Ubc9 Interacts with the Androgen Receptor and Activates Receptor-dependent Transcription*
- From the ‡Department of Physiology, Institute of Biomedicine, and §the Department of Clinical Chemistry, University of Helsinki, FIN-00014 Helsinki, Finland
Abstract
Ubc9, a homologue of the class E2 ubiquitin-conjugating enzymes, has recently been shown to catalyze conjugation of a small ubiquitin-like molecule-1 (SUMO-1) to a variety of target proteins. SUMO-1 modifications have been implicated in the targeting of proteins to the nuclear envelope and certain intranuclear structures and in converting proteins resistant to ubiquitin-mediated degradation. In the present work, we find that Ubc9 interacts with the androgen receptor (AR), a member of the steroid receptor family of ligand-activated transcription factors. In transiently transfected COS-1 cells, AR-dependent but not basal transcription is enhanced by the coexpression of Ubc9. The N-terminal half of the AR hinge region containing the C-terminal part of the bipartite nuclear localization signal is essential for the interaction with Ubc9. Deletion of this part of the nuclear localization signal, which does not completely prevent the transfer of AR to the nucleus, abolishes the AR-Ubc9 interaction and attenuates the transcriptional response to cotransfected Ubc9. The C93S substitution of Ubc9, which prevents SUMO-1 conjugation by abrogating the formation of a thiolester bond between SUMO-1 and Ubc9, does not influence the capability of Ubc9 to stimulate AR-dependent transactivation, implying that Ubc9 is able to act as an AR coregulator in a fashion independent of its ability to catalyze SUMO-1 conjugation.
Footnotes
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↵* This work was supported by grants from the Medical Research Council (Academy of Finland), the Finnish Foundation for Cancer Research, the Sigrid Jusélius Foundation, Biocentrum Helsinki, Helsinki University Central Hospital, and the Finnish Medical Society Duodecim.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵¶ To whom correspondence should be addressed: Dept. of Physiology, Inst. of Biomedicine, University of Helsinki, P. O. Box B9, Siltavuorenpenger 20 J, FIN-00014 Helsinki, Finland. Tel.: 358-9-1918544; Fax: 358-9-1918681; E-mail:olli.janne{at}helsinki.fi.
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↵2 H. Poukka, P. Aarnisalo, J. J. Palvimo, and O. A. Jänne, unpublished observations.
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↵3 H. Poukka, U. Karvonen, J. J. Palvimo, and O. A. Jänne, unpublished observations.
- Abbreviations:
- AR
-
androgen receptor
- AD
-
activation domain
- AP-1
-
activator protein-1
- ARE
-
androgen response element
- DBD
-
DNA-binding domain
- GR
-
glucocorticoid receptor
- LUC
-
luciferase
- NF-κB
-
nuclear factor κB
- NLS
-
nuclear localization signal
- SUMO-1
-
small ubiquitin-like molecule-1
- E2
-
ubiquitin carrier protein
- E1
-
ubiquitin-activating enzyme
- hAR
-
human AR
- CREB
-
cAMP response element-binding protein
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- Received January 25, 1999.
- Revision received April 9, 1999.
- The American Society for Biochemistry and Molecular Biology, Inc.
