Decrease in levels of the evolutionarily conserved microRNA miR-124 affects oligodendrocyte numbers in Zebrafish, Danio rerio

Invert Neurosci. 2015 Sep;15(3):4. doi: 10.1007/s10158-015-0180-1. Epub 2015 Jul 10.

Abstract

Oligodendrocytes produce multi-lamellar myelin membranes that surround axons in the central nervous system (CNS). Preservation and generation of myelin are potential therapeutic targets for dysmyelinating and demyelinating diseases. MicroRNAs (miRNAs) play a vital role in oligodendrocyte differentiation and overall CNS development. miR-124 is a well-conserved neuronal miRNA with important roles in neuronal differentiation and function. miR-124 levels increase following loss of myelin in both human and rodent brains. While the role of neuronal miR-124 in neurogenesis has been established, its effects on axonal outgrowth and oligodendrocytes are not currently known. We therefore explored the possible effect of selective knockdown of miR-124 in Danio rerio using a morpholino-based knockdown approach. No morphological abnormalities or loss of motor neurons were detected despite loss of axonal outgrowth. Morpholino-based knockdown of miR-124 led to reciprocal increases in mRNA levels of target genes that inhibit axonal and dendritic projections. Importantly, loss of miR-124 led to decreased oligodendrocyte cell numbers and myelination of axonal projections in the ventral hindbrain. Taken together, our results add a new dimension to the existing complexity of neuron-glial relationships and highlight the utility of Danio rerio as a model system to investigate such interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Dose-Response Relationship, Drug
  • Embryo, Nonmammalian
  • Gene Expression Regulation, Developmental / drug effects
  • Gene Expression Regulation, Developmental / physiology*
  • Larva
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Morpholinos / pharmacology
  • Oligodendroglia / drug effects
  • Oligodendroglia / metabolism*
  • Zebrafish / anatomy & histology*

Substances

  • MicroRNAs
  • Morpholinos