Induction of autophagy by TOCP in differentiated human neuroblastoma cells lead to degradation of cytoskeletal components and inhibition of neurite outgrowth

Toxicology. 2013 Aug 9;310:92-7. doi: 10.1016/j.tox.2013.05.012. Epub 2013 Jun 3.

Abstract

Tri-ortho-cresyl phosphate (TOCP), an organophosphorus ester, can cause neurotoxicity such as organophosphorus ester-induced delayed neuropathy (OPIDN) in humans and sensitive animals. Moreover, it also affects the development of central nervous system and differentiation of neuronal cells. In this study, retinoic acid-induced differentiated human neuroblastoma SH-SY5Y cells are utilized to investigate the effects of TOCP on neurite outgrowth and the underlying mechanisms. We found that low concentrations of TOCP induced autophagy and inhibited neurite outgrowth in a dose-dependent manner with no effect on cell viability. The protein levels of high molecular weight neurofilament (NF-H), low molecular weight neurofilament (NF-L) and β-tubulin also decreased. Pretreatment cells with 3-methyladenine (3-MA), an autophagy inhibitor, not only inhibited the TOCP-induced autophagy, but also reversed the inhibition of neurite outgrowth and the degradation of NF-H, NF-L, and β-tubulin by TOCP. Taken together, these results indicated that TOCP treatment induced autophagy in differentiated SH-SY5Y cells, which lead to degradation of cytoskeletal components and inhibition of neurite outgrowth.

Keywords: 3-MA; 3-methyladenine; CHX; Cytoskeletal component; DMEM; Degradation; Dulbecco's modified Eagle's medium; ECL; Human neuroblastoma; NF-H; NF-L; Neurite outgrowth; OP; OPIDN; Organophosphate; PI3K; PVDF; RA; Rapa; TBS; TOCP; cycloheximide; enhanced chemiluminescence; high molecular weight neurofilament; low molecular weight neurofilament; organophosphates; organophosphorous compound-induced delayed neuropathy; phosphatidylinositol-3-kinase; polyvinylidene fluoride; rapamycin; retinoic acid; tri-ortho-cresyl phosphate; tris-buffered saline.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagy / drug effects*
  • Cell Differentiation / drug effects*
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cytoskeleton / drug effects*
  • Cytoskeleton / metabolism
  • Cytoskeleton / pathology
  • Dose-Response Relationship, Drug
  • Green Fluorescent Proteins / genetics
  • Humans
  • Microscopy, Confocal
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Neurites / drug effects*
  • Neurites / metabolism
  • Neurites / pathology
  • Neurotoxicity Syndromes / etiology
  • Neurotoxicity Syndromes / metabolism
  • Neurotoxicity Syndromes / pathology
  • Plasticizers / toxicity*
  • Transfection
  • Tritolyl Phosphates / toxicity*

Substances

  • MAP1LC3A protein, human
  • Microtubule-Associated Proteins
  • Plasticizers
  • Tritolyl Phosphates
  • Green Fluorescent Proteins
  • tri-o-cresyl phosphate