Epsilon Open Archive

Abstract

Non-coding RNAs (ncRNAs) are RNAs that do not encode proteins but instead carry out their functions at the RNA level. During the past decade, ncRNAs have been recognized as major regulators in organisms representing all kingdoms of life. Despite their recent discovery, these ncRNAs are involved in vital processes ranging from cell differentiation and organism development to virulence and stress responses. To exert these important functions, ncRNAs affect e.g. chromatin modification, RNA destabilization, inhibition of translation, RNA modification, and protein translocation. Their sizes are as diverse as their functions, varying from ~20 nucleotides up to several thousands of nucleotides. The social amoeba Dictyostelium discoideum has for many years been an appreciated model system for e.g. organism development, infection, and chemotaxis, but its ncRNAs have been largely unexplored. In this thesis, experimental as well as computational approaches were employed to investigate the ncRNA profile of this genetically tractable model organism. The identified RNAs include RNA classes with homologs in other organisms, such as small nucleolar RNAs, spliceosomal RNAs, and small interfering RNAs, as well as a large number of entirely novel RNAs. Many of the D. discoideum ncRNAs are developmentally regulated, indicating a function in organism development. Although many ncRNAs are now known to play crucial roles in biology, the functions of most ncRNAs are yet to be discovered. In this quest, easily manipulated model organisms will be invaluable. This thesis further establishes D. discoideum as an attractive model system for discerning ncRNA function and regulation.