Antagonist efficacy in MORS196L mutant is affected by the interaction between transmembrane domains of the opioid receptor
Antagonist efficacy in MORS196L mutant is affected by the interaction between transmembrane domains of the opioid receptor
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DOI：
10.1124/jpet.104.076505
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发表时间：
2005-04-01
影响因子：
3.5
通讯作者：
Law, PY
中科院分区：
文献类型：
--
作者：
Claude-Geppert, PA;Liu, JH;Law, PY
在先前的研究中，我们证明了当跨膜4（TM 4）中的保守丝氨酸残基突变为亮氨酸时，拮抗剂如纳洛酮或纳洛酮作为μ阿片受体（莫尔）/δ阿片受体（DOR）嵌合受体（μ δ 2，其中从第一个细胞外环到羧基末端的DOR序列剪接到莫尔序列）的完全激动剂。然而，当莫尔的TM 4中的Ser（196）突变为Leu时，拮抗剂表现出部分激动性质。由于分子模拟研究表明受体活化过程中的跨膜运动，所观察到的部分激动性质可能是由于TM 1和TM 7相互作用。因此，构建了具有莫尔TM 1和TM 7序列（μ δ（2）μ（7）S196 L）或具有莫尔TM 1和TM 67序列（μ δ（2）μ（67）S196 L）的莫尔/DOR嵌合突变体受体以检验这种假设。通过四种阿片受体激活试验，我们发现，如果TM 1和TM 7来自不同的阿片受体，则阿片受体拮抗剂在嵌合突变受体中是完全激动剂。此外，当MORS 196 L受体突变体的两个TM 7氨基酸残基突变（T327 A和C330 S），产生具有DOR TM 7序列的突变受体时，阿片样物质拮抗剂纳洛酮表现出完全的激动性质。这些数据表明，阿片类药物拮抗剂在Ser 196突变体的疗效可以受到TM 1和TM 7之间的相互作用。
In a previous study, we demonstrated that antagonists such as naloxone or naltrexone acted as full agonists at the mu-opioid receptor (MOR)/delta-opioid receptor (DOR) chimeric receptor (mu delta 2, where the DOR sequence from the first extracellular loop to the carboxyl terminus was spliced to the MOR sequence) when a conserved serine residue in transmembrane 4 (TM4) was mutated to leucine. However, when Ser(196) in the TM4 of MOR was mutated to Leu, antagonists exhibited partial agonistic properties. Since molecular modeling studies suggested transmembrane movement during receptor activation, the observed partial agonistic properties could be due to TM1 and TM7 interaction. Hence, MOR/DOR chimeric mutant receptors with the MOR TM1 and TM7 sequence (mu delta(2)mu(7)S196L) or with the MOR TM1 and TM6/7 sequence (mu delta(2)mu(67)S196L) were constructed to test such a hypothesis. Using four tests of opioid receptor activation, we found that the opioid antagonists were full agonists in chimeric mutant receptor if the TM1 and TM7 were from different opioid receptors. Additionally, when two of the TM7 amino acid residues of MORS196L receptor mutants were mutated (T327A and C330S), resulting in a mutant receptor with DOR TM7 sequence, opioid antagonist naloxone exhibited full agonistic properties. These data suggest that the efficacy of opioid antagonists in the Ser196 mutant can be affected by the interaction between TM1 and TM7.