Browsing by Subject "Calcium Channel Blockers"

Now showing 1 - 4 of 4
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    Imaging-Based Reporter Systems to Define CVB-Induced Membrane Remodeling in Living Cells.
    (Viruses, 2020-09-25) Lennemann, Nicholas J; Evans, Azia S; Coyne, Carolyn B
    Enteroviruses manipulate host membranes to form replication organelles, which concentrate viral and host factors to allow for efficient replication. However, this process has not been well-studied in living cells throughout the course of infection. To define the dynamic process of enterovirus membrane remodeling of major secretory pathway organelles, we have developed plasmid-based reporter systems that utilize viral protease-dependent release of a nuclear-localized fluorescent protein from the endoplasmic reticulum (ER) membrane during infection, while retaining organelle-specific fluorescent protein markers such as the ER and Golgi. This system thus allows for the monitoring of organelle-specific changes induced by infection in real-time. Using long-term time-lapse imaging of living cells infected with coxsackievirus B3 (CVB), we detected reporter translocation to the nucleus beginning ~4 h post-infection, which correlated with a loss of Golgi integrity and a collapse of the peripheral ER. Lastly, we applied our system to study the effects of a calcium channel inhibitor, 2APB, on virus-induced manipulation of host membranes. We found that 2APB treatment had no effect on the kinetics of infection or the percentage of infected cells. However, we observed aberrant ER structures in CVB-infected cells treated with 2APB and a significant decrease in viral-dependent cell lysis, which corresponded with a decrease in extracellular virus titers. Thus, our system provides a tractable platform to monitor the effects of inhibitors, gene silencing, and/or gene editing on viral manipulation of host membranes, which can help determine the mechanism of action for antivirals.
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    Otoprotective Effects of Stephania tetrandra S. Moore Herb Isolate against Acoustic Trauma.
    (Journal of the Association for Research in Otolaryngology : JARO, 2018-12) Yu, Yan; Hu, Bing; Bao, Jianxin; Mulvany, Jessica; Bielefeld, Eric; Harrison, Ryan T; Neton, Sarah A; Thirumala, Partha; Chen, Yingying; Lei, Debin; Qiu, Ziyu; Zheng, Qingyin; Ren, Jihao; Perez-Flores, Maria Cristina; Yamoah, Ebenezer N; Salehi, Pezhman
    Noise is the most common occupational and environmental hazard, and noise-induced hearing loss (NIHL) is the second most common form of sensorineural hearing deficit. Although therapeutics that target the free-radical pathway have shown promise, none of these compounds is currently approved against NIHL by the United States Food and Drug Administration. The present study has demonstrated that tetrandrine (TET), a traditional Chinese medicinal alkaloid and the main chemical isolate of the Stephania tetrandra S. Moore herb, significantly attenuated NIHL in CBA/CaJ mice. TET is known to exert antihypertensive and antiarrhythmic effects through the blocking of calcium channels. Whole-cell patch-clamp recording from adult spiral ganglion neurons showed that TET blocked the transient Ca2+ current in a dose-dependent manner and the half-blocking concentration was 0.6 + 0.1 μM. Consistent with previous findings that modulations of calcium-based signaling pathways have both prophylactic and therapeutic effects against neural trauma, NIHL was significantly diminished by TET administration. Importantly, TET has a long-lasting protective effect after noise exposure (48 weeks) in comparison to 2 weeks after noise exposure. The otoprotective effects of TET were achieved mainly by preventing outer hair cell damage and synapse loss between inner hair cells and spiral ganglion neurons. Thus, our data indicate that TET has great potential in the prevention and treatment of NIHL.
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    Overcoming Confounding to Characterize the Effects of Calcium Channel Blockers.
    (Function (Oxford, England), 2023-01) Rajagopal, Sudarshan; Rosenberg, Paul B
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    Sequential ionic and conformational signaling by calcium channels drives neuronal gene expression.
    (Science, 2016-02-19) Li, Boxing; Tadross, Michael R; Tsien, Richard W
    Voltage-gated CaV1.2 channels (L-type calcium channel α1C subunits) are critical mediators of transcription-dependent neural plasticity. Whether these channels signal via the influx of calcium ion (Ca(2+)), voltage-dependent conformational change (VΔC), or a combination of the two has thus far been equivocal. We fused CaV1.2 to a ligand-gated Ca(2+)-permeable channel, enabling independent control of localized Ca(2+) and VΔC signals. This revealed an unexpected dual requirement: Ca(2+) must first mobilize actin-bound Ca(2+)/calmodulin-dependent protein kinase II, freeing it for subsequent VΔC-mediated accumulation. Neither signal alone sufficed to activate transcription. Signal order was crucial: Efficiency peaked when Ca(2+) preceded VΔC by 10 to 20 seconds. CaV1.2 VΔC synergistically augmented signaling by N-methyl-d-aspartate receptors. Furthermore, VΔC mistuning correlated with autistic symptoms in Timothy syndrome. Thus, nonionic VΔC signaling is vital to the function of CaV1.2 in synaptic and neuropsychiatric processes.