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

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/ Rotenone, a natural compound used for many years as an insecticide or pesticide, is associated with toxicity on neurons in vivo and in vitro. Previously, we have shown that the pesticide produces a complete and selective suppression of axon formation in cultured hippocampal neurons. We now show that rotenone inhibits the axon growth by activation of the RhoA/ROCK pathway as a result of changes in microtubule dynamics and the simultaneous release of Lfc, a microtubule‐associated Guanine Nucleotide Exchange Factor (GEF) for Ras homology member A (RhoA). Open Science: This manuscript was awarded with the Open Materials Badge. For more information see: https://cos.io/our-services/open-science-badges/