Abundantly expressed class of noncoding RNAs conserved through the multicellular evolution of dictyostelid social amoebae

Jonas Kjellin, Lotta Avesson, Johan Reimegård, Zhen Liao, Ludwig Eichinger, Angelika Noegel, Gernot Glöckner, Pauline Schaap, Fredrik Söderbom (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review


Aggregative multicellularity has evolved multiple times in diverse groups of eukaryotes, exemplified by the well-studied development of dictyostelid social amoebae, e.g. Dictyostelium discoideum However, it is still poorly understood why multicellularity emerged in these amoebae while the great majority of other members of Amoebozoa are unicellular. Previously a novel type of noncoding RNA, Class I RNAs, was identified in D. discoideum and demonstrated to be important for normal multicellular development. Here we investigated Class I RNA evolution and its connection to multicellular development. We identified a large number of new Class I RNA genes by constructing a co-variance model combined with a scoring system based on conserved upstream sequences. Multiple genes were predicted in representatives of each major group of Dictyostelia and expression analysis confirmed that our search approach identifies expressed Class I RNA genes with high accuracy and sensitivity and that the RNAs are developmentally regulated. Further studies showed that Class I RNAs are ubiquitous in Dictyostelia and share highly conserved structure and sequence motifs. In addition, Class I RNA genes appear to be unique to dictyostelid social amoebae since they could not be identified in outgroup genomes, including their closest known relatives. Our results show that Class I RNA is an ancient class of ncRNAs, likely to have been present in the last common ancestor of Dictyostelia dating back at least 600 million years. Based on previous functional analyses and the presented evolutionary investigation, we hypothesize that Class I RNAs were involved in evolution of multicellularity in Dictyostelia.

Original languageEnglish
JournalGenome Research
Early online date21 Jan 2021
Publication statusE-pub ahead of print - 21 Jan 2021


  • social amoeba
  • Dictyostelium discoideum
  • non-coding RNA
  • evolution
  • Class I RNA
  • dictyostelids
  • multicellularity
  • Dictyostelia

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