ORCID Profile
0000-0002-9903-714X
Current Organisation
IT University of Copenhagen
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Publisher: Elsevier BV
Date: 03-2020
DOI: 10.1016/J.BCP.2019.113631
Abstract: Chronic low-grade inflammation and oxidative damage are strongly associated with pathologies including cardiovascular disease. As a consequence, there is considerable interest in agents that mitigate damage. Selenium compounds can act as potent protective agents against oxidation due to the high reactivity and nucleophilicity of the selenium atom. 1,4-Anhydro-4-seleno-d-talitol (SeTal, a novel water-soluble selenium-based sugar) is a potent oxidant scavenger in vitro and in human plasma. Here we show that SeTal is highly stable in solutions that mimic biological fluids and the gastrointestinal tract, and is not rapidly degraded or metabolized unlike some other selenium-containing compounds. SeTal remains intact during extended storage, and it rapidly penetrates into, and effluxes from, primary human coronary artery endothelial and smooth muscle cells, but does not induce loss of metabolic activity, or modulate cell survival and growth rates at concentrations ≤2 mM. Steady-state intracellular concentrations can reach 2-10 μM. SeTal affords protection against H
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2018
DOI: 10.1161/HYPERTENSIONAHA.117.10152
Abstract: Microtubules can regulate GPCR (G protein–coupled receptor) signaling in various cell types. In vascular smooth muscle, activation of the β-adrenoceptor leads to production of cAMP to mediate a vasorelaxation. Little is known about the role of microtubules in smooth muscle, and given the importance of this pathway in vascular smooth muscle cells, we investigated the role of microtubule stability on β-adrenoceptor signaling in rat renal and mesenteric arteries. In isometric tension experiments, incubation with the microtubule inhibitors colchicine and nocodazole enhanced isoprenaline-mediated relaxations of renal and mesenteric arteries that the microtubule stabilizer, paclitaxel, prevented. Sharp microelectrode experiments showed that colchicine treatment caused increased hyperpolarization of mesenteric artery segments in response to isoprenaline. Application of the Kv7 channel blocker, XE991, attenuated the effect of colchicine on isoprenaline relaxations, whereas iberiotoxin—a BKCa channel blocker—had no effect. In addition, colchicine improved the relaxations to the Kv7.2 to 7.5 activator, S-1, in both renal and mesenteric artery segments compared with dimethyl sulfoxide incubation. We determined that increased mesenteric artery myocytes treated with colchicine showed increased Kv7.4 membrane expression, but Western blot analysis showed no change in total Kv7.4 protein. This study is the first to show microtubule disruption improves the β-adrenoceptor–mediated relaxations of mesenteric and renal arteries and determine this enhancement to be because of increased membrane expression of the Kv7 voltage-gated potassium channels.
Publisher: Wiley
Date: 05-01-2018
DOI: 10.1111/BPH.14097
Publisher: Rockefeller University Press
Date: 03-02-2021
Abstract: The dynein motor protein transports proteins away from the cell membrane along the microtubule network. Recently, we found the microtubule network was important for regulating the membrane abundance of voltage-gated Kv7.4 potassium channels in vascular smooth muscle. Here, we aimed to investigate the influence of dynein on the microtubule-dependent internalization of the Kv7.4 channel. Patch-cl recordings from HEK293B cells showed Kv7.4 currents were increased after inhibiting dynein function with ciliobrevin D or by coexpressing p50/dynamitin, which specifically interferes with dynein motor function. Mutation of a dynein-binding site in the Kv7.4 C terminus increased the Kv7.4 current and prevented p50 interference. Structured illumination microscopy, proximity ligation assays, and coimmunoprecipitation showed colocalization of Kv7.4 and dynein in mesenteric artery myocytes. Ciliobrevin D enhanced mesenteric artery relaxation to activators of Kv7.2–Kv7.5 channels and increased membrane abundance of Kv7.4 protein in isolated smooth muscle cells and HEK293B cells. Ciliobrevin D failed to enhance the negligible S-1–mediated relaxations after morpholino-mediated knockdown of Kv7.4. Mass spectrometry revealed an interaction of dynein with caveolin-1, confirmed using proximity ligation and coimmunoprecipitation assays, which also provided evidence for interaction of caveolin-1 with Kv7.4, confirming that Kv7.4 channels are localized to caveolae in mesenteric artery myocytes. Lastly, cholesterol depletion reduced the interaction of Kv7.4 with caveolin-1 and dynein while increasing the overall membrane expression of Kv7.4, although it attenuated the Kv7.4 current in oocytes and interfered with the action of ciliobrevin D and channel activators in arterial segments. Overall, this study shows that dynein can traffic Kv7.4 channels in vascular smooth muscle in a mechanism dependent on cholesterol-rich caveolae.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Thomas Jepps.