References of "Kätzel, Thorben 40020977"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailConstitutive expression of tdTomato protein as a cytotoxicity and proliferation marker for space radiation biology
Chishti, Arif A.; Hellweg, Christine E.; Berger, Thomas et al

in Life Sciences in Space Research (2015), 4

The radiation risk assessment for long-term space missions requires knowledge on the biological effectiveness of different space radiation components, e.g. heavy ions, on the interaction of radiation and ... [more ▼]

The radiation risk assessment for long-term space missions requires knowledge on the biological effectiveness of different space radiation components, e.g. heavy ions, on the interaction of radiation and other space environmental factors such as microgravity, and on the physical and biological dose distribution in the human body. Space experiments and ground-based experiments at heavy ion accelerators require fast and reliable test systems with an easy readout for different endpoints. In order to determine the effect of different radiation qualities on cellular proliferation and the biological depth dose distribution after heavy ion exposure, a stable human cell line expressing a novel fluorescent protein was established and characterized. tdTomato, a red fluorescent protein of the new generation with fast maturation and high fluorescence intensity, was selected as reporter of cell proliferation. Human embryonic kidney (HEK/293) cells were stably transfected with a plasmid encoding tdTomato under the control of the constitutively active cytomegalovirus (CMV) promoter (ptdTomato-N1). The stably transfected cell line was named HEK-ptdTomato-N1 8. This cytotoxicity biosensor was tested by ionizing radiation (X-rays and accelerated heavy ions) exposure. As biological endpoints, the proliferation kinetics and the cell density reached 100 h after irradiation reflected by constitutive expression of the tdTomato were investigated. Both were reduced dose-dependently after radiation exposure. Finally, the cell line was used for biological weighting of heavy ions of different linear energy transfer (LET) as space-relevant radiation quality. The relative biological effectiveness of accelerated heavy ions in reducing cellular proliferation peaked at an LET of 91 keV/μm. The results of this study demonstrate that the HEK-ptdTomato-N1 reporter cell line can be used as a fast and reliable biosensor system for detection of cytotoxic damage caused by ionizing radiation. © 2015 The Committee on Space Research (COSPAR). [less ▲]

Detailed reference viewed: 104 (1 UL)
Full Text
See detailINFLUENCE OF 1,25-DIHYDROXYVITAMIN D3 ON MONOCYTIC THP-1 CELLS IN A TNF-ALPHA-INDUCED INFLAMMATORY STATE: A COMBINED EXPERIMENTAL AND SYSTEMS BIOLOGY APPROACH
Kätzel, Thorben UL

Doctoral thesis (2014)

The focus of this thesis is the understanding of the molecular mechanisms related to the recently discovered anti-inflammatory function of vitamin D and its ability to suppress tumor growth and chronic ... [more ▼]

The focus of this thesis is the understanding of the molecular mechanisms related to the recently discovered anti-inflammatory function of vitamin D and its ability to suppress tumor growth and chronic inflammation. Our aim is the analysis of the modulatory effects of 1,25-dihydroxyvitamin D3 (1 ,25(OH)2D3 or 1,25-D3) on gene expression in THP-1 cells in a TNF- alpha-induced inflammatory state. This monocyte cell line was used as a model system for potential monocyte-endothelial interactions. For the gene expression profiling, the cells were treated with TNF-alpha and 1,25-D3 and analysed at three different time points, 1h, 4h and 24h, by using Illumina Human HT-12 v4.0 micro arrays to achieve specific changes in the mRNA expression levels. The validation of the micro array data was performed by RT-qPCR and resulted in gene clusters regulating cellular growth, cell development and cellular movement. Specifically, we were able to identify the genes BCL2, CCL2, MGAT3, NCF1, ORM1 and RAB37 and their expression levels were analysed in the presence and absence of vitamin D and TNF-alpha using quantitative PCR. Furthermore, the expression of the acute phase plasma alpha-globulin glycoprotein alpha-1-acid glycoprotein (AGP) encoded by ORM1 gene, and beta -1,4-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase (Gnt-III) encoded by MGAT3 gene were investigated via quantitative western blot and ELISA experiments after treatment of cells with 1,25-D3 and TNF-alpha , where post-stimulation protein levels evolved correspondingly for the former protein. Subsequent invasion assays showed an inhibitory effect on invasion efficacy of THP-1 cells after knockdown of ORM1 with specific siRNA. Moreover, microarray data and database knowledge were used to generate a network containing previously identified and validated target genes. This candidate network is modeled computationally with a biochemical reaction-based Boolean model. It was further curated by an evolutionary algorithm-based pruning step removing unnecessary nodes and interactions, called MORGEN. This ultimately resulted in a model allowing the qualitative description of the observed gene expression patterns. In conclusion, 1,25-D3 affects a range of genes in THP-1 cells in TNF- alpha-induced-inflammatory state. We showed that it potentially alters transendothelial migration of monocytic cells, among other ways, via increase of AGP expression after exposure of the cells to both 1,25-D3 and TNF- alpha. Furthermore, the generated model could be reduced significantly via implementation of MORGEN. This promises a valuable new tool for network reduction, an essential step for generation of elaborated models with computationally feasible properties that help to understand the complex network and deregulation of signaling networks in different diseases. [less ▲]

Detailed reference viewed: 138 (23 UL)