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Supervillin associates with androgen receptor and modulates its transcriptional activity
Huei-Ju Ting1, Shuyuan Yeh, Kazuo Nishimura
1George Whipple Laboratory for Cancer Research, Department of Pathology, and the Cancer Center, University of Rochester, Rochester, NY 14642, USA.
Abstract:
Activation of androgen receptor (AR) via androgen in muscle cells has been closely linked to their growth and differentiation. Here, we report the cloning and characterization of supervillin (SV), a 205-kDa actin-binding protein, as an AR coregulator from the skeletal muscle cDNA library. Mammalian two-hybrid and glutathione S-transferase pull-down assays indicate a domain within SV (amino acids 594-1268) can interact with AR N terminus and DNA-binding domain-ligand-binding domain in a ligand-enhanced manner. Subcellular colocalization studies with fluorescence staining indicate SV can colocalize with AR in the presence of 5 alpha-dihydrotestosterone in COS-1 cells. The functional reporter assays showed full-length SV and the SV peptide (amino acids 831-1281) within the interaction domain can enhance AR transactivation. Furthermore, SV can enhance the endogenous AR target gene, p27(KIP1), expression in prostate PC-3(AR2) cells. SV preferentially enhanced AR rather than other tested nuclear receptors and could be induced by natural androgens better than other steroids. SV can also cooperate with other AR coregulators, such as ARA55 or ARA70, to enhance AR transactivation further. Unlike SRC-1 that can enhance the interaction between AR N terminus and AR C terminus, SV shows a mild suppressive effect on N-C interactions, suggesting SV may go through a different mechanism to enhance AR transactivation. Together, our data demonstrate that SV is an AR coregulator that can enhance AR transactivation in muscle and other cells.
Insights
Supervillin (SV) is identified as a novel androgen receptor (AR) coregulator. This actin-binding protein enhances AR activity and gene expression in muscle and prostate cells.
Area of Science:
- Molecular Biology
- Cell Biology
- Endocrinology
Background:
- Androgen receptor (AR) activation is crucial for muscle growth and differentiation.
- Identifying AR coregulators is key to understanding AR-mediated cellular processes.
Purpose of the Study:
- To clone and characterize supervillin (SV) as a potential AR coregulator.
- To investigate the interaction mechanism and functional role of SV in AR transactivation.
Main Methods:
- Mammalian two-hybrid and glutathione S-transferase pull-down assays for protein interaction.
- Subcellular colocalization studies using fluorescence staining.
- Functional reporter assays and analysis of endogenous gene expression.
Main Results:
- Supervillin (SV) interacts with the androgen receptor (AR) in a ligand-dependent manner.
- SV enhances AR transactivation and the expression of AR target genes like p27(KIP1).
- SV preferentially modulates AR activity compared to other nuclear receptors and cooperates with other AR coregulators.
Conclusions:
- Supervillin (SV) functions as a novel AR coregulator.
- SV enhances AR-mediated gene expression through mechanisms distinct from SRC-1.
- SV plays a significant role in AR signaling in muscle and other cell types.