The LKB1-AMPK-α1 signaling pathway triggers hypoxic pulmonary vasoconstriction downstream of mitochondria

Javier Moral-Sanz, Sophronia A. Lewis, Sandy MacMillan, Fiona A. Ross, Adrian Thomson, Benoit Viollet, Marc Foretz, Carmel Moran, D. Grahame Hardie, A. Mark Evans

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Abstract

Hypoxic pulmonary vasoconstriction (HPV), which aids ventilation-perfusion matching in the lungs, is triggered by mechanisms intrinsic to pulmonary arterial smooth muscles. The unique sensitivity of these muscles to hypoxia is conferred by mitochondrial cytochrome c oxidase subunit 4 isoform 2, the inhibition of which has been proposed to trigger HPV through increased generation of mitochondrial reactive oxygen species. Contrary to this model, we have shown that the LKB1-AMPK-α1 signaling pathway is critical to HPV. Spectral Doppler ultrasound revealed that deletion of the AMPK-α1 catalytic subunit blocked HPV in mice during mild (8% O2) and severe (5% O2) hypoxia, whereas AMPK-α2 deletion attenuated HPV only during severe hypoxia. By contrast, neither of these genetic manipulations affected serotonin-induced reductions in pulmonary vascular flow. HPV was also attenuated by reduced expression of LKB1, a kinase that activates AMPK during energy stress, but not after deletion of CaMKK2, a kinase that activates AMPK in response to increases in cytoplasmic Ca2+ Fluorescence imaging of acutely isolated pulmonary arterial myocytes revealed that AMPK-α1 or AMPK-α2 deletion did not affect mitochondrial membrane potential during normoxia or hypoxia. However, deletion of AMPK-α1, but not of AMPK-α2, blocked hypoxia from inhibiting KV1.5, the classical "oxygen-sensing" K+ channel in pulmonary arterial myocytes. We conclude that LKB1-AMPK-α1 signaling pathways downstream of mitochondria are critical for the induction of HPV, in a manner also supported by AMPK-α2 during severe hypoxia.

Original languageEnglish
Article numbereaau0296
Pages (from-to)1-9
Number of pages9
JournalScience Signaling
Volume11
Issue number550
DOIs
Publication statusPublished - 2 Oct 2018

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AMP-Activated Protein Kinases
Mitochondria
Vasoconstriction
Lung
Muscle
Muscle Cells
Electron Transport Complex IV
Doppler Ultrasonography
Ventilation
Critical Pathways
Mitochondrial Membrane Potential
Optical Imaging
Reactive Oxygen Species
Serotonin
Protein Isoforms
Ultrasonics
Fluorescence
Oxygen
Membranes
Smooth Muscle

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Moral-Sanz, J., Lewis, S. A., MacMillan, S., Ross, F. A., Thomson, A., Viollet, B., ... Evans, A. M. (2018). The LKB1-AMPK-α1 signaling pathway triggers hypoxic pulmonary vasoconstriction downstream of mitochondria. Science Signaling, 11(550), 1-9. [eaau0296]. https://doi.org/10.1126/scisignal.aau0296
Moral-Sanz, Javier ; Lewis, Sophronia A. ; MacMillan, Sandy ; Ross, Fiona A. ; Thomson, Adrian ; Viollet, Benoit ; Foretz, Marc ; Moran, Carmel ; Hardie, D. Grahame ; Evans, A. Mark. / The LKB1-AMPK-α1 signaling pathway triggers hypoxic pulmonary vasoconstriction downstream of mitochondria. In: Science Signaling. 2018 ; Vol. 11, No. 550. pp. 1-9.
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abstract = "Hypoxic pulmonary vasoconstriction (HPV), which aids ventilation-perfusion matching in the lungs, is triggered by mechanisms intrinsic to pulmonary arterial smooth muscles. The unique sensitivity of these muscles to hypoxia is conferred by mitochondrial cytochrome c oxidase subunit 4 isoform 2, the inhibition of which has been proposed to trigger HPV through increased generation of mitochondrial reactive oxygen species. Contrary to this model, we have shown that the LKB1-AMPK-α1 signaling pathway is critical to HPV. Spectral Doppler ultrasound revealed that deletion of the AMPK-α1 catalytic subunit blocked HPV in mice during mild (8{\%} O2) and severe (5{\%} O2) hypoxia, whereas AMPK-α2 deletion attenuated HPV only during severe hypoxia. By contrast, neither of these genetic manipulations affected serotonin-induced reductions in pulmonary vascular flow. HPV was also attenuated by reduced expression of LKB1, a kinase that activates AMPK during energy stress, but not after deletion of CaMKK2, a kinase that activates AMPK in response to increases in cytoplasmic Ca2+ Fluorescence imaging of acutely isolated pulmonary arterial myocytes revealed that AMPK-α1 or AMPK-α2 deletion did not affect mitochondrial membrane potential during normoxia or hypoxia. However, deletion of AMPK-α1, but not of AMPK-α2, blocked hypoxia from inhibiting KV1.5, the classical {"}oxygen-sensing{"} K+ channel in pulmonary arterial myocytes. We conclude that LKB1-AMPK-α1 signaling pathways downstream of mitochondria are critical for the induction of HPV, in a manner also supported by AMPK-α2 during severe hypoxia.",
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Moral-Sanz, J, Lewis, SA, MacMillan, S, Ross, FA, Thomson, A, Viollet, B, Foretz, M, Moran, C, Hardie, DG & Evans, AM 2018, 'The LKB1-AMPK-α1 signaling pathway triggers hypoxic pulmonary vasoconstriction downstream of mitochondria', Science Signaling, vol. 11, no. 550, eaau0296, pp. 1-9. https://doi.org/10.1126/scisignal.aau0296

