LC3 overexpression reduces Aβ neurotoxicity through increasing α7nAchR expression and autophagic activity in neurons and mice

Neuropharmacology. 2015 Jun:93:243-51. doi: 10.1016/j.neuropharm.2015.02.003. Epub 2015 Feb 14.

Abstract

Autophagy is an intracellular degradation pathway with dynamic interactions for eliminating damaged organelles and protein aggregates by lysosomal digestion. The EGFP-conjugated microtubule-associated protein 1 light chain 3 (EGFP-LC3) serves to monitor autophagic process. Extracellular β-amyloid peptide accumulation is reported as a major cause in Alzheimer's disease (AD) pathogenesis; large numbers of autophagic vacuoles accumulate in patients' brains. We previously demonstrated that extracellular Aβ (eAβ) induces strong autophagic response and α7nAChR acts as a carrier to bind with eAβ; which further inhibits Aβ-induced neurotoxicity via autophagic degradation. In the present study, we overexpressed LC3 in both neuroblastoma cells (SH-SY5Y/pEGFP-LC3) and mice (TgEGFP-LC3) to assess the effect of LC3 overexpression on Aβ neurotoxicity. SH-SY5Y/pEGFP-LC3 cells and primary cortical neuron cultures derived from E17 (embryonic day 17) TgEGFP-LC3 mice showed not only better resistance against Aβ neurotoxicity but also higher α7nAChR expression and autophagic activity than control. Administration of α-bungarotoxin (α-BTX) to block α7nAChR antagonized the neuroprotective action of SH-SY5Y/pECGF-LC3 cells, suggesting that eAβ binding with α7nAChR is an important step in Aβ detoxification. LC3 overexpression thus exerts neuroprotection through increasing α7nAChR expression for eAβ binding and further enhancing autophagic activity for Aβ clearance in vitro and in vivo.

Keywords: Apoptosis; Autophagy; Aβ; LC3; α7nAChR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / genetics
  • Actins / metabolism
  • Amyloid beta-Peptides / pharmacology*
  • Animals
  • Autophagy / drug effects*
  • Bungarotoxins / pharmacology
  • Caspase 3 / metabolism
  • Cells, Cultured
  • Cerebral Cortex / cytology
  • Dose-Response Relationship, Drug
  • Embryo, Mammalian
  • Gene Expression Regulation / drug effects*
  • Gene Expression Regulation / genetics
  • Humans
  • Mice
  • Mice, Transgenic
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism*
  • Neuroblastoma / pathology
  • Neurons / drug effects*
  • Neurons / metabolism
  • Nicotinic Antagonists / pharmacology
  • Peptide Fragments / pharmacology*
  • alpha7 Nicotinic Acetylcholine Receptor / genetics
  • alpha7 Nicotinic Acetylcholine Receptor / metabolism*

Substances

  • Actins
  • Amyloid beta-Peptides
  • Bungarotoxins
  • Map1lc3b protein, mouse
  • Microtubule-Associated Proteins
  • Nicotinic Antagonists
  • Peptide Fragments
  • alpha7 Nicotinic Acetylcholine Receptor
  • amyloid beta-protein (1-42)
  • amyloid beta-protein (25-35)
  • Caspase 3