Summary Chronic neuropathic pain is a major public issue due to its high incidence in the general population, the associated social burden and very limited efficacy of current treatment. Identification of new targets and mechanisms underlying this disorder is essential for the discovery of novel treatments and preventative tactics for better neuropathic pain management. We recently carried out a next generation RNA sequencing approach and identified a large, native, full-length long noncoding RNA (lncRNA) in mouse and human dorsal root ganglion (DRG). Because its expression is increased in injured DRG in response to peripheral nerve injury, but not to inflammation, we named it as nerve injury-specific lncRNA (NIS-lncRNA). NIS-lncRNA has two splice variants: variant 1 (V1) and V2. Our pilot work revealed that blocking the nerve injury-induced increase in the levels of DRG NIS-lncRNA V1 and V2 ameliorated neuropathic pain. Mimicking this increase elevated the expression of C-C chemokine ligand 2 (CCL2, a key player in neuropathic pain genesis) in the DRG and led to neuropathic pain-like symptoms in naive mice. These effects required the expression of DRG FUS (Fused in sarcoma), a DNA-binding protein that is required for transcription initiation. These pilot findings suggest that DRG NIS-lncRNA, as a therapeutic target, contributes to a peripheral mechanism underlying neuropathic pain through promotion of DRG FUS-controlled Ccl2 gene transcription. This proposal will validate NIS-lncRNA as a therapeutic target in neuropathic pain models. In Specific Aim 1, we will characterize the modified long-acting antisense oligonucleotides (ASOs) that specifically knock down V1 and V2 (V1 ASO and V2 ASO), respectively, delivered intrathecally for their in vivo stability and efficacy to reduce chronic constriction injury (CCI)-induced neuropathic pain. To better predict clinical applicability, we will also validate their efficacy in spinal nerve ligation-, paclitaxel (chemotherapy)- and streptozotocin (diabetic)-induced neuropathic pain. To confirm the role of NIS-lncRNA in neuropathic pain, we will examine the effect of genetic knockdown/knockout of DRG NIS-lncRNA through microinjection of AAV5-Cre into the DRG of NIS-lncRNAfl/fl mice or cross-breeding of the NIS-lncRNAfl/fl mice with conditional advillincre mice on CCI-induced pain hypersensitivity. In Specific Aim 2, we will determine how blocking the increased NIS-lncRNA in the injured DRG produces antinociceptive effects in neuropathic pain. We will validate the expression pattern of NIS-lncRNA in the DRG after CCI. We will examine whether blocking the CCI-induced increase in DRG NIS-lncRNA inhibits DRG CCL2 elevation, CCL2-mediated DRG neuronal hyper-excitability and spinal cord dorsal central sensitization after CCI. We will define whether CCI-induced increase in DRG NIS-lncRNA promotes the binding of FUS with the promoter of Ccl2 gene and subsequently increases FUS-controlled CCL2 expression in the injured DRG after CCI. In Specific Aim 3, we will collaborate with Dr. Davidson at the University of Cincinnati to validate the role of NIS- lncRNA in human DRG. We will verify the expression of NIS-lncRNA in human DRG, define its expression pattern, and examine its role in CCL2 expression and neuronal excitability in the viable human DRG neurons exposed to paclitaxel. Completing this proposal will advance neuropathic pain management and may provide a novel non-opioid target for this disorder.
|Effective start/end date||9/30/19 → 3/31/24|
- National Institutes of Health: $3,464,207.00