Levels of sdRNAs in cytoplasm and their association with ribosomes are dependent upon stress conditions but independent from snoRNA expression
In recent years, a number of small RNA molecules derived from snoRNAs have been observed. Findings concerning the functions of sdRNAs in cells are limited primarily to their involvement in microRNA pathways. However, similar molecules have been observed in Saccharomyces cerevisiae, which is an organism lacking miRNA machinery. Considering our previous observations, we examined the subcellular localization of sdRNAs in yeast. Our findings reveal that both sdRNAs and their precursors, snoRNAs, are present in the cytoplasm at levels dependent upon stress conditions. Moreover, both sdRNAs and snoRNAs interact with translating ribosomes in a stress-dependent manner. As a consequence of binding to ribosomes, yeast sdRNAs exhibit inhibitory activity on translation. However, observed levels of sdRNAs and snoRNAs in the cytoplasm and their association with ribosomes suggest independent regulation of these molecules by yet unknown factors.