A positive allosteric modulator of TRPC6 promotes neuroprotective effects in vitro

Abstract

Alzheimer’s disease is a neurodegenerative disorder and the primary cause of dementia among elderly individuals. Unfortunately, there is no known cure for Alzheimer’s disease. Recently, a TRPC6-mediated intracellular signaling pathway was discovered, which plays a vital role in memory formation by regulating dendritic spine stability. Knockdown of TRPC6 expression was found to prevent store-operated calcium entry. The overexpression of TRPC6 or its pharmacological activation restores store-operated calcium entry in hippocampal neurons affected by Alzheimer’s disease [1, 2]. TRPC6 overexpression rescues mushroom spine loss in presenilin and APP knock-in mouse models of Alzheimer’s disease [1] and protects neurons from ischemic brain damage. Mice that overexpress TRPC6 in the brain exhibit improved cognitive function and increased excitatory synapse formation. These findings propose TRPC6 as a promising molecular target for the treatment of synaptic deficiency. We recently demonstrated that compound 51164 (N-(2-chlorophenyl)-2-(4-phenylpiperazine-1-yl) acetamide), a piperazine derivative, enhances TRPC6 channels and induces an upregulation of postsynaptic neuronal store-operated calcium entry. Furthermore, it increases mushroom spine percentage and recovers synaptic plasticity in mouse models of Alzheimer’s disease that have an amyloidogenic nature [2]. However, additional investigations of 51164 have demonstrated that the compound is unstable in plasma and cannot penetrate the blood-brain barrier (unpublished data). As such, the aim of this study is to discover a new piperazine derivative that functions as a positive modulator for TRPC6-specific and showcases neuroprotective qualities.

In this study, we present in silico and in vitro investigations of a novel TRPC6 specific modulator. Based on our in silico research, we narrowed down the selection to 14 compounds through the piperazine derivative 51164 that met all drug-lead likeness criteria and showed a high affinity for the active center of TRPC6. Calcium imaging technique was usedto establish that the compound z12_30 triggered the activation of TRPC6 but not the structurally linked TRPC3 channel. In addition, a molecular dynamics approach revealed that z12_30 forms a stable complex with the TRPC6 active site. As a result, z12_30 was selected as the lead compound for further investigation. Studies showed that z12_30 safeguards hippocampal mushroom spines from amyloid toxicity in vitro and effectively restores synaptic plasticity in brain slices from aged 5xFAD mice. Preclinical trials demonstrate that z12_30 remains stable in both human and mouse plasma samples.

We suggest that z12_30 is a promising prototype of a TRPC6-selective drug suitable for treating synaptic deficiency in hippocampal neurons affected by Alzheimer’s disease.

Keywords

TRPC6 / synapse / Alzheimer’s disease / translational neuroscience

References

[1] Zhang H, Sun S, Wu L, et al. Store-Operated Calcium Channel Complex in Postsynaptic Spines: A New Therapeutic Target for Alzheimer’s Disease Treatment. Journal of Neuroscience. 2016;36(47):11837–11850. doi: 10.1523/JNEUROSCI.1188-16.2016

[2] Zhang H., Sun S., Wu L., et al. Store-Operated Calcium Channel Complex in Postsynaptic Spines: A New Therapeutic Target for Alzheimer’s Disease Treatment // Journal of Neuroscience. 2016. Vol. 36, N 47. P. 11837–11850. doi: 10.1523/JNEUROSCI.1188-16.2016

[3] Popugaeva E, Chernyuk D, Zhang H, et al. Derivatives of Piperazines as Potential Therapeutic Agents for Alzheimer’s Disease. Molecular Pharmacology. 2019;95(4):337–348. doi: 10.1124/mol.118.114348

[4] Popugaeva E., Chernyuk D., Zhang H., et al. Derivatives of Piperazines as Potential Therapeutic Agents for Alzheimer’s Disease // Molecular Pharmacology. 2019. Vol. 95, N 4. P. 337–348. doi: 10.1124/mol.118.114348

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