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  1. Article ; Online: Subtype-specific responses of hKv7.4 and hKv7.5 channels to polyunsaturated fatty acids reveal an unconventional modulatory site and mechanism

    Damon JA Frampton / Koushik Choudhury / Johan Nikesjö / Lucie Delemotte / Sara I Liin

    eLife, Vol

    2022  Volume 11

    Abstract: The KV7.4 and KV7.5 subtypes of voltage-gated potassium channels play a role in important physiological processes such as sound amplification in the cochlea and adjusting vascular smooth muscle tone. Therefore, the mechanisms that regulate KV7.4 and KV7 ... ...

    Abstract The KV7.4 and KV7.5 subtypes of voltage-gated potassium channels play a role in important physiological processes such as sound amplification in the cochlea and adjusting vascular smooth muscle tone. Therefore, the mechanisms that regulate KV7.4 and KV7.5 channel function are of interest. Here, we study the effect of polyunsaturated fatty acids (PUFAs) on human KV7.4 and KV7.5 channels expressed in Xenopus oocytes. We report that PUFAs facilitate activation of hKV7.5 by shifting the V50 of the conductance versus voltage (G(V)) curve toward more negative voltages. This response depends on the head group charge, as an uncharged PUFA analogue has no effect and a positively charged PUFA analogue induces positive V50 shifts. In contrast, PUFAs inhibit activation of hKV7.4 by shifting V50 toward more positive voltages. No effect on V50 of hKV7.4 is observed by an uncharged or a positively charged PUFA analogue. Thus, the hKV7.5 channel’s response to PUFAs is analogous to the one previously observed in hKV7.1–7.3 channels, whereas the hKV7.4 channel response is opposite, revealing subtype-specific responses to PUFAs. We identify a unique inner PUFA interaction site in the voltage-sensing domain of hKV7.4 underlying the PUFA response, revealing an unconventional mechanism of modulation of hKV7.4 by PUFAs.
    Keywords docosahexaenoic acid ; electrophysiology ; KCNQ ; lipid ; molecular dynamics simulations ; omega 3 ; Medicine ; R ; Science ; Q ; Biology (General) ; QH301-705.5
    Subject code 572
    Language English
    Publishing date 2022-06-01T00:00:00Z
    Publisher eLife Sciences Publications Ltd
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Endocannabinoids enhance hKV7.1/KCNE1 channel function and shorten the cardiac action potential and QT intervalResearch in context

    Irene Hiniesto-Iñigo / Laura M. Castro-Gonzalez / Valentina Corradi / Mark A. Skarsfeldt / Samira Yazdi / Siri Lundholm / Johan Nikesjö / Sergei Yu Noskov / Bo Hjorth Bentzen / D. Peter Tieleman / Sara I. Liin

    EBioMedicine, Vol 89, Iss , Pp 104459- (2023)

    2023  

    Abstract: Summary: Background: Genotype-positive patients who suffer from the cardiac channelopathy Long QT Syndrome (LQTS) may display a spectrum of clinical phenotypes, with often unknown causes. Therefore, there is a need to identify factors influencing disease ...

    Abstract Summary: Background: Genotype-positive patients who suffer from the cardiac channelopathy Long QT Syndrome (LQTS) may display a spectrum of clinical phenotypes, with often unknown causes. Therefore, there is a need to identify factors influencing disease severity to move towards an individualized clinical management of LQTS. One possible factor influencing the disease phenotype is the endocannabinoid system, which has emerged as a modulator of cardiovascular function. In this study, we aim to elucidate whether endocannabinoids target the cardiac voltage-gated potassium channel KV7.1/KCNE1, which is the most frequently mutated ion channel in LQTS. Methods: We used two-electrode voltage clamp, molecular dynamics simulations and the E4031 drug-induced LQT2 model of ex-vivo guinea pig hearts. Findings: We found a set of endocannabinoids that facilitate channel activation, seen as a shifted voltage-dependence of channel opening and increased overall current amplitude and conductance. We propose that negatively charged endocannabinoids interact with known lipid binding sites at positively charged amino acids on the channel, providing structural insights into why only specific endocannabinoids modulate KV7.1/KCNE1. Using the endocannabinoid ARA-S as a prototype, we show that the effect is not dependent on the KCNE1 subunit or the phosphorylation state of the channel. In guinea pig hearts, ARA-S was found to reverse the E4031-prolonged action potential duration and QT interval. Interpretation: We consider the endocannabinoids as an interesting class of hKV7.1/KCNE1 channel modulators with putative protective effects in LQTS contexts. Funding: ERC (No. 850622), Canadian Institutes of Health Research, Canada Research Chairs and Compute Canada, Swedish National Infrastructure for Computing.
    Keywords Arrhythmia ; Electrophysiology ; KCNQ1 ; Kv7 ; Long QT Syndrome ; Molecular dynamics ; Medicine ; R ; Medicine (General) ; R5-920
    Subject code 572
    Language English
    Publishing date 2023-03-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

    More links

    Kategorien

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

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