Funded Projects

G-protein coupled receptor 3 (GPR3) is an orphan receptor present in the central nervous system (CNS) that plays important role in many normal physiological functions and is involved in a variety of pathological conditions. Although the brain chemical that activates this receptor has not been identified, work with GPR3 knockout mice has identified GPR3 as a novel drug target for several Central Nervous System (CNS) mediated diseases including neuropathic pain. However, despite the emerging behavioral implications of the GPR3 system, little is known about how GPR3 affects behavior due to the lack of potent and selective chemical probes that allow scientists to examine functioning of the receptor. Recently, two cannabinoid chemicals present in the cannabis plant were discovered as affecting GPR3. This study will modify the chemical structure of these compounds to increase their potency and selectivity so that they may be used as pharmacological tools to investigate the role of GPR3 in modulating pain. In addition, this project focuses on identifying new compounds that show promise for development into therapeutics for the treatment of pain.

Chronic orofacial pain during Temporomandibular Disorders (TMD) and oral cancer is a significant health problem with scarce non-opioid treatment options. This study aims to validate critical regulators of the balance between protective immunity and immunopathology during chronic inflammatory diseases?tumor necrosis factor alpha superfamily members, LIGHT (TNFSF14) and lymphotoxin-beta (LT?) and their receptors, LT?R and Herpes Virus Entry Mediator (HVEM)?as novel therapeutic targets. The study also seeks to determine whether inhibition of LIGHT and LT? signaling prevents the development and inhibits maintenance of chronic TMD and oral cancer pain via peripheral mechanisms involving plasticity of immune, muscle and tumor cells as well as sensory neurons. The study will define the contribution of LIGHT and LT? signaling to TMD-induced excitability of trigeminal sensory neurons innervating the masseter muscle and joint. New validated therapeutic targets for prevention and treatment of orofacial pain that can be peripherally targeted would reduce side effects of current pain medicates related to drug dependence or tolerance.

Postoperative ileus (POI) following gastrointestinal (GI) surgery leads to significant patient morbidity and prolonged hospitalizations. Recent studies have demonstrated that intestinal manipulation and surgical trauma activate inflammatory macrophages (M?) and release inflammatory mediators such as nitric oxide (NO) to inhibit intestinal smooth muscle cells in POI. Intestinal M? are a highly heterogeneous and dynamic population in the innate immune system. Preliminary studies show that transient receptor potential vanilloid 4 (TRPV4) channel, a molecular sensor of tissue damage and inflammation, is exclusively expressed by the F4/80+/CD206+ intestinal anti-inflammatory M2 M?. Activation of TRPV4 produces an intestinal contractile response and improves GI transit in a mouse model of POI. The current proposal aims to elucidate the cellular and molecular mechanisms underlying the activation of TRPV4 in the intestinal M2 M?.

Many chronic pain conditions are dependent upon activity of the sympathetic nervous system. Sympathetic blockade is used clinically in chronic pain conditions, but the clinical and preclinical evidence for this practice is incomplete. We propose that certain pathological pain conditions require intact sympathetic innervation of the sensory nervous system at the level of the dorsal root ganglion (DRG) and that release of sympathetic transmitters enhances local inflammation and leads to pain. Our preliminary data show large, rapid, and long-lasting reduction of pain behaviors and inflammatory responses following a"microsympathectomy" (mSYMPX) in both neuropathic and inflammatory pain models. Our aims are to: 1) characterize the effects of mSYMPX on pain and on local inflammation in the DRG; 2) explore the molecular mechanisms for sympathetic regulation of inflammatory responses in the DRG; and 3) assess the functional role of sympathetic transmitters in the sympathetically mediated inflammatory responses in the DRG.

Multi-protein complexes have emerged as a mechanism for spatiotemporal specificity and efficiency in the function and regulation of myriad cellular signals. In particular, many ion channels are clustered either with the receptors that modulate them, or with other ion channels whose activities are linked. Often the clustering is mediated by scaffolding proteins, such as the AKAP79/150 protein that is a focus of this research. This research will focus on three different channels critical to nervous function. One is the"M-type" (KCNQ, Kv7) K+ channel that plays fundamental roles in the regulation of excitability in nerve and muscle. It is thought to associate with Gq/11- coupled receptors, protein kinases, calcineurin (CaN), calmodulin (CaM) and phosphoinositides via AKAP79/150. Another channel of focus is TRPV1, a nociceptive channel in sensory neurons that is also thought to be regulated by signaling proteins recruited by AKAP79/150. The third are L-type Ca2+ (CaV1.2) channels that are critical to synaptic plasticity, gene regulation and neuronal firing. This research will probe complexes containing AKAP79/150 and these three channels using"super-resolution" STORM imaging of primary sensory neurons and heterologously-expressed tissue-culture cells, in which individual complexes can be visualized at 10-20 nm resolution with visible light, breaking the diffraction barrier of physics. The researchers hypothesize that AKAP79/150 brings several of these channels together to enable functional coupling, which the researchers will examine by patch-clamp electrophysiology of the neurons. Förster resonance energy transfer (FRET) will also be performed under total internal reflection fluorescence (TIRF) or confocal microscopy, further testing for complexes containing KCNQ, TRPV1 and CaV1.2 channels. Since all three of these channels bind to AKAP79/150, the researchers hypothesize that they co-assemble into complexes in neurons, together with certain G protein-coupled receptors. Furthermore, the researchers hypothesize these complexes to not be static, but rather to be dynamically regulated by other cellular signals, which the researchers will examine using rapid activation of kinases or phosphatases. Several types of mouse colonies of genetically altered AKAP150 knock-out or knock-in mice will be utilized.

