Oxygen impairs oligodendroglial development via oxidative stress and reduced expression of HIF-1\u03b1

Christina Brill,Till Scheuer,Christoph Bührer,Stefanie Endesfelder,Thomas Schmitz

doi:10.1038/srep43000

Christina Brill, Till Scheuer + Show 3 more

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https://doi.org/10.1038/srep43000

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Journal: Scientific Reports	Publication Date: Feb 23, 2017
Citations: 15	License type: open-access

Affiliation: Charité - Universitätsmedizin Berlin

Abstract

The premature increase of oxygen tension may contribute to oligodendroglial precursor cell (OPC) damage in preterm infants. Fetal OPCs are exposed to low oxygen tissue tensions not matched when cells are cultured in room air. Maturation (A2B5, O4, O1, MBP, CNP, arborization), oxidative stress (nitrotyrosine Western blot, NRF2 and SOD2 expression), apoptosis (TUNEL), proliferation (Ki67), and expression of transcription factors regulated by Hypoxia-Inducible-Factor-1-alpha (Hif-1α) expressed in OPCs (Olig1, Olig2, Sox9, Sox10) were assessed in rat OPCs and OLN93 cells cultured at 5% O2 and 21% O2. Influences of Hif-1α were investigated by Hif-1α luciferase reporter assays and Hif-1α-knockdown experiments. At 21% O2, cell proliferation was decreased and process arborization of OPCs was reduced. Expression of MBP, CNP, Olig1, Sox9 and Sox10 was lower at 21% O2, while Nrf2, SOD2, nitrotyrosine were increased. Apoptosis was unchanged. Luciferease reporter assay in OLN93 cells indicated increased Hif-1α activity at 5% O2. In OLN93 cells at 5% O2, Hif-1α knockdown decreased the expression of MBP and CNP, similar to that observed at 21% O2. These data indicate that culturing OPCs at 21% O2 negatively affects development and maturation. Both enhanced oxidative stress and reduced expression of Hif-1α-regulated genes contribute to these hyperoxia-induced changes.

Highlights

The premature increase of oxygen tension may contribute to oligodendroglial precursor cell (OPC) damage in preterm infants
In primary cultured OPCs, oxidative stress caused by exposure to peroxides disrupts oligodendroglial maturation and downregulates gene expression of factors needed for oligodendroglial development[13]
The reduction of OPCs at 21% O2 was found after 48 hours as well as after 96 hours culture time (Fig. 1a,b) A pronounced decrease in the numbers of immature O4+oligodendroglia was observed after 48 and 96 hours (Fig. 1c,d)

Summary

Introduction

The premature increase of oxygen tension may contribute to oligodendroglial precursor cell (OPC) damage in preterm infants. In OLN93 cells at 5% O2, Hif-1α knockdown decreased the expression of MBP and CNP, similar to that observed at 21% O2 These data indicate that culturing OPCs at 21% O2 negatively affects development and maturation. Both enhanced oxidative stress and reduced expression of Hif-1α-regulated genes contribute to these hyperoxia-induced changes. The 21% O2 commonly used for cell cultures produce fairly high partial oxygen pressures of more than 150 mmHg, whereas under physiological conditions in the cerebral cortex, neural cells are exposed to much lower oxygen tensions of about 16–38 mmHg (2–5% O2)[6,7] These circumstances, have not yet been investigated with regards to the development of oligodendroglia. To be upregulated by hypoxia via the HIF-1αpathway[19] and neuroprotective pre-conditioning prior to an injurious challenge by hypoxia-ischemia has just recently been demonstrated to depend on the presence of HIF-1α20

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