Molecular Regulation of the Kappa Opioid Receptor by 14-3-3 gamma

About This Grant

PROJECT SUMMARY / ABSTRACT The cost of treating pain in the United States exceeds $500 billion annually, yet pain remains a large problem with nearly one-third of the population reporting chronic pain. Opioids are very potent analgesics (i.e. relieve pain), but also have many negative effects such as addiction, sedation, and deadly respiratory depression. These adverse effects have led to the opioid overdose crisis, which now claims over 80,000 American lives per year. As these dangerous adverse effects are mediated by the central nervous system, a promising approach for the safe and non-addictive treatment for pain is to target the peripheral nervous system. Inhibiting these neurons can alleviate pain by preventing synaptic transmission of painful signals to the brain. The long-term goal of this project is to understand the mechanisms underlying the long-term inhibition of opioid receptor signaling that are known to occur in peripheral neurons. Our previous work has identified that 14-3-3γ, a highly conserved scaffolding protein, is a critical mediator of the long-term inhibition of the kappa opioid receptor (KOR) by norbinaltorphimine. We demonstrated that induced expression of 14-3-3γ blocks KOR-mediated antinociception and antinociceptive signaling. This inhibition appeared to be selective to KOR and did not reduce KOR-mediated signaling that has been linked to peripheral sensitization. In effect, expression of 14-3-3γ in peripheral neurons biased KOR-mediated signaling away from analgesic pathways and towards pronociceptive pathways. This proposed work will use multidisciplinary methods to investigate the apparent specific interaction between 14-3-3γ and KOR, and will pharmacologically define the impact on cellular signaling. Specifically, 1) the impact of 14-3-3γ expression on the transducer profile or localization of KOR will be determined in primary cultures of peripheral sensory neurons using biosensors and microscopy, 2) molecular models, mutagenesis, live-cell microscopy, and biochemical assays will elucidate the molecular specificity between KOR and 14-3-3γ, and 3) structural determination and super-resolution microscopy methods will determine the molecular mechanism of inhibition. Additionally, these studies will serve as an outstanding training vehicle. My long-term goal is to become an independent scientist that studies structure, function, and impact of opioid receptor regulation and signaling. The innovative research approach described within this application will ensure that I have comprehensive training in the fields of pharmacology, biochemistry, and structural biology to form the basis of my future research career. Ultimately, this grant will lay the foundation for a successful career as an independent investigator studying mechanisms of opioid receptor signaling and regulation, and how these insights can be leveraged to help human health.