Spatiotemporal Expression of EAPP Modulates Neuronal Apoptosis and Reactive Astrogliosis After Spinal Cord Injury

Triad1 Promotes the Inflammatory Response and Neuronal Apoptosis to Aggravate Acute Spinal Cord Injury in Rats

Objective

Spinal cord injury (SCI) is one of the most devastating central injuries, resulting in serious locomotor deficits. Triad1 is known to play an important role in SCI, but its effects on the inflammatory response and physiological behavior have not been thoroughly studied. This study is aimed at examining the effects of Triad1 on the inflammatory response and neuronal injury in acute SCI in rats.

Methods

Twenty-four male Sprague–Dawley (SD) rats were randomly divided into a control group, SCI group, sh-NC group, and Triad1 knockout group (sh-Triad1). The Basso Beattie Bresnahan locomotor rating scale was utilized for the assessment of the motor ability of rats. Hematoxylin and eosin (H&E), Luxol fast blue (LFB), and TUNEL staining were used to assess the pathological injury, demyelination, and neuronal apoptosis, respectively. ELISA was used to detect the levels of IL-1β, IL-10, and TNF-α, and qRT-PCR was used to examine the expression level of Triad1. Furthermore, the protein levels of Triad1, Bax, Bcl-2, and cleaved caspase-3 were determined using western blotting.

Results

The Triad1 expression level was upregulated in damaged spinal cord tissue. Knockdown of Triad1 improved motor function and reduced SCI as well as apoptosis of spinal cord neurons. In addition, the knockdown of Triad1 inhibited the inflammatory response caused by SCI.

Conclusion

Knockdown of Triad1 can reduce SCI in rats with acute SCI by inhibiting the inflammatory response and apoptosis.

Skeletal muscle transcriptional networks linked to type I myofiber grouping in Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative disorder impacting cognition, movement, and quality of life in >10 million individuals worldwide. We recently characterized and quantified a skeletal muscle pathology in PD represented by exaggerated type I myofiber grouping presumed to result from denervation-reinnervation processes. Our previous findings indicated that impaired neuromuscular junction integrity may be involved in type I grouping, which is associated with excessive motor unit activation during weight-bearing tasks. In this study, we performed transcriptional profiling to test the hypothesis that type I grouping severity would link to distinct gene expression networks. We generated transcriptome-wide poly(A) RNA-Seq data from skeletal muscle of individuals with PD [n = 12 (9 men, 3 women); 67 ± 2 yr], age- and sex-matched older adults (n = 12; 68 ± 2 yr), and sex-matched young adults (n = 12; 30 ± 1 yr). Differentially expressed genes were evaluated across cohorts. Weighted gene correlation network analysis (WGCNA) was performed to identify gene networks most correlated with indicators of abnormal type I grouping. Among coexpression networks mapping to phenotypes pathologically increased in PD muscle, one network was highly significantly correlated to type I myofiber group size and another to percentage of type I myofibers found in groups. Annotation of coexpressed networks revealed that type I grouping is associated with altered expression of genes involved in neural development, postsynaptic signaling, cell cycle regulation and cell survival, protein and energy metabolism, inflammation/immunity, and posttranscriptional regulation (microRNAs). These transcriptomic findings suggest that skeletal muscle may play an active role in signaling to promote myofiber survival, reinnervation, and remodeling, perhaps to an extreme in PD.NEW & NOTEWORTHY Despite our awareness of the impact of Parkinson's disease (PD) on motor function for over two centuries, limited attention has focused on skeletal muscle. We previously identified type I myofiber grouping, a novel indicator of muscle dysfunction in PD, presumably a result of heightened rates of denervation/reinnervation. Using transcriptional profiling to identify networks associated with this phenotype, we provide insight into potential mechanistic roles of skeletal muscle in signaling to promote its survival in PD.

