Actin polymerization contributes to enhanced pulmonary vasoconstrictor reactivity following chronic hypoxia

Laura Weise-Cross, Michelle A. Sands, Joshua R. Sheak, Brad R. S. Broughton, Jessica B. Snow, Laura V. Gonzalez Bosc, Nikki L. Jernigan, Benjimen R. Walker, Thomas C. Resta

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Chronic hypoxia (CH) augments basal and endothelin 1 (ET-1)-induced pulmonary vasoconstrictor reactivity through reactive oxygen species (ROS) generation and RhoA/Rho kinase (ROCK)-dependent myofilament Ca2+ sensitization. Because ROCK promotes actin polymerization and the actin cytoskeleton regulates smooth muscle tension, we hypothesized that actin polymerization is required for enhanced basal and ET-1-dependent vasoconstriction following CH. To test this hypothesis, both endpoints were monitored in pressurized, endothelium-disrupted pulmonary arteries (4th-5th order) from control and CH (4 wk at 0.5 atm) rats. The actin polymerization inhibitors cytochalasin and latrunculin attenuated both basal and ET-1-induced vasoconstriction only in CH vessels. To test whether CH directly alters the arterial actin profile, we measured filamentous (F) and globular (G) actin ratios by fluorescent labeling of F-actin and G-actin in fixed pulmonary arteries and actin sedimentation assays using homogenized pulmonary artery lysates. We observed no difference in actin polymerization between groups under baseline conditions, but ET-1 enhanced actin polymerization in pulmonary arteries from CH rats. This response was blunted by the ROS scavenger tiron, the ROCK inhibitor fasudil, and the mDia (RhoA effector) inhibitor SMIFH2. Immunoblotting revealed an effect of CH to increase both phosphorylated (inactive) and total levels of the actin disassembly factor cofilin, but not phospho-cofilin/total cofilin ratios. We conclude that actin polymerization contributes to increased basal pulmonary arterial constriction and ET-1-induced vasoconstrictor reactivity following CH in a ROS-, ROCK-dependent manner. Our results further suggest that enhanced ET-1-mediated actin polymerization following CH is dependent on mDia, but independent of changes in the phosphorylated/total cofilin ratio.
Original languageEnglish
Pages (from-to)H1011-H1021
Number of pages11
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume314
Issue number5
DOIs
Publication statusPublished - May 2018
Externally publishedYes

Keywords

  • chronic hypoxia
  • pulmonary hypertension
  • actin polymerization
  • Rho kinase
  • reactive oxygen species

Cite this

Weise-Cross, Laura ; Sands, Michelle A. ; Sheak, Joshua R. ; Broughton, Brad R. S. ; Snow, Jessica B. ; Gonzalez Bosc, Laura V. ; Jernigan, Nikki L. ; Walker, Benjimen R. ; Resta, Thomas C. . / Actin polymerization contributes to enhanced pulmonary vasoconstrictor reactivity following chronic hypoxia. In: American Journal of Physiology - Heart and Circulatory Physiology. 2018 ; Vol. 314, No. 5. pp. H1011-H1021.
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title = "Actin polymerization contributes to enhanced pulmonary vasoconstrictor reactivity following chronic hypoxia",
abstract = "Chronic hypoxia (CH) augments basal and endothelin 1 (ET-1)-induced pulmonary vasoconstrictor reactivity through reactive oxygen species (ROS) generation and RhoA/Rho kinase (ROCK)-dependent myofilament Ca2+ sensitization. Because ROCK promotes actin polymerization and the actin cytoskeleton regulates smooth muscle tension, we hypothesized that actin polymerization is required for enhanced basal and ET-1-dependent vasoconstriction following CH. To test this hypothesis, both endpoints were monitored in pressurized, endothelium-disrupted pulmonary arteries (4th-5th order) from control and CH (4 wk at 0.5 atm) rats. The actin polymerization inhibitors cytochalasin and latrunculin attenuated both basal and ET-1-induced vasoconstriction only in CH vessels. To test whether CH directly alters the arterial actin profile, we measured filamentous (F) and globular (G) actin ratios by fluorescent labeling of F-actin and G-actin in fixed pulmonary arteries and actin sedimentation assays using homogenized pulmonary artery lysates. We observed no difference in actin polymerization between groups under baseline conditions, but ET-1 enhanced actin polymerization in pulmonary arteries from CH rats. This response was blunted by the ROS scavenger tiron, the ROCK inhibitor fasudil, and the mDia (RhoA effector) inhibitor SMIFH2. Immunoblotting revealed an effect of CH to increase both phosphorylated (inactive) and total levels of the actin disassembly factor cofilin, but not phospho-cofilin/total cofilin ratios. We conclude that actin polymerization contributes to increased basal pulmonary arterial constriction and ET-1-induced vasoconstrictor reactivity following CH in a ROS-, ROCK-dependent manner. Our results further suggest that enhanced ET-1-mediated actin polymerization following CH is dependent on mDia, but independent of changes in the phosphorylated/total cofilin ratio.",
keywords = "chronic hypoxia, pulmonary hypertension, actin polymerization, Rho kinase, reactive oxygen species",
author = "Laura Weise-Cross and Sands, {Michelle A.} and Sheak, {Joshua R.} and Broughton, {Brad R. S.} and Snow, {Jessica B.} and {Gonzalez Bosc}, {Laura V.} and Jernigan, {Nikki L.} and Walker, {Benjimen R.} and Resta, {Thomas C.}",
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language = "English",
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Actin polymerization contributes to enhanced pulmonary vasoconstrictor reactivity following chronic hypoxia. / Weise-Cross, Laura; Sands, Michelle A.; Sheak, Joshua R.; Broughton, Brad R. S.; Snow, Jessica B.; Gonzalez Bosc, Laura V.; Jernigan, Nikki L.; Walker, Benjimen R.; Resta, Thomas C. .

