Project description:Transcriptional alterations are characteristic of persistent pain states but the key regulators remain elusive. Using a conditional knockout (cKO) strategy in mice we sought to determine whether loss of the transcriptional co-repressor histone deacetylase four (HDAC4) would have implications for sensory neuron transcription and nociception. HDAC4 was found to be largely dispensable for transcriptional regulation of naïve sensory neurons but was required for transcriptional responses after injury, with Calca and Trpv1 expression consistently downregulated in HDAC4 cKO compared to littermate controls (0.2-0.44 fold). This downregulation corresponded to reduced sensitivity to capsaicin in vitro (76% +/- 4.4% wildtype capsaicin responders vs 56.9% +/- 4.7% cKO responders) and to reduced thermal hypersensitivity in the complete Freund’s adjuvant model of inflammatory pain (1.3-1.4 fold improvement). These data indicate that HDAC4 is a novel inflammatory pain mediator and may be a good therapeutic target, capable of orchestrating the regulation of multiple downstream effectors. Total RNA was extracted from HDAC4 cKO and HDAC4 fl/fl naïve adult lumbar dorsal root ganglia (n=3/group). mRNA expression was compared using Affymetrix Mouse Gene Arrays (Mouse Gene 2.0ST) run on a GeneChip Fluidics Station 450. Chips were scanned on an Affymetrix GeneChip Scanner.
Project description:Nociceptive neurons respond to inflammation, initiating protective reflexes and alerting the host. Here we found that TRPV1 nociceptors express and activate the cytosolic DNA-sensing protein Stimulator of Interferon Genes (STING) in response to inflammation. Neuronal activation of STING promotes signaling through TBK1 and triggers a Type I interferon (IFN-I) response. The absence of STING led to heightened pain responses to chemical irritants or heat. In contrast, mice expressing a nociceptor-specific gain-of-function mutation in STING exhibited an IFN gene signature that reduced nociceptor excitability and inflammatory hyperalgesia. Importantly, several IFN-regulated genes (IRGs) were specific to nociceptor ion channels responsible for controlling neuronal activity and pain threshold. Therefore, STING promotes a pain-resolving IFN-I signaling pathway in nociceptors, thereby preventing sensitization and persistent pain
Project description:Transcriptional alterations are characteristic of persistent pain states but the key regulators remain elusive. Using a conditional knockout (cKO) strategy in mice we sought to determine whether loss of the transcriptional co-repressor histone deacetylase four (HDAC4) would have implications for sensory neuron transcription and nociception. HDAC4 was found to be largely dispensable for transcriptional regulation of naïve sensory neurons but was required for transcriptional responses after injury, with Calca and Trpv1 expression consistently downregulated in HDAC4 cKO compared to littermate controls (0.2-0.44 fold). This downregulation corresponded to reduced sensitivity to capsaicin in vitro (76% +/- 4.4% wildtype capsaicin responders vs 56.9% +/- 4.7% cKO responders) and to reduced thermal hypersensitivity in the complete Freund’s adjuvant model of inflammatory pain (1.3-1.4 fold improvement). These data indicate that HDAC4 is a novel inflammatory pain mediator and may be a good therapeutic target, capable of orchestrating the regulation of multiple downstream effectors.
Project description:The goal of this study was to evaluate the role of HDAC4 in spinal sensitization. We analyzed gene expression changes associated with the subcellular localization of HDAC4 in the spinal cord dorsal horn following CFA-induced inflammatory pain. The analysis was performed in basal conditions and after intraplantar injection of CFA to the hind paw of mice that received intraspinal injection of rAAV-constructs influencing the subcellular localization of HDAC4.
