Sublytic C5b-9-stimulated Schwann cell survival through PI 3-kinase-mediated phosphorylation of BAD

Glia. 2001 Oct;36(1):58-67. doi: 10.1002/glia.1095.

Abstract

Sublytic C5b-9 induces cell cycle activation, proliferation, and rescue from apoptosis in Schwann cells. The signaling pathways for C5b-9-mediated rescue were investigated. Following serum withdrawal, DNA fragmentation, detected by TUNEL and FACS analysis, was 56.7% +/- 7.3 and 91.9% +/- 2.4 in cultured sciatic nerve Schwann cells from 6-day-old rats after 18 h and 24 h, respectively. Apoptosis was confirmed by inhibition of DNA fragmentation in a dose-dependent manner by DMQD-CHO, a caspase-3 inhibitor. Treatment with sublytic C5b-9 generated with purified components (C5*9) or Ab+C7-depleted serum (C7dHS)+C7 rescued 89% and 86% of Schwann cells, respectively, as compared with cells treated with C5*6, C8, C9, or Ab+C7dHS. Sublytic C5b-9 increased Schwann cell PI-3 kinase and Akt activity maximally at 5 min 3.14 +/- 0.5-fold and 3.56 +/- 0.4-fold, respectively, over controls. ERK-1 activity was maximally stimulated 2.98-fold at 15 min. Inhibition of PI-3 kinase by LY294002 abrogated the C5b-9-mediated Schwann cell rescue from apoptosis, while inhibition of ERK-1 with PD098,059 did not. PI-3 kinase-Akt pathway activation by C5b-9 induced, within 15 min, a 6.34 +/- 1.2-fold increase in BAD phosphorylation at Ser 136, but not at Ser 112. Downstream Bcl-x(L) protein was increased 2.61-fold +/- 0.34-fold by 18 h and 3.9-fold +/- 0.84-fold by 24 h over controls. LY294002 prevented both BAD phosphorylation at Ser 136 and Bcl-x(L) protein induction, while PD098,059 did not. Our data indicated that sublytic C5b-9 rescued Schwann cell from apoptosis via activation of PI-3 kinase-Akt, BAD phosphorylation on Ser 136 and increased expression of Bcl-x(L). Sublytic C5b-9 detected on Schwann cell in vivo during inflammatory neuropathy may facilitate survival of Schwann cell capable of remyelination.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Carrier Proteins / metabolism*
  • Cell Survival / drug effects
  • Cell Survival / physiology*
  • Cells, Cultured / cytology
  • Cells, Cultured / metabolism
  • Complement Membrane Attack Complex / metabolism*
  • Complement Membrane Attack Complex / pharmacology
  • Culture Media, Serum-Free / pharmacology
  • Enzyme Inhibitors / pharmacology
  • In Situ Nick-End Labeling
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphorylation / drug effects
  • Polyradiculoneuropathy / metabolism
  • Polyradiculoneuropathy / physiopathology
  • Protein-Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Schwann Cells / cytology
  • Schwann Cells / drug effects
  • Schwann Cells / metabolism*
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*
  • bcl-Associated Death Protein
  • bcl-X Protein

Substances

  • Bad protein, rat
  • Bcl2l1 protein, rat
  • Carrier Proteins
  • Complement Membrane Attack Complex
  • Culture Media, Serum-Free
  • Enzyme Inhibitors
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-Associated Death Protein
  • bcl-X Protein
  • Phosphatidylinositol 3-Kinases
  • Akt1 protein, rat
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases