Rotenone inhibits axonogenesis via an Lfc/RhoA/ROCK pathway in cultured hippocampal neurons

J Neurochem. 2018 Sep;146(5):570-584. doi: 10.1111/jnc.14547. Epub 2018 Aug 16.

Abstract

Rotenone, a broad-spectrum insecticide, piscicide and pesticide, produces a complete and selective suppression of axonogenesis in cultured hippocampal neurons. This effect is associated with an inhibition of actin dynamics through activation of Ras homology member A (RhoA) activity. However, the upstream signaling mechanisms involved in rotenone-induced RhoA activation were unknown. We hypothesized that rotenone might inhibit axon growth by the activation of RhoA/ROCK pathway because of the changes in microtubule (MT) dynamics and the concomitant release of Lfc, a MT-associated Guanine Nucleotide Exchange Factor (GEF) for RhoA. In this study, we demonstrate that rotenone decreases MT stability in morphologically unpolarized neurons. Taxol (3 nM), a drug that stabilizes MT, attenuates the inhibitory effect of rotenone (0.1 μM) on axon formation. Radiometric Forster Resonance Energy Transfer, revealed that this effect is associated with inhibition of rotenone-induced RhoA and ROCK activation. Interestingly, silencing of Lfc, but not of the RhoA GEF ArhGEF1, prevents the inhibitory effect of rotenone on axon formation. Our results suggest that rotenone-induced MT de-stabilization releases Lfc from MT thereby promoting RhoA and ROCK activities and the consequent inhibition of axon growth. Open Science: This manuscript was awarded with the Open Materials Badge. For more information see: https://cos.io/our-services/open-science-badges/.

Keywords: ROCK; Lfc; RhoA; axon; neurons; neurotoxicity; rotenone.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Embryo, Mammalian
  • Female
  • Guanine Nucleotide Exchange Factors / genetics
  • Guanine Nucleotide Exchange Factors / metabolism*
  • Hippocampus / cytology
  • Insecticides / therapeutic use*
  • Neurogenesis / drug effects*
  • Neurons / drug effects*
  • Phosphorylation / drug effects
  • Pregnancy
  • Rats
  • Rotenone / pharmacology*
  • Signal Transduction / drug effects*
  • Transduction, Genetic
  • Tubulin / metabolism
  • rho GTP-Binding Proteins / metabolism
  • rho-Associated Kinases / metabolism
  • tau Proteins / metabolism

Substances

  • Guanine Nucleotide Exchange Factors
  • Insecticides
  • Lfc protein, rat
  • Tubulin
  • tau Proteins
  • Rotenone
  • rho-Associated Kinases
  • rho GTP-Binding Proteins