TY  - JOUR
A1  - Sander, Bodo
A1  - Xu, Wenshan
A1  - Eilers, Martin
A1  - Popov, Nikita
A1  - Lorenz, Sonja
T1  - A conformational switch regulates the ubiquitin ligase HUWE1
JF  - eLife
N2  - 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.
KW  - Medicine
KW  - Structural Biology
KW  - Molecular Biophysics
KW  - HUWE1
KW  - HECT Ligase
KW  - Ubiquitin
KW  - P14ARF
KW  - X-Ray Chrystallography
KW  - Enzyme Regulation
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-171862
VL  - 6
ER  - 
TY  - JOUR
A1  - Schülein-Völk, Christina
A1  - Wolf, Elmar
A1  - Zhu, Jing
A1  - Xu, Wenshan
A1  - Taranets, Lyudmyla
A1  - Hellmann, Andreas
A1  - Jänicke, Laura A.
A1  - Diefenbacher, Markus E.
A1  - Behrens, Axel
A1  - Eilers, Martin
A1  - Popov, Nikita
T1  - Dual Regulation of Fbw7 Function and Oncogenic Transformation by Usp28
JF  - CELL REPORTS
N2  - 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.
KW  - Fbw7
KW  - oncogenic transformation
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-118219
SN  - 2211-1247
N1  - The sequencing data have been submitted to the GEO repository under accession number GSE59354.
VL  - 9
IS  - 3
ER  -