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:Molecular characterization of the individual neuron types existing in the primate dorsal root ganglion and the relation to model organisms used for studying somatosensation and pain is critical for understanding the cellular origin of chronic pain and for translational aspects of biomedical research. However, molecular insights into the primate dorsal root ganglion are missing and a systematic comparison of strategies for somatosensation between the mouse and primates is lacking. Here we classify non-human primate sensory neurons based on their transcriptome and identify neuronal types with heritability to chronic pain. We identify nine neuronal types and use machine learning to expose an overall cross-species conserved strategy and shared taxonomy for nociception, although with differences at individual gene level, highlighting the importance of incorporating primate knowledge for the successful translation of discoveries in rodent model organisms. Genomic loci implicated in chronic pain were mapped onto specific primate sensory neuron types to identify the cellular origin of chronic pain. The common-variant genome-wide association results for chronic pain point to the same cells at the same pain sites and concentrate on two different neuronal types between pain disorders, suggesting that causative cell types and molecular mechanisms are different between different pain conditions.
Project description:Six different mouse pain models were studied: (1) tumour-injection model for bone cancer pain; (2) partial sciatic nerve ligation (PSL) for neuropathic pain; (3) mechanical joint loading for osteoarthritis pain; (4) oxaliplatin-induced painful neuropathy for chemotherapy-induced pain; (5) hyperalgesic priming model for chronic muscle pain; and (6) complete Freund’s adjuvant (CFA)-injection for inflammatory pain. Transcriptomic microarray analyses were performed using RNA isolated from dorsal root ganglia.
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:Beta-endorphinergic neurons in the hypothalamic arcuate nucleus (ARC) synthesize beta-endorphin (β-EP) to alleviate nociceptive behaviors, although the underlying regulatory mechanisms remain unknown. Here, we elucidated a novel epigenetic pathway driven by microRNA regulation of beta-endorphin synthesis in ARC neurons to control neuropathic pain. In pain-injured rats miR-203a-3p was the most highly upregulated miRNA in the ARC. A similar increase was identified in the cerebrospinal fluid of trigeminal neuralgia patients. Mechanistically, histone deacetylase 9 downregulation increased acetylation of histone H3 lysine-18, facilitating the binding of NR4A2 transcription factor to the miR-203a-3p gene promoter increasing miR-203a-3p expression following nerve injury. Further, increased miR-203a-3p was found to maintain neuropathic pain by targeting proprotein convertase 1, an endopeptidase necessary for the cleavage of proopiomelanocortin, the precursor of β-EP. Our findings highlight an epigenetic regulatory pathway for β-EP synthesis that contributes to neuropathic pain development and maintenance mechanisms providing for new therapeutic targets for neuropathic pain treatment.
Project description:Isobaric tags for relative and absolute quantitation -based proteomics analysis was performed to profile changes in the abundance of spinal cord proteins in two well-established animal pain models of chronic pain using wild-type and Nav1.8 knockout mice
Project description:Exercise stimulates systemic and tissue-specific adaptations that protect against lifestyle related diseases including obesity and type 2 diabetes. Exercise places high mechanical and energetic demands on contracting skeletal muscle, which require finely-tuned protein post-translational modifications involving signal transduction (e.g. phosphorylation) to elicit appropriate short- and long-term adaptive responses. To uncover the breadth of protein phosphorylation events underlying the adaptive responses to endurance exercise and skeletal muscle contraction, we performed global, unbiased mass spectrometry-based phosphoproteomic analyses of skeletal muscle from two rodent models, in situ muscle contraction in rats and treadmill-based endurance exercise in mice.
Project description:Two out-bred rat selection lines were separated to produce different hypersensitivity phenotypes following nerve injury. These lines were termed High Pain and Low Pain (HP or LP). Each sub-strain was either subject to a Sham surgery or a Spinal Nerve Ligation (SNL) surgery to the L4 and L5 spinal nerves. Three days following surgery L4/L5 Dorsal Root Ganglia (DRG) were dissected from these animals. For the rat line separation protocol see: Devor M, Raber P (1990) Heritability of symptoms in an experimental model of neuropathic pain. Pain 42:51-67. 12 Hybridizations, 3 per condition; Sham HP DRG; 3 day SNL HP DRG; Sham LP DRG; 3 day SNL LP DRG.