Functional mapping of androgen receptor enhancer activity

Area of Science:

• Molecular Biology
• Genomics
• Cancer Research

Background:

• Androgen receptor (AR) plays a key role in prostate cancer development and progression.
• Activated AR binds to DNA cis-regulatory elements to drive gene expression.
• A significant excess of AR binding sites exists compared to differentially expressed genes, with their regulatory role unclear.

Purpose of the Study:

• To elucidate the regulatory mechanisms of AR-mediated transcription.
• To functionally characterize AR binding sites and their enhancer activity.
• To understand how excess AR binding sites influence gene transcription.

Main Methods:

• Generated a locus-specific map of enhancer activity for AR binding sites.
• Utilized Self-Transcribing Active Regulatory Regions sequencing (STARRseq) for functional testing.
• Correlated enhancer annotations with in vitro cell lines and clinical prostate cancer samples.

Main Results:

• Only 7% of AR binding sites exhibited androgen-dependent enhancer activity.
• The majority of AR binding sites were inactive or constitutively active enhancers.
• AR-regulated enhancers form chromosomal loops with promoters, essential for transcription.
• Somatic mutations in these enhancers can affect their activity.

Conclusions:

• AR-regulated enhancers function as regulatory hubs.
• These hubs enhance interactions between AR binding sites and gene promoters.
• A functional map of AR enhancer activity provides insights into prostate cancer gene regulation.