Activation of calcium- and voltage-gated potassium channels of large conductance by leukotriene B4

Anna Bukiya, Jacob McMillan, Jianxi Liu, Bangalore Shivakumar, Abby L. Parrill, Alejandro Dopico

Research output: Contribution to journalArticle

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Abstract

Calcium/voltage-gated, large conductance potassium (BK) channels control numerous physiological processes, including myogenic tone. BK channel regulation by direct interaction between lipid and channel protein sites has received increasing attention. Leukotrienes (LTA4, LTB4, LTC4, LTD4, and LTE4) are inflammatory lipid mediators. We performed patch clamp studies in Xenopus oocytes that co-expressed BK channel-forming (cbv1) and accessory β1 subunits cloned from rat cerebral artery myocytes. Leukotrienes were applied at 0.1 nM -10 μM to either leaflet of cell-free membranes at a wide range of [Ca2+ ]i and voltages. Only LTB4 reversibly increased BK steady-state activity (EC50 = 1 nM ; Emax reached at 10 nM ), with physiological [Ca2+]i and voltages favoring this activation. Homomeric cbv1 or cbv1-β2 channels were LTB4-resistant. Computational modeling predicted that LTB4 docked onto the cholane steroid-sensing site in the BK β1 transmembrane domain 2 (TM2). Co-application of LTB4 and cholane steroid did not further increase LTB4-induced activation. LTB4 failed to activate β1 subunit-containing channels when β1 carried T169A, A176S, or K179I within the docking site. Co-application of LTB4 with LTA4, LTC4, LTD4, or LTE4 suppressed LTB4-induced activation. Inactive leukotrienes docked onto a portion of the site, probably preventing tight docking of LTB4. In summary, we document the ability of two endogenous lipids from different chemical families to share their site of action on a channel accessory subunit. Thus, cross-talk between leukotrienes and cholane steroids might converge on regulation of smooth muscle contractility via BK β1. Moreover, the identification of LTB4 as a highly potent ligand for BK channels is critical for the future development of β1-specific BK channel activators.

Original languageEnglish (US)
Article numberA36
Pages (from-to)35314-35325
Number of pages12
JournalJournal of Biological Chemistry
Volume289
Issue number51
DOIs
StatePublished - Dec 19 2014

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Voltage-Gated Potassium Channels
Leukotriene B4
Chemical activation
Calcium
Large-Conductance Calcium-Activated Potassium Channels
Cholanes
Leukotrienes
Leukotriene A4
Leukotriene E4
Leukotriene D4
Leukotriene C4
Steroids
Accessories
Lipids
Electric potential
Physiological Phenomena
Cerebral Arteries
Potassium Channels
Clamping devices
Xenopus

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Activation of calcium- and voltage-gated potassium channels of large conductance by leukotriene B4. / Bukiya, Anna; McMillan, Jacob; Liu, Jianxi; Shivakumar, Bangalore; Parrill, Abby L.; Dopico, Alejandro.

In: Journal of Biological Chemistry, Vol. 289, No. 51, A36, 19.12.2014, p. 35314-35325.

Research output: Contribution to journalArticle

Bukiya, Anna ; McMillan, Jacob ; Liu, Jianxi ; Shivakumar, Bangalore ; Parrill, Abby L. ; Dopico, Alejandro. / Activation of calcium- and voltage-gated potassium channels of large conductance by leukotriene B4. In: Journal of Biological Chemistry. 2014 ; Vol. 289, No. 51. pp. 35314-35325.
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abstract = "Calcium/voltage-gated, large conductance potassium (BK) channels control numerous physiological processes, including myogenic tone. BK channel regulation by direct interaction between lipid and channel protein sites has received increasing attention. Leukotrienes (LTA4, LTB4, LTC4, LTD4, and LTE4) are inflammatory lipid mediators. We performed patch clamp studies in Xenopus oocytes that co-expressed BK channel-forming (cbv1) and accessory β1 subunits cloned from rat cerebral artery myocytes. Leukotrienes were applied at 0.1 nM -10 μM to either leaflet of cell-free membranes at a wide range of [Ca2+ ]i and voltages. Only LTB4 reversibly increased BK steady-state activity (EC50 = 1 nM ; Emax reached at 10 nM ), with physiological [Ca2+]i and voltages favoring this activation. Homomeric cbv1 or cbv1-β2 channels were LTB4-resistant. Computational modeling predicted that LTB4 docked onto the cholane steroid-sensing site in the BK β1 transmembrane domain 2 (TM2). Co-application of LTB4 and cholane steroid did not further increase LTB4-induced activation. LTB4 failed to activate β1 subunit-containing channels when β1 carried T169A, A176S, or K179I within the docking site. Co-application of LTB4 with LTA4, LTC4, LTD4, or LTE4 suppressed LTB4-induced activation. Inactive leukotrienes docked onto a portion of the site, probably preventing tight docking of LTB4. In summary, we document the ability of two endogenous lipids from different chemical families to share their site of action on a channel accessory subunit. Thus, cross-talk between leukotrienes and cholane steroids might converge on regulation of smooth muscle contractility via BK β1. Moreover, the identification of LTB4 as a highly potent ligand for BK channels is critical for the future development of β1-specific BK channel activators.",
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T1 - Activation of calcium- and voltage-gated potassium channels of large conductance by leukotriene B4

AU - Bukiya, Anna

AU - McMillan, Jacob

AU - Liu, Jianxi

AU - Shivakumar, Bangalore

AU - Parrill, Abby L.

AU - Dopico, Alejandro

PY - 2014/12/19

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AB - Calcium/voltage-gated, large conductance potassium (BK) channels control numerous physiological processes, including myogenic tone. BK channel regulation by direct interaction between lipid and channel protein sites has received increasing attention. Leukotrienes (LTA4, LTB4, LTC4, LTD4, and LTE4) are inflammatory lipid mediators. We performed patch clamp studies in Xenopus oocytes that co-expressed BK channel-forming (cbv1) and accessory β1 subunits cloned from rat cerebral artery myocytes. Leukotrienes were applied at 0.1 nM -10 μM to either leaflet of cell-free membranes at a wide range of [Ca2+ ]i and voltages. Only LTB4 reversibly increased BK steady-state activity (EC50 = 1 nM ; Emax reached at 10 nM ), with physiological [Ca2+]i and voltages favoring this activation. Homomeric cbv1 or cbv1-β2 channels were LTB4-resistant. Computational modeling predicted that LTB4 docked onto the cholane steroid-sensing site in the BK β1 transmembrane domain 2 (TM2). Co-application of LTB4 and cholane steroid did not further increase LTB4-induced activation. LTB4 failed to activate β1 subunit-containing channels when β1 carried T169A, A176S, or K179I within the docking site. Co-application of LTB4 with LTA4, LTC4, LTD4, or LTE4 suppressed LTB4-induced activation. Inactive leukotrienes docked onto a portion of the site, probably preventing tight docking of LTB4. In summary, we document the ability of two endogenous lipids from different chemical families to share their site of action on a channel accessory subunit. Thus, cross-talk between leukotrienes and cholane steroids might converge on regulation of smooth muscle contractility via BK β1. Moreover, the identification of LTB4 as a highly potent ligand for BK channels is critical for the future development of β1-specific BK channel activators.

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