Methylisothiazolinone, a neurotoxic biocide, disrupts the association of SRC family tyrosine kinases with focal adhesion kinase in developing cortical neurons

J Pharmacol Exp Ther. 2006 Jun;317(3):1320-9. doi: 10.1124/jpet.106.103044. Epub 2006 Mar 17.


Methylisothiazolinone (MIT) is a biocide widely used in industrial and cosmetic products with potential as a neurotoxicant. We previously reported that short acute exposures to relatively high concentrations of MIT (100 microM) lead to widespread and selective neuronal death in vitro. To evaluate the biological properties of chronic exposures to MIT, freshly dissociated rat cortical neurons were continuously exposed to low concentrations (0.1-3 microM) of the biocide in serum-containing media. Although we observed minimal effects on cell viability, MIT induced a dramatic inhibition of neurite outgrowth. Immunoblotting and immunoprecipitation experiments revealed that focal adhesion kinase (FAK) phosphorylation was primarily affected by the MIT treatment. The phosphorylation level at tyrosines 576 and 861 of FAK was significantly decreased and likely contributed to the overall reduction of tyrosine phosphorylation of this protein. MIT inhibited Src family kinases (SFKs) in cell-free assays and led to the physical dissociation of FAK from the signaling complexes that it normally forms with c-Src and Fyn in developing neurons. High-density neuronal cultures were then employed to increase cell-to-cell contact. This approach resulted in an overall enhancement of SFKs and FAK phosphorylation and could overcome the deficits induced by MIT. This study suggests that a disruption of FAK-SFK complexes due to SFK inhibition leads to FAK dysfunction, with detrimental effects to immature neurons. Prolonged exposure to low levels of MIT and related compounds may have damaging consequences to the developing nervous system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Survival / drug effects
  • Cells, Cultured
  • Cerebral Cortex / cytology
  • Cerebral Cortex / embryology*
  • Disinfectants / toxicity*
  • Focal Adhesion Protein-Tyrosine Kinases / antagonists & inhibitors
  • Focal Adhesion Protein-Tyrosine Kinases / metabolism*
  • Neurons / drug effects*
  • Neurons / enzymology
  • Neurons / pathology
  • Phosphorylation
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction / drug effects
  • Thiazoles / toxicity*
  • src-Family Kinases / antagonists & inhibitors
  • src-Family Kinases / metabolism*


  • Disinfectants
  • Thiazoles
  • 2-methyl-4-isothiazolin-3-one
  • Focal Adhesion Protein-Tyrosine Kinases
  • src-Family Kinases