Migraine is the most common neurological disorder. Currently available treatments fail to effectively manage migraine in most patients. Development of new therapeutics has been slow due in large part to a poor understanding of the underlying pathology of migraine. Endogenous proteases, released in the meninges by resident mast cells, have been proposed as a potential driver of migraine pain via an action on protease activated receptor type 2 (PAR2). The central hypothesis is that PAR2 expression in nociceptors that project to the meninges plays a key role in the pathogenesis of migraine pain. The aims are to: 1) use the established PAR2 development pipeline to design new PAR2 antagonists with improved drug-like properties; 2) use pharmacological tools in a novel mouse migraine model to further understand the potential role of PAR2 in migraine; and 3) use mouse genetics to study the cell type–specific role of PAR2 in migraine pain.

TWIK-related spinal cord K+ (TRESK) channel is abundantly expressed in all primary afferent neurons (PANs) in trigeminal ganglion (TG) and dorsal root ganglion (DRG), mediating background K+ currents and controlling the excitability of PANs. TRESK mutations cause migraine headache but not body pain in humans, suggesting that TG neurons are more vulnerable to TRESK dysfunctions. TRESK knock out (KO) mice exhibit more robust behavioral responses than wild-type controls in mouse models of trigeminal pain, especially headache. We will investigate the mechanisms through which TRESK dysfunction differentially affects TG and DRG neurons. Based on our preliminary finding that changes of endogenous TRESK activity correlate with changes of the excitability of TG neurons during estrous cycles in female mice, we will examine whether estrogen increases migraine susceptibility in women through inhibition of TRESK activity in TG neurons. We will test the hypothesis that frequent migraine attacks reduce TG TRESK currents.

Neuropathic pain conditions are difficult to treat, and novel non-narcotic analgesics are desperately needed. The G protein-coupled receptor 160 (GPR160) has emerged as a novel target for analgesic development, as GPR160 in the spinal cord may play a role in the transition from acute to chronic pain. Cocaine- and Amphetamine-Regulated transcript peptide (CARTp) was identified as a ligand for GPR160. Blocking endogenous CARTp signaling in the spinal cord attenuates neuropathic pain, whereas intrathecal injection of CARTp evokes painful hypersensitivity in rodents through GPR160-dependent extracellular signal-regulated kinase (ERK) and cyclic AMP response element-binding pathways (CREB). This project will isolate and biochemically characterize GPR160 and establish methods for biochemical characterization of GPR160 interaction with CARTp activator. Researchers will miniaturize and optimize biochemical assay and scale up protein production for future high throughput biochemical screening to identify potent inhibitors of GPR160 activation. These studies are critical for defining the molecular mechanism of CARTp/GPR160 interactions and initiating large-scale screens for new inhibitors to develop novel therapeutics.

Opioids and other addictive substances have powerful rewarding properties that drive the development of addiction. They also have aversive properties that motivate their avoidance and protect against addiction. This project will explore the role of Type 2 Taste Receptor proteins (Tas2Rs or T2Rs) in regulating the aversive properties of opioids, potentially establishing an entirely new class of receptors that can be targeted for the development of novel addiction therapeutics.

This International Cooperative Biodiversity Group application aims to discover and develop small molecule drug leads from cultured marine microbes and diverse coral reef organisms collected from Fiji and the Solomon Islands. Drug discovery efforts will focus on four major disease areas of relevance to the United States and low- and middle-income countries: infectious disease, including tuberculosis and drug-resistant pathogens; neglected tropical diseases, including hookworms and roundworms; cancer; and neurodegenerative and central nervous system disorders. Screening in these therapeutic areas will be performed in collaboration with two major pharmaceutical companies, two highly respected academic groups, and various testing centers and government resources that are available to facilitate drug discovery and development. The acquisition of source material for this program will be linked to biotic surveys, informed by ecological investigations addressing the chemical mediation of biotic interactions, and enriched using ecology-based strategies designed to maximize secondary metabolite production and detection.

An International Cooperative Biodiversity Group with an interdisciplinary leadership team of physicians, pharmacologists, evolutionary biologists, and chemists will discover and develop therapeutic agents produced by Brazilian symbiotic bacteria. The team will target three therapeutic areas: 1) infectious fungal pathogens, 2) Chagas disease and leishmaniasis, and 3) cancers of the blood. All three areas represent major threats to human health that need to be addressed with new therapeutic agents. Internationally, invasive fungal diseases kill more people than malaria or TB, while Chagas disease imposes a special burden on Brazil, killing as many Brazilians as TB. Leishmaniasis has now passed Chagas disease in the Brazilian population. Despite major improvements in cancer chemotherapy, cancer is projected to result in 8 million deaths internationally this year (13% of all deaths, WHO) and an estimated 13 million per year by 2030.

This project aims to develop and clinically validate a 64-channel spinal cord stimulation therapy for treating chronic neuropathic pain of the lower extremities, groin, and lower back. With an increased channel count and the ability to precisely target medial and lateral structures of the spinal cord, the system will treat chronic pain with greater efficacy and reduced side effects. This project will pursue a safe, effective, and non-addictive treatment for neuropathic pain through the testing of enhanced HD64 active leads to be manufactured under GMP regulations. The leads will then undergo electrical, mechanical, biocompatibility, and sterilization testing before being tested in a 10-subject early feasibility study.