D-amino acid scan of γ-melanocyte-stimulating hormone:: Importance of Trp8 on human MC3 receptor selectivity
D-amino acid scan of γ-melanocyte-stimulating hormone:: Importance of Trp8 on human MC3 receptor selectivity
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DOI：
10.1021/jm000211e
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发表时间：
2000-12-28
影响因子：
7.3
通讯作者：
Hruby, VJ
中科院分区：
文献类型：
--
作者：
Grieco, P;Balse, PM;Hruby, VJ
在我们寻找有效的受体选择性激动剂和拮抗剂时，我们在此报告了短肽γ-黑素细胞刺激激素（γ-MSH）每个位置的 D-氨基酸取代结果。天然γ-MSH在所有三种受体（即人MC3、MC4和MC5）上表现出弱结合，并且在MC3R上的选择性比MC4R和MC5R高1-2个数量级。用相应的D-异构体依次取代γ-MSH序列中的每个残基产生的类似物大多数具有比天然肽更弱的结合亲和力，除了两个类似物之外。对于 DTrp(8) 类似物，与天然分子相比，MC3R 的结合亲和力增加了约 1 个数量级 (IC50 = 6 nM)，与 MC IR 和 MC5R 的活性相比，MC3R 的选择性增加了 2 个数量级。与天然肽相比，DPhe(6) 类似物对 MC3R 的效力高出约 10 倍 (IC50 = 8.8 nM)，但缺乏亚型选择性。对人 MC3R、MC4R 和 MC5R 中细胞内 cAMP 积累的测量表明，天然肽对 MC3R 显示出有效的活性 (EC50 = 5.9 nM)，并且与 MC4R 和 MC5R 相比，对该受体的选择性约为 50-100 倍。与 MC4R 和 MC5R 相比，DArg(10) (EC50 = 35 nM) 和 DPhe(11) (EC50 = 11 nM) 类似物对 MC3R 的选择性分别高出 1 和 2 个数量级。与 MC4R 和 MC5R 相比，DTrp(8) 化合物 (EC50 = 0.33 nM) 对 MC3R 的选择性分别提高了约 300 倍和 250 倍。最后，DTyr(1) 肽对 MC3R (EC50 = 12 nM) 的选择性是 MC4R 和 MC5R 的 40-200 倍。一般来说，趋势是芳香族残基 1、6、8 和 11 以及碱性残基 Arg(10)（而非 Arg(7)）的 D-氨基酸取代导致 MC3R 相对于 MC4R 和 MC5R 的选择性增加，并且仅观察到激动剂活性。因此，本研究中鉴定的 γ -MSH 的关键残基包括芳香族残基 1、6、8 和 11 以及碱性残基 Arg(10)（但不是 Arg(7)），它们对于 MC3 相对于 MC4 和 MC5 亚型的选择性非常重要。此外，该研究揭示了 8 位 DTrp 在赋予效力和选择性方面的极端重要性，因为这是迄今为止报道的人类 MC3R 最具选择性的类似物。
In our search;for potent and receptor-selective agonists and antagonists, we report here the results of D-amino acid substitution at each position of the short peptide gamma -melanocyte-stimulating hormone (gamma -MSH). The native gamma -MSH shows weak binding at all three receptors (i.e., the human MC3, MC4, and MC5) and a selectivity of 1-2 orders of magnitude at the MC3R over the MC4R and MC5R. Sequential replacement of each residue in the gamma -MSH sequence with the corresponding D-isomer results in analogues which mostly have weaker binding affinity than the native peptide, except for two analogues. For the DTrp(8) analogue, there is an increase in binding affinity by about 1 order of magnitude (IC50 = 6 nM) at the MC3R compared-with that of the natural molecule and an increase in selectivity for the MC3R by 2 orders of magnitude compared with the activity at the MC IR and MC5R. The DPhe(6) analogue is about 10-fold more potent (IC50 = 8.8 nM) at the MC3R compared with the native peptide but lacks subtype selectivity. Measurement of the intracellular cAMP accumulation in human MC3R, MC4R, and MC5R revealed that the native peptide shows potent activity at the MC3R (EC50 = 5.9 nM)and is about 50-100-fold selective at this receptor compared with the MC4R and MC5R. The DArg(10) (EC50 = 35 nM) and DPhe(11) (EC50 = 11 nM) analogues are selective for the MC3R by 1 and 2 orders of magnitude compared with the MC4R and MC5R, respectively. The DTrp(8) compound (EC50 = 0.33 nM) shows about 300- and 250-fold increase in selectivity at the MC3R compared with the MC4R and MC5R, respectively. Finally, the DTyr(1) peptide is selective for the MC3R (EC50 = 12 nM) by 40-200-fold compared with the MC4R and MC5R. In general, the trend is that D-amino acid substitutions of the aromatic residues 1, 6, 8, and 11 and the basic residue Arg(10), but not Arg(7), result in an increase in MC3R selectivity over the MC4R and MC5R and only agonist activity is observed. Thus, the key residues of gamma -MSH identified in this study include the aromatic residues 1, 6, 8, and 11 and the basic residue Arg(10) (but not Arg(7)), as important for MC3 selectivity over the MC4 and MC5 subtypes. Further, the study reveals the extreme importance of DTrp at position 8 in imparting potency and selectivity since this is the most selective analogue for the human MC3R reported thus far.