Tip60 and Histone Deacetylase 1 Regulate Androgen Receptor Activity through Changes to the Acetylation Status of the Receptor

Abstract

The androgen receptor (AR), a member of the nuclear hormone receptor superfamily, is thought to play an important role in the development of prostate cancer. The AR is a hormone-dependent transcription factor that activates expression of numerous androgen-responsive genes. Histone acetyltransferase-containing proteins have been shown to increase activity of several transcription factors, including nuclear hormone receptors, by eliciting histone acetylation, which facilitates promoter access to the transcriptional machinery. Conversely, histone deacetylases (HDACs) have been identified which reduce levels of histone acetylation and are associated with transcriptional repression by various transcription factors. We have previously shown that Tip60 (Tat-interactive protein, 60 kDa) is a bona fide co-activator protein for the AR. Here we show that Tip60 directly acetylates the AR, which we demonstrate is a requisite for Tip60-mediated transcription. To define a mechanism for repression of AR function, we demonstrate that AR activity is specifically down-regulated by the histone deacetylase activity of HDAC1. Furthermore, using both mammalian two-hybrid and immunoprecipitation experiments, we show that AR and HDAC1 interact, suggestive of a direct role for down-regulation of AR activity by HDAC1. In chromatin immunoprecipitation assays, we provide evidence that AR, Tip60, and HDAC1 form a trimeric complex upon the endogenous AR-responsive PSA promoter, suggesting that acetylation and deacetylation of the AR is an important mechanism for regulating transcriptional activity.Prostate cell growth, development, and homeostasis are critically dependent upon the androgen receptor (AR), 1 an androgen-responsive transcription factor that activates expression of target genes in response to hormonal signals derived from the testis. The AR is a member of the nuclear hormone receptor (NHR) family and, in common with other family members, is a modular protein composed of numerous independently functioning domains (1-3). Upon binding to androgens within the cytoplasm, the AR translocates to the nucleus (4) where it recognizes and binds specific promoter elements and activates transcription of target genes through the concerted action of two transcriptional activation domains, namely activation function-1 (AF-1) and -2 (AF-2) (5).The AF-2 domain of NHRs plays a fundamental role in receptor-mediated transcriptional activation. Upon ligandbinding, the C-terminal AF-2 undergoes a shift in conformation generating a platform suitable for protein-protein interaction with co-activator molecules (6, 7). To date, numerous co-activator molecules have been identified that function to enhance the transcriptional potential of NHRs (8). The majority of coactivators identified share the capacity to elicit histone acetyltransferase (HAT) activity, a catalytic process heavily implicated in target gene activation via chromatin remodeling (9, 10). Of the identified HAT-containing co-activators, several have emerged to play significant roles in NHR act...

Endogenous Inhibition of Histone Deacetylase 1 by Tumor-Suppressive Maspin

“…It is possible that maspin distorts the HDAC1 catalytic site only to block the entry of biological substrate (e.g., N-acetyl group of histone lysine residues) but not small molecular weight inhibitors. Alternatively, by locking HDAC1 in an inactive state, maspin may enhance the accessibility of other HDACs by pharmacologic inhibitors, thus lowering the apparent IC 50 values.…”

A central domain of cyclin D1 mediates nuclear receptor corepressor activity

“…Furthermore, repressor domain interaction with HDAC3 (Figure 5c and d) and the ability of TSA to partially reverse cyclin D1 corepressor activity (Petre et al, 2002) suggest that it may serve as a scaffold to recruit HDAC activity to AR. HDACs (specifically HDACs 1-3) have been previously documented to inhibit AR transactivation potential (Gaughan et al, 2002), yet the mechanism by which the receptor associates with these corepressors remains somewhat unclear. In addition, although AR-HDAC1 interaction can be detected by both mammalian two-hybrid and co-immunoprecipitation assays, the requirement for accessory scaffolding factors has yet to be examined (Gaughan et al, 2002).…”

“…HDACs (specifically HDACs 1-3) have been previously documented to inhibit AR transactivation potential (Gaughan et al, 2002), yet the mechanism by which the receptor associates with these corepressors remains somewhat unclear. In addition, although AR-HDAC1 interaction can be detected by both mammalian two-hybrid and co-immunoprecipitation assays, the requirement for accessory scaffolding factors has yet to be examined (Gaughan et al, 2002).…”

Expression of Tip60, an androgen receptor coactivator, and its role in prostate cancer development

“…ChIP assays were performed as previously descried (Gaughan et al, 2002). For the PCR reactions the following set of primers were used: F: AGG GAT CAG GGA TCA TCA CA and R: GCT AGC ACT TGC TGT TTC TGC which amplify the À406 to À164 PSA promoter containing androgenresponsive element II (Shang et al, 2002).…”