Silencing the enhancer of zeste homologue 2, Ezh2, represses axon regeneration of dorsal root ganglion neurons

Transcriptional reprogramming post-peripheral nerve injury: A systematic review

Neuropathic pain is characterised by periodic or continuous hyperalgesia, numbness, or allodynia, and results from insults to the somatosensory nervous system. Peripheral nerve injury induces transcriptional reprogramming in peripheral sensory neurons, contributing to increased spinal nociceptive input and the development of neuropathic pain. Effective treatment for neuropathic pain remains an unmet medical need as current therapeutics offer limited effectiveness and have undesirable effects. Understanding transcriptional changes in peripheral nerve injury-induced neuropathy might offer a path for novel analgesics. Our literature search identified 65 papers exploring transcriptomic changes post-peripheral nerve injury, many of which were conducted in animal models. We scrutinize their transcriptional changes data and conduct gene ontology enrichment analysis to reveal their common functional profile. Focusing on genes involved in 'sensory perception of pain' (GO:0019233), we identified transcriptional changes for different ion channels, receptors, and neurotransmitters, shedding light on its role in nociception. Examining peripheral sensory neurons subtype-specific transcriptional reprograming and regeneration-associated genes, we delved into downstream regulation of hypersensitivity. Identifying the temporal program of transcription regulatory mechanisms might help develop better therapeutics to target them effectively and selectively, thus preventing the development of neuropathic pain without affecting other physiological functions.

Prediction of cell-cell communication patterns of dorsal root ganglion cells: single-cell RNA sequencing data analysis

JOURNAL/nrgr/04.03/01300535-202406000-00042/inline-graphic1/v/2023-10-30T152229Z/r/image-tiff

Dorsal root ganglion neurons transmit peripheral somatic information to the central nervous system, and dorsal root ganglion neuron excitability affects pain perception. Dorsal root ganglion stimulation is a new approach for managing pain sensation. Knowledge of the cell-cell communication among dorsal root ganglion cells may help in the development of new pain and itch management strategies. Here, we used the single-cell RNA-sequencing (scRNA-seq) database to investigate intercellular communication networks among dorsal root ganglion cells. We collected scRNA-seq data from six samples from three studies, yielding data on a total of 17,766 cells. Based on genetic profiles, we identified satellite glial cells, Schwann cells, neurons, vascular endothelial cells, immune cells, fibroblasts, and vascular smooth muscle cells. Further analysis revealed that eight types of dorsal root ganglion neurons mediated proprioceptive, itch, touch, mechanical, heat, and cold sensations. Moreover, we predicted several distinct forms of intercellular communication among dorsal root ganglion cells, including cell-cell contact, secreted signals, extracellular matrix, and neurotransmitter-mediated signals. The data mining predicted that Mrgpra3-positive neurons robustly express the genes encoding the adenosine Adora2b (A2B) receptor and glial cell line-derived neurotrophic factor family receptor alpha 1 (GFRα-1). Our immunohistochemistry results confirmed the coexpression of the A2B receptor and GFRα-1. Intrathecal injection of the A2B receptor antagonist PSB-603 effectively prevented histamine-induced scratching behaviour in a dose-dependent manner. Our results demonstrate the involvement of the A2B receptor in the modulation of itch sensation. Furthermore, our findings provide insight into dorsal root ganglion cell-cell communication patterns and mechanisms. Our results should contribute to the development of new strategies for the regulation of dorsal root ganglion excitability.

Annexin A1 in the nervous and ocular systems

The therapeutic potential of Annexin A1, an important member of the Annexin superfamily, has become evident in results of experiments with multiple human systems and animal models. The anti-inflammatory and pro-resolving effects of Annexin A1 are characteristic of pathologies involving the nervous system. In this review, we initially describe the expression sites of Annexin A1, then outline the mechanisms by which Annexin A1 maintains the neurological homeostasis through either formyl peptide receptor 2 or other molecular approaches; and, finally, we discuss the neuroregenerative potential qualities of Annexin A1. The eye and the nervous system are anatomically and functionally connected, but the association between visual system pathogenesis, especially in the retina, and Annexin A1 alterations has not been well summarized. Therefore, we explain the beneficial effects of Annexin A1 for ocular diseases, especially for retinal diseases and glaucoma on the basis of published findings, and we explore present and future delivery strategies for Annexin A1 to the retina.

