Bacterial genotoxins promote inside-out integrin β1 activation, formation of focal adhesion complexes and cell spreading

PLoS One. 2015 Apr 13;10(4):e0124119. doi: 10.1371/journal.pone.0124119. eCollection 2015.

Abstract

Integrins are membrane bound receptors that regulate several cellular processes, such as cell adhesion, migration, survival and proliferation, and may contribute to tumor initiation/progression in cells exposed to genotoxic stress. The extent of integrin activation and its role in cell survival upon intoxication with bacterial genotoxins are still poorly characterized. These toxins induce DNA strand breaks in the target cells and activate the DNA damage response (DDR), coordinated by the Ataxia Telangectasia Mutated (ATM) kinase. In the present study, we demonstrate that induction of DNA damage by two bacterial genotoxins promotes activation of integrin β1, leading to enhanced assembly of focal adhesions and cell spreading on fibronectin, but not on vitronectin. This phenotype is mediated by an ATM-dependent inside-out integrin signaling, and requires the actin cytoskeleton remodeler NET1. The toxin-mediated cell spreading and anchorage-independent survival further relies on ALIX and TSG101, two components of the endosomal sorting complex required for transport (ESCRT), known to regulate integrin intracellular trafficking. These data reveal a novel aspect of the cellular response to bacterial genotoxins, and provide new tools to understand the carcinogenic potential of these effectors in the context of chronic intoxication and infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Caco-2 Cells
  • Cell Adhesion / drug effects*
  • Cell Adhesion / physiology
  • Cell Movement / drug effects*
  • Cell Movement / physiology
  • Cell Survival / drug effects
  • Endotoxins / pharmacology*
  • Fluorescent Antibody Technique
  • Focal Adhesions / drug effects*
  • Focal Adhesions / physiology
  • HeLa Cells
  • Humans
  • Integrin beta1 / metabolism*
  • Mutagens / pharmacology*
  • Salmonella typhi / pathogenicity
  • Signal Transduction / drug effects*
  • Typhoid Fever / microbiology

Substances

  • Endotoxins
  • Integrin beta1
  • Mutagens
  • salmonella toxin

Grants and funding

This work was supported by grants awarded by Swedish Research Council and the Swedish Cancer Society to TF and MP. LL is supported by the Karolinska Institutet doctoral funding (KID). TF is a fellow of the Swedish Cancer Society. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.