Structure-function Analysis of TrkA - PLC³ and the development of inhibitors based on such interactions that play an analgesic role

• Grant number: 22/06958-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Effective date (Start): December 01, 2022
• Effective date (End): June 01, 2025
• Field of knowledge: Biological Sciences - Biochemistry
• Principal Investigator: Deborah Schechtman
• Grantee: Allan Pradelli Roldão
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 19/06982-6 - Characterization and development of new modulators of the TrkA and PKMzeta pathways in inflammatory and chronic pain, AP.TEM
• Associated scholarship(s): 23/03290-1 - Development of a platform for crystallization of PLC³ SH2 domains bound to peptides to map target regions for selective inhibitors, BE.EP.DR

Abstract

Nociception consists of the process of thermal and mechanical stimuli by peripheral neurons (nociceptors). In an inflammatory context caused by tissue injury, there is the recruitment of immune cells that secrete several pro-inflammatory factors. Amongst them, the nerve growth factor (NGF), acts on the process of hyperalgesia, which is an increased response on stimuli perception of the injured region. Several studies report the importance of NGF in this phenomenon through the activation of its high affinity receptor, TrkA. This receptor is coupled to a tyrosine kinase, that flares some signaling cascades involved in the development and maintenance of nociception, such as MAP kinase and PI3K/Akt pathways. In the context of pain, there is another pathway flared by the direct activation of TrkA: the PLC³ (phospholipase C³) pathway. The activation of this lipase leads to the activation of a cations channel, TRPV1, present on the nociceptors membrane, and depolarization. The role of TrkA on sensorial pain is being investigated mainly by the presence of point mutations on the kinase domain that lead to the lack of pain sensitization on the naked mole rat and in patients with the Congenital Insensitivity to Pain with Anhidrosis (CIPA). In vivo studies conducted at our laboratory indicated that the inhibition of the interaction/activation of PLC³ and TrkA using a mimetic peptide to the C-terminus tail of the receptor led to analgesia. Thus, it is of great interest to study on a structural basis the specificity of the interaction of TrkA and PLC³, an interaction mediated by PLC³ SH2 domains. Our goal is to study how we can specifically inhibit such interaction. Given that PLC³ has two SH2 binding domains, our interest is to investigate the affinity of these domains by different growth factor receptors coupled to tyrosine kinases through modeling and binding studies. This will give us a hint regarding the selectivity of the domains by the receptors. We are also interested in finding alternative drug leads derived from our peptide, such as peptoids or retro inverso peptides, or peptidomimetic drugs that can inhibit the interaction TrkA-PLC³. Crystallography and NMR studies of the complex SH2/peptides might help us to develop new molecules and help to determine the specificity of peptides.