From a Cone Snail Toxin to a Competitive MC4R Antagonist

Abstract

The melanocortin 4 receptor (MC4R) plays a role in energy homeostasis and represents a target for treating energy balance disorders. For decades, synthetic ligands have been derived from MC4R endogenous agonists and antagonists, such as setmelanotide used to treat rare forms of genetic obesity. Recently, animal venoms have demonstrated their capacity to provide melanocortin ligands with toxins from a scorpion and a spider. Here, we described a cone snail toxin, N-CTX-Ltg1a, with a nanomolar affinity for hMC4R but unrelated to any known toxins or melanocortin ligands. We then derived from the conotoxin the linear peptide HT1-0, a competitive antagonist of G s, G 15, and β-arrestin2 pathways with a low nanomolar affinity for hMC4R. Similar to endogenous ligands, HT1-0 needs hydrophobic and basic residues to bind hMC4R. Altogether, it represents the first venom-derived peptide of high affinity on MC4R and paves the way for the development of new MC4R antagonists.

Natural Peptide Toxins as an Option for Renewed Treatment of Type 2 Vasopressin Receptor-Related Diseases

“…Indeed, several GPCR toxins with original activities and promising applications have been described recently. These toxins act on the M2 muscarinic receptor implied in arterial contraction [ 80 ], on the melanocortin type 4 receptor implied in energy homeostasis [ 81 , 82 ] and on angiotensin receptors implied in cardiovascular homeostasis [ 83 ].…”