The inhibition of Bax activation-induced apoptosis by RasGRP2 via R-Ras-PI3K-Akt signaling pathway in the endothelial cells

Sci Rep. 2019 Nov 13;9(1):16717. doi: 10.1038/s41598-019-53419-4.

Abstract

Apoptosis of endothelial cells is a very important event in various diseases and angiogenesis. We recently reported that ras guanyl nucleotide releasing protein 2 (RasGRP2), which is a guanine nucleotide exchange factor, was expressed in the human umbilical vein endothelial cells (HUVECs) and that Rap1 activation by its overexpression inhibited apoptosis by suppressing tumor necrosis factor-α induced-reactive oxygen species (ROS) production. However, other signaling pathways and roles of RasGRP2 not mediated via Rap1 are not well understood. Therefore, we compared the Mock (M) and the RasGRP2-stable overexpression (R) immortalized HUVECs using BAM7 and anisomycin, which are apoptosis inducers. BAM7 and anisomycin induced apoptosis without causing ROS production, and such apoptosis was significantly increased in M cells, but not in R cells. RasGRP2 suppressed BAM7- and anisomycin-induced apoptosis, but not via the Rap1 pathway as observed using Rap1 knockdown. Furthermore, RasGRP2 activated not only Rap1 but also R-Ras, and suppressed apoptosis by activating R-Ras-phosphoinositide 3-kinase (PI3K)-Akt signaling pathway. The phosphorylation of Akt by RasGRP2 inhibited Bax translocation by promoting translocation of hexokinase-2 (HK-2) from cytoplasm to mitochondria. Taken together, it was suggested that RasGRP2 suppresses the Bax activation-induced apoptosis by promoting HK-2 translocation to mitochondria via R-Ras-PI3K-Akt signaling pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis*
  • Endothelium, Vascular / metabolism
  • Endothelium, Vascular / pathology*
  • Guanine Nucleotide Exchange Factors / genetics
  • Guanine Nucleotide Exchange Factors / metabolism*
  • Human Umbilical Vein Endothelial Cells
  • Humans
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Reactive Oxygen Species / metabolism
  • Signal Transduction
  • bcl-2-Associated X Protein / genetics
  • bcl-2-Associated X Protein / metabolism*
  • rap1 GTP-Binding Proteins / genetics
  • rap1 GTP-Binding Proteins / metabolism
  • ras Proteins / genetics
  • ras Proteins / metabolism*

Substances

  • BAX protein, human
  • Guanine Nucleotide Exchange Factors
  • RASGRP2 protein, human
  • Reactive Oxygen Species
  • bcl-2-Associated X Protein
  • Proto-Oncogene Proteins c-akt
  • RRAS protein, human
  • rap1 GTP-Binding Proteins
  • ras Proteins