Druggability of Phospholipase C-β Isoforms with Small Peptides Patterned after the Autoinhibitory XY Linker
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The phospholipase C-β (PLCβ) signaling pathway plays a pivotal role in peripheral nociception, particularly during inflammation and pain transduction. Despite their validation as important therapeutic targets, PLCβ 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 PLCβ activity. We report that peptides patterned after this motif inhibited PIP 2 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 PLCβ inhibitors with in vivo anti-inflammatory and antinociceptive activity, providing pharmacological tools for this enzyme family.
SIGNIFICANCE
Phospholipases C (PLC) are intracellular signaling proteins, with PLCβ 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 PLCβ 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 PLCβ 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.
