The RIP140 Gene Is a Transcriptional Target of E2F1

RIP140 is a transcriptional coregulator involved in energy homeostasis and ovulation which is controlled at the transcriptional level by several nuclear receptors. We demonstrate here that RIP140 is a novel target gene of the E2F1 transcription factor. Bioinformatics analysis, gel shift assay, and chromatin immunoprecipitation demonstrate that the RIP140 promoter contains bona fide E2F response elements. In transiently transfected MCF-7 breast cancer cells, the RIP140 promoter is transactivated by overexpression of E2F1/DP1. Interestingly, RIP140 mRNA is finely regulated during cell cycle progression (5-fold increase at the G1/S and G2/M transitions). The positive regulation by E2F1 requires sequences located in the proximal region of the promoter (−73/+167), involves Sp1 transcription factors, and undergoes a negative feedback control by RIP140. Finally, we show that E2F1 participates in the induction of RIP140 expression during adipocyte differentiation. Altogether, this work identifies the RIP140 gene as a new transcriptional target of E2F1 which may explain some of the effect of E2F1 in both cancer and metabolic diseases

Presence of regulatory sequences within intron 2 of the mouse thymidine kinase gene.

The intron 2 of the murine thymidine kinase (TK) gene was observed to contain two DNase hypersensitive site. In vitro footprinting experiments indicated specific binding sites for nuclear proteins which were characterized within the sequence of intron 2. Two GC boxes (binding sites for transcription factor SP1) and two new protein binding regions, one at the promoter proximal end of intron 2, the other one close to the border to exon 3 were found. Oligonucleotides were synthesized comprising the two new binding sites and were shown in gel mobility shift experiments to be capable of forming specific complexes with nuclear proteins. These proteins are present in growing as well as in quiescent cells suggesting that the sites described here do not contribute to growth regulation of TK expression. That they might play a role in upregulation of TK expression is, however, indicated by the results of CAT assays in which inclusion of downstream sequences of the TK gene containing parts or all of intron 2 were found to positively modulate the activity of the TK promoter

Taxonomische Klassifizierung von "Megabakterien"-Isolaten aus Wellensittichen (Melopsittacus undulatus Shaw, 1805)

Die taxonomische Zuordnung von sogenannten »Megabakterien« wurde mittels lichtmikroskopischer und elektronenmikroskopischer Techniken sowie Fluoreszenz-in-situ-Hybridisierungsverfahren (FISH-Technik) untersucht. Für diese Untersuchungen wurden »Megabakterien«- Isolate aus Wellensittichen (Melopsittacus undulatus Shaw, 1805) herangezogen. Die Ergebnisse zeigen, daß es sich bei den untersuchten Keimen um eukaryotische Zellen und nicht um Bakterien oder Archaebakterien handelt, wie es der Name vermuten läßt. Die morphologischen Parameter dieser Keime weisen auf eine mögliche Zuordnung zu Pilzen hin. Die Namensgebung »Megabakterium« ist demzufolge für die untersuchten Keime nicht korrekt