AR-V7 Utilizes a Noncanonical Nuclear Localization Signal to Sustain Androgen-Independent Nuclear Import and Signaling.

Authors

Urko Del Castillo, Naira E Abou-Ghali, Colin Burdette, Michelle Naidoo, CheukMan C Au, Kiran Kumari Sahu, Xuanrong Chen, Xi Kathy Zhou, Jacob Geri, Paraskevi Giannakakou

Published in

bioRxiv : the preprint server for biology. Sep 24, 2026. Epub Sep 24, 2026.

Abstract

AR-V7 is the most prevalent androgen receptor splice variant in metastatic castration-resistant prostate cancer, yet how it enters the nucleus independently of androgen binding has remained unclear. We previously demonstrated that AR-V7 undergoes nuclear import via a non-canonical pathway distinct from the microtubule-based, importin-α/β- and Ran-dependent mechanism used by full-length AR. Here, using systematic truncation and alanine-scanning mutagenesis, we identify a non-classical nuclear localization motif at the junction of the DNA-binding domain (DBD) and cryptic exon 3 (CE3) that is required for efficient AR-V7 nuclear import. Specific basic residues within the DBD and CE3 are required not only for nuclear entry but also for transcriptional activity. Unexpectedly, mutants retaining partial nuclear localization were transcriptionally silent, suggesting that CE3 contributes to transcriptional engagement through mechanisms separate from nuclear transport. Genome-wide transcriptomic analysis of a strongly import-deficient mutant confirmed that disruption of nuclear entry abolishes the AR-V7 transcriptional program. To map compartment-specific protein interactions, we applied antibody-guided photocatalytic proximity labeling. Nuclear AR-V7 associated most prominently with both canonical BAF and PBAF SWI/SNF chromatin remodeling complexes, together with known transcriptional coregulators and DNA-repair factors, whereas the cytoplasm-restricted mutant engaged different networks centered on mRNA deadenylation and decay, cytoskeletal regulation, and chaperone systems. Together, these findings define a variant-specific NLS, separate nuclear import from CE3-dependent transcriptional competence, and identify the cytoplasmic networks that become accessible when AR-V7 nuclear entry is impaired. They reveal two mechanistically distinct vulnerabilities for suppressing AR-V7 signaling: blocking nuclear translocation and disrupting CE3-dependent transcriptional engagement within the nucleus.
Advanced prostate cancer is treated with drugs that target the hormone pocket of the androgen receptor. Tumors escape by making a shortened active receptor that lacks this pocket, leaving it undruggable. The shortened protein must still reach the nucleus to switch genes on, so nuclear entry is a step worth attacking. We find that the splicing event creating this variant also creates the tag that carries it into the nucleus, and that it enters by an alternative route the full receptor does not use. We also identify the protein partners the variant encounters inside and outside the nucleus, and the two sets differ strikingly, raising the question of what a cytoplasmic form of this protein does.

PMID:
42818066
Bibliographic data and abstract were imported from PubMed on 01 Oct 2026.

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