Project description:We demonstrated the pain-specific response to the algesic peptide fragment MBP84-104 of myelin basic protein that induces pain if injected into sciatic nerve of rats and mice. We used the wild-type peptide MBP 84-104, H89G mutant peptide (MBP84-104-H89G), scramble peptide (MBP84-104-SCR) and phosphomimetic peptide MBP84-104-mimTT to stimulate the primary rat Schwann cell cultures. After 24h we isolated total RNA and conducted genome wide RNA-seq. In addition, we performed RNA-seq using Schwann cells constitutively expressing an MBP84-104-mCherry construct. The gene expression data was analyzed using Ingenuity Pathway Analysis software. We conclude that the Schwann cells expressing MBP84-104 constructs stimulate pain-specific signaling pathways thus representing a relevant model to study neuropathic pain.
Project description:An insulating myelin sheath ensures saltatory conduction of mechanosensory A afferents. Myelin damage results in the electrical instability of A fibers and the ability to generate pain in response to light touch/pressure (mechanical allodynia). We have hypothesized and then established that the release of T cell epitopes of myelin basic protein (MBP) enables nociceptive circuitry in myelinated fibers. Thus, mass spectrometry analysis of the rat sciatic nerve proteome followed by bioinformatics examination of the datasets revealed a loss of MBP and activation of T-helper cell signaling in the nerves undergoing chronic constriction injury (CCI). Matrix metalloproteinase-9 (MMP-9) proteolysis resulted in the MBP digest peptides, including the MBP84-104 and MBP68-86 regions, which exhibit prominent immunogenic epitopes. Myelin-forming Schwann cells and paranodal areas accumulated MHCII, MMP-9 and the degraded MBP at the sciatic nerve injury site. Administration of the immunodominant MBP84-104 and MBP68-86 peptides but not of the control peptides in a naïve rat sciatic nerve produced robust mechanical allodynia. Allodynia was accompanied by the T cell infiltration and an increase in MHCII, IL-17A and TNF- levels at the nerve injection site and the segmental ganglia. The pro-nociceptive activity of the synthetic MBP84-104 diminished in athymic nude rats lacking T cells. SB-3CT, an antagonist of MMP-9, inhibited mechanical allodynia, neuroinflammation and spinal sensitization after CCI. Collectively, our novel data implicate, for the first time, MMP-mediated cleavage of MBP and the resulting MBP digest fragments as a major cause of neuropathic pain. Gene extression profiling of total RNAs extracted from rat sciatic nerves, dorsal root ganglion and spinal cords after MBP84-104 peptide injection
Project description:An insulating myelin sheath ensures saltatory conduction of mechanosensory A afferents. Myelin damage results in the electrical instability of A fibers and the ability to generate pain in response to light touch/pressure (mechanical allodynia). We have hypothesized and then established that the release of T cell epitopes of myelin basic protein (MBP) enables nociceptive circuitry in myelinated fibers. Thus, mass spectrometry analysis of the rat sciatic nerve proteome followed by bioinformatics examination of the datasets revealed a loss of MBP and activation of T-helper cell signaling in the nerves undergoing chronic constriction injury (CCI). Matrix metalloproteinase-9 (MMP-9) proteolysis resulted in the MBP digest peptides, including the MBP84-104 and MBP68-86 regions, which exhibit prominent immunogenic epitopes. Myelin-forming Schwann cells and paranodal areas accumulated MHCII, MMP-9 and the degraded MBP at the sciatic nerve injury site. Administration of the immunodominant MBP84-104 and MBP68-86 peptides but not of the control peptides in a naïve rat sciatic nerve produced robust mechanical allodynia. Allodynia was accompanied by the T cell infiltration and an increase in MHCII, IL-17A and TNF- levels at the nerve injection site and the segmental ganglia. The pro-nociceptive activity of the synthetic MBP84-104 diminished in athymic nude rats lacking T cells. SB-3CT, an antagonist of MMP-9, inhibited mechanical allodynia, neuroinflammation and spinal sensitization after CCI. Collectively, our novel data implicate, for the first time, MMP-mediated cleavage of MBP and the resulting MBP digest fragments as a major cause of neuropathic pain.
