Topo IIIalpha and BLM act within the Fanconi anemia pathway in response to DNA-crosslinking agents

The Bloom protein (BLM) and Topoisomerase IIIalpha are found in association with proteins of the Fanconi anemia (FA) pathway, a disorder manifesting increased cellular sensitivity to DNA crosslinking agents. In order to determine if the association reflects a functional interaction for the maintenance of genome stability, we have analyzed the effects of siRNA-mediated depletion of the proteins in human cells. Depletion of Topoisomerase IIIalpha or BLM leads to increased radial formation, as is seen in FA. BLM and Topoisomerase IIIalpha are epistatic to the FA pathway for suppression of radial formation in response to DNA interstrand crosslinks since depletion of either of them in FA cells does not increase radial formation. Depletion of Topoisomerase IIIalpha or BLM also causes an increase in sister chromatid exchanges, as is seen in Bloom syndrome cells. Human Fanconi anemia cells, however, do not demonstrate increased sister chromatid exchanges, separating this response from radial formation. Primary cell lines from mice defective in both Blm and Fancd2 have the same interstrand crosslink-induced genome instability as cells from mice deficient in the Fancd2 protein alone. These observations demonstrate that the association of BLM and Topoisomerase IIIalpha with Fanconi proteins is a functional one, delineating a BLM-Topoisomerase IIIalpha-Fanconi pathway that is critical for suppression of chromosome radial formation.

Rainer Werner Fassbinder’s "Garbage, The City, and Death". A Four Act Scandal in Post-war Germany

Rainer Werner Fassbinder’s Garbage, The City, and Death. A Four Act Scandal in Post-war Germany The paper explores the dramaturgy of the scandals around the play Garbage, The City and Death (Der Müll, die Stadt und der Tod) by German playwright, theatre and film maker Rainer Werner Fassbinder. Published in 1976, the play immediately caused a scandal in West Germany, because it was accused of reproducing anti-Semitic stereotypes. The presentation sheds light on the different phases of the scandal and their historical and cultural contexts in post-war Germany – starting as a literary scandal in 1976, being transformed into a theatre scandal in the 1980ies and finally being dissolved by the German premiere in 2009. The paper is structured as follows: Act One: The Literary Scandal. Destroying Fassbinder’s Garbage, Act Two: Preventing the Staging of the Play, Act Three: Blocking the Opening Night, Act Four: Performing the Play in Germany. By analysing the dramaturgical structure of this specific scandal, the paper discusses the following hypotheses: 1. Scandals arise through the circulation of decontextualised information in public. This is due to either a lack of information about the actual object or incident being scandalised or a lack of information about the context of the object or incident. This lack is caused by the logic of the scandal itself: Because the play or the performance is prohibited, it has been withdrawn from the public, making it impossible to form a well-founded opinion on the controversy. 2. The scandal is driven forward by an emotionalising rhetoric built around the decontextualised information. 3. Once the gap of information is filled, the scandalising rhetoric turns into a rhetoric of irrelevance: Reviews of the first performance of Garbage, The City and Death in Germany considered the play hardly a matter of public concern.

The Drosophila chk2 gene loki is essential for embryonic DNA double-strand-break checkpoints induced in S phase or G2

Cell cycle checkpoints are signal transduction pathways that control the order and timing of cell cycle transitions, ensuring that critical events are completed before the occurrence of the next cell cycle transition. The Chk2 family of kinases is known to play a central role in mediating the cellular responses to DNA damage or DNA replication blocks in various organisms. Here we show through a phylogenetic study that the Drosophila melanogaster serine/threonine kinase Loki is the homolog of the yeast Mek1p, Rad53p, Dun1p, and Cds1 proteins as well as the human Chk2. Functional analyses allowed us to conclude that, in flies, chk2 is involved in monitoring double-strand breaks (DSBs) caused by irradiation during S and G2 phases. In this process it plays an essential role in inducing a cell cycle arrest in embryonic cells. Our results also show that, in contrast to C. elegans chk2, Drosophila chk2 is not essential for normal meiosis and recombination, and it also appears to be dispensable for the MMS-induced DNA damage checkpoint and the HU-induced DNA replication checkpoint during larval development. In addition, Drosophila chk2 does not act at the same cell cycle phases as its yeast homologs, but seems rather to be involved in a pathway similar to the mammalian one, which involves signaling through the ATM/Chk2 pathway in response to genotoxic insults. As mutations in human chk2 were linked to several cancers, these similarities point to the usefulness of the Drosophila model system.