Hypoxia-reoxygenation affects whole-genome expression in the newborn eye.
OBJECTIVE
Resuscitation of newborns is one of the most frequent procedures in neonatal medicine. The use of supplementary oxygen during resuscitation of the asphyxiated newborn has been shown to be detrimental to vulnerable tissues. We wanted to assess transcriptional changes in ocular tissue after the acute use of oxygen in the delivery room in a hypoxia-reoxygenation model of the newborn mouse.


METHODS
C57BL/6 mice (n = 57), postnatal day 7, were randomized to receive either 120 minutes of hypoxia, at 8% O2, followed by 30 minutes of reoxygenation with 21, 40, 60, or 100% O2 or to normoxia followed by 30 minutes of 21% or 100% O2. Whole ocular homogenates were analyzed by Affymetrix 750k expression array, and RT-PCR was performed for validation. Bayesian analysis of variance for microarray data (BAMarray) was used to identify single significant genes, and Gene Set Enrichment Analysis (GSEA) was applied to reveal significant pathway systems.


RESULTS
In total, ∼ 92% of the gene expression changes were altered in response to reoxygenation with 60% or 100% O2 compared to expression at the lower percentages of 21% and 40%. After 100% O2 treatment, genes involved in inflammation (Ccl12), angiogenesis (Igfr1, Stat3), and metabolism (Hk2) were upregulated. Pathway analyses after hypoxia-reoxygenation revealed significant alterations of six pathways which included apoptosis, TGF-beta signaling, oxidative phosphorylation, voltage-gated calcium channel complex, mitochondrion, and regulation of RAS protein signal transduction.


CONCLUSIONS
Hypoxia-reoxygenation can induce immediate transcriptional responses in ocular tissue involving inflammation, angiogenesis, energy failure, and Ras signaling.
Department of Pediatric Research, Clinic of Women and Child Health, Oslo University Hospital, Rikshospitalet, University of Oslo, Oslo, Norway.
Embjørg J
EJ
Wollen
Przemko
P
Kwinta
Miroslaw
M
Bik-Multanowski
Anna
A
Madetko-Talowska
Yngve
Y
Sejersted
Marianne S
MS
Wright
Clara-Cecilie
CC
Günther
Ståle
S
Nygård
Ola Didrik
OD
Saugstad
Jacek J
JJ
Pietrzyk
D000818:Animals; D000831:Animals, Newborn; D004195:Disease Models, Animal; D018507:Gene Expression Regulation, Developmental; D018496:Hyperoxia / Q000235:genetics* / Q000378:metabolism; D000860:Hypoxia / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D046228:Microarray Analysis; D018945:Monocyte Chemoattractant Proteins / Q000096:biosynthesis / Q000235:genetics*; D018384:Oxidative Stress / Q000235:genetics*; D012313:RNA / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000096:biosynthesis / Q000235:genetics*; D015398:Signal Transduction
C491224:Ccl12 protein, mouse; D018945:Monocyte Chemoattractant Proteins; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D012313:RNA
gene expression; hyperoxia; hypoxia; resuscitation