SUMOylation modulates the transcriptional activity of androgen receptor in a target gene and pathway selective manner.
Bottom Line: Fittingly, SUMOylation mutant AR cells proliferate faster and are more sensitive to apoptosis.Moreover, ChIP-seq analyses show that the SUMOylation can modulate the chromatin occupancy of AR on many loci in a fashion that parallels their differential androgen-regulated expression.De novo motif analyses reveal that FOXA1, C/EBP and AP-1 motifs are differentially enriched at the wtAR- and the AR-K386R,K520R-preferred genomic binding positions.
Affiliation: Institute of Biomedicine, University of Eastern Finland, Kuopio, PO Box 1627, FI-70211 Kuopio, Finland.Show MeSH
Related in: MedlinePlus
Mentions: We next performed de novo motif analyses with all ARBs to identify over-represented transcription factor-binding motifs in the ARBs. As expected, the de novo ARE consensus (that closely resembles the ARE motif in the JASPAR-database) was the most enriched motif among all ARBs (in >60% of wtAR-, AR-2KR-preferred and shared ARBs) (Figure 6A and B). Further analysis revealed no clear differences in the number of AREs per ARE-containing ARBs between the preferred and shared ARBs, with the means (±SD) 1.28 ± 0.52, 1.20 ± 0.47 and 1.31 ± 0.56 for the wtAR-, the AR-2KR- and the shared ARBs, respectively. Other significantly enriched motifs were those for ERG, FOXA1, C/EBP and AP-1 (Figure 6A). While the de novo ARE and ERG motifs were fairly similarly enriched in all three ARB subsets, there were significant differences in the enrichment of FOXA1, C/EBP and AP-1 motifs to the three ARB subsets. Based on western blotting analysis, factors binding to these motifs (FOXA1, C/EBPβ and c-Jun, major AP-1 component) are expressed in our PC3 model cells (Supplementary Figure S10). Both FOXA1 and C/EBP motifs were found three times more often within the wtAR-preferred then AR-2KR-preferred ARBs, whereas the AP-1 motif was nearly three times more prevalent within the AR-2KR-preferred ARBs (Figure 6B and C, Supplementary Figure S11). As shown in Figure 6C, more pronounced loading of both the FOXA1 and the C/EBPβ, for example, onto SAFB and ANKRD17 loci in wtAR than AR-2KR cells is in line with the in silico predictions in panel B. Moreover, c-Jun appears to be more avidly loaded, for example, onto ADRA1B locus in AR-2KR- than in wtAR-expressing PC3 cells (Figure 6C). De novo analysis of the HEK293 data showed, in addition to the AREs, a similar over-enrichment of FOXA1 within the wtAR-preferred ARBs. GATA1 was also over-enriched in the wtAR-preferred ARBs, whereas EBF1 and PAX2 were more prevalent in the AR-2KR preferred ARBs (Supplementary Figure S12A and B). The differences in the enriched motifs between the PC-3 and the HEK293 cells likely reflect cell-specific differences in the expression of their cognate transcription factors. Compared to LNCaP and VCaP prostate cancer cells in which about half of the identified ARBs have a FOXA1 motif (31,32), the PC-3 ARBs and the HEK293 ARBs less frequently harbor a FOXA1 motif. This may be due to the lower amount of FOXA1 in the latter two cell lines (Supplementary Figure S10).
Affiliation: Institute of Biomedicine, University of Eastern Finland, Kuopio, PO Box 1627, FI-70211 Kuopio, Finland.