α 1G T-type calcium channel determines the angiogenic potential of pulmonary microvascular endothelial cells

Am J Physiol Cell Physiol. 2019 Mar 1;316(3):C353-C364. doi: 10.1152/ajpcell.00336.2018. Epub 2019 Jan 16.

Abstract

Pulmonary microvascular endothelial cells (PMVECs) display a rapid angioproliferative phenotype, essential for maintaining homeostasis in steady-state and promoting vascular repair after injury. Although it has long been established that endothelial cytosolic Ca2+ ([Ca2+]i) transients are required for proliferation and angiogenesis, mechanisms underlying such regulation and the transmembrane channels mediating the relevant [Ca2+]i transients remain incompletely understood. In the present study, the functional role of the microvascular endothelial site-specific α1G T-type Ca2+ channel in angiogenesis was examined. PMVECs intrinsically possess an in vitro angiogenic "network formation" capacity. Depleting extracellular Ca2+ abolishes network formation, whereas blockade of vascular endothelial growth factor receptor or nitric oxide synthase has little or no effect, suggesting that the network formation is a [Ca2+]i-dependent process. Blockade of the T-type Ca2+ channel or silencing of α1G, the only voltage-gated Ca2+ channel subtype expressed in PMVECs, disrupts network formation. In contrast, blockade of canonical transient receptor potential (TRP) isoform 4 or TRP vanilloid 4, two other Ca2+ permeable channels expressed in PMVECs, has no effect on network formation. T-type Ca2+ channel blockade also reduces proliferation, cell-matrix adhesion, and migration, three major components of angiogenesis in PMVECs. An in vivo study demonstrated that the mice lacking α1G exhibited a profoundly impaired postinjury cell proliferation in the lungs following lipopolysaccharide challenge. Mechanistically, T-type Ca2+ channel blockade reduces Akt phosphorylation in a dose-dependent manner. Blockade of Akt or its upstream activator, phosphatidylinositol-3-kinase (PI3K), also impairs network formation. Altogether, these findings suggest a novel functional role for the α1G T-type Ca2+ channel to promote the cell's angiogenic potential via a PI3K-Akt signaling pathway.

Keywords: Akt; T-type calcium channel; angiogenesis; endothelial cell.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calcium Channels, T-Type / metabolism*
  • Cell Movement / drug effects
  • Cell Proliferation / drug effects
  • Cells, Cultured
  • Endothelial Cells / drug effects
  • Endothelial Cells / metabolism*
  • Female
  • Lipopolysaccharides / pharmacology
  • Lung / drug effects
  • Lung / metabolism*
  • Male
  • Mice
  • Neovascularization, Pathologic / metabolism*
  • Phosphatidylinositol 3-Kinase / metabolism
  • Rats
  • Signal Transduction / drug effects
  • TRPC Cation Channels / metabolism
  • Vascular Endothelial Growth Factor A / metabolism

Substances

  • Calcium Channels, T-Type
  • Lipopolysaccharides
  • TRPC Cation Channels
  • TRPC4 ion channel
  • Vascular Endothelial Growth Factor A
  • Phosphatidylinositol 3-Kinase
  • Calcium