Confo Therapeutics N.V, Ghent, Belgium.
Materials and Structural Analysis, Thermo Fisher Scientific, Eindhoven, The Netherlands.
Nat Commun. 2024 Oct 1;15(1):7029. doi: 10.1038/s41467-024-50827-7.
The melanocortin receptor 4 (MC4R) belongs to the melanocortin receptor family of G-protein coupled receptors and is a key switch in the leptin-melanocortin molecular axis that controls hunger and satiety. Brain-produced hormones such as α-melanocyte-stimulating hormone (agonist) and agouti-related peptide (inverse agonist) regulate the molecular communication of the MC4R axis but are promiscuous for melanocortin receptor subtypes and induce a wide array of biological effects. Here, we use a chimeric construct of conformation-selective, nanobody-based binding domain (a ConfoBody Cb80) and active state-stabilized MC4R-β2AR hybrid for efficient de novo discovery of a sequence diverse panel of MC4R-specific, potent and full agonistic nanobodies. We solve the active state MC4R structure in complex with the full agonistic nanobody pN162 at 3.4 Å resolution. The structure shows a distinct interaction with pN162 binding deeply in the orthosteric pocket. MC4R peptide agonists, such as the marketed setmelanotide, lack receptor selectivity and show off-target effects. In contrast, the agonistic nanobody is highly specific and hence can be a more suitable agent for anti-obesity therapeutic intervention via MC4R.
黑素皮质素受体 4（MC4R）属于 G 蛋白偶联受体黑素皮质素受体家族，是控制饥饿和饱腹感的瘦素-黑素皮质素分子轴的关键开关。大脑产生的激素，如α-黑色素细胞刺激素（激动剂）和刺鼠相关肽（反向激动剂），调节 MC4R 轴的分子通讯，但对黑素皮质素受体亚型具有混杂性，并诱导广泛的生物学效应。在这里，我们使用构象选择性、基于纳米体的结合域（ConfoBody Cb80）和活性状态稳定的 MC4R-β2AR 杂种的嵌合构建体，有效地从头发现了一系列序列多样的、具有高亲和力和完全激动作用的 MC4R 特异性纳米体。我们以 3.4Å 的分辨率解决了与完全激动性纳米体 pN162 结合的活性状态 MC4R 结构。该结构显示出与 pN162 结合的独特相互作用，其结合深置于正位口袋中。MC4R 肽激动剂，如市售的 setmelanotide，缺乏受体选择性，并显示出脱靶效应。相比之下，激动性纳米体具有高度特异性，因此可以作为通过 MC4R 进行抗肥胖治疗干预的更合适的药物。