EGFR-Activated JAK2/STAT3 Pathway Confers Neuroprotection in Spinal Cord Ischemia-Reperfusion Injury: Evidence from High-Throughput Sequencing and Experimental Models

This study aimed to investigate the molecular mechanisms underlying spinal cord ischemia-reperfusion (SCI/R) injury. Through RNA-Seq high-throughput sequencing and bioinformatics analysis, we found that EGFR was downregulated in the spinal cord of SCI/R mice and may function via mediating the JAK2/STAT3 signaling pathway. In vitro cell experiments indicated that overexpression of EGFR activated the JAK2/STAT3 signaling pathway and reduced neuronal apoptosis levels. In vivo animal experiments further confirmed this conclusion, suggesting that EGFR inhibits SCI/R-induced neuronal apoptosis by activating the JAK2/STAT3 signaling pathway, thereby improving SCI/R-induced spinal cord injury in mice. This study revealed the molecular mechanisms of SCI/R injury and provided new therapeutic strategies for treating neuronal apoptosis.

Expansion of plasma MicroRNAs over the first month following human stroke

Few have characterized miRNA expression during the transition from injury to neural repair and secondary neurodegeneration following stroke in humans. We compared expression of 754 miRNAs from plasma samples collected 5, 15, and 30 days post-ischemic stroke from a discovery cohort (n = 55) and 15-days post-ischemic stroke from a validation cohort (n = 48) to healthy control samples (n = 55 and 48 respectively) matched for age, sex, race and cardiovascular comorbidities using qRT-PCR. Eight miRNAs remained significantly altered across all time points in both cohorts including many described in acute stroke. The number of significantly dysregulated miRNAs more than doubled from post-stroke day 5 (19 miRNAs) to days 15 (50 miRNAs) and 30 (57 miRNAs). Twelve brain-enriched miRNAs were significantly altered at one or more time points (decreased expression, stroke versus controls: miR-107; increased expression: miR-99-5p, miR-127-3p, miR-128-3p, miR-181a-3p, miR-181a-5p, miR-382-5p, miR-433-3p, miR-491-5p, miR-495-3p, miR-874-3p, and miR-941). Many brain-enriched miRNAs were associated with apoptosis over the first month post-stroke whereas other miRNAs suggested a transition to synapse regulation and neuronal protection by day 30. These findings suggest that a program of decreased cellular proliferation may last at least 30 days post-stroke, and points to specific miRNAs that could contribute to neural repair in humans.

Electroacupuncture Alleviates Neuropathic Pain by Suppressing Ferroptosis in Dorsal Root Ganglion via SAT1/ALOX15 Signaling

Neuropathic pain affects globally about 7-10% of the general population. Electroacupuncture (EA) effectively relieves neuropathic pain symptoms without causing any side effects; however, the underlying molecular mechanisms remain unclear. We established a chronic constriction injury (CCI)-induced rat model of neuropathic pain. RNA sequencing was used to screen for differentially expressed genes in the dorsal root ganglion after CCI and EA treatment. We identified gene markers of ferroptosis spermidine/spermine N1-acetyltransferase 1 (Sat1) and arachidonate 15-lipoxygenase (Alox15) to be dysregulated in the CCI-induced neuropathic pain model. Furthermore, EA relieved CCI-induced pain as well as ferroptosis-related symptoms in the dorsal root ganglion, including lipid peroxidation and iron overload. Finally, SAT1 knockdown also alleviated mechanical and thermal pain hypersensitivity and reversed ferroptosis damage. In conclusion, we showed that EA inhibited ferroptosis by regulating the SAT1/ALOX15 pathway to treat neuropathic pain. Our findings provide insight into the mechanisms of EA and suggest a novel therapeutic target for neuropathic pain.

