FBS Colloquia No.421RNA Biofunction Laboratory

Multifunctional Potential of HSATIII Repeat RNAs in Cellular Stress Responses


When cells are exposed to stresses such as heat, they reorganize the regulation of gene expression to respond to changes in their environment. Our research focuses on Human Satellite III (HSATIII) repeat RNAs, which function in this process. HSATIII RNAs are transcribed in response to heat stress and related stimuli from Satellite III repeat regions dispersed throughout the primate genome. Although HSATIII RNAs represent a heterogeneous population of transcripts with variable sequences and lengths, most of their sequences are commonly composed of GGAAU repeats. Under stress conditions, HSATIII RNAs are known to function as architectural RNA (arcRNAs) which is essential for the formation of nuclear stress bodies (nSBs), nuclear structures induced by stress.
In recent years, we have shown that HSATIII RNAs play multiple roles in cells, including their functions in nSBs. In the nucleus, HSATIII RNAs regulate splicing, a process of RNA maturation, through nuclear stress bodies by combining two distinct molecular mechanisms. We have also obtained results suggesting that the intracellular behavior of HSATIII RNAs and their interactions with binding proteins change in response to temperature shifts and over time following stress removal. The possibility that RNAs composed of simple repeat sequences can exert distinct molecular functions depending on cellular context is intriguing, as it may broaden our understanding of stress responses and the functional concepts of repeat RNAs. In this presentation, I will discuss these findings, including our latest unpublished data.