Computationally Guided Identification of Allosteric Agonists of the Metabotropic Glutamate 7 Receptor

Therapeutic Potential for Metabotropic Glutamate Receptor 7 Modulators in Cognitive Disorders

Metabotropic glutamate receptor 7 (mGlu7) is the most highly conserved and abundantly expressed mGlu receptor in the human brain. The presynaptic localization of mGlu7, coupled with its low affinity for its endogenous agonist, glutamate, are features that contribute to the receptor's role in modulating neuronal excitation and inhibition patterns, including long-term potentiation, in various brain regions. These characteristics suggest that mGlu7 modulation may serve as a novel therapeutic strategy in disorders of cognitive dysfunction, including neurodevelopmental disorders that cause impairments in learning, memory, and attention. Primary mutations in the GRM7 gene have recently been identified as novel causes of neurodevelopmental disorders, and these patients exhibit profound intellectual and cognitive disability. Pharmacological tools, such as agonists, antagonists, and allosteric modulators, have been the mainstay for targeting mGlu7 in its endogenous homodimeric form to probe effects of its function and modulation in disease models. However, recent research has identified diversity in dimerization, as well as trans-synaptic interacting proteins, that also play a role in mGlu7 signaling and pharmacological properties. These novel findings represent exciting opportunities in the field of mGlu receptor drug discovery and highlight the importance of further understanding the functions of mGlu7 in complex neurologic conditions at both the molecular and physiologic levels. SIGNIFICANCE STATEMENT: Proper expression and function of mGlu7 is essential for learning, attention, and memory formation at the molecular level within neural circuits. The pharmacological targeting of mGlu7 is undergoing a paradigm shift by incorporating an understanding of receptor interaction with other cis- and trans- acting synaptic proteins, as well as various intracellular signaling pathways. Based upon these new findings, mGlu7's potential as a drug target in the treatment of cognitive disorders and learning impairments is primed for exploration.

Discovery of : A Highly Potent, Selective, and CNS Penetrant mGluR7 Allosteric Agonist

The low affinity metabotropic glutamate receptor mGluR₇ has been implicated in numerous CNS disorders; however, a paucity of potent and selective activators has hampered full delineation of the functional role and therapeutic potential of this receptor. In this work, we present the identification, optimization, and characterization of highly potent, novel mGluR₇ agonists. Of particular interest is the chromane CVN636, a potent (EC₅₀ 7 nM) allosteric agonist which demonstrates exquisite selectivity for mGluR₇ compared to not only other mGluRs, but also a broad range of targets. CVN636 demonstrated CNS penetrance and efficacy in an in vivo rodent model of alcohol use disorder. CVN636 thus has potential to progress as a drug candidate in CNS disorders involving mGluR₇ and glutamatergic dysfunction.

Computational Drug Design Applied to the Study of Metabotropic Glutamate Receptors

Metabotropic glutamate (mGlu) receptors are a family of eight GPCRs that are attractive drug discovery targets to modulate glutamate action and response. Here we review the application of computational methods to the study of this family of receptors. X-ray structures of the extracellular and 7-transmembrane domains have played an important role to enable structure-based modeling approaches, whilst we also discuss the successful application of ligand-based methods. We summarize the literature and highlight the areas where modeling and experiment have delivered important understanding for mGlu receptor drug discovery. Finally, we offer suggestions of future areas of opportunity for computational work.

Progress toward allosteric ligands of metabotropic glutamate 7 (mGlu7) receptor: 2008-present

Metabotropic glutamate type 7 (mGlu7) receptor is a member of the group III family of mGlu receptors. It is widely distributed in the central nervous system (CNS) and is preferentially expressed on presynaptic nerve terminals where it is thought to play a critical role in modulating normal neuronal function and synaptic transmission, making it particularly relevant in neuropharmacology. The lack of small-molecule mGlu7 ligands with adequate potency, selectivity and drug-like properties has resulted in difficulties in the preclinical validation of mGlu7 modulation in disease models. In the last decade, allosteric modulators of mGlu7 receptors have emerged as valuable tools with good potency, selectivity and physicochemical properties to study and unleash the therapeutic potential of mGlu7 receptors. This review focusses on the medicinal chemistry of mGlu7 receptor allosteric ligands discovered since 2008.