Differential Modulation of Androgen Receptor Action by Deoxyribonucleic Acid Response Elements

Abstract

In addition to the steroid response elements (SREs), which are recognized by several steroid receptors, a second class of DNA elements exhibiting selectivity for the androgen receptor (AR) and named androgen response elements (AREs) has been identified. Here we provide evidence for the differential role of these element classes in modulating AR function. AR complexes attached to response elements representative of each class were purified. Limited protease digests of ARE- or SRE-bound AR complexes led to the generation of different patterns, in line with differential accessibilities. In transactivation assays, mutations in the AR dimerization interface of the DNA-binding domain had various effects, depending on the response elements tested. The R598D mutant displayed much enhanced activity on SREs, whereas far less effect was seen on the selective AREs. The A596T mutant had reduced activity on AREs but not on SREs. Ectopic expression of the coactivators transcriptional intermediary factor 2 (TIF2) and ARA55 stimulated AR activity to different extents, depending on the response element. When using cysteine-rich secretory protein 1 (CRISP-1) SRE as reference, the most significant difference was observed with Pem ARE-2. A differential response of each element class was furthermore observed in the presence of two enzymes involved in the sumoylation pathway. Ubiquitin-conjugating enzyme 9 (Ubc9) overexpression enhanced AR action conveyed by SREs, whereas little effect was seen on Pem ARE-1 and repression on Pem ARE-2. Protein inhibitor of activated STAT (PIAS)xalpha overexpression had little influence on SRE-mediated AR activity but was repressive when using AREs. Altogether, these results demonstrate that DNA response elements play an important modulatory role in transmitting AR action and may be determinative for specificity of gene expression in cell or tissue types.

The Rhox genes

“…Androgen-dependent expression is conferred by the four AREs in region II (Barbulescu et al 2001, Geserick et al 2003, Bhardwaj et al 2008. These AREs also contribute to the tissue-and cell type-specific expression pattern of the Pp, as recently shown by Bhardwaj et al (2008).…”

“…This conclusion comes from several lines of evidence, including: i) Rhox5 mRNA levels (measured with either Rhox5 or Pp-specific probes) are dramatically reduced in animals deficient in the ability to produce LH (the peptide hormone responsible for inducing testosterone production in Leydig cells) as a result of hypophysectomy, chemical treatment, or genetic mutations , 1996c, Maiti et al 1996a, Sutton et al 1998; ii) testosterone reverses the defect in Rhox5 expression caused by loss of LH , Sutton et al 1998; and ix) the Pp possesses four androgen-response elements (AREs), each of which is required for its AR-and androgen-dependent expression in transfected cell lines (Barbulescu et al 2001, Geserick et al 2003, Bhardwaj et al 2008, Faus & Haendler 2008. Together, these studies strongly suggest that the Rhox5 Pp is a direct target of AR in Sertoli cells.…”

“…The highly androgen/AR-dependent expression of Rhox5 has lead to Rhox5 being widely used as a marker to examine perturbations disturbing androgen signaling (Sutton et al 1998, Barbulescu et al 2001, Geserick et al 2003, De Gendt et al 2004, MacLean & Wilkinson 2005, Terada et al 2005, Bhardwaj et al 2008, Prante et al 2008. Because the Rhox5 gene encodes a transcription factor, another implication of its androgen/AR-dependent expression is that it is a candidate to regulate the transcription of genes that mediate androgen action during spermatogenesis (MacLean & Wilkinson 2005).…”

Intra-domain communication between the N-terminal and DNA-binding domains of the androgen receptor: modulation of androgen response element DNA binding

“…A more resistant conformation was observed for the AR-NTD-DBD bound to DNA in the present study, although no clear differences were observed between selective and non-selective sequences. Recently, Gerserick et al (2003) revealed a change in sensitivity to proteolysis that depended on whether the AR was bound to selective or non-selective elements. Complexes formed with nuclear extracts on selective response elements were less accessible to digestion compared with complexes bound to nonselective elements.…”

A bioinformatics-based functional analysis shows that the specifically androgen-regulated gene SARG contains an active direct repeat androgen response element in the first intron

“…Recent evidence indicates that binding to different AREs indeed induces different conformational changes (Geserick et al 2003). A different DBD conformation might directly or indirectly affect the association with coactivators, as shown for ER (Wood et al 2001, Hall et al 2002.…”