MicroRNA Alteration in Developing Rat Oligodendrocyte Precursor Cells Induced by Hypoxia-Ischemia

Loss of microRNA-15a/16-1 function promotes neuropathological and functional recovery in experimental traumatic brain injury

The diffuse axonal damage in white matter and neuronal loss, along with excessive neuroinflammation, hinder long-term functional recovery after traumatic brain injury (TBI). MicroRNAs (miRs) are small noncoding RNAs that negatively regulate protein-coding target genes in a posttranscriptional manner. Recent studies have shown that loss of function of the miR-15a/16-1 cluster reduced neurovascular damage and improved functional recovery in ischemic stroke and vascular dementia. However, the role of the miR-15a/16-1 cluster in neurotrauma is poorly explored. Here, we report that genetic deletion of the miR-15a/16-1 cluster facilitated the recovery of sensorimotor and cognitive functions, alleviated white matter/gray matter lesions, reduced cerebral glial cell activation, and inhibited infiltration of peripheral blood immune cells to brain parenchyma in a murine model of TBI when compared with WT controls. Moreover, intranasal delivery of the miR-15a/16-1 antagomir provided similar brain-protective effects conferred by genetic deletion of the miR-15a/16-1 cluster after experimental TBI, as evidenced by showing improved sensorimotor and cognitive outcomes, better white/gray matter integrity, and less inflammatory responses than the control antagomir-treated mice after brain trauma. miR-15a/16-1 genetic deficiency and miR-15a/16-1 antagomir also significantly suppressed inflammatory mediators in posttrauma brains. These results suggest miR-15a/16-1 as a potential therapeutic target for TBI.

Altered expression of transfer RNAs and their possible roles in brain white matter injury

Transfer RNAs (tRNAs) can regulate cell behavior and are associated with neurological disorders. Here, we aimed to investigate the expression levels of tRNAs in oligodendrocyte precursor cells (OPCs) and their possible roles in the regulation of brain white matter injury (WMI). Newborn Sprague-Dawley rats (postnatal day 5) were used to establish a model that mimicked neonatal brain WMI. RNA-array analysis was performed to examine the expression of tRNAs in OPCs. psRNAtarget software was used to predict target mRNAs of significantly altered tRNAs. Gene ontology (GO) and KEGG were used to analyze the pathways for target mRNAs. Eighty-nine tRNAs were changed after WMI (fold change absolute ≥1.5, P  < 0.01), with 31 downregulated and 58 upregulated. Among them, three significantly changed tRNAs were identified, with two being significantly increased (chr10.trna1314-ProTGG and chr2.trna2771-ProAGG) and one significantly decreased (chr10.trna11264-GlyTCC). Further, target mRNA prediction and GO/KEGG pathway analysis indicated that the target mRNAs of these tRNAs are mainly involved in G-protein coupled receptor signaling pathways and beta-alanine metabolism, which are both related to myelin formation. In summary, the expression of tRNAs in OPCs was significantly altered after brain WMI, suggesting that tRNAs may play important roles in regulating WMI. This improves the knowledge about WMI pathophysiology and may provide novel treatment targets for WMI.

The Neglected Sibling: NLRP2 Inflammasome in the Nervous System

While classical NOD-like receptor pyrin domain containing protein 1 (NLRP1) and NLRP3 inflammasomal proteins have been extensively investigated, the contribution of NLRP2 is still ill-defined in the nervous system. Given the putative significance of NLRP2 in orchestrating neuroinflammation, further inquiry is needed to gain a better understanding of its connectome, hence its specific targeting may hold a promising therapeutic implication. Therefore, bioinformatical approach for extracting information, specifically in the context of neuropathologies, is also undoubtedly preferred. To the best of our knowledge, there is no review study selectively targeting only NLRP2. Increasing, but still fragmentary evidence should encourage researchers to thoroughly investigate this inflammasome in various animal- and human models. Taken together, herein we aimed to review the current literature focusing on the role of NLRP2 inflammasome in the nervous system and more importantly, we provide an algorithm-based protein network of human NLRP2 for elucidating potentially valuable molecular partnerships that can be the beginning of a new discourse and future therapeutic considerations.

Effect of Hyperbaric oxygen on myelin injury and repair after hypoxic-ischemic brain damage in adult rat

INTRODUCTION

Hypoxic-ischemic encephalopathy (HIE) is one of the leading causes of death and neurological disability with limited options for treatment in neonates, children and adults worldwide. The pathogenesis and treatment of white matter (WM) injury in adult patients with HIE remains largely elusive.

