Prostaglandin-induced VASP phosphorylation controls alpha II-spectrin breakdown in apoptotic cells

Int Immunopharmacol. 2008 Feb;8(2):319-24. doi: 10.1016/j.intimp.2007.10.004. Epub 2007 Oct 24.

Abstract

In pathological conditions, the inflammatory mediator prostaglandin E2 (PGE2) has been shown to induce apoptosis through a cAMP-dependent pathway. However, underlying mechanisms have remained illusive. Irrespective whether apoptosis is induced by the intrinsic or extrinsic pathway, the cysteine protease caspase-3 becomes activated and cleaves many key proteins including spectrins. Cleavage of the plasma membrane-associated spectrins leads to cell shrinkage, membrane blebbing, the formation of apoptotic bodies, and irreversible cell death. Recently, we identified a novel interaction between alpha II-spectrin and vasodilator-stimulated phosphoprotein (VASP), which is abrogated by the cAMP-dependent protein kinase (PKA)-mediated phosphorylation of VASP. In the present study we investigated whether VASP binding to alpha II-spectrin affects spectrin breakdown in PGE2-induced apoptosis. PGE2 dose- and time-dependently triggered VASP phosphorylation. Following induction of apoptosis, caspase-3-mediated alpha II-spectrin breakdown and membrane blebbing were markedly delayed in wild-type as compared to VASP-deficient endothelial cells. This suggests that VASP binding to alpha II-spectrin attenuates alpha II-spectrin cleavage in apoptotic cells and that PGE2-induced VASP phosphorylation regulates this process. Our findings may therefore provide the molecular basis for PGE2-induced apoptosis in pathological events.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis*
  • Caspase 3 / physiology
  • Cell Adhesion Molecules / metabolism*
  • Dinoprostone / pharmacology*
  • Dose-Response Relationship, Drug
  • Mice
  • Microfilament Proteins / metabolism*
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Spectrin / metabolism*
  • Vasodilator-Stimulated Phosphoprotein

Substances

  • Cell Adhesion Molecules
  • Microfilament Proteins
  • Phosphoproteins
  • Vasodilator-Stimulated Phosphoprotein
  • Spectrin
  • Caspase 3
  • Dinoprostone