Project description:There is an imminent need for safe and efficient chronic pain medications. Regulator of G-protein signaling 4 (RGS4) is a multi-functional signal transduction protein, widely expressed in the pain matrix. Here, we demonstrate that RGS4 plays a prominentrole in the maintenance of chronic pain symptoms in male and female mice. Using genetically modified mice, we show a dynamicrole of RGS4 in recovery from symptoms of sensory hypersensitivity deriving from hindpaw inflammation or hindlimb nerveinjury. We also demonstrate an important role of RGS4 actions in gene expression patterns induced by chronic pain states in themouse thalamus. Our findings provide novel insight into mechanisms associated with the maintenance of chronic pain states anddemonstrate that interventions in RGS4 activity promote recovery from sensory hypersensitivity symptoms.
Project description:We focused on NR2F1 and NR2F2 (CoupTF1/CoupTF2) since they are expressed from neural crest through Schwann cell maturity, and found that knockdown of nuclear receptors Nr2f1 and Nr2f2 in primary Schwann cells downregulated genes such as Myelin Basic Protein (Mbp), Desert Hedgehog (Dhh), and N-Myc Downstream Regulated 1 (Ndrg1). In this study, we have elucidated a NR2F-regulated target gene network in Schwann cells, which revealed enrichment for non-myelinating Schwann cell genes. We used Cut&Run in S16 Schwann cells to show novel, genome-wide binding sites of NR2F1/2 and downstream transcription factors, YY1, SREBP1, Retinoid X Receptor (RXRG) and TEA-Domain factor (TEAD1). Our study elucidates the transcriptional cooperation that forms unique enhancer landscapes and the regulatory network that targets non-myelinating Schwann cells.
Project description:The important contribution of glia to mechanisms of injury and repair of the nervous system is increasingly recognized. In stark contrast to the central nervous system (CNS), the peripheral nervous system (PNS) has a remarkable capacity for regeneration after injury. Schwann cells are recognized as key contributors to PNS regeneration but the molecular underpinnings of the Schwann cell response to injury remain incompletely understood. To gain insight into the acute SC injury response, we provide an RNAseq database of Schwann cells purified acutely from the naïve and injured rodent sciatic nerve at 3, 5, and 7 days post injury. Bioinformatic analysis provides validation of cell purity and dataset integrity as well as identification of discrete modules of genes that follow distinct patterns of regulation in the first days after injury and their corresponding molecular pathways. Our dataset provides a helpful resource for further deciphering the SC injury response and provides a depth of transcriptional data that can complement the findings of recent single cell sequencing approaches. In addition, as more data becomes available on the response of CNS glia to injury, we anticipate that this dataset will provide a valuable platform for understanding key differences in the PNS and CNS glial responses to injury and for designing approaches to ameliorate CNS regeneration.
Project description:The human coronavirus OC43 is responsible for 15-30% of seasonal “common cold” infections with typically mild respiratory symptoms. We demonstrated that the coronavirus OC43 derived small peptide encoded by the viral p65 proteins may exhibit molecular mimicry with the pro-algesic fragment of Myelin Basic Protein (MBP). After intrasciatic injection, the p65-derived peptide induced robust pain hypersensitivity in rats lasting for up to 21 days. Transcriptomic analysis at day 21 revealed extensive spinal up-regulation of pro-nociceptive genes. Strikingly, genome-wide isoform switching due to activation of transcriptional start sites and alternative splicing events has occurred. We hypothesized that the coronavirus-derived peptides can dysregulate MBP function in the PNS/CNS and promote neuropathic chronic pain. Our findings offer paradigm-shifting mechanistic understanding of the viral origin of idiopathic neurological effects including chronic neuropathic pain, a condition currently refractory to therapeutic treatment. This new knowledge will lead to new diagnostic, prognostic, and therapeutic approaches to benefit patients with chronic pain.
Project description:The combined effects of NP and MBP were much more toxic than NP or MBP exposed alone. We used microarrays to detail the global programme of gene expression underlying cellularisation and identified distinct classes of up-regulated genes and miRNAs after treated with 0.1μM NP, 0.1mM MBP, 0.1μM NP+0.1mM MBP and solvent control.