EFFECT OF THE PESTICIDE ROTENONE ON THE DEVELOPMENT OF NEURONAL POLARITY

Various xenobiotics such as pesticides and herbicides are considered to be factors involved in the pathogenesis of neurodegenerative diseases. Thus, chronic exposure to the natural pesticide Rotenone induces a parkinsonian-like syndrome in rodents. However, the mechanisms that operate in the neurotoxicity process induced by the pesticide have not been fully elucidated so far. We have shown that exposure to the pesticide affects the morphogenesis of hippocampal and dopaminergic neurons in culture, producing a dose-dependent inhibition of the development of neuronal polarity. Pull-down tests showed that rotenone modifies the activity of RhoGTPases by decreasing the activity of Cdc42 and Rac1 and increasing the activity of RhoA. Subsequently, we demonstrate that the pesticide reduces the stability of microtubules (MT) in morphologically nonpolarized neurons. Taxol, a TM stabilizing drug, attenuates the aforementioned inhibitory effect of rotenone on axon formation. Radiometric Forster Resonance Energy Transfer (FRET) assays revealed that the effect of taxol is associated with an inhibition of pesticide-induced RhoA and ROCK activation. Strikingly, the silencing of Lfc, but not other RhoA-GEF Arhgef1, reverses the inhibitory effect of rotenone-induced axonogenesis. In conclusion, the results obtained suggest that the increase in RhoA / ROCK activity in neurons treated with rotenone is specifically mediated by an increase in Lfc activity as a result of the destabilization of MTs. The fact that deletion of Lfc but not Arhgef1 reduces rotenone-induced RhoA activation and inhibition of axonal growth is fully compatible with this idea. This is further supported by our observations showing that: 1) rotenone induces destabilization of MTs, a phenomenon that causes the probable release of Lfc from MTs, leading to the activation of RhoA; 2) taxol, by stabilizing MTs, mimics the silencing effects of Lfc; 3) The pesticide increases the expression levels of the Lfc protein; and 4) The suppression of ArhGEF1 does not reverse the inhibitory effect of rotenone. Therefore, our results specifically and for the first time involve the Lfc / RhoA / ROCK signaling pathway in the inhibition of axon formation caused by rotenone in cultured hippocampal pyramidal neurons. In future studies, we consider it of interest to explore whether or not the pesticide affects other neuronal domains (for example, dendritic spines) where this signaling pathway has been strongly implicated.

msanchez@immf.uncor.edu

SUBSIDIES

  • Neurobiological bases of the effects of ghrelin at the central level: Peptide-induced memory facilitation. Accrediting and / or Financing Entity: SECyT. Director: Dra. Susana Rubiales. Role: Co-owner. Amount: $ 30,000.

  • Neurobiological bases of the effects of ghrelin at the central level. Studies related to memory consolidation, eating and anxiety. Accrediting and / or Financing Entity: CONICET. Director: Dra. Susana Rubiales. Role: Investigator. Amount: $ 290000.

  • Biogenesis of dendritic Golgi (gops): cellular and molecular mechanisms. Accrediting and / or Financing Entity: National Agency for Scientific and Technological Promotion. PICT-2015-1436. Director: Dr. Alfredo Cáceres. Role: Member of the Responsible Group. Amount: $ 777,263

Human Resources Training (last 5 years):

  • Bioq Doctoral Thesis Tribunal. Mary Luz Perea Vega (directed by Dr. Susana Rubiales, Professor of Human Pharmacology, Fac. Of Chemical Sciences-UNC; Principal Investigator Conicet, IFEC). From 2015 to the present.

  • Bioq Doctoral Thesis Tribunal. Lucía Fernandez Hubeid (directed by Dr. Miriam Virgolini, Associate Professor of Toxicology, Fac. De Ciencias Químicas-UNC; Adjunct Researcher Conicet, IFEC). From 2019 to the present.

  • Address of the Intern Lic. Santiago Alderete. From 2019 to the present.

Publications and conferences presented (last 5 years):

Publications:

  • Bisbal M, Remedi M, Quassollo G, Cáceres A, Sanchez M. Rotenone inhibits axonogenesis via an Lfc/RhoA/ROCK pathway in cultured hippocampal neurons. J Neurochem. 146(5):570-584. 2018
  • Bisbal M, Sanchez M. Neurotoxicity of the pesticide rotenone on neuronal polarization: a mechanistic approach. Neural Regen Res. 14(5):762-766. 2019.

Congresses presented:

  • Perea Vega ML, Martin MG, Sanchez MS, De Barioglio SR. Ghrelin modulates hippocampal plasticity by inducing an increase in the expression of BDNF and an increase in the density of dendritic spines. Oral presentation: 10/17. XXV Conference of Young Researchers Encarnación- Paraguay AUGM
  • Perea Vega ML, Martin MG, Pérez M, Sanchez MS, De Barioglio SR. Ghrelin modulates hippocampal plasticity by inducing increased BDNF expression and increased density of dendritic spines. Poster: 11/13/13/17 Joint Meeting of Biosciences Societies. Buenos Aires.

Publication (selected):

  • Bisbal M, Remedi M, Quassollo G, Cáceres A, Sanchez M. Rotenone inhibits axonogenesis via an Lfc/RhoA/ROCK pathway in cultured hippocampal neurons. J Neurochem. 146(5):570-584. 2018.

Teaching activity:

  • Adjunct Professor of Basic Pharmacology. UNIVERSITY INSTITUTE OF BIOMEDICAL SCIENCES OF CORDOBA (IUCBC).
  • Visiting Professor of Pathophysiology. UNIVERSITY INSTITUTE OF BIOMEDICAL SCIENCES OF CORDOBA (IUCBC).
  • Visiting Professor of Biology, Histology, Physiology and Human Anatomy. UNIVERSITY INSTITUTE OF BIOMEDICAL SCIENCES OF CORDOBA (IUCBC).