METHODS

Sixty male Sprague-Dawley rats were randomly divided into control group, sham-operated group (HBO treatment 6 days after sham operation), and Hypoxia-ischemia (HI) induced brain damage group (receiving left carotid arteries ligation + hypoxia treatment), 1.5ATA hyperbaric oxygen group (HI + 1.5ATA HBOT) and 2.5ATA HBOT group (HI + 2.5ATA HBOT). All the rats were evaluated by water maze before operation, and 6 days after operation, and the function of learning and memory was evaluated; Demyelination in the hippocampus and prefrontal cortex was observed by Luxol fast blue staining (LFB) and MBP immunostaining; the number of Myelin Oligodendrocyte Glycoprotein (MOG),glial fibrillary acidic protein (GFAP), ionic calcium-binding adaptor (Iba-1) and NG2 positive cells in the hippocampus and prefrontal cortex were determined by immunofluorescence staining. The expression of interleukin-1β (IL-1β), IL-6 and tumor necrosis factor (TNF-α), Hypoxia Inducible Factor 1 Subunit Alpha (HIF1-α) and Superoxide dismutase (SOD) in brain and serum of rats were measured by Western Blot method and Enzyme linked immunosorbent assay (ELISA).

RESULTS

Compared with those in the normal control group and sham-operated group, in the HI group, the learning and memory abilities of rats were significantly decreased (P < 0.05), the intensity of LFB and MBP immunostaining in hippocampus and prefrontal cortex was significantly decreased (P < 0.05); the number of MOG positive oligodendrocytes (OLs) significantly decreased (P < 0.05), whereas the number of Iba-1, GFAP, NG2 positive microglias, astrocytes and oligodendrocyte precursors (OPCs) was increased (P < 0.05); the level of IL-1β, IL-6, TNF-α and HIF-1a in brain and serum were significantly increased (P < 0.05), whereas SOD was significantly decreased in brain and increased in serum. Compared with those in the HI group, in both 1.5ATA and 2.5ATA HBOT group, the learning and memory abilities were significantly increased (P < 0.05); the intensity of LFB and MBP immunostaining in the hippocampus and prefrontal cortex was significantly increased (P < 0.05); the number of MOG positive OLs significantly increased (P < 0.05); the number of Iba-1, GFAP, NG2 positive microglias, astrocytes and OPCs was decreased (P < 0.05); the level of IL-1β, IL-6, TNF-α and HIF-1a in brain and serum were significantly decreased (P < 0.05); the level of SOD was significantly increased in brain and decreased in serum. Morever, compared with those in the 1.5ATA group, 2.5ATA provided better treatment results (P < 0.05).

CONCLUSION

In the present study, we demonstrated the mechanism of different pressure HBOT on HI induced brain injury from three levels: (1) On a tissue level, HBOT protects against HI induced myelin injury; (2) On a cellular level, HBOT attenuates HI-induced OL loss, suppresss the reactive activation of astrocyte and microglia, and may promote OPC to differentiate into OL; (3) On a molecular level, HBOT inhibites neuroinflammation, and balances oxidative damage and antioxidant capacity. Among the above effects, 2.5ATA HBOT is better than 1.5ATA HBOT. Ongoing research will continue to seek out the signalling pathways and molecules mechanisms on different pressure of HBOT-related myelin protection, and possibly expand suitable HBOT use in adult HIE clinically.

Inhibiting miR-466b-5p Attenuates Neonatal White Matter Injury by Targeting Lpar1

miR-466b-5p is aberrantly upregulated in oligodendrocyte precursor cells (OPCs) after white matter injury (WMI). However, its roles in neonatal WMI pathogenesis are unknown. In this study, P3 rats were subjected to hypoxia-ischemia to establish a neonatal WMI model. A bioinformatic analysis was conducted to predict the possible target of miR-466b-5p as Lpar1. RT-PCR was performed to validate the expression of miR-466b-5p and Lpar1 mRNA. The miR-466b-5p antagomir was intracerebroventricularly administrated to inhibit miR-466b-5p; OPC differentiation, apoptosis, proliferation, and myelination were analyzed using immunofluorescence staining, western blotting, and electron microscopy. In addition, the behavioral performance of the rats was measured with the Morris water maze test. Sox10 expression and PLP trafficking were examined to elucidate the mechanism by which miR-466b-5p regulates WMI pathogenesis. We found that after inhibiting miR-466b-5p, the Edg2 protein was increased, OPC differentiation and myelinated axon formation were enhanced, and the rats' behavioral performance was improved, whereas OPC proliferation and apoptosis were not affected. Furthermore, the expression of Sox10 was promoted while PLP trafficking was attenuated after miR-466b-5p inhibition. We conclude that miR-466b-5p is involved in the regulation of WMI pathogenesis, partly through the Lpar1/Edg2/Sox10 and Lpar1/Edg2/PLP signaling pathways.

