Lead Exposure Induces Telomere Instability in Human Cells

PLoS One. 2013 Jun 26;8(6):e67501. doi: 10.1371/journal.pone.0067501. Print 2013.

Abstract

Lead (Pb) is an important environmental contaminant due to its widespread use over many centuries. While it affects primarily every organ system of the body, the most pernicious effects of Pb are on the central nervous system leading to cognitive and behavioral modification. Despite decades of research, the mechanisms responsible for Pb toxicity remain poorly understood. Recent work has suggested that Pb exposure may have consequences on chromosomal integrity as it was shown that Pb exposure leads to the generation of γH2Ax foci, a well-established biomarker for DNA double stranded break (DSB formation). As the chromosomal localization of γH2Ax foci plays an important role in determining the molecular mechanism responsible for their formation, we examined the localization of Pb-induced foci with respect to telomeres. Indeed, short or dysfunctional telomeres (uncapped or damaged telomeres) may be recognized as DSB by the DNA repair machinery, leading to "telomere-Induced Foci" (TIFs). In the current study, we show that while Pb exposure did not increase intra-chromosomal foci, it significantly induced TIFs, leading in some cases, to chromosomal abnormalities including telomere loss. The evidence suggests that these chromosomal abnormalities are likely due to perturbation of telomere replication, in particular on the lagging DNA strand. We propose a mechanism by which Pb exposure leads to the loss of telomere maintenance. As numerous studies have demonstrated a role for telomere maintenance in brain development and tissue homeostasis, our results suggest a possible mechanism for lead-induced neurotoxicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cells, Cultured
  • Chromosomal Instability / drug effects*
  • Environmental Exposure / adverse effects
  • Humans
  • Lead / adverse effects*
  • Lead Poisoning / complications
  • Lymphocytes / drug effects
  • Lymphocytes / pathology*
  • Telomere / genetics*
  • Telomere Homeostasis / drug effects*
  • Urinary Bladder Neoplasms / chemically induced
  • Urinary Bladder Neoplasms / genetics
  • Urinary Bladder Neoplasms / pathology*

Substances

  • Lead

Grants and funding

M.V. is supported by the European 7th framework grant BOOSTER: grant agreement no. 242361 (http://ec.europa.eu/research/fp7/index_en.cfm). W.H. is supported by the European 7th framework grant DoReMi: grant agreement no. 249689 (http://ec.europa.eu/research/fp7/index_en.cfm). This work was supported by the grants from the Agence Nationale de la Recherche (ANR) (http://www.agence-nationale-recherche.fr/) and the Institute National Du Cancer (INCa) (http://www.e-cancer.fr/recherche), Hemi-BREAKS and HEMIBREAKS-T. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.