@article{SanderXuEilersetal.2017,
  author    = {Sander, Bodo and Xu, Wenshan and Eilers, Martin and Popov, Nikita and Lorenz, Sonja},
  title     = {A conformational switch regulates the ubiquitin ligase HUWE1},
  series = {eLife},
  volume    = {6},
  journal   = {eLife},
  doi       = {10.7554/eLife.21036},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171862},
  year      = {2017},
  abstract  = {The human ubiquitin ligase HUWE1 has key roles in tumorigenesis, yet it is unkown how its activity is regulated. We present the crystal structure of a C-terminal part of HUWE1, including the catalytic domain, and reveal an asymmetric auto-inhibited dimer. We show that HUWE1 dimerizes in solution and self-associates in cells, and that both occurs through the crystallographic dimer interface. We demonstrate that HUWE1 is inhibited in cells and that it can be activated by disruption of the dimer interface. We identify a conserved segment in HUWE1 that counteracts dimer formation by associating with the dimerization region intramolecularly. Our studies reveal, intriguingly, that the tumor suppressor p14ARF binds to this segment and may thus shift the conformational equilibrium of HUWE1 toward the inactive state. We propose a model, in which the activity of HUWE1 underlies conformational control in response to physiological cues—a mechanism that may be exploited for cancer therapy.},
  language  = {en}
}
@article{RodriguesPopovKayeetal.2013,
  author    = {Rodrigues, L{\´e}nia and Popov, Nikita and Kaye, Kenneth M. and Simas, J. Pedro},
  title     = {Stabilization of Myc through Heterotypic Poly-Ubiquitination by mLANA Is Critical for \(\gamma\)-Herpesvirus Lymphoproliferation},
  series = {PLoS PATHOGENS},
  volume    = {9},
  journal   = {PLoS PATHOGENS},
  number    = {8},
  doi       = {10.1371/journal.ppat.1003554},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131227},
  pages     = {e1003554},
  year      = {2013},
  abstract  = {Host colonization by lymphotropic \(\gamma\)-herpesviruses depends critically on expansion of viral genomes in germinal center (GC) B-cells. Myc is essential for the formation and maintenance of GCs. Yet, the role of Myc in the pathogenesis of \(\gamma\)-cherpesviruses is still largely unknown. In this study, Myc was shown to be essential for the lymphotropic \(\gamma\)-herpesvirus MuHV- 4 biology as infected cells exhibited increased expression of Myc signature genes and the virus was unable to expand in Myc defficient GC B- cells. We describe a novel strategy of a viral protein activating Myc through increased protein stability resulting in increased progression through the cell cycle. This is acomplished by modulating a physiological posttranslational regulatory pathway of Myc. The molecular mechanism involves Myc heterotypic poly- ubiquitination mediated via the viral E3 ubiquitin- ligase mLANA protein. \(EC_5S^{mLANA}\) modulates cellular control of Myc turnover by antagonizing \(SCF^{Fbw7}\) mediated proteasomal degradation of Myc, mimicking \(SCF^{\beta-TrCP}\). The findings here reported reveal that modulation of Myc is essential for \(\gamma\)-herpesvirus persistent infection, establishing a link between virus induced lymphoproliferation and disease.},
  language  = {en}
}
@article{SchueleinVoelkWolfZhuetal.2014,
  author    = {Sch{\"u}lein-V{\"o}lk, Christina and Wolf, Elmar and Zhu, Jing and Xu, Wenshan and Taranets, Lyudmyla and Hellmann, Andreas and J{\"a}nicke, Laura A. and Diefenbacher, Markus E. and Behrens, Axel and Eilers, Martin and Popov, Nikita},
  title     = {Dual Regulation of Fbw7 Function and Oncogenic Transformation by Usp28},
  series = {CELL REPORTS},
  volume    = {9},
  journal   = {CELL REPORTS},
  number    = {3},
  issn      = {2211-1247},
  doi       = {10.1016/j.celrep.2014.09.057},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-118219},
  pages     = {1099-1109},
  year      = {2014},
  abstract  = {Fbw7, the substrate recognition subunit of SCF(Fbw7) ubiquitin ligase, mediates the turnover of multiple proto-oncoproteins and promotes its own degradation. Fbw7-dependent substrate ubiquitination is antagonized by the Usp28 deubiquitinase. Here, we show that Usp28 preferentially antagonizes autocatalytic ubiquitination and stabilizes Fbw7, resulting in dose-dependent effects in Usp28 knockout mice. Monoallelic deletion of Usp28 maintains stable Fbw7 but drives Fbw7 substrate degradation. In contrast, complete knockout triggers Fbw7 degradation and leads to the accumulation of Fbw7 substrates in several tissues and embryonic fibroblasts. On the other hand, overexpression of Usp28 stabilizes both Fbw7 and its substrates. Consequently, both complete loss and ectopic expression of Usp28 promote Ras-driven oncogenic transformation. We propose that dual regulation of Fbw7 activity by Usp28 is a safeguard mechanism for maintaining physiological levels of proto-oncogenic Fbw7 substrates, which is equivalently disrupted by loss or overexpression of Usp28.},
  language  = {en}
}
@article{PeterBultinckMyantetal.2014,
  author    = {Peter, Stefanie and Bultinck, Jennyfer and Myant, Kevin and Jaenicke, Laura A. and Walz, Susanne and M{\"u}ller, Judith and Gmachl, Michael and Treu, Matthias and Boehmelt, Guido and Ade, Casten P. and Schmitz, Werner and Wiegering, Armin and Otto, Christoph and Popov, Nikita and Sansom, Owen and Kraut, Norbert and Eilers, Martin},
  title     = {H Tumor cell-specific inhibition of MYC function using small molecule inhibitors of the HUWE1 ubiquitin ligase},
  series = {EMBO Molecular Medicine},
  volume    = {6},
  journal   = {EMBO Molecular Medicine},
  number    = {12},
  issn      = {1757-4684},
  doi       = {10.15252/emmm.201403927},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-118132},
  pages     = {1525-41},
  year      = {2014},
  abstract  = {Deregulated expression of MYC is a driver of colorectal carcinogenesis, necessitating novel strategies to inhibit MYC function. The ubiquitin ligase HUWE1 (HECTH9, ARF-BP1, MULE) associates with both MYC and the MYC-associated protein MIZ1. We show here that HUWE1 is required for growth of colorectal cancer cells in culture and in orthotopic xenograft models. Using high-throughput screening, we identify small molecule inhibitors of HUWE1, which inhibit MYC-dependent transactivation in colorectal cancer cells, but not in stem and normal colon epithelial cells. Inhibition of HUWE1 stabilizes MIZ1. MIZ1 globally accumulates on MYC target genes and contributes to repression of MYC-activated target genes upon HUWE1 inhibition. Our data show that transcriptional activation by MYC in colon cancer cells requires the continuous degradation of MIZ1 and identify a novel principle that allows for inhibition of MYC function in tumor cells.},
  language  = {en}
}