Druggability of Phospholipase C-β Isoforms with Small Peptides Patterned after the Autoinhibitory XY Linker

Abstract

The phospholipase C-{beta} (PLC{beta}) signaling pathway plays a pivotal role in peripheral nociception, particularly during inflammation and pain transduction. Despite their validation as important therapeutic targets, PLC{beta} isoforms are yet undruggable due to the difficulties to identify potent and selective modulators. Here, we addressed this question and used the autoinhibitory XY linker present in these enzymes as a source of peptide inhibitors of PLC{beta} activity. We report that peptides patterned after this motif inhibited PIP2 hydrolysis and the consequent calcium release from endoplasmic reticulum. In primary nociceptor cultures, active peptides notably attenuated bradykinin-induced electrogenesis and TRPV1 sensitization, thus reducing nociceptor hyperexcitability. Noteworthy, intraplantar administration of a lead peptide prevented inflammation and hypersensitivity in a mouse model of inflammatory pain. Collectively, our findings indicate that peptides patterned after the autoinhibitory XY linker act as selective PLC{beta} inhibitors with in vivo anti-inflammatory and antinociceptive activity, providing pharmacological tools for this enzyme family. SIGNIFICANCEPhospholipases C (PLC) are intracellular signaling proteins, with PLC{beta} isoforms crucial in somatosensory neuron signaling. These enzymes interact with G-protein coupled receptors for pro-inflammatory and algesic agents, sensitizing nociceptors by increasing their excitability. Despite their importance, selective PLC{beta} modulators remain limited; U73122 is widely used, though it lacks specificity and has off-target effects. Here, we introduce peptide inhibitors based on the XY autoinhibitory motif that selectively block PLC{beta} activity, reduce bradykinin-induced neuronal responses and TRPV1 sensitization, and do not affect other PLC isoforms. In a murine inflammatory pain model, local administration of our lead peptide showed both anti-inflammatory and antinociceptive effects, highlighting its therapeutic potential. This approach expands the toolkit of PLC-isoform selective modulators for drug development.