cAMP-induced nuclear condensation of CRTC2 promotes transcription elongation and cystogenesis in autosomal dominant polycystic kidney disease (RNA-Seq)

Forming biomolecular condensates by phase separation has recently emerged as a new principle for regulating gene expression in response to extracellular signaling. However, the molecular mechanisms underlying the coupling of signaling transduction and gene activation through condensate formation and how dysregulation of these mechanisms contributes to disease progression remain elusive. Here we report that CREB-regulated transcription coactivator 2 (CRTC2) translocates to nucleus and forms phase-separated condensates upon activation of cAMP signaling. We show that CRTC2 interacts with positive transcription elongation factor b (P-TEFb), and cAMP-induced CRTC2 condensate formation activates P-TEFb by extracting P-TEFb from its inhibitory complex. Aberrantly elevated cAMP signaling plays central roles in the development of autosomal dominant polycystic kidney disease (ADPKD). We demonstrate that, in contrast to a dispersed cytosolic distribution in the normal tubular epithelia cells, CRTC2 localizes in nucleus and forms condensates in cystic epithelial cells of mouse and human ADPKD kidneys. We show that genetic depletion of CRTC2 markedly suppresses cyst growth in an orthologous ADPKD mouse model. Using integrative transcriptomic and cistromic analyses, we identify CRTC2-regulated cystogenic genes, whose activation depends on CRTC2 condensation-facilitated P-TEFb recruitment and RNA polymerase II pausing release. Together, our findings elucidate a mechanism by which CRTC2 nuclear condensation conveys cAMP signaling to transcription elongation activation and promotes cystogenesis in ADPKD. RNA-sequencing of different condition: sgControl and sgCRTC2 in WT9-12.

通过相分离形成生物分子凝集体，近来已成为响应细胞外信号调控基因表达的全新调控范式。然而，通过凝集体形成实现信号转导与基因激活偶联的分子机制，以及此类机制失调如何推动疾病进展，目前仍不甚明晰。本研究报道，环腺苷酸（cAMP）信号激活后，CREB调控的转录辅激活因子2（CREB-regulated transcription coactivator 2，CRTC2）会转位至细胞核并形成相分离凝集体。我们发现，CRTC2可与正转录延伸因子b（positive transcription elongation factor b，P-TEFb）相互作用，且cAMP诱导的CRTC2凝集体形成可通过将P-TEFb从其抑制复合物中解离出来，从而激活P-TEFb。异常升高的cAMP信号在常染色体显性遗传性多囊肾病（autosomal dominant polycystic kidney disease，ADPKD）的发生发展中发挥核心作用。我们证实，与正常肾小管上皮细胞中弥散的胞质分布不同，在小鼠和人类ADPKD肾脏的囊性上皮细胞中，CRTC2定位于细胞核并形成凝集体。遗传敲除CRTC2可显著抑制同源ADPKD小鼠模型中的囊肿生长。借助整合转录组与顺式转录组（cistromic）分析，我们鉴定出受CRTC2调控的囊肿生成相关基因，这些基因的激活依赖于CRTC2凝集体介导的P-TEFb招募以及RNA聚合酶Ⅱ暂停释放。综上，本研究阐明了一种全新机制：CRTC2细胞核凝集体可将cAMP信号传递至转录延伸激活过程，并促进ADPKD中的囊肿生成。不同条件下的RNA测序：WT9-12细胞中的sgControl与sgCRTC2组。