Research progress on the regulatory role of microRNAs in spinal cord injury

Spinal cord injury (SCI) is a severe CNS injury that results in abnormalities in, or loss of, motor, sensory and autonomic nervous function. miRNAs belong to a new class of noncoding RNA that regulates the production of proteins and biological function of cells by silencing translation or interfering with the expression of target mRNAs. Following SCI, miRNAs related to oxidative stress, inflammation, autophagy, apoptosis and many other secondary injuries are differentially expressed, and these miRNAs play an important role in the progression of secondary injuries after SCI. The purpose of this review is to elucidate the differential expression and functional roles of miRNAs after SCI, thus providing references for further research on miRNAs in SCI.

Oligodendrocyte-specific Argonaute profiling identifies microRNAs associated with experimental autoimmune encephalomyelitis

BACKGROUND

MicroRNAs (miRNAs) belong to a class of evolutionary conserved, non-coding small RNAs with regulatory functions on gene expression. They negatively affect the expression of target genes by promoting either RNA degradation or translational inhibition. In recent years, converging studies have identified miRNAs as key regulators of oligodendrocyte (OL) functions. OLs are the cells responsible for the formation and maintenance of myelin in the central nervous system (CNS) and represent a principal target of the autoimmune injury in multiple sclerosis (MS).

METHODS

MiRAP is a novel cell-specific miRNA affinity-purification technique which relies on genetically tagging Argonaut 2 (AGO2), an enzyme involved in miRNA processing. Here, we exploited miRAP potentiality to characterize OL-specific miRNA dynamics in the MS model experimental autoimmune encephalomyelitis (EAE).

RESULTS

We show that 20 miRNAs are differentially regulated in OLs upon transition from pre-symptomatic EAE stages to disease peak. Subsequent in vitro differentiation experiments demonstrated that a sub-group of them affects the OL maturation process, mediating either protective or detrimental signals. Lastly, transcriptome profiling highlighted the endocytosis, ferroptosis, and FoxO cascades as the pathways associated with miRNAs mediating or inhibiting OL maturation.

CONCLUSIONS

Altogether, our work supports a dual role for miRNAs in autoimmune demyelination. In particular, the enrichment in miRNAs mediating pro-myelinating signals suggests an active involvement of these non-coding RNAs in the homeostatic response toward neuroinflammatory injury.

CAPN6 in disease: An emerging therapeutic target (Review)

As a member of the calpain protein family, calpain6 (CAPN6) is highly expressed mainly in the placenta and embryos. It plays a number of important roles in cellular processes, such as the stabilization of microtubules, the main-tenance of cell stability, the control of cell movement and the inhibition of apoptosis. In recent years, various studies have found that CAPN6 is one of the contributing factors associated with the tumorigenesis of uterine tumors and osteosarcoma, and that CAPN6 participates in the development of tumors by promoting cell proliferation and angiogenesis, and by inhibiting apoptosis, which is mainly regulated by the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) pathway. Due to its abnormal cellular expression, CAPN6 has also been found to be associated with a number of diseases, such as white matter damage and muscular dystrophy. Therefore, CAPN6 may be a novel therapeutic target for these diseases. In the present review, the role of CAPN6 in disease and its possible use as a target in various therapies are discussed.

Genome-Wide Association Study of Body Weights in Hu Sheep and Population Verification of Related Single-Nucleotide Polymorphisms

Body weight (BW) is a critical economic trait for meat production in sheep. The current study aimed to perform a genome-wide association study (GWAS) to detect significant single-nucleotide polymorphisms (SNPs) that are associated with BW in Hu sheep. The comparison and analysis of the G1 and G2 generations of a nucleus meat Hu sheep breeding herd revealed four SNPs identified by GWAS. The subsequent verification of the significant SNP loci in the Hu sheep G3 generation nucleus herd also detected nine SNPs in significant SNP regions. Two SNPs were significantly associated with the BW of Hu sheep (p < 0.05). OARX_76354330.1 and s64890.1 could be identified as functional SNPs for the growth traits of Hu sheep. CAPN6, as a candidate gene, was significantly different in the biceps femoris and longissimus dorsi muscles of weaning (60-day) and 6-month sheep, which facilitated the discovery of causal variants for BW and contributed to the marker-assisted selection breeding of Hu sheep.