Effect of DJ-1 on the neuroprotection of astrocytes subjected to cerebral ischemia/reperfusion injury

Abstract

Astrocytes are involved in neuroprotection, and DJ-1 is an important antioxidant protein that is abundantly expressed in reactive astrocytes. However, the role of DJ-1 in astrocytes’ neuroprotection in cerebral ischemia/reperfusion injury and its potential mechanism is unclear. Thus, to explore effects and mechanisms of DJ-1 on the neuroprotection of astrocytes, we used primary co-cultures of neurons and astrocytes under oxygen and glucose deprivation/reoxygenation in vitro and transient middle cerebral artery occlusion/reperfusion in vivo to mimic ischemic reperfusion insult. Lentiviral was used to inhibit and upregulate DJ-1 expression in astrocytes, and DJ-1 siRNA blocked DJ-1 expression in rats. Inhibiting DJ-1 expression led to decreases in neuronal viability. DJ-1 knockdown also attenuated total and nuclear Nrf2 and glutathione (GSH) levels in vitro and vivo. Similarly, loss of DJ-1 decreased Nrf2/ARE-binding activity and expression of Nrf2/ARE pathway-driven genes. Overexpression of DJ-1 yielded opposite results. This suggests that the mechanism of action of DJ-1 in astrocyte-mediated neuroprotection may involve regulation of the Nrf2/ARE pathway to increase GSH after cerebral ischemia/reperfusion injury. Thus, DJ-1 may be a new therapeutic target for treating ischemia/reperfusion injury.Key Messages Astrocytes protect neurons in co-culture after OGD/RDJ-1 is upregulated in astrocytes and plays an important physiological roles in neuronal protection under ischemic conditionsDJ-1 protects neuron by the Nrf2/ARE pathway which upregulates GSH

DJ-1 exerts anti-inflammatory effects and regulates NLRX1-TRAF6 via SHP-1 in stroke

“…Previously, we reported that astroglial DJ-1 plays a critical role in neuroprotection in ischemic injury [20]. These findings led us to further study the protective mechanism of astroglial DJ-1.…”

“…DJ-1 siRNA was obtained and used as described in our previous studies [20]. AAV was purchased from Neuron Biotech (Shanghai, China).…”

“…To assess neurological deficits in the rats on day 1 after MCAO/R, a modified scoring system was applied as described in our previous studies [20]. The scoring system was as follows: grade 0, no neurological damage; grade 1, failure to extend the contralateral forelimb fully; grade 2, circling to right; grade 3, falling to the right; grade 4, no spontaneous autonomic activity or loss of consciousness; grade 5, death.…”

“…After MCAO/R, brains were sliced into 2-mm-thick sections and stained with 2% 2,3,5-triphenyltetrazolium chloride (TTC, Sigma, USA) at 37°C for 30 min as previously described [20,25]. Then, the sections were fixed in 4% paraformaldehyde at 4°C for 24 h. Each section was photographed, and the volume was quantified using ImageJ (version 6.0, NIH, Bethesda, MD, USA).…”

“…DJ-1 (also known as PARK7) has been linked to an early-onset autosomal recessive form of PD [18] and is abundantly expressed in reactive astrocytes in Parkinson's disease [19]. Our previous study showed that upregulated astroglial DJ-1 in the infarct region plays a critical role in astrocyte neuroprotection after stroke [20], suggesting that DJ-1 affects the function of astrocytes. DJ-1 knockout (KO) astrocytes exhibit increased LPS-induced expression of proinflammatory mediators, which aggravate inflammatory damage induced by IFN-γ [21].…”