Decreased expression of LATS1 correlates with astrogliosis after spinal cord injury

Large tumor suppressor kinase 1 (LATS1) is a serine/threonine kinase of the AGC kinase family in mammals and involved in various biological processes, it is a key regulator of cell cycle progression. However, the role of LATS1 in central nervous system trauma is still unknown. In present study, we performed an acute spinal cord injury (SCI) model in adult rats and investigated the dynamic changes of LATS1 expression in the spinal cord. We found that LATS1 protein levels were significantly decreased at day 1 after injury. Meanwhile, double immunofluorescence staining showed these changes were striking in astrocytes, which were largely proliferated after SCI. In vitro, LATS1 overexpression inhibited astrocyte proliferation. Conversely, LATS1 depletion by siRNA promoted cell proliferation in primary astrocyte. Moreover, LATS1 overexpression reduced cyclin D1 expression and increased the expression of p27^kip1. In addition, LATS1 overexpression also promoted yes-associated protein 1 (YAP) phosphorylation. Our data suggested that LATS1 might play an important role in spinal cord injury and suppress astrogliosis through regulating the expression of cyclin D1, p27^kip1 and p-YAP.

Protective effect of epigenetic silencing of CyclinD1 against spinal cord injury using bone marrow-derived mesenchymal stem cells in rats

This study focuses on the protective effect of epigenetic silencing of CyclinD1 against spinal cord injury (SCI) using bone marrow-derived mesenchymal stem cells (BMSCs) in rats. Eighty-eight adult female Wistar rats were randomly assigned into the sham group, the control group, the si-CyclinD1 + BMSCs group and the BMSCs group. CyclinD1 protein and mRNA expressions after siRNA transfection were detected by Western blotting and qRT-PCR. The siRNA-CyclinD1 BMSCs were transplanted into rats in the si-CyclinD1 + BMSCs group using stereotaxic method 6 hr after SCI. Hindlimb locomotor performance was determined using inclined plane test and Basso-Beattie-Bresnahan (BBB) locomotor rating scale. Expressions of glial fibrillary acidic protein (GFAP) and nerve growth factor (NGF) were detected by immunohistochemistry. Inclined plane and BBB scores in the control, si-CyclinD1 + BMSCs, and BMSCs groups were significantly lower than the sham group, but these scores were evidently decreased in the control group and increased in the si-CyclinD1 + BMSCs group compared with the BMSCs group. The repair degree of spinal cord tissues of rats in the si-CyclinD1 + BMSCs group was obvious than the BMSCs group. GFAP and NGF protein expressions were markedly decreased in the control, si-CyclinD1 + BMSCs and BMSCs groups when compared with the sham group. GFAP- and NGF-positive cells were significantly increased in the si-CyclinD1 + BMSCs group while decreased in the control group. Our study provides evidence that epigenetic silencing of CyclinD1 using BMSCs might accelerate the repair of SCI in rats.

Identification of crucial genes associated with rat traumatic spinal cord injury

The aim of the present study was to investigate the key genes associated with traumatic spinal cord injuries (TSCI). The dataset GSE52763 was downloaded from the Gene Expression Omnibus, for which lumbar spinal cord samples were obtained from rats at 1 and 3 weeks following contusive spinal cord injury and 1 week subsequent to a sham laminectomy, and used to identify differentially expressed genes (DEGs). Functional enrichment analysis, co‑expression analysis and transcription factor (TF) identification were performed for DEGs common to the 1 and 3 week injury samples. In total, 234 upregulated and 51 downregulated DEGs were common to the 1 and 3 week injury samples. The upregulated DEGs were significantly enriched in Gene Ontology terms concerning immunity (e.g. Itgal and Ccl2) and certain pathways, including natural killer cell mediated cytotoxicity [e.g. Ras‑related C3 botulinum toxin substrate 2 (Rac2) and TYRO protein tyrosine kinase binding protein (Tyrobp)]. The downregulated DEGs were highly enriched in female gonad development [e.g. progesterone receptor (Pgr)], and the steroid biosynthesis pathway. A total of 139 genes had co‑expression associations and the majority of them were upregulated genes. The upregulated co‑expressed genes were predominantly enriched in biological regulation, including TGFB induced factor homeobox 1 (Tgif1) and Rac2. The downregulated co‑expressed genes were enriched in anatomical structure development (e.g. Dnm3). A total of 92 co‑expressed genes composed the protein‑protein interaction network. Additionally, 9 TFs (e.g. Pgr and Tgif1) were identified from the DEGs. It was hypothesized that the genes including Tgif1, Rac2, Tyrobp, and Pgr may be closely associated with TSCI.