组蛋白变体H3.3的含入包括染色质的活跃领地。探索H3.3在前列腺癌(PC)中的功能，我们发现缺乏H3.3伴侣蛋白HIRA抑制了PC的体外和异种移植模型的生长，失调了雄激素诱导的基因表达，并改变了靶基因增强子中雄激素受体(AR)结合。H3.3以多种方式影响转录，包括通过磷酸化H3.3丝30位点(即H3.3S31Ph)来激活p300，以及增强子上H3K27醋酸化(H3K27Ac)。反过来，H3K27Ac会招募了结合区域蛋白BRD4以实现增强子-启动子相互作用和转录激活。我们观察到HIRA缺乏会降低H3.3的含入量，减弱H3.3S31Ph和H3K27Ac的存在，并改变BRD4的招募。这些结果表明H3.3丰富的增强子染色质作为H3K27Ac介导的BRD4招募平台，与AR在增强子上发生相互作用并保留AR，从而导致转录的重编程。此外，HIRA缺乏失调了由AR和胡甘剂 (GR) 共调控的基因的糖皮质激素驱动转录，表明存在一个H3.3/HIRA依赖的核受体功能机制。与正常前列腺组织相比，高风险PC组中HIRA复合蛋白的表达增加，并且与负面预后有关。综上所述，我们的结果展示了HIRA依赖H3.3途径在调控核受体活性中的功能。© 2023年作者。由牛津大学出版社代表核酸研究出版。

Incorporation of histone variant H3.3 comprises active territories of chromatin. Exploring the function of H3.3 in prostate cancer (PC), we found that knockout (KO) of H3.3 chaperone HIRA suppresses PC growth in vitro and in xenograft settings, deregulates androgen-induced gene expression and alters androgen receptor (AR) binding within enhancers of target genes. H3.3 affects transcription in multiple ways, including activation of p300 by phosphorylated H3.3 at Ser-31 (H3.3S31Ph), which results in H3K27 acetylation (H3K27Ac) at enhancers. In turn, H3K27Ac recruits bromodomain protein BRD4 for enhancer-promoter interaction and transcription activation. We observed that HIRA KO reduces H3.3 incorporation, diminishes H3.3S31Ph and H3K27Ac, modifies recruitment of BRD4. These results suggest that H3.3-enriched enhancer chromatin serves as a platform for H3K27Ac-mediated BRD4 recruitment, which interacts with and retains AR at enhancers, resulting in transcription reprogramming. In addition, HIRA KO deregulates glucocorticoid- (GR) driven transcription of genes co-regulated by AR and GR, suggesting a common H3.3/HIRA-dependent mechanism of nuclear receptors function. Expression of HIRA complex proteins is increased in PC compared with normal prostate tissue, especially in high-risk PC groups, and is associated with a negative prognosis. Collectively, our results demonstrate function of HIRA-dependent H3.3 pathway in regulation of nuclear receptors activity.© The Author(s) 2023. Published by Oxford University Press on behalf of Nucleic Acids Research.