Semi-synthetic nanobody-ligand conjugates exhibit tunable signaling properties and enhanced transcriptional outputs at neurokinin receptor-1

Abstract

Antibodies have proven highly valuable for therapeutic development; however, they are typically poor candidates for applications that require activation of G protein-coupled receptors (GPCRs), the largest collection of targets for clinically approved drugs. Nanobodies (Nbs), the smallest antibody fragments retaining full antigen-binding capacity, have emerged as promising tools for pharmacologic applications, including GPCR modulation. Past work has shown that conjugation of Nbs with ligands can provide GPCR agonists that exhibit improved activity and selectivity compared to their parent ligands. The neurokinin-1 receptor (NK1R), a GPCR targeted for the treatment of pain, is activated by peptide agonists such as Substance P (SP) and neurokinin A (NKA), which induce signaling through multiple pathways (Gs, Gqand β-arrestin). In this study, we investigated whether conjugating NK1R ligands with Nbs that bind to a separate location on the receptor would provide chimeric compounds with distinctive signaling properties. We employed sortase A-mediated ligation to generate several conjugates consisting of Nbs linked to NK1R ligands. Many of these conjugates exhibited divergent and unexpected signaling properties and transcriptional outputs. For example, some Nb-NKA conjugates showed enhanced receptor binding capacity, high potency partial agonism, prolonged cAMP production, and an increase in transcriptional output associated with Gssignaling; whereas other conjugates were virtually inactive. Nanobody conjugation caused only minor alterations in ligand-induced upstream Gqsignaling with unexpected enhancements in transcriptional (downstream) responses. Our findings underscore the potential of nanobody conjugation for providing compounds with advantageous properties such as biased agonism, prolonged duration of action, and enhanced transcriptional responses. These compounds hold promise not only for facilitating fundamental research on GPCR signal transduction mechanisms but also for the development of more potent and enduring therapeutics.

Nanobody-Mediated Dualsteric Engagement of the Angiotensin Receptor Broadens Biased Ligand Pharmacology

“…To explore how the addition of interactions with the AT1R N-terminus would affect the pharmacology of peptide ligands, we exploited the high-affinity interaction (K d ~ 10 nM) between Nb6e and the 6e peptide, a 14-amino acid tag derived from E2 ubiquitin-conjugating enzyme UBC6e (Cabalteja et al, 2022a;Ling et al, 2019). We have previously used this system to create dualsteric ligands for other GPCRs (Braga Emidio and Cheloha, 2023;Cabalteja et al, 2022a;Cabalteja et al, 2022b). We inserted the 6e tag between a FLAG tag and residue 2 of human AT1R (6e-AT1R) (Fig.…”

“…In another example, semi-synthetic Nb-ligand conjugates demonstrated adjustable signaling properties and improved transcriptional outputs at neurokinin receptor-1 (Braga Emidio and Cheloha, 2023).…”