RNA binding proteins mediate posttranscriptional RNA metabolism and play regulatory roles in many developmental processes in eukaryotes. Despite their known effects on the floral transition from vegetative to reproductive growth in plants, the underlying mechanisms remain largely obscure. Here, we show that a hitherto unknown RNA binding protein, hnRNP R-LIKE PROTEIN (HRLP), inhibits cotranscriptional splicing of a key floral repressor gene FLOWERING LOCUS C ( FLC ). This, in turn, facilitates R-loop formation near FLC intron I to repress its transcription, thereby promoting the floral transition in Arabidopsis thaliana . HRLP, together with the splicing factor ARGININE/SERINE-RICH 45, forms phase-separated nuclear condensates with liquid-like properties, which is essential for HRLP function in regulating FLC splicing, R-loop formation, and RNA Polymerase II recruitment. Our findings reveal that inhibition of cotranscriptional splicing of FLC by nuclear HRLP condensates constitutes the molecular basis for down-regulation of FLC transcript levels to ensure the reproductive success of Arabidopsis .

中文翻译：

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HRLP相分离调控拟南芥开花时间

RNA 结合蛋白介导转录后 RNA 代谢，并在真核生物的许多发育过程中发挥调节作用。尽管它们对植物从营养生长到生殖生长的花过渡有已知的影响，但其潜在机制仍然很大程度上模糊不清。在这里，我们展示了一种迄今为止未知的 RNA 结合蛋白 hnRNP R-LIKE PROTEIN (HRLP)，抑制关键花抑制基因的共转录剪接开花位点 C(FLC）。反过来，这有助于在附近形成 R 环FLC内含子 I 抑制其转录，从而促进拟南芥. HRLP 与剪接因子 ARGININE/SERINE-RICH 45 一起形成具有液体状特性的相分离核凝聚物，这对于 HRLP 调节功能至关重要FLC剪接、R 环形成和 RNA 聚合酶 II 募集。我们的研究结果表明，抑制共转录剪接FLC由核 HRLP 缩合物构成的分子基础FLC转录水平，以确保繁殖成功拟南芥.