and in plants
MicroRNAs were also discovered in plants, but it has been assumed that they arose independently from animal microRNAs, since they (1) don't show any sequence similarity to them, (2) have a different biogenesis pathway and (3) have a substantially different mode of action: Plant microRNAs bind only one to a handful of targets with high sequence specificity and induce with the aid of Argonaute proteins the specific cleavage of the target RNA. In collaboration with American, French and Norwegian groups, Ulrich Technau and his team managed to isolate 87 microRNAs from the sea anemone.
Yehu Moran, David Fredman and Daniela Praher from the Technau team were able to show that the microRNAs of the sea anemone depict all the hallmarks of plant microRNAs: They have an almost perfect complementarity to their target RNAs, which are subsequently cleaved and not inhibited like in other animals. Moran also discovered a gene in the sea anemone, HYL-1, which is essential for the microRNA biogenesis in plants and was never detected in any other animal model organism before. Moreover, when one compares the sequences of microRNAs, one microRNA with similarity to a plant microRNA as well as one microRNA with similarity to an animal microRNA can be found. Altogether, these findings suggest the first evolutionary link between microRNAs of plants and animals.
In summary, while the sea anemone's genome, gene repertoire and gene regulation on the DNA level is surprisingly similar to vertebrates, its post-transcriptional regulation is plant-like and probably dates back to t
|Contact: Ulrich Technau|
University of Vienna