Cinnamyl-3,4-dihydroxy-α-cyanocinnamate and nordihydroguaiaretic acid inhibit human Kv1.5 currents independently of lipoxygenase

Gong, Ying-Zi; Ding, Wei‐Guang; Wu, Jie; Tsuji, Keiko; Horie, Minoru; Matsuura, Hiroshi

doi:10.1016/j.ejphar.2008.10.010

Cited by 15 publications

(10 citation statements)

References 35 publications

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“…1B). The currents recorded were activated rapidly upon depolarization to reach a peak and stabilized thereafter during the moderately depolarized test steps (≤ +30 mV), but decayed minimally during the strongly depolarized test potentials (≥40 mV), which is consistent with the previous studies [24], [25], thus indicating that low temperature cultivation provoked the elevation of the hKv1.5 currents without any characteristic changes. Since reduced temperature culture rescued the currents of trafficking-defective mutants of CFTR [18] and hERG channels [21], we investigate whether low temperature treatment could modify the function of hKv1.5 mutant channels.…”

Section: Resultssupporting

confidence: 91%

Improved Functional Expression of Human Cardiac Kv1.5 Channels and Trafficking-Defective Mutants by Low Temperature Treatment

et al. 2014

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We herein investigated the effect of low temperature exposure on the expression, degradation, localization and activity of human Kv1.5 (hKv1.5). In hKv1.5-expressing CHO cells, the currents were significantly increased when cultured at a reduced temperature (28°C) compared to those observed at 37°C. Western blot analysis indicated that the protein levels (both immature and mature proteins) of hKv1.5 were significantly elevated under the hypothermic condition. Treatment with a proteasome inhibitor, MG132, significantly increased the immature, but not the mature, hKv1.5 protein at 37°C, however, there were no changes in either the immature or mature hKv1.5 proteins at low temperature following MG132 exposure. These observations suggest that the enhancement of the mature hKv1.5 protein at reduced temperature may not result from the inhibition of proteolysis. Moreover, the hKv1.5 fluorescence signal in the cells increased significantly on the cell surface at 28°C versus those cultured at 37°C. Importantly, the low temperature treatment markedly shifted the subcellular distribution of the mature hKv1.5, which showed considerable overlap with the trans-Golgi component. Experiments using tunicamycin, an inhibitor of N-glycosylation, indicated that the N-glycosylation of hKv1.5 is more effective at 28°C than at 37°C. Finally, the hypothermic treatment also rescued the protein expression and currents of trafficking-defective hKv1.5 mutants. These results indicate that low temperature exposure stabilizes the protein in the cellular organelles or on the plasma membrane, and modulates its maturation and trafficking, thus enhancing the currents of hKv1.5 and its trafficking defect mutants.

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Section: Resultssupporting

confidence: 91%

Improved Functional Expression of Human Cardiac Kv1.5 Channels and Trafficking-Defective Mutants by Low Temperature Treatment

et al. 2014

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“…Previous studies have shown that I502, I508, V512 and V516 are important for mediating the blocking action of various drugs on hK v 1.5 channel, such as S0100176 and AVE0118 (Decher et al , ; Decher et al , ). Similarly, R487 and H463 are also important for the blocking actions of protons (Kehl et al , ), drugs (Rezazadeh et al , ; Gong et al , ) and AA derivative N ‐arachidonoylethanolamine (Barana et al ., ). Based on the crystal structure of K v 1.2, T480, I508, V512 and V516 are predicted to face toward the inner cavity of the channel, whereas I502 is positioned away from the central cavity of the pore and forms a hydrophobic interface with the adjacent S5 domain (Decher et al ., ; Eldstrom et al ., ; Tikhonov and Zhorov, ).…”

Section: Discussionmentioning

confidence: 99%

Putative binding sites for arachidonic acid on the human cardiac K_v1.5 channel

Bai

Ding

Kojima

et al. 2015

British J Pharmacology

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BACKGROUND AND PURPOSEIn human heart, the K v 1.5 channel contributes to repolarization of atrial action potentials. This study examined the electrophysiological and molecular mechanisms underlying arachidonic acid (AA)-induced inhibition of the human K v 1.5 (hK v 1.5) channel. EXPERIMENTAL APPROACHSite-directed mutagenesis was conducted to mutate amino acids that reside within the pore domain of the hK v 1.5 channel. Whole-cell patch-clamp method was used to record membrane currents through wild type and mutant hK v 1.5 channels heterologously expressed in CHO cells. Computer docking simulation was conducted to predict the putative binding site(s) of AA in an open-state model of the K v 1.5 channel. KEY RESULTSThe hK v 1.5 current was minimally affected at the onset of depolarization but was progressively reduced during depolarization by the presence of AA, suggesting that AA acts as an open-channel blocker. AA itself affected the channel at extracellular sites independently of its metabolites and signalling pathways. The blocking effect of AA was attenuated at pH 8.0 but not at pH 6.4. The blocking action of AA developed rather rapidly by co-expression of K v β1.3. The AA-induced block was significantly attenuated in H463C, T480A, R487V, I502A, I508A, V512A and V516A, but not in T462C, A501V and L510A mutants of the hK v 1.5 channel. Docking simulation predicted that H463, T480, R487, I508, V512 and V516 are potentially accessible for interaction with AA. CONCLUSIONS AND IMPLICATIONSAA itself interacts with multiple amino acids located in the pore domain of the hK v 1.5 channel. These findings may provide useful information for future development of selective blockers of hK v 1.5 channels.