The LKB1-AMPK-α1 signaling pathway triggers hypoxic pulmonary vasoconstriction downstream of mitochondria. / Moral-Sanz, Javier; Lewis, Sophronia A.; MacMillan, Sandy; Ross, Fiona A.; Thomson, Adrian; Viollet, Benoit; Foretz, Marc; Moran, Carmel; Hardie, D. Grahame; Evans, A. Mark.

In: Science Signaling, Vol. 11, No. 550, eaau0296, 02.10.2018, p. 1-9.

Research output: Contribution to journalArticle

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AU - Thomson, Adrian

AU - Viollet, Benoit

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AU - Moran, Carmel

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PY - 2018/10/2

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N2 - Hypoxic pulmonary vasoconstriction (HPV), which aids ventilation-perfusion matching in the lungs, is triggered by mechanisms intrinsic to pulmonary arterial smooth muscles. The unique sensitivity of these muscles to hypoxia is conferred by mitochondrial cytochrome c oxidase subunit 4 isoform 2, the inhibition of which has been proposed to trigger HPV through increased generation of mitochondrial reactive oxygen species. Contrary to this model, we have shown that the LKB1-AMPK-α1 signaling pathway is critical to HPV. Spectral Doppler ultrasound revealed that deletion of the AMPK-α1 catalytic subunit blocked HPV in mice during mild (8% O2) and severe (5% O2) hypoxia, whereas AMPK-α2 deletion attenuated HPV only during severe hypoxia. By contrast, neither of these genetic manipulations affected serotonin-induced reductions in pulmonary vascular flow. HPV was also attenuated by reduced expression of LKB1, a kinase that activates AMPK during energy stress, but not after deletion of CaMKK2, a kinase that activates AMPK in response to increases in cytoplasmic Ca2+ Fluorescence imaging of acutely isolated pulmonary arterial myocytes revealed that AMPK-α1 or AMPK-α2 deletion did not affect mitochondrial membrane potential during normoxia or hypoxia. However, deletion of AMPK-α1, but not of AMPK-α2, blocked hypoxia from inhibiting KV1.5, the classical "oxygen-sensing" K+ channel in pulmonary arterial myocytes. We conclude that LKB1-AMPK-α1 signaling pathways downstream of mitochondria are critical for the induction of HPV, in a manner also supported by AMPK-α2 during severe hypoxia.

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Moral-Sanz J, Lewis SA, MacMillan S, Ross FA, Thomson A, Viollet B et al. The LKB1-AMPK-α1 signaling pathway triggers hypoxic pulmonary vasoconstriction downstream of mitochondria. Science Signaling. 2018 Oct 2;11(550):1-9. eaau0296. https://doi.org/10.1126/scisignal.aau0296