Integrative Multi-Omics Analysis of Oncogenic EZH2 Mutants: From Epigenetic Reprogramming to Molecular Signatures

Somatic heterozygous mutations in the active site of the enhancer of zeste homolog 2 (EZH2) are prevalent in diffuse large B-cell lymphoma (DLBCL) and acute myeloid leukemia (AML). The methyltransferase activity of EZH2 towards lysine 27 on histone H3 (H3K27) and non-histone proteins is dysregulated by the presence of gain-of-function (GOF) and loss-of-function (LOF) mutations altering chromatin compaction, protein complex recruitment, and transcriptional regulation. In this study, a comprehensive multi-omics approach was carried out to characterize the effects of differential H3K27me3 deposition driven by EZH2 mutations. Three stable isogenic mutants (EZH2Y641F, EZH2A677G, and EZH2H689A/F667I) were examined using EpiProfile, H3K27me3 CUT&Tag, ATAC-Seq, transcriptomics, label-free proteomics, and untargeted metabolomics. A discrete set of genes and downstream targets were identified for the EZH2 GOF and LOF mutants that impacted pathways involved in cellular proliferation, differentiation, and migration. Disruption of protein networks and metabolic signatures able to sustain aberrant cell behavior was observed in response to EZH2 mutations. This systems biology-based analysis sheds light on EZH2-mediated cell transformative processes, from the epigenetic to the phenotypic level. These studies provide novel insights into aberrant EZH2 function along with targets that can be explored for improved diagnostics/treatment in hematologic malignancies with mutated EZH2.

Intrathecal liproxstatin-1 delivery inhibits ferroptosis and attenuates mechanical and thermal hypersensitivities in rats with complete Freund’s adjuvant-induced inflammatory pain

Previous studies have confirmed the relationship between iron-dependent ferroptosis and a peripheral nerve injury-induced neuropathic pain model. However, the role of ferroptosis in inflammatory pain remains inconclusive. Therefore, we aimed to explore whether ferroptosis in the spinal cord and dorsal root ganglion contributes to complete Freund’s adjuvant (CFA)-induced painful behaviors in rats. Our results revealed that various biochemical and morphological changes were associated with ferroptosis in the spinal cord and dorsal root ganglion tissues of CFA rats. These changes included iron overload, enhanced lipid peroxidation, disorders of anti-acyl-coenzyme A synthetase long-chain family member 4 and glutathione peroxidase 4 levels, and abnormal morphological changes in mitochondria. Intrathecal treatment of liproxstatin-1 (a ferroptosis inhibitor) reversed these ferroptosis-related changes and alleviated mechanical and thermal hypersensitivities in CFA rats. Our study demonstrated the occurrence of ferroptosis in the spinal cord and dorsal root ganglion tissues in a rodent model of inflammatory pain and indicated that intrathecal administration of ferroptosis inhibitors, such as liproxstatin-1, is a potential therapeutic strategy for treating inflammatory pain.

Physical Activity Modulates miRNAs Levels and Enhances MYOD Expression in Myoblasts

Stem cells functions are regulated by different factors and non-conding RNAs, such as microRNA. MiRNAsplay an important role in modulating the expression of genes involved in the commitment and differentiation of progenitor cells. MiRNAs are post transcriptional regulators which may be modulated by physical exercise. MiRNAs, by regulating different signaling pathways, play an important role in myogenesis as well as in muscle activity. MiRNAs quantification may be considered for evaluating physical performance or muscle recovery. With the aim to identify specific miRNAs potentially involved in myogenesis and modulated by physical activity, we investigated miRNAs expression following physical performance in Peripheral Blood Mononuclear Cells (PBMCs) and in sera of half marathon (HM) runnners. The effect of runners sera on Myogenesis in in vitro cellular models was also explored. Therefore, we performed Microarray Analysis and Real Time PCR assays, as well as in vitro cell cultures analysis to investigate myogenic differentiation. Our data demonstrated gender-specific expression patterns of PBMC miRNAs before physical performance. In particular, miR223-3p, miR26b-5p, miR150-5p and miR15-5p expression was higher, while miR7a-5p and miR7i-5p expression was lower in females compared to males. After HM, miR152-3p, miR143-3p, miR27a-3p levels increased while miR30b-3p decreased in both females and males: circulating miRNAs mirrored these modulations. Furthermore, we also observed that the addition of post-HM participants sera to cell cultures exerted a positive effect in stimulating myogenesis. In conclusion, our data suggest that physical activity induces the modulation of myogenesis-associated miRNAs in bothfemales and males, despite the gender-associated different expression of certain miRNAs, Noteworthy, these findings might be useful for evaluating potential targets for microRNA based-therapies in diseases affecting the myogenic stem cells population.