@article{LorenzinBenaryBaluapurietal.2016, author = {Lorenzin, Francesca and Benary, Uwe and Baluapuri, Apoorva and Walz, Susanne and Jung, Lisa Anna and von Eyss, Bj{\"o}rn and Kisker, Caroline and Wolf, Jana and Eilers, Martin and Wolf, Elmar}, title = {Different promoter affinities account for specificity in MYC-dependent gene regulation}, series = {eLife}, volume = {5}, journal = {eLife}, doi = {10.7554/eLife.15161}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-162913}, pages = {e15161}, year = {2016}, abstract = {Enhanced expression of the MYC transcription factor is observed in the majority of tumors. Two seemingly conflicting models have been proposed for its function: one proposes that MYC enhances expression of all genes, while the other model suggests gene-specific regulation. Here, we have explored the hypothesis that specific gene expression profiles arise since promoters differ in affinity for MYC and high-affinity promoters are fully occupied by physiological levels of MYC. We determined cellular MYC levels and used RNA- and ChIP-sequencing to correlate promoter occupancy with gene expression at different concentrations of MYC. Mathematical modeling showed that binding affinities for interactions of MYC with DNA and with core promoter-bound factors, such as WDR5, are sufficient to explain promoter occupancies observed in vivo. Importantly, promoter affinity stratifies different biological processes that are regulated by MYC, explaining why tumor-specific MYC levels induce specific gene expression programs and alter defined biological properties of cells.}, language = {en} } @phdthesis{Wiese2015, author = {Wiese, Katrin Evelyn}, title = {Sensing supraphysiological levels of MYC : mechanisms of MIZ1-dependent MYC-induced Apoptosis in Mammary Epithelial Cells}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-132532}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2015}, abstract = {Deregulated MYC expression contributes to cellular transformation as well as progression and maintenance of human tumours. Interestingly, in the absence of additional genetic alterations, potentially oncogenic levels of MYC sensitise cells to a variety of apoptotic stimuli. Hence, MYC-induced apoptosis has long been recognised as a major barrier against cancer development. However, it is largely unknown how cells discriminate physiological from supraphysiological levels of MYC in order to execute an appropriate biological response. The experiments described in this thesis demonstrate that induction of apoptosis in mammary epithelial cells depends on the repressive actions of MYC/MIZ1 complexes. Analysis of gene expression profiles and ChIP-sequencing experiments reveals that high levels of MYC are required to invade low-affinity binding sites and repress target genes of the serum response factor SRF. These genes are involved in cytoskeletal dynamics as well as cell adhesion processes and are likely needed to transmit survival signals to the AKT kinase. Restoration of SRF activity rescues MIZ1- dependent gene repression and increases AKT phosphorylation and downstream function. Collectively, these results indicate that association with MIZ1 leads to an expansion of MYC's transcriptional response that allows sensing of oncogenic levels, which points towards a tumour-suppressive role for the MYC/MIZ1 complex in epithelial cells.}, subject = {Myc}, language = {en} }