure. In this work, the effect of ionising radiation and/or of inhibition or knock out of several pathway components on the NF-κB signalling was investigated. Activation of NF-κB dependent gene expression was detected by means of stably transfected human embryonic kidney cells (HEK/293) which express the reporter gene destabilized Enhanced Green Fluorescent Protein (d2EGFP) under control of a NF-κB responsive promoter (HEK-pNF-κB-d2EGFP/Neo L2). d2EGFP fluorescence was determined by means of FACS analysis after diffuse or cell nucleus-targeted irradiation with α-particles performed at the PTB, Braunschweig. Both irradiation conditions were capable of activating the NF-κB pathway with a peak at 5x10<sup>6</sup> particles per cm<sup>2</sup> (1.26 Gy) for diffuse irradiation and after seven nuclear particle traversals (1.2 Gy) for targeted irradiation. Gene expression of NF-κB-regulated genes was analysed using quantitative real time qRT-PCR. For diffuse irradiation, a time-dependent expression pattern was observed for gadd45β, nfkbia, and bcl-2. For targeted irradiation the gene expression patterns were less pronounced. As NF-κB activation is discussed to result in a survival advantage of irradiated cells, the influence of NF-κB essential modulator (NEMO) on cellular survival (colony forming ability assay) after X-irradiation was analysed using wild-type and NEMOdeficient mouse embryonic fibroblasts (MEF). Results clearly show a better survival for the NF-κB proficient cell line, supporting this hypothesis. Analysing the upstream events in the NF-κB pathway it was shown that the proteasome inhibitor MG-132 abolished EGFP expression after treatment with TNF-α or with X-rays, pointing out that proteasomal degradation of IκB is involved after both treatments. Inhibition of the ataxia telangiectasia mutated (ATM) protein kinase by KU-55933 clearly demonstrated that NF-κB activation upon DNA double strand break processing depends on functional ATM after X-irradiation but not after TNF-α treatment of HEK cells. In conclusion, NF-κB activation via ATM kinase seems to be a relevant regulator of the cellular response to ionising radiation.
|Document Type:||Thesis (Diploma)|
|Title:||NF-κB in the Mammalian Cellular Response to Exposure with Ionising Radiation|
|Number of Pages:||111|
|Keywords:||NF-κB, Space Radiation Exposure, Space Missions, Ionising Radiation, Mammalian Cells|
|Department:||Mathematisch-Naturwissenschaftliche Fakultät, Fachbereich Biologie|
|HGF - Research field:||Aeronautics, Space and Transport|
|HGF - Program:||Space|
|HGF - Program Themes:||W FR - Forschung unter Weltraumbedingungen|
|DLR - Research area:||Space|
|DLR - Program:||W FR - Forschung unter Weltraumbedingungen|
|DLR - Research theme (Project):||W - Vorhaben Strahlenbiologie (old)|
|Institutes and Institutions:||Institute of Aerospace Medicine > Radiation Biology|
|Deposited By:||Kerstin Kopp|
|Deposited On:||19 Jun 2008|
|Last Modified:||27 Apr 2009 14:59|
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