hScrib, a human homologue of Drosophila neoplastic tumor suppressor, is a novel death substrate targeted by caspase during the process of apoptosis

Genes Cells. 2008 Jul;13(7):771-85. doi: 10.1111/j.1365-2443.2008.01204.x.

Abstract

hScrib, human homologue of Drosophila neoplastic tumor suppressor, was identified as a target of human papillomavirus E6 oncoprotein for the ubiquitin-mediated degradation. Here, we report that hScrib is a novel death substrate targeted by caspase. Full-length hScrib was cleaved by caspase during death ligands-induced apoptosis, which generates a p170 C-terminal fragments in Hela cells. In vitro cleavage assay using recombinant caspases showed that hScrib is cleaved by the executioner caspases. DNA damage-induced apoptosis caused loss of expression of full-length hScrib, which was recovered by addition of capase-3 inhibitor in HaCat cells. TUNEL positive apoptotic cells, which were identified 4 h after UV irradiation in HaCat cells, showed loss of hScrib expression at the adherens junction. Mutational analysis identified the caspase-dependent cleavage site of hScrib at the position of Asp-504. Although MDCK cells transfected with GFP-fused wild-type hScrib showed loss of E-cadherin expression and shrinkage of cytoplasm by UV irradiation, cells transfected with hScrib with Ala substitution of Asp-504 showed resistance to caspase-dependent cleavage of hScrib and intact expression of E-cadherin. These results indicate that caspase-dependent cleavage of hScrib is a critical step for detachment of cell contact during the process of apoptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / physiology*
  • Apoptosis / radiation effects
  • Caco-2 Cells
  • Caspases / physiology*
  • Cell Communication / genetics
  • Cell Communication / physiology
  • Cell Communication / radiation effects
  • Cell Death / genetics
  • Cell Death / radiation effects
  • Cell Line
  • DNA Damage / physiology
  • DNA Damage / radiation effects
  • Dogs
  • Drosophila / genetics*
  • Drosophila / metabolism
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Gene Targeting
  • HeLa Cells
  • Humans
  • Ligands
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Structural Homology, Protein
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism*
  • Ultraviolet Rays

Substances

  • Drosophila Proteins
  • Ligands
  • Membrane Proteins
  • SCRIB protein, human
  • Scrib protein, Drosophila
  • Tumor Suppressor Proteins
  • Caspases