Neuroprotection via RNA-binding protein RBM3 expression is regulated by hypothermia but not by hypoxia in human SK-N-SH neurons

Abstract

ObjectiveTherapeutic hypothermia is an established treatment for perinatal asphyxia. Yet, many term infants continue to die or suffer from neurodevelopmental disability. Several experimental studies have demonstrated a beneficial effect of mild-to-moderate hypothermia after hypoxic injury, but the understanding of hypothermia-induced neuroprotection remains incomplete. In general, global protein synthesis is attenuated by hypothermia, but a small group of RNA-binding proteins including the RNA-binding motif 3 (RBM3) is upregulated in response to cooling. The aim of this study was to establish an in vitro model to investigate the effects of hypoxia and hypothermia on neuronal cell survival, as well as to examine the kinetics of concurrent cold-shock protein RBM3 gene expression.MethodsExperiments were performed by using human SK-N-SH neurons exposed to different oxygen concentrations (21%, 8%, or 0.2% O2) for 24 hours followed by moderate hypothermia (33.5°C) or normothermia for 24, 48, or 72 hours. Cell death was determined by quantification of lactate dehydrogenase and neuron-specific enolase releases into the cell cultured medium, and cell morphology was assessed by using immunofluorescence staining. The regulation of RBM3 gene expression was assessed by reverse transcriptase-quantitative polymerase chain reaction and Western blot analysis.ResultsExposure to hypoxia (0.2% O2) for 24 hours resulted in significantly increased cell death in SK-N-SH neurons, whereas exposure to 8% O2 had no significant impact on cell viability. Post-hypoxia treatment with moderate hypothermia for 48 or 72 hours rescued the neurons from hypoxia-induced cell death. Moreover, exposure to severe hypoxia led to observable cell swelling, which was also attenuated by moderate hypothermia. Finally, moderate hypothermia but not hypoxia led to the induction of RBM3 expression on both transcriptional and translational levels.ConclusionModerate hypothermia protects neurons from hypoxia-induced cell death. The expression of the cold-shock protein RBM3 is induced by moderate hypothermia and could be one possible mediator of hypothermia-induced neuroprotection.

RBM3 and CIRP expressions in targeted temperature management treated cardiac arrest patients—A prospective single center study

“…The increase in RBM3 mRNA expression was most likely induced by hypothermia as other possible confounders including age, degree of hypoxia (pH, lactate), or tROSC had no observable effect (Fig 3). Our findings are in correlation with previously published data originating from cell or tissue culture models [8, 11, 13]. Previously published trials have correlated elevated NSE concentration with poor neurological outcome (Fig 2B) [27].…”

Neuroprotection by Therapeutic Hypothermia

“…RBM3 is also a cold-induced protein which is induced by hypothermia (Derry et al, 1995; Danno et al, 1997) and has an impact on neuroprotection against various toxic insults such as hypoxia, UV and nitric oxide (Rosenthal et al, 2017; Yang et al, 2017; Zhuang et al, 2017). One study has further discussed whether mild hypothermia and RBM3 prevents neural cells from UV irradiation-elicited apoptosis using human neuroblastoma cell line SH-SY5Y as a cell model for neural cell death (Zhuang et al, 2017).…”

Morphoregulatory functions of the RNA-binding motif protein 3 in cell spreading, polarity and migration

“…In muscle cells, induction of RBM3 opposes necrosis and apoptosis, and preserves cell morphology, in response to reactive oxygen species and atrophic conditions 19 , 20 . In neural cells, RBM3 protects against cell death induced by ER stress 5 , 18 , hypoxia/ischemia 15 , 21 , and varied other metabolic and disease related stresses 14 , 17 , 22 – 25 . Moreover, RBM3 induction has been causally linked to the neuroprotective effects of therapeutic hypothermia 22 , 26 .…”