Inhibition of mitochondrial complex II in neuronal cells triggers unique pathways culminating in autophagy with implications for neurodegeneration

Sci Rep. 2021 Jan 15;11(1):1483. doi: 10.1038/s41598-020-79339-2.

Abstract

Mitochondrial dysfunction and neurodegeneration underlie movement disorders such as Parkinson's disease, Huntington's disease and Manganism among others. As a corollary, inhibition of mitochondrial complex I (CI) and complex II (CII) by toxins 1-methyl-4-phenylpyridinium (MPP+) and 3-nitropropionic acid (3-NPA) respectively, induced degenerative changes noted in such neurodegenerative diseases. We aimed to unravel the down-stream pathways associated with CII inhibition and compared with CI inhibition and the Manganese (Mn) neurotoxicity. Genome-wide transcriptomics of N27 neuronal cells exposed to 3-NPA, compared with MPP+ and Mn revealed varied transcriptomic profile. Along with mitochondrial and synaptic pathways, Autophagy was the predominant pathway differentially regulated in the 3-NPA model with implications for neuronal survival. This pathway was unique to 3-NPA, as substantiated by in silico modelling of the three toxins. Morphological and biochemical validation of autophagy markers in the cell model of 3-NPA revealed incomplete autophagy mediated by mechanistic Target of Rapamycin Complex 2 (mTORC2) pathway. Interestingly, Brain Derived Neurotrophic Factor (BDNF), which was elevated in the 3-NPA model could confer neuroprotection against 3-NPA. We propose that, different downstream events are activated upon neurotoxin-dependent CII inhibition compared to other neurotoxins, with implications for movement disorders and regulation of autophagy could potentially offer neuroprotection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Methyl-4-phenylpyridinium / pharmacology
  • Animals
  • Autophagy / physiology*
  • Cell Death
  • Cell Line
  • Cell Survival
  • Cells, Cultured
  • Electron Transport Complex I / antagonists & inhibitors
  • Electron Transport Complex I / metabolism
  • Electron Transport Complex II / antagonists & inhibitors
  • Electron Transport Complex II / metabolism*
  • Gene Expression / genetics
  • Gene Expression Profiling / methods
  • Mitochondria / metabolism
  • Movement Disorders / physiopathology
  • Neurodegenerative Diseases / metabolism
  • Neurodegenerative Diseases / physiopathology
  • Neurons / metabolism*
  • Neuroprotection
  • Neurotoxins / toxicity
  • Nitro Compounds / pharmacology
  • Propionates / pharmacology
  • Rats
  • Transcriptome / genetics

Substances

  • Neurotoxins
  • Nitro Compounds
  • Propionates
  • Electron Transport Complex II
  • Electron Transport Complex I
  • 3-nitropropionic acid
  • 1-Methyl-4-phenylpyridinium