Nrf2 and the ubiquitin proteasome system in the mouse model of traumatic brain injury / 医学研究生学报

ABSTRACT

Objective Nrf2 is an important neuroprotective factor and the ubiquitin proteasome system ( UPS) , as a highly specific intracellular protein degradation pathway, plays an important role in maintaining gene and protein functions.This paper pres-ents a preliminary study on the relationship between Nrf2 and the ubiquitin proteasome system in the mouse model of traumatic brain in-jury ( TBI) . Methods Forty-two healthy male ICR mice were randomly divided into three groups control, TBI +sulforaphane ( SFN) and TBI+vehicle, and 12 Nrf2-knockout mice were included in the TBI+Nrf2 -/-group.The animals of the TBI+SFN group were treated with SFN while those of the TBI+vehicle group with the same volume of 10%corn oil at 5 minutes after TBI.At 24 hours after TBI, brain samples were collected from the mice for determining the Nrf2 expression and ubiquitinated protein content by Western blot and the changes in the Nrf2 and ubiquitinated proteins were observed by immunohistochemistry and electron microscopy. Results Compared with the controls, the mice in the TBI+vehicle group showed significantly increased expressions of Nrf2 ( 0.09 ± 0.02 vs 0.66 ±0.09, P<0.05) and ubiquitinated proteins (3.27 ± 0.21 vs 10.58 ±0.75, P<0.05).In comparison with animals in the TBI+vehicle group, those in the TBI+SFN group exhibited a signifi-cant increase in the Nrf2 protein level (0.66 ±0.09 vs 1.22 ±0.14, P<0.05) but a decrease in the ubiquitinated protein level (10.58 ±0.75 vs 6.97 ±0.86, P<0.05), and those in the TBI+Nrf2 -/-group showed a markedly decreased expression of the Nrf2 protein (0.66 ±0.09 vs 0.17 ±0.02, P<0.05) but increased expression of the ubiquitinated protein (10.58 ±0.75 vs 14.35 ± 0.65, P<0.05).Similar results were observed by immunohistochemistry and electron microscopy. Conclusion Nrf2 played a neu-roprotective role in the mouse model of traumatic brain injury by regulating the ubiquitin proteasome system.