Exploring miR-9 Involvement in Ciona intestinalis Neural Development Using Peptide Nucleic Acids

Int J Mol Sci. 2020 Mar 15;21(6):2001. doi: 10.3390/ijms21062001.


The microRNAs are small RNAs that regulate gene expression at the post-transcriptional level and can be involved in the onset of neurodegenerative diseases and cancer. They are emerging as possible targets for antisense-based therapy, even though the in vivo stability of miRNA analogues is still questioned. We tested the ability of peptide nucleic acids, a novel class of nucleic acid mimics, to downregulate miR-9 in vivo in an invertebrate model organism, the ascidian Ciona intestinalis, by microinjection of antisense molecules in the eggs. It is known that miR-9 is a well-conserved microRNA in bilaterians and we found that it is expressed in epidermal sensory neurons of the tail in the larva of C. intestinalis. Larvae developed from injected eggs showed a reduced differentiation of tail neurons, confirming the possibility to use peptide nucleic acid PNA to downregulate miRNA in a whole organism. By identifying putative targets of miR-9, we discuss the role of this miRNA in the development of the peripheral nervous system of ascidians.

Keywords: PNA; antisense therapy; invertebrate; microRNA; nervous system development; tunicates.

MeSH terms

  • Animals
  • Cell Differentiation*
  • Ciona intestinalis* / embryology
  • Ciona intestinalis* / genetics
  • Larva / genetics
  • Larva / metabolism
  • MicroRNAs* / genetics
  • MicroRNAs* / metabolism
  • Neurogenesis*
  • Neurons / metabolism*
  • Peptide Nucleic Acids* / genetics
  • Peptide Nucleic Acids* / pharmacology


  • MicroRNAs
  • Peptide Nucleic Acids