RNA-dependent protein kinase as a mediator of opioid receptor signaling: exploring protein-protein interactions underlying analgesia, tolerance, and hyperalgesia during pathological pain states.

• Grant number: 24/09222-0
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: January 20, 2025
• End date: January 19, 2026
• Field of knowledge: Interdisciplinary Subjects
• Principal Investigator: Guilherme de Araújo Lucas
• Grantee: Leonardo Cirqueira Pimentel
• Supervisor: Carmen Domene
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Institution abroad: University of Bath, England
• Associated to the scholarship: 23/07855-3 - RNA-dependent protein kinase as a mediator of opioid receptor signaling: exploring protein-protein interactions underlying analgesia, tolerance, and hyperalgesia during pathological pain states., BP.PD

Abstract

Chronic pain has always been a significant health issue, leading to huge demand on healthcare system. Opioids are the most successful alternative to relieve severe pain, with applications in diverse conditions such as post-surgical pain, musculoskeletal, abdominal, and chest pain, management of palliative/end-of-life care and cancer. Among the well-documented drawbacks of addiction and tolerance, opioid repeated exposure leads also to a paradoxical pain. Opioid activation of µ-opioid receptor-1 (MOR1) triggers beta-Arrestin-2 which, in turn, causes MOR1 internalization and desensitization of the transient receptor potential vanilloid 1 channel (TRPV1). Our preliminary results show that TRPV1 is directly involved in post-inflammatory thermal hyperalgesia, through activation by RNA-dependent protein kinase (PKR), a sentinel molecule that reacts to pro-inflammatory stimuli. Additionally, there is strong evidence that opioid-induced pain and thermal hyperalgesia share a common mechanism. Our hypothesis is that PKR modulates these effects that first seem unrelated. This proposal aims to combine experimental and computational methods to evaluate the interaction between PKR and TRPV1, MOR1 and beta-arrestin-2. The effect of opioid administration on the expression profile and the phosphorylation status of PKR, PACT, ²-arrestin-2, and MOR1 will be monitored in the spinal cord dorsal horn neurons of mice submitted to incisional or burning inflammatory pain. In addition, in silico methods will determine important structural information about the interactions, such as the complex pose, key residues for the interactions and phosphorylation sites. Moreover, virtual screening will be employed to prospect ligands that could modulate complexes formation. Understanding the mechanism of hyperalgesia and opioid induced pain should offer valuable insights regarding chronic pain mechanisms, thus yielding new possibilities to improve the well-being of people whom chronic pain is a serious burden.