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

TY - JOUR

T1 - The LKB1-AMPK-α1 signaling pathway triggers hypoxic pulmonary vasoconstriction downstream of mitochondria

AU - Moral-Sanz, Javier

AU - Lewis, Sophronia A.

AU - MacMillan, Sandy

AU - Ross, Fiona A.

AU - Thomson, Adrian

AU - Viollet, Benoit

AU - Foretz, Marc

AU - Moran, Carmel

AU - Hardie, D. Grahame

AU - Evans, A. Mark

N1 - A British Heart Foundation Programme Grant (29885 to AME) was the primary source of funding for this study. Initial studies received additional supported by a Wellcome Trust Programme Grant (081195 to AME). Contributions from FAR and DGH were also supported by a Wellcome Trust Investigator Award (204766 to DGH). Author contributions: JMS, SL, AT, CM and AME carried out ultrasound experiments and analysis. JMS and AME carried out mitochondrial imaging. JMS and AME carried out electrophysiology and analysis. SL, JMS and AME completed qPCR. FAR and DGH carried out protein phosphorylation and analysis. SM carried out blood pressure measurements. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper or the Supplementary Materials. The authors would like to thank Kei Sakamoto (Nestlé Institute of Health Sciences, Lausanne, Switzerland) for providing additional supplies of the AMPK activator (C13) at a critical time.

PY - 2018/10/2

Y1 - 2018/10/2

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.

AB - 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.

U2 - 10.1126/scisignal.aau0296

DO - 10.1126/scisignal.aau0296

M3 - Article

C2 - 30279167

SN - 1937-9145

VL - 11

SP - 1

EP - 9

JO - Science Signaling

JF - Science Signaling

IS - 550

M1 - eaau0296

ER -