The role of ubiquitin in opioid receptor function

Opioid Receptors are responsible for determining our sensitivity to pain and are critical targets for clinical analgesics such as fentanyl and morphine. How they are regulated is critical for our understanding and the development of better pain management. Opioid receptors are typically found in the axon terminals of pain sensing neurons, often in the extremities, but by necessity are able to transmit information to the nucleus in the cell body, which may be a meter away (think of the pain from banging a toe, the cell body for that nerve is in the spine).

How does the receptor achieve this? This project will investigate this fundamental question, focussing on the role of endosomal trafficking and the axonal transport of the activated receptors, to explain how receptors are moved around the neuron, carrying information with them.

This studentship will combine the expertise in GPCR pharmacology of the Hislop lab and the protein engineering of the Sapkota lab to determine how opioid receptors are trafficked to the cell body and how this process underlies signal transduction. We will investigate the role of the ubiquitin-lysosome system in controlling opioid trafficking, that has been implicated in GPCR downregulation and is regulated by a balance of activities of ubiquitin ligases and deubiquitinating enzymes.

This exciting project will use a combination of cutting-edge BRET based biosensors and microfluidic/compartmentalised cultures to allow activation of receptors exclusively within the axon, to determine the role of ubiquitination in the regulation of opioid receptor signalling and function. The project will also exploit novel protein engineering technologies developed by the Sapkota lab (2) to control the ubiquitination level of opioid receptors.

This technology uses engineered protein connectivity to specifically target proteins for ubiquitination on demand to drive downregulation. This project will utilise this technology to ubiquitinate receptors 'on-demand' to allow exquisite control of the dynamic processes influencing receptor signalling both acutely and at the transcriptional level.

This studentship will use a diverse array of modern scientific techniques including state of the art protein engineering combined with neuronal culture and microfluidics, biochemical analysis and fluorescent imaging techniques to fully determine how opioid receptors are regulated and identifying potential targets for therapeutic intervention.