Development of mGlu7 receptor allosteric modulators for neurological and psychiatric disorders

项目摘要 代谢型谷氨酸受体7（mGlu 7）在突触前广泛调节神经递质的释放， 中枢神经系统，是诱导海马和杏仁核长时程增强（LTP）所必需的， 这表明它在突触可塑性中起着重要作用。最近，GRM 7基因中的原发性突变与 智力障碍、刻板印象和癫痫，这些都是神经发育障碍的常见症状。 此外，我们发现临床上患者的脑中mGlu 7蛋白水平显著降低， 被诊断患有神经发育障碍，Rett综合征（RTT）。甲基的功能丧失突变 CpG结合蛋白2（MECP 2）是一种表观遗传转录调控因子，是导致RTT的主要原因，RTT是一种免疫调节因子。 导致刻板行为、运动延迟、焦虑、认知缺陷、自闭症 特征、癫痫发作和呼吸暂停。与RTT患者和模型小鼠中mGlu 7的减少一致，增强了 mGlu 7活性与小分子正变构调节剂（PAM）一起校正多种突触可塑性， 在具有Mecp 2敲除（KO）等位基因的小鼠中的认知、社会和呼吸表型。这些早期研究 采用了一种对mGlu 7与其他几种代谢型谷氨酸受体没有选择性的化合物。 我们最近优化了VU 6027459，这是一种高度选择性的mGlu 7工具，具有合适的药代动力学 用于体内啮齿动物使用的参数。使用VU 6027459，我们进一步验证了mGlu 7增强在以下中的作用： 逆转异常RTT表型。我们建议使用RTT的单基因疾病，与一个 药物开发活动，作为mGlu 7 PAM开发的临床进入途径;预计 未来的研究可以扩展到其他适应症，如原发性癫痫或精神分裂症。 我们以前的RTT研究集中在具有MECP 2/Mecp 2等位基因的患者和小鼠，该等位基因是功能性的。 null.然而，大部分RTT患者在MECP 2基因中存在单点突变，我们的研究表明， 初步数据表明，人RTT组织中mGlu 7表达水平存在差异， 特定的突变。这表明在这种疾病中进行疗效测试的疗法需要临床前研究。 在反映这种临床异质性的各种小鼠模型中进行验证。使用扩展的临床样本集 和小鼠模型不同的突变，我们将测试的假设，mGlu 7水平可能是差异 在不同MECP 2突变的背景下受到影响，并确定特定突变是否是疾病状态的基础 最有可能对mGlu 7 PAM表现出有效和安全的反应，或者mGlu 7 PAM是否在整个研究中具有效用。 整个突变谱最后，我们将进行生物标志物研究，建立在我们的发现，Mecp 2- 缺陷小鼠在整个病程中表现出EEG频谱变化和REM睡眠减少。这些 研究结果反映了RTT患者的睡眠异常，这表明EEG代表了临床上可翻译的 和非侵入性生物标志物

PROJECT SUMMARY Metabotropic glutamate receptor 7 (mGlu7) regulates presynaptic neurotransmitter release widely throughout the CNS and is required for the induction of long-term potentiation (LTP) in the hippocampus and amygdala, suggesting a central role in synaptic plasticity. Recently, primary mutations in the GRM7 gene have been linked to intellectual disability, stereotypies, and seizures, symptoms common in neurodevelopmental disorders. Additionally, we have found that mGlu7 protein levels are significantly reduced in the brains of patients clinically diagnosed with the neurodevelopmental disorder, Rett syndrome (RTT). Loss-of-function mutations in Methyl CpG Binding Protein 2 (MECP2), an epigenetic regulation of transcription, are the major cause of RTT, which is a disease resulting in the development of stereotyped behaviors, motor delays, anxiety, cognitive deficits, autistic features, seizures, and apneas. Consistent with reductions in mGlu7 in RTT patients and model mice, potentiating mGlu7 activity with small molecule positive allosteric modulators (PAMs) corrects multiple synaptic plasticity, cognitive, social, and respiratory phenotypes in mice with an Mecp2 knockout (KO) allele. These early studies employed a compound that was not selective for mGlu7 versus several other metabotropic glutamate receptors. We have recently optimized VU6027459, a highly selectivity mGlu7 tool that exhibits suitable pharmacokinetic parameters for in vivo rodent use. Using VU6027459, we have further validated a role for mGlu7 potentiation in reversing abnormal RTT phenotypes. We propose to use the monogenetic disorder of RTT, in tandem with a drug development campaign, as a clinical entry path for the development of mGlu7 PAMs; it is anticipated that future studies could then expand into alternate indications, such as primary epilepsies or schizophrenia. Our previous RTT studies have focused on patients and mice with an MECP2/Mecp2 allele that is a functional null. A large proportion of RTT patients, however, have single point mutations in the MECP2 gene, and our preliminary data suggest that there are differences in mGlu7 expression levels in human RTT tissue that correlate with specific mutations. This indicates that therapeutics for efficacy testing in this disease require preclinical validation in various mouse models that reflect this clinical heterogeneity. Using an expanded clinical sample set and mice modeling different mutations, we will test the hypothesis that mGlu7 levels may be differentially impacted in the context of distinct MECP2 mutations and determine if specific mutations underlie disease states most likely to exhibit efficacious and safe responses to mGlu7 PAMs or if mGlu7 PAMs will have utility across the entire mutation spectrum. Finally, we will perform biomarker studies that build upon our findings that Mecp2- deficient mice exhibit EEG spectral changes and reductions in REM sleep across the disease course. These findings mirror sleep abnormalities seen in RTT patients, suggesting that EEG represents a clinically translatable and noninvasive biomarker for the program.