MicroRNA-21-5p agomir inhibits apoptosis of oligodendrocyte precursor cell and attenuates white matter injury in neonatal rats

Brain Res Bull. 2022 Oct 15:189:139-150. doi: 10.1016/j.brainresbull.2022.08.014. Epub 2022 Aug 17.

Abstract

Background and research question/hypothesis: Excessive oligodendrocyte precursor cell (OPC) apoptosis occurs during intrauterine infection-induced white matter injury (WMI) in premature infants, preventing excessive apoptosis of OPCs is one of the mechanisms protecting WMI. Micro-RNA-21-5p (miR-21-5p) mediating anti-apoptotic activity was observed in other diseases. Therefore, the aim of this study was to determine whether miR-21-5p protects against WMI by modulating phosphatase and tensin homologue deleted on chromosome 10/phosphatidylinositol-3-kinase/protein kinase B (PTEN/PI3K/Akt) signalling pathway.

Methods: A lipopolysaccharide (LPS)-induced neonatal Sprague-Dawley (SD) rat model of preterm WMI was established. To explore the effect of miR-21-5p on WMI, we intraventricularly injected miR-21-5p agomir and miR-21-5p antagomir to activate or inhibit endogenous miR-21-5p. Immunofluorescent labelling of myelin basic protein, immunohistochemical labelling of 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase), and terminal deoxynucleotidyl transferase dUTP nick end labelling assays were conducted to observe pathological white matter changes. The antibody of anti-oligodendrocyte marker 4 (O4) was used to specifically recognise OPCs. The expressions of miR-21-5p and PTEN mRNA in the brain were detected with quantitative real-time polymerase chain reaction (qRT-PCR). PTEN, Akt, and phosphorylated Akt (p-Akt) protein levels were assayed with western blotting, and apoptotic proteins associated with PI3K/Akt signalling were quantified.

Results: Intense white matter dysplasia and excessive OPC apoptosis were observed in the brains of rats with WMI. When the miR-21-5p agonist miR-21-5p agomir was used in the WMI group, apoptosis of OPCs was significantly reduced, and myelin maturation increased. MiR-21-5p agomir relieved WMI. MiR-21-5p agomir inhibited the mRNA and protein expression of PTEN, increased p-Akt phosphorylation, and decreased the expression and activation of related apoptotic proteins.On the other hand, the administration of miR-21-5p specific blocker, miR-21-5p antagomir, reduced the level of p-AKT, increased OPC apoptosis, and worsened WMI.

Interpretation: Our findings revealed that miR-21-5p agomir had anti-OPC over-apoptotic effects and enhanced myelin development in WMI by modulating the PTEN/Akt signalling pathway.

Keywords: Apoptosis; Intrauterine infection; Micro-RNA-21-5p; Oligodendrocyte precursor cell; White matter injury.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 2',3'-Cyclic-Nucleotide Phosphodiesterases / metabolism
  • 2',3'-Cyclic-Nucleotide Phosphodiesterases / pharmacology
  • Animals
  • Animals, Newborn
  • Antagomirs / pharmacology
  • Apoptosis
  • DNA Nucleotidylexotransferase / metabolism
  • DNA Nucleotidylexotransferase / pharmacology
  • Lipopolysaccharides / pharmacology
  • MicroRNAs* / metabolism
  • Myelin Basic Protein / metabolism
  • Myelin Basic Protein / pharmacology
  • Oligodendrocyte Precursor Cells* / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphatidylinositols / pharmacology
  • Phosphoric Diester Hydrolases / metabolism
  • Phosphoric Diester Hydrolases / pharmacology
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA, Messenger
  • Rats
  • Rats, Sprague-Dawley
  • Tensins / metabolism
  • White Matter* / metabolism

Substances

  • Antagomirs
  • Lipopolysaccharides
  • MicroRNAs
  • Myelin Basic Protein
  • Phosphatidylinositols
  • RNA, Messenger
  • Tensins
  • mirn21 microRNA, rat
  • Proto-Oncogene Proteins c-akt
  • DNA Nucleotidylexotransferase
  • 2',3'-Cyclic-Nucleotide Phosphodiesterases
  • Phosphoric Diester Hydrolases