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 314, No. 5, 05.2018, p. H1011-H1021.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Actin polymerization contributes to enhanced pulmonary vasoconstrictor reactivity following chronic hypoxia

AU - Weise-Cross, Laura

AU - Sands, Michelle A.

AU - Sheak, Joshua R.

AU - Broughton, Brad R. S.

AU - Snow, Jessica B.

AU - Gonzalez Bosc, Laura V.

AU - Jernigan, Nikki L.

AU - Walker, Benjimen R.

AU - Resta, Thomas C.

PY - 2018/5

Y1 - 2018/5

N2 - Chronic hypoxia (CH) augments basal and endothelin 1 (ET-1)-induced pulmonary vasoconstrictor reactivity through reactive oxygen species (ROS) generation and RhoA/Rho kinase (ROCK)-dependent myofilament Ca2+ sensitization. Because ROCK promotes actin polymerization and the actin cytoskeleton regulates smooth muscle tension, we hypothesized that actin polymerization is required for enhanced basal and ET-1-dependent vasoconstriction following CH. To test this hypothesis, both endpoints were monitored in pressurized, endothelium-disrupted pulmonary arteries (4th-5th order) from control and CH (4 wk at 0.5 atm) rats. The actin polymerization inhibitors cytochalasin and latrunculin attenuated both basal and ET-1-induced vasoconstriction only in CH vessels. To test whether CH directly alters the arterial actin profile, we measured filamentous (F) and globular (G) actin ratios by fluorescent labeling of F-actin and G-actin in fixed pulmonary arteries and actin sedimentation assays using homogenized pulmonary artery lysates. We observed no difference in actin polymerization between groups under baseline conditions, but ET-1 enhanced actin polymerization in pulmonary arteries from CH rats. This response was blunted by the ROS scavenger tiron, the ROCK inhibitor fasudil, and the mDia (RhoA effector) inhibitor SMIFH2. Immunoblotting revealed an effect of CH to increase both phosphorylated (inactive) and total levels of the actin disassembly factor cofilin, but not phospho-cofilin/total cofilin ratios. We conclude that actin polymerization contributes to increased basal pulmonary arterial constriction and ET-1-induced vasoconstrictor reactivity following CH in a ROS-, ROCK-dependent manner. Our results further suggest that enhanced ET-1-mediated actin polymerization following CH is dependent on mDia, but independent of changes in the phosphorylated/total cofilin ratio.

AB - Chronic hypoxia (CH) augments basal and endothelin 1 (ET-1)-induced pulmonary vasoconstrictor reactivity through reactive oxygen species (ROS) generation and RhoA/Rho kinase (ROCK)-dependent myofilament Ca2+ sensitization. Because ROCK promotes actin polymerization and the actin cytoskeleton regulates smooth muscle tension, we hypothesized that actin polymerization is required for enhanced basal and ET-1-dependent vasoconstriction following CH. To test this hypothesis, both endpoints were monitored in pressurized, endothelium-disrupted pulmonary arteries (4th-5th order) from control and CH (4 wk at 0.5 atm) rats. The actin polymerization inhibitors cytochalasin and latrunculin attenuated both basal and ET-1-induced vasoconstriction only in CH vessels. To test whether CH directly alters the arterial actin profile, we measured filamentous (F) and globular (G) actin ratios by fluorescent labeling of F-actin and G-actin in fixed pulmonary arteries and actin sedimentation assays using homogenized pulmonary artery lysates. We observed no difference in actin polymerization between groups under baseline conditions, but ET-1 enhanced actin polymerization in pulmonary arteries from CH rats. This response was blunted by the ROS scavenger tiron, the ROCK inhibitor fasudil, and the mDia (RhoA effector) inhibitor SMIFH2. Immunoblotting revealed an effect of CH to increase both phosphorylated (inactive) and total levels of the actin disassembly factor cofilin, but not phospho-cofilin/total cofilin ratios. We conclude that actin polymerization contributes to increased basal pulmonary arterial constriction and ET-1-induced vasoconstrictor reactivity following CH in a ROS-, ROCK-dependent manner. Our results further suggest that enhanced ET-1-mediated actin polymerization following CH is dependent on mDia, but independent of changes in the phosphorylated/total cofilin ratio.

KW - chronic hypoxia

KW - pulmonary hypertension

KW - actin polymerization

KW - Rho kinase

KW - reactive oxygen species

U2 - 10.1152/ajpheart.00664.2017

DO - 10.1152/ajpheart.00664.2017

M3 - Article

VL - 314

SP - H1011-H1021

JO - American Journal of Physiology - Heart and Circulatory Physiology

JF - American Journal of Physiology - Heart and Circulatory Physiology

SN - 0363-6135

IS - 5

ER -