Mitsukawa Kayo, Yamamoto Rina, Ofner Silvio, Nozulak Joachim, Pescott Oliver, Lukic Snezana, Stoehr Natacha, Mombereau Cedric, Kuhn Rainer, McAllister Kevin H, van der Putten Herman, Cryan John F, Flor Peter J
Neuroscience Research, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland.
Proc Natl Acad Sci U S A. 2005 Dec 20;102(51):18712-7. doi: 10.1073/pnas.0508063102. Epub 2005 Dec 9.
Metabotropic glutamate receptor (mGluR) subtypes (mGluR1 to mGluR8) act as important pre- and postsynaptic regulators of neurotransmission in the CNS. These receptors consist of two domains, an extracellular region containing the orthosteric agonist site and a transmembrane heptahelical domain involved in G protein activation and recognition of several recently synthesized pharmacological modulators. The presynaptic receptor mGluR7 shows the highest evolutionary conservation within the family, but no selective pharmacological tool was known. Here we characterize an mGluR7-selective agonist, N,N'-dibenzhydrylethane-1,2-diamine dihydrochloride (AMN082), which directly activates receptor signaling via an allosteric site in the transmembrane domain. At transfected mammalian cells expressing mGluR7, AMN082 potently inhibits cAMP accumulation and stimulates GTPgammaS binding (EC50-values, 64-290 nM) with agonist efficacies comparable with those of L-2-amino-4-phosphonobutyrate (L-AP4) and superior to those of L-glutamate. AMN082 (< or = 10 microM) failed to show appreciable activating or inhibitory effects at other mGluR subtypes and selected ionotropic GluRs. Chimeric receptor studies position the binding site of AMN082 in the transmembrane region of mGluR7, and we demonstrate that this allosteric agonist has little, if any, effect on the potency of orthosteric ligands. Here we provide evidence for full agonist activity mediated by the heptahelical domain of family 3 G protein-coupled receptors (which have mGluR-like structure) that may lead to drug development opportunities. Further, AMN082 is orally active, penetrates the blood-brain barrier, and elevates the plasma stress hormones corticosterone and corticotropin in an mGluR7-dependent fashion. Therefore, AMN082 is a valuable tool for unraveling the role of mGluR7 in stress-related CNS disorders.
代谢型谷氨酸受体（mGluR）亚型（mGluR1至mGluR8）是中枢神经系统中神经传递重要的突触前和突触后调节剂。这些受体由两个结构域组成，一个是包含正构激动剂位点的细胞外区域，另一个是参与G蛋白激活以及识别几种最近合成的药理调节剂的跨膜七螺旋结构域。突触前受体mGluR7在该家族中显示出最高的进化保守性，但尚无已知的选择性药理工具。在此，我们对一种mGluR7选择性激动剂N，N'-二苯甲基乙烷-1,2-二胺二盐酸盐（AMN082）进行了表征，它通过跨膜结构域中的变构位点直接激活受体信号传导。在转染表达mGluR7的哺乳动物细胞中，AMN082能有效抑制cAMP积累并刺激GTPγS结合（EC50值为64 - 290 nM），其激动剂效力与L-2-氨基-4-膦酸丁酸（L-AP4）相当，且优于L-谷氨酸。AMN082（≤10 μM）在其他mGluR亚型和选定的离子型谷氨酸受体上未显示出明显的激活或抑制作用。嵌合受体研究将AMN082的结合位点定位在mGluR7的跨膜区域，并且我们证明这种变构激动剂对正构配体的效力几乎没有影响（如果有影响的话也很小）。在此，我们提供了由3类G蛋白偶联受体（具有mGluR样结构）的七螺旋结构域介导的完全激动剂活性的证据，这可能会带来药物开发机会。此外，AMN082具有口服活性，能穿透血脑屏障，并以mGluR7依赖的方式升高血浆应激激素皮质酮和促肾上腺皮质激素。因此，AMN082是阐明mGluR7在应激相关中枢神经系统疾病中作用的有价值工具。
