Therapeutic potential of GLS1 inhibition for the pharmacotherapy of schizophrenia

描述(申请人提供)：调节失调的谷氨酸能神经传递与精神分裂症的精神病理密切相关。最近的研究强调了突触前减少谷氨酸传递的治疗前景。我们已经证明，谷氨酰胺酶(GLS1)基因敲除小鼠的神经元在谷氨酸能突触传递中显示出活性依赖的突触前减少。虽然GLS1基因敲除的小鼠在出生后不久就会死亡，但具有一个功能GLS1等位基因(GLS1hets)的GLS1单倍体不足的小鼠非常正常。引人注目的是，功能成像显示，小鼠的海马区有局灶性代谢低下，主要涉及CA1亚区和下丘脑，这与精神分裂症患者最近的成像结果完全相反。此外，当用前精神病药物挑战时，GLS1HET小鼠表现出与精神分裂症韧性一致的行为和神经化学表型。因此，降低谷氨酰胺酶活性似乎对精神分裂症有治疗潜力。为了将这一发现转化为临床应用，我们建议测试GLS1 HET小鼠实际上对一系列亲精神分裂症侮辱具有弹性的假设。利用组织特异性的GLS1缺失，我们将询问海马区的低代谢是否源于海马区GLS1的减少，以及这种调节是否足以产生弹性表型。为了开始了解弹性表型对精神分裂症病理生理学的影响，我们将确定海马体中作为低活动度特征基础的突触变化。为了直接测试GLS1抑制的治疗潜力，我们将在成年小鼠中诱导GLS1单倍性不足，进行我们所称的遗传药物治疗，以调查干预的急性和慢性影响。我们将在发育早期诱发GLS1单倍体功能不全，以探索早期干预和神经发育贡献的潜在好处。最后，我们将进行高通量筛选，以确定具有纳摩尔功效的小分子GLS1抑制剂作为候选药物。GLS1抑制剂不仅对精神分裂症有治疗潜力，而且对中风和其他涉及兴奋性毒性的神经退行性疾病也有治疗潜力，因此具有中枢神经系统活性的GLS1抑制剂可能具有广阔的治疗前景。总之，计划中的临床前研究和候选药物的确定应该为GLS1抑制作为一种新的精神分裂症药物疗法走向临床试验提供基础。 与公共卫生相关：我们最近产生了一套连贯的临床和基本发现，提出了一种假设，即通过药物抑制GLS1基因的产物磷酸激活的谷氨酰胺酶，应该证明对精神分裂症有疗效。我们建议使用GLS1缺陷小鼠作为概念验证来检验这一假设。其目的是深入了解GLS1抑制的治疗基础，阐明涉及的电路，并获得必要的知识，走向临床药物开发。

DESCRIPTION (provided by applicant): Dysregulated glutamatergic neurotransmission has been strongly implicated in the psychopathology of schizophrenia. Recent studies have highlighted the therapeutic promise of presynaptic reductions in glutamate transmission. We have shown that neurons from glutaminase (GLS1) knockout mice show an activity-dependent presynaptic reduction in glutamatergic synaptic transmission. While GLS1 knockout mice die shortly after birth, GLS1 haploinsufficient mice with one functional GLS1 allele (GLS1 hets) are remarkably normal. Strikingly, functional imaging reveals that the mice have focal hypometabolism in the hippocampus, mainly involving the CA1 subregion and the subiculum that is the exact inverse of recent imaging findings in patients with schizophrenia. Moreover, when challenged with pro-psychotic drugs, GLS1 het mice manifest behavioral and neurochemical phenotypes consistent with schizophrenia resilience. Thus, reducing glutaminase activity appears to have therapeutic potential for schizophrenia. To translate this discovery to clinical application, we propose testing the hypothesis that GLS1 het mice are in fact resilient to a range of pro-schizophrenic insults. Using tissue-specific GLS1 deletions, we will ask whether the hippocampal hypometabolism arises from the reduction in GLS1 in the hippocampus, and whether this modulation is sufficient to produce the resilience phenotype. To begin to understand the implications of the resilience phenotype for the pathophysiology of schizophrenia, we will identify the synaptic alterations in the hippocampus that underlie the hypoactivity profile. To test the therapeutic potential of GLS1 inhibition directly, we will induce GLS1 haploinsufficiency in adult mice, doing what we term genetic-pharmacotherapy, to investigate the acute and chronic effects of the intervention. We will induce GLS1 haploinsufficiency earlier in development to explore potential benefits of early intervention and neurodevelopmental contributions. Finally, we will do high-throughput screening to identify small-molecule GLS1 inhibitors with nanomolar efficacy as drug candidates. GLS1 inhibition has therapeutic potential not only for schizophrenia, but also for stroke, and other neurodegenerative disorders involving excitotoxicity, so a CNS-active GLS1 inhibitor will likely have broad therapeutic promise. In summary, the planned preclinical studies together with identification of drug candidates should provide the basis for movement of GLS1 inhibition towards clinical trials as a novel pharmacotherapy for schizophrenia. PUBLIC HEALTH RELEVANCE: We have recently generated a coherent set of clinical and basic findings raising the hypothesis that pharmacological inhibition of phosphate-activated glutaminase, the product of gene GLS1, should prove therapeutic in schizophrenia. We propose to test this hypothesis using GLS1-deficient mice as a proof of concept. The aims are to gain insight into the therapeutic basis for GLS1 inhibition, to elucidate the circuitry involved, and to gain the necessary knowledge for moving toward clinical drug development.