Neuroprotective effect of long noncoding RNA-nuclear-enriched abundant transcript 1 on traumatic brain injury in mice and its possible mechanism / 中华创伤杂志

ABSTRACT

Objective:To explore the impact of the expression of long noncoding RNA-nuclear-enriched abundant transcript 1 (NEAT1) on neurological function and neuronal apoptosis after traumatic brain injury (TBI) in mice and the possible mechanism.Methods:According to the random number table, 90 C57BL/6J mice were divided into sham group, blank control group, empty virus group 1, empty virus group 2, NEAT1 over-expression group and NEAT1 knockdown group, with 15 mice per group. The traumatic brain injury (TBI) was simulated by controlled cortical injury (CCI) model, and NEAT1 was regulated by intracerebroventricular injection with recombinant adenovirus. The neurological severity score (NSS) and Morris water maze test were used to evaluate the neurological function in blank control group, NEAT1 over-expression group and NEAT1 knockdown group within 1 week and 14-21 days after injury. The Western blot was used to observe the expressions of P53-induced protein with a death domain 1 (Pidd1), caspase-2, caspase-9 and caspase-3 in blank control group at 6 hour and 1, 3, 7 days after injury. The TUNEL method and immunofluorescence were used to observe the neurological apoptosis and expression of Pidd1 in blank control group, NEAT1 over-expression group and NEAT1 knockdown group at 3 days after injury. The Western blot analysis was used to detect protein expressions of Pidd1, caspase-2, cytochrome c (Cyt c) and caspase-3 in sham group, blank control group, empty virus groups, NEAT1 over-expression group and NEAT1 knockdown group at 3 days after injury.Results:The NSS was significantly reduced in NEAT1 over-expression group [(3.5±0.7)points], and was significantly increased in NEAT1 knockdown group [(5.0±1.5)points]at day 1 after injury, when compared with blank control group [(4.9±1.0)points]( P<0.01). The Morris water maze test showed that the time to find platform was decreased in NEAT1 over-expression group[(10.9±2.8)seconds], and was prolonged in NEAT1 knockdown group [(30.7±6.2)seconds] at day 19 after injury ( P<0.05 or 0.01), when compared with blank control group [(20.1±5.6)seconds]. The Western blot analysis showed that the expressions of Pidd1, caspase-2, caspase-9 and caspase-3 had significant increase at day 3 after injury ( P<0.01). The TUNEL test showed that the apoptosis rate of neurons was significantly decreased in NEAT1 over-expression group [(18.0±2.7)%], and the apoptosis rate was significantly increased in NEAT1 knockdown group [(63.0±8.6)%] at day 3 after injury ( P<0.01). Immunofluorescence showed that the expression of Pidd1 protein in cytoplasm of the neurons was decreased in NEAT1 over-expression group [(22.7±2.2)%]( P<0.01), and was increased in NEAT1 knockdown group [(72.7±7.0)%]( P<0.01) at day 3 after injury, when compared with blank control group. The Western blot analysis showed that the expressions of Pidd1, capsase-2, Cyt c and caspase-3 were significantly reduced in NEAT1 over-expression group (0.5±0.0, 0.3±0.0, 0.5±0.0, 0.4±0.0) at day 3 after injury, when compared with blank control group. However, the results were opposite in NEAT1 knockdown group. Conclusion:After TBI, the NEAT1 can reduce the activation of caspase-3 through the Pidd1-caspase-2-Cyt c pathway after TBI, regulate neuronal apoptosis, and ultimately play a protective role in neurological function.