The role of cold-inducible RNA binding protein in the neuroprotection of hypothermia against MPP+ toxicity

摘要

Hypothermia has a promising therapeutic advantage in the prevention of a broad range of brain damages Our preliminary results showed that human SK-N-SH neuroblastoma cells cultured in cold condition (32?C) significantly upregulated the cold-inducible RNA binding protein (CIRBP) expression However the function of CIRBP upregulation under cold exposure is unclear Herein we investigated the role of CIRBP in cold exposure-induced neuroprotection against 1-methyl-4-phenylpyridinium (MPP+) toxicity MPP+ is an inhibitor of mitochondrial complex I and widely used to selectively induced dopaminergic neuron death as a model of Parkinson’s disease Firstly we found that cold exposure for 24 h significantly reduced endogenous and MPP+-induced H2O2 production and subsequently prevented neuron death 48 h after MPP+ treatment Because it has been reported that transcription factor of nuclear factor erythroid 2-related factor 2 (Nrf2) is activated by oxidative stress and up-regulates the downstream antioxidant enzymes including ?-glutamylcysteine synthetase (?-GCS) NAD(P)H dehydrogenase quinone 1 (NQO-1) and heme oxygenase-1 (HO-1) to protect cells from oxidative insult we investigated the involvement of Nrf2 antioxidant system in cold exposure-induced neuroprotection Results from time-course study revealed that cold exposure induced upregulation of nuclear Nrf2 protein and HO-1 mRNA (1 h) ?-GCS protein and HO-1 mRNA (6 h) HO-1 (12 h) and RBM3 (12-48 h) mRNA and ?-GCS protein (24 h) and CIRBP mRNA and protein (24-48 h) expression Cold exposure prevented MPP+-induced downregulation of CIRBP and???-GCS and RNA binding motif 3 (RBM3 another cold-inducible protein) as well as upregulation of HO-1 and NQO-1 mRNA expression Cold exposure can block MPP+-induced decrease in ARE promoter activity CIRBP overexpression using cirbp-EGFP fusion protein plasmid or cotransfection cirbp/puromycin plasmid with ARE-pGL3 plasmid but not transfection of cirbp/puromycin plasmid only significantly reduced MPP+-induced neuron death though a significant increase in H2O2 level was found However the effect of CIRBP overexpression on MPP+-induced changes in the expression of Nrf2-regulated antioxidant enzymes and its neuroprotective effect was less pronounced than that under cold exposure We considered and examined whether the disparity was caused by the different distribution of CIRBP in cells Results from immunocytochemistry and overexpression of cirbp-EGFP fusion protein studies showed that higher CIRBP expression was found in the nucleus than in the cytosol after MPP+ treatment and also in both cold exposure and CIRBP overexpression These results imply that CIRBP plays partial role in cold exposure-induced neuroprotection

獎項日期	2015 2月 4
原文	English
監督員	Jih-Ing Chuang (Supervisor)