The new KV3.4 inhibitor BDS-I[1-8] as a potential pharmacological opportunity in Alzheimer's disease therapy

Kv3.4 regulates cell migration and invasion through TGF-β-induced epithelial-mesenchymal transition in A549 cells

Epithelial-mesenchymal transition (EMT) is the process by which epithelial cells acquire mesenchymal characteristics. This process induces cell migration and invasion, which are closely related to cancer metastasis and malignancy. EMT consists of various intermediate states that express both epithelial and mesenchymal traits, called partial EMT. Recently, several studies have focused on the roles of voltage-gated potassium (Kv) channels associated with EMT in cancer cell migration and invasion. In this study, we demonstrate the relationship between Kv3.4 and EMT and confirm the effects of cell migration and invasion. With TGF-β treatment, EMT was induced and Kv3.4 was also increased in A549 cells, human lung carcinoma cells. The knockdown of Kv3.4 blocked the EMT progression reducing cell migration and invasion. However, the Kv3.4 overexpressed cells acquired mesenchymal characteristics and increased cell migration and invasion. The overexpression of Kv3.4 also has a synergistic effect with TGF-β in promoting cell migration. Therefore, we conclude that Kv3.4 regulates cancer migration and invasion through TGF-β-induced EMT and these results provide insights into the understanding of cancer metastasis.

Reducing voltage-dependent potassium channel Kv3.4 levels ameliorates synapse loss in a mouse model of Alzheimer's disease

Synapse loss is associated with cognitive decline in Alzheimer's disease, and owing to their plastic nature, synapses are an ideal target for therapeutic intervention. Oligomeric amyloid beta around amyloid plaques is known to contribute to synapse loss in mouse models and is associated with synapse loss in human Alzheimer's disease brain tissue, but the mechanisms leading from Aβ to synapse loss remain unclear. Recent data suggest that the fast-activating and -inactivating voltage-gated potassium channel subtype 3.4 (Kv3.4) may play a role in Aβ-mediated neurotoxicity. Here, we tested whether this channel could also be involved in Aβ synaptotoxicity. Using adeno-associated virus and clustered regularly interspaced short palindromic repeats technology, we reduced Kv3.4 expression in neurons of the somatosensory cortex of APP/PS1 mice. These mice express human familial Alzheimer's disease-associated mutations in amyloid precursor protein and presenilin-1 and develop amyloid plaques and plaque-associated synapse loss similar to that observed in Alzheimer's disease brain. We observe that reducing Kv3.4 levels ameliorates dendritic spine loss and changes spine morphology compared to control virus. In support of translational relevance, Kv3.4 protein was observed in human Alzheimer's disease and control brain and is associated with synapses in human induced pluripotent stem cell-derived cortical neurons. We also noted morphological changes in induced pluripotent stem cell neurones challenged with human Alzheimer's disease-derived brain homogenate containing Aβ but, in this in vitro model, total mRNA levels of Kv3.4 were found to be reduced, perhaps as an early compensatory mechanism for Aβ-induced damage. Overall, our results suggest that approaches to reduce Kv3.4 expression and/or function in the Alzheimer's disease brain could be protective against Aβ-induced synaptic alterations.

The Antioxidant Activity of Limonene Counteracts Neurotoxicity Triggered byAβ1-42 Oligomers in Primary Cortical Neurons

Many natural-derived compounds, including the essential oils from plants, are investigated to find new potential protective agents in several neurodegenerative disorders such as Alzheimer's disease (AD). In the present study, we tested the neuroprotective effect of limonene, one of the main components of the genus Citrus, against the neurotoxicity elicited by Aβ_1-42 oligomers, currently considered a triggering factor in AD. To this aim, we assessed the acetylcholinesterase activity by Ellman's colorimetric method, the mitochondrial dehydrogenase activity by MTT assay, the nuclear morphology by Hoechst 33258, the generation of reactive oxygen species (ROS) by DCFH-DA fluorescent dye, and the electrophysiological activity of K_V3.4 potassium channel subunits by patch-clamp electrophysiology. Interestingly, the monoterpene limonene showed a specific activity against acetylcholinesterase with an IC₅₀ almost comparable to that of galantamine, used as positive control. Moreover, at the concentration of 10 µg/mL, limonene counteracted the increase of ROS production triggered by Aβ_1-42 oligomers, thus preventing the upregulation of K_V3.4 activity. This, in turn, prevented cell death in primary cortical neurons, showing an interesting neuroprotective profile against Aβ_1-42-induced toxicity. Collectively, the present results showed that the antioxidant properties of the main component of the genus Citrus, limonene, may be useful to prevent neuronal suffering induced by Aβ_1-42 oligomers preventing the hyperactivity of K_V3.4.

Pharmacological inhibition of Kv3 on oxidative stress-induced cataract progression

Oxidative stress is one of the most important risk factors for cataractogenesis. Previous studies have indicated that BDS-II, a Kv3 channel blocker, plays pivotal roles in oxidative stress-related diseases. This study demonstrates that BDS-II exerts a protective effect on cataractogenesis. Specifically, BDS-II was observed to inhibit lens opacity induced by H₂O₂. BDS-II was also determined to inhibit cataract progression in a sodium selenite-induced in vivo cataract model by inhibiting reduction of the total GSH. In addition, BDS-II was demonstrated to protect human lens epithelial cells against H₂O₂-induced cell death. Our results suggest that BDS-II is a potential pharmacological candidate in cataract therapy.

Lavender and coriander essential oils and their main component linalool exert a protective effect against amyloid-β neurotoxicity

Alzheimer's disease (AD) is a neurodegenerative disorder leading to cognitive deficits and cognitive decline. Since no cure or preventing therapy is currently available to counteract AD, natural-derived compounds are investigated to find new potential neuroprotective agents for its treatment. In the present study, we tested the neuroprotective effect of lavender and coriander essential oils (EOs) and their main active constituent linalool, against the neurotoxicity elicited by Aβ_1-42 oligomers, a key molecular factor in the neurodegeneration of AD. Importantly, our findings on neuronally differentiated PC12 cells exposed to Aβ_1-42 oligomers are in accordance with previous in vivo studies reporting the neuroprotective potential of lavender and coriander EOs and linalool. We found that lavender and coriander EOs at the concentration of 10 μg/mL as well as linalool at the same concentration were able to improve viability and to reduce nuclear morphological abnormalities in cells treated with Aβ_1-42 oligomers for 24 hours. Lavender and coriander EOs and linalool also showed to counteract the increase of intracellular reactive oxygen species production and the activation of the pro-apoptotic enzyme caspase-3 induced by Aβ_1-42 oligomers. Our findings provide further evidence that these EOs and their main constituent linalool could be natural agents of therapeutic interest against Aβ_1-42 -induced neurotoxicity.