Uncoupling protein 2 deficiency aggravates astrocytic endoplasmic reticulum stress and nod-like receptor protein 3 inflammasome activation

Astrocytes play crucial roles in determining the susceptibility to oxidative stress in the brain, and uncoupling protein 2 (UCP2) has been demonstrated to regulate reactive oxygen species (ROS) production. However, it is unclear whether UCP2 is expressed in astrocytes, and whether it participates in the regulation of astrocytic functions. Here we show that UCP2 knockout exacerbated dopaminergic neuron loss in a murine model of 1,2,3,6-methyl-phenyl-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD), accompanied by overactivation of astrocytes. We further detected expression of UCP2 in primary cultures of mesencephalic astrocytes. UCP2 knockout increased intracellular ROS production and induced oxidative stress in response to 1-methyl-4-phenylpyridinium (MPP+) treatment. Subsequently, UCP2 deficiency exacerbated endoplasmic reticulum (ER) stress, as evidenced by the upregulations of C/EBP homologous protein (CHOP), cleavage of caspase-12, and aggravated neuroinflammation via the activation of nod-like receptor protein 3 (NLRP3) inflammasomes in astrocytes. Collectively, our study indicates that UCP2 expressed in astrocytes modulates ER stress and neuroinflammation, and is crucial for the survival of dopaminergic neuron in the pathogenesis of PD. These findings gives us insights into the potential of UCP2 as a novel therapeutic avenue for PD treatment. (C) 2014 Elsevier Inc. All rights reserved.