Accumulation of Mitochondrial RPPH1 RNA Is Associated with Cellular Senescence.

Post-transcriptional gene regulation is an important step in the regulation of eukaryotic gene expression. Subcellular compartmentalization of RNA species plays a crucial role in the control of mRNA turnover, spatial restriction of protein synthesis, and the formation of macromolecular complexes. Although long noncoding RNAs (lncRNAs) are one of the key regulators of post-transcriptional gene expression, it is not heavily studied whether localization of lncRNAs in subcellular organelles has functional consequences. Here, we report on mitochondrial lncRNAs whose expression fluctuates in the process of cellular senescence. One of the mitochondrial lncRNAs, RPPH1 RNA, is overexpressed and accumulates in mitochondria of senescent fibroblasts, possibly modulated by the RNA-binding protein AUF1. In addition, RPPH1 RNA overexpression promotes spontaneous replicative cellular senescence in proliferating fibroblasts. Using MS2 aptamer-based RNA affinity purification strategy, we identified putative target mRNAs of RPPH1 RNA and revealed that partial complementarity of RPPH1 RNA to its target mRNAs prevents those mRNAs decay in proliferating fibroblasts. Altogether, our results demonstrate the role of mitochondrial noncoding RNA in the regulation of mRNA stability and cellular senescence.