A cell model for conditional profiling of androgen-receptor-interacting proteins

The lncRNA SLNCR Recruits the Androgen Receptor to EGR1-Bound Genes in Melanoma and Inhibits Expression of Tumor Suppressor p21

Melanoma is the deadliest form of skin cancer, affecting men more frequently and severely than women. Although recent studies suggest that differences in activity of the androgen receptor (AR) underlie the observed sex bias, little is known about AR activity in melanoma. Here we show that AR and EGR1 bind to the long non-coding RNA SLNCR and increase melanoma proliferation through coordinated transcriptional regulation of several growth-regulatory genes. ChIP-seq reveals that ligand-free AR is enriched on SLNCR-regulated melanoma genes and that AR genomic occupancy significantly overlaps with EGR1 at consensus EGR1 binding sites. We present a model in which SLNCR recruits AR to EGR1-bound genomic loci and switches EGR1-mediated transcriptional activation to repression of the tumor suppressor p21^Waf1/Cip1. Our data implicate the regulatory triad of SLNCR, AR, and EGR1 in promoting oncogenesis and may help explain why men have a higher incidence of and more rapidly progressive melanomas compared with women.

CHD1 Loss Alters AR Binding at Lineage-Specific Enhancers and Modulates Distinct Transcriptional Programs to Drive Prostate Tumorigenesis

Deletion of the gene encoding the chromatin remodeler CHD1 is among the most common alterations in prostate cancer (PCa); however, the tumor-suppressive functions of CHD1 and reasons for its tissue-specific loss remain undefined. We demonstrated that CHD1 occupied prostate-specific enhancers enriched for the androgen receptor (AR) and lineage-specific cofactors. Upon CHD1 loss, the AR cistrome was redistributed in patterns consistent with the oncogenic AR cistrome in PCa samples and drove tumor formation in the murine prostate. Notably, this cistrome shift was associated with a unique AR transcriptional signature enriched for pro-oncogenic pathways unique to this tumor subclass. Collectively, these data credential CHD1 as a tumor suppressor in the prostate that constrains AR binding/function to limit tumor progression.

Endogenous androgen receptor proteomic profiling reveals genomic subcomplex involved in prostate tumorigenesis

Androgen receptor (AR) is a key player in prostate cancer development and progression. Here we applied immunoprecipitation mass spectrometry of endogenous AR in LNCaP cells to identify components of the AR transcriptional complex. In total, 66 known and novel AR interactors were identified in the presence of synthetic androgen, most of which were critical for AR-driven prostate cancer cell proliferation. A subset of AR interactors required for LNCaP proliferation were profiled using chromatin immunoprecipitation assays followed by sequencing, identifying distinct genomic subcomplexes of AR interaction partners. Interestingly, three major subgroups of genomic subcomplexes were identified, where selective gain of function for AR genomic action in tumorigenesis was found, dictated by FOXA1 and HOXB13. In summary, by combining proteomic and genomic approaches we reveal subclasses of AR transcriptional complexes, differentiating normal AR behavior from the oncogenic state. In this process, the expression of AR interactors has key roles by reprogramming the AR cistrome and interactome in a genomic location-specific manner.

In vivo phosphorylation of FtsZ2 in Arabidopsis thaliana

The tubulin-like FtsZ protein initiates assembly of the bacterial and plastid division machineries. In bacteria, phosphorylation of FtsZ impairs GTPase activity, polymerization and interactions with other division proteins. Using a proteomics approach, we have shown that AtFtsZ2 is phosphorylated in vivo in Arabidopsis and that PGK1 (phosphoglycerate kinase 1) interacts with AtFtsZ2 in planta, suggesting a possible role in FtsZ phosphorylation.

RWDD1 interacts with the ligand binding domain of the androgen receptor and acts as a coactivator of androgen-dependent transactivation

During embryogenesis, the development of the male genital is dependent on androgens. Their actions are mediated by the androgen receptor (AR), which functions as a transcription factor. To identify AR coregulators that support AR action during the critical time window of androgen-dependent development in the genital tubercle of male mice, we performed yeast two-hybrid screenings with cDNA libraries of genital tubercles from male mouse embryos using human AR as bait. RWD domain containing 1 (RWDD1) was identified as an AR-interacting protein from three independent libraries of the embryonic days E15, E16 and E17. The interaction between the AR and RWDD1 was confirmed in vitro and in vivo and the ligand binding domain of the AR was shown to be sufficient to mediate the interaction. RWDD1 enhanced AR-dependent transactivation in reporter assays with promoters of different complexity and in different cell lines. These results suggest that RWDD1 functions as a coactivator of androgen-dependent transcription.