Long noncoding RNA and phase separation in cellular stress response

Stress response is important for sensing and adapting to environmental changes. Recently, RNA-protein (RNP) condensates, which are a type of membrane-less organelle formed by liquid-liquid phase separation, have been proposed to regulate the stress response. Because RNP condensates are formed through interactions between positively charged proteins and negatively charged RNAs, the ratio of proteins to RNAs is critical for phase-separated condensate formation. In particular, long noncoding RNAs (lncRNAs) can efficiently nucleate phase-separated RNP condensates because of their secondary structure and long length. Therefore, increased attention has been paid to lncRNAs because of their potential role as a regulator of biological condensates by phase separation under stress response. In this review, we summarize the current research on the involvement of lncRNAs in the formation of RNP condensates under stress response. We also demonstrate that lncRNA-driven phase separation provides a useful basis to understanding the response to several kinds of cellular stresses.