The serum- and glucocorticoid-inducible kinase Sgk-1 is involved in pulmonary vascular remodeling: role in redox-sensitive regulation of tissue factor by thrombin

Circ Res. 2006 Mar 31;98(6):828-36. doi: 10.1161/01.RES.0000210539.54861.27. Epub 2006 Feb 16.

Abstract

The stress-responsive serum- and glucocorticoid-inducible kinase Sgk-1 is involved in osmoregulation and cell survival and may contribute to fibrosis and hypertension. However, the function of Sgk-1 in vascular remodeling and thrombosis, 2 major determinants of pulmonary hypertension (PH), has not been elucidated. We investigated the role of Sgk-1 in thrombin signaling and tissue factor (TF) expression and activity in pulmonary artery smooth muscle cells (PASMC). Thrombin increased Sgk-1 activity and mRNA and protein expression. H2O2 similarly induced Sgk-1 expression. Antioxidants, dominant-negative Rac, and depletion of the NADPH oxidase subunit p22phox diminished thrombin-induced Sgk-1 expression. Inhibition of p38 mitogen-activated protein kinase, phosphatidylinositol 3-kinase, and phosphoinositide-dependent kinase-1 prevented thrombin-induced Sgk-1 expression. Thrombin or Sgk-1 overexpression enhanced TF expression and procoagulant activity, whereas TF upregulation by thrombin was diminished by kinase-deficient Sgk-1 and was not detectable in fibroblasts from mice deficient in sgk-1 (sgk1(-/-)). Similarly, dexamethasone treatment failed to induce TF expression and activity in lung tissue from sgk1(-/-) mice. Transcriptional induction of TF by Sgk-1 was mediated through nuclear factor kappaB. Finally, Sgk-1 and TF proteins were detected in the media of remodeled pulmonary vessels associated with PH. These data show that thrombin potently induces Sgk-1 involving NADPH oxidases, phosphatidylinositol 3-kinase, p38 mitogen-activated protein kinase, and phosphoinositide-dependent kinase-1, and that activation of nuclear factor kappaB by Sgk-1 mediates TF expression and activity by thrombin. Because enhanced procoagulant activity can promote pulmonary vascular remodeling, and Sgk-1 and TF were present in the media of remodeled pulmonary vessels, this pathway may play a critical role in vascular remodeling in PH.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3-Phosphoinositide-Dependent Protein Kinases
  • Animals
  • Cells, Cultured
  • Humans
  • Hypertension, Pulmonary / etiology
  • Hypertension, Pulmonary / pathology
  • Immediate-Early Proteins / genetics
  • Immediate-Early Proteins / physiology*
  • Mice
  • Mice, Knockout
  • Muscle, Smooth, Vascular / pathology
  • NADPH Oxidases / physiology
  • NF-kappa B / physiology
  • Oxidation-Reduction
  • Phosphatidylinositol 3-Kinases / physiology
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / physiology*
  • Pulmonary Artery / pathology*
  • Reactive Oxygen Species
  • Thrombin / pharmacology*
  • Thromboplastin / genetics*
  • p38 Mitogen-Activated Protein Kinases / physiology

Substances

  • Immediate-Early Proteins
  • NF-kappa B
  • Reactive Oxygen Species
  • Thromboplastin
  • NADPH Oxidases
  • 3-Phosphoinositide-Dependent Protein Kinases
  • Protein Serine-Threonine Kinases
  • serum-glucocorticoid regulated kinase
  • p38 Mitogen-Activated Protein Kinases
  • Thrombin