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“…Notably, AA‐861 (1–10 μM) also inhibits 12/15‐LOX (43), in agreement with our observations above. The flavonoid baicalein exerts actions as an antioxidant (44, 45), while CDC inhibits Kv1.5 channel currents (46), as well as 5‐LOX at low micromolar concentrations (47). As expected, CDC and baicalein potently blocked Alox12 activity, yet these compounds significantly decreased formation of 12‐HETE and hepoxilins from leukocyte‐type Alox15 as well.…”

Section: Discussionmentioning

confidence: 99%

Systematic analysis of rat 12/15‐lipoxygenase enzymes reveals critical role for spinal eLOX3 hepoxilin synthase activity in inflammatory hyperalgesia

et al. 2013

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Previously, we observed significant increases in spinal 12-lipoxygenase (LOX) metabolites, in particular, hepoxilins, which contribute to peripheral inflammation-induced tactile allodynia. However, the enzymatic sources of hepoxilin synthase (HXS) activity in rats remain elusive. Therefore, we overexpressed each of the 6 rat 12/15-LOX enzymes in HEK-293T cells and measured by LC-MS/MS the formation of HXB3, 12-HETE, 8-HETE, and 15-HETE from arachidonic acid (AA) at baseline and in the presence of LOX inhibitors (NDGA, AA-861, CDC, baicalein, and PD146176) vs. vehicle-treated and mock-transfected controls. We detected the following primary intrinsic activities: 12-LOX (Alox12, Alox15), 15-LOX (Alox15b), and HXS (Alox12, Alox15). Similar to human and mouse orthologs, proteins encoded by rat Alox12b and Alox12e possessed minimal 12-LOX activity with AA as substrate, while eLOX3 (encoded by Aloxe3) exhibited HXS without 12-LOX activity when coexpressed with Alox12b or supplemented with 12-HpETE. CDC potently inhibited HXS and 12-LOX activity in vitro (relative IC50s: CDC, ~0.5 and 0.8 μM, respectively) and carrageenan-evoked tactile allodynia in vivo. Notably, peripheral inflammation significantly increased spinal eLOX3; intrathecal pretreatment with either siRNA targeting Aloxe3 or an eLOX3-selective antibody attenuated the associated allodynia. These findings implicate spinal eLOX3-mediated hepoxilin synthesis in inflammatory hyperesthesia and underscore the importance of developing more selective 12-LOX/HXS inhibitors.

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Cinnamyl-3,4-dihydroxy-α-cyanocinnamate and nordihydroguaiaretic acid inhibit human Kv1.5 currents independently of lipoxygenase

Cited by 15 publications

References 35 publications

Improved Functional Expression of Human Cardiac Kv1.5 Channels and Trafficking-Defective Mutants by Low Temperature Treatment

Improved Functional Expression of Human Cardiac Kv1.5 Channels and Trafficking-Defective Mutants by Low Temperature Treatment

Putative binding sites for arachidonic acid on the human cardiac K_v1.5 channel

Systematic analysis of rat 12/15‐lipoxygenase enzymes reveals critical role for spinal eLOX3 hepoxilin synthase activity in inflammatory hyperalgesia

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Cinnamyl-3,4-dihydroxy-α-cyanocinnamate and nordihydroguaiaretic acid inhibit human Kv1.5 currents independently of lipoxygenase

Cited by 15 publications

References 35 publications

Improved Functional Expression of Human Cardiac Kv1.5 Channels and Trafficking-Defective Mutants by Low Temperature Treatment

Improved Functional Expression of Human Cardiac Kv1.5 Channels and Trafficking-Defective Mutants by Low Temperature Treatment

Putative binding sites for arachidonic acid on the human cardiac Kv1.5 channel

Systematic analysis of rat 12/15‐lipoxygenase enzymes reveals critical role for spinal eLOX3 hepoxilin synthase activity in inflammatory hyperalgesia

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Putative binding sites for arachidonic acid on the human cardiac K_v1.5 channel