Blast injury to the brain is one of the major causes of death and can also significantly affect cognition and physical and psychological skills in survivors of blast. The complex mechanisms via which blast injury causes impairment of cognition and other symptoms are poorly understood. In this study, we investigated the effects of varying degrees of primary blast overpressure (BOP; 80 and 200 kPa) on the pathophysiological and magnetic resonance imaging (MRI) changes and neurocognitive performance as assessed by the monkey Cambridge Neuropsychological Test Automated Battery (mCANTAB) in non-human primates (NHP). The study aimed to examine the effects of neurobehavioral and histopathological changes in NHP. MRI and histopathology revealed ultrastructural changes in the brain, notably in the Purkinje neurons in the cerebellum and pyramidal neurons in the hippocampus, which were most vulnerable to the blast. The results correlated well with the behavioral changes and changes in motor coordination and working memory of the affected monkeys. In addition, there was white matter damage affecting myelinated axons, astrocytic hypertrophy, and increased aquaporin-4 (AQP-4) expression in astrocytes, suggesting cerebral edema. Increased apoptosis appeared to involve astrocytes and oligodendrocytes in the animals following blast exposure. The small sample size could have contributed to the non-significant outcome in cognitive performance post-blast and limited quantitative analyses. Nevertheless, the study has provided initial descriptive changes for establishing a primary BOP threshold for brain injury to serve as a useful platform for future investigations that aim to estimate brain injury potential and set safe limits of exposure.

No abstract

TNF receptor associated factor 3 (TRAF3), a member of the TRAF family of intracellular signaling proteins, can directly influence the phosphorylation status and activation of c-Jun N-terminal kinase, participating in CD40-induced apoptosis in carcinoma. However, its expression profile and function are still unclear in spinal cord injury (SCI). In this study, we performed an acute spinal cord contusion injury model in adult rats and detected the dynamic change patterns of TRAF3 expression in spinal cord. Western blot and immunohistochemistry revealed a striking upregulation of TRAF3 after SCI. Double immunofluorescence staining prompted that TRAF3 immunoreactivity was found in neurons rather than astrocytes. Moreover, co-localization of TRAF3/active caspase-3 was detected in neuronal nuclei. To further investigate the function of TRAF3, a neuronal cell line PC12 was employed to establish an apoptosis model in vitro. We analyzed the association of TRAF3 with active caspase-3 on PC12 cells by western blot and immunofluorescent labeling, which was parallel with the data in vivo. Additionally, knocking TRAF3 down with siRNA demonstrated the probable pro-apoptotic role of TRAF3 in the process of neuronal apoptosis. To summarize, we firstly uncover the temporal and spatial expression changes of TRAF3 in SCI. Our data suggest that TRAF3 might be implicated in central nervous system pathophysiology after SCI.

No abstract

MOAP1 (modulator of apoptosis 1) is a BAX-binding protein tightly regulated by the ubiquitinproteasome system. Apoptotic stimuli stabilize MOAP1 protein and facilitate its interaction with BAX to promote apoptosis. Here we show that in contrast to being resistant to apoptotic stimuli, MOAP1deficient cells are hypersensitive to cell death mediated by starvation rendered by EBSS treatment. MOAP1-deficient cells exhibited impairment in macroautophagy/autophagy signaling induced by EBSS. Mechanistic analysis revealed that MOAP1-deficient cells had no notable defect in the recruitment of the pre-autophagosomal phosphatidylinositol-3-phosphate (PtdIns3P)-binding proteins, ZFYVE1/DFCP1 and WIPI2, nor in the LC3 lipidation mechanism regulated by the ATG12-ATG5-ATG16L1 complex upon EBSS treatment. Interestingly, MOAP1 is required for facilitating efficient closure of phagophore in the EBSStreated cells. Analysis of LC3-positive membrane structures using Halo-tagged LC3 autophagosome completion assay showed that predominantly unclosed phagophore rather than closed autophagosome was present in the EBSS-treated MOAP1-deficient cells. The autophagy substrate SQSTM1/p62, which is normally contained within the enclosed autophagosome under EBSS condition, was also highly sensitive to degradation by proteinase K in the absence of MOAP1. MOAP1 binds LC3 and the binding is critically dependent on a LC3-interacting region (LIR) motif detected at its N-terminal region. Re-expression of MOAP1, but not its LC3-binding defective mutant, MOAP1-LIR, in the MOAP1-deficient cells, restored EBSS-induced autophagy. Together, these observations suggest that MOAP1 serves a distinct role in facilitating autophagy through interacting with LC3 to promote efficient phagophore closure during starvation.