The antidiabetic drug troglitazone protects against PrP (106‑126)‑induced neurotoxicity via the PPARγ‑autophagy pathway in neuronal cells

Mol Med Rep. 2021 Jun;23(6):430. doi: 10.3892/mmr.2021.12069. Epub 2021 Apr 13.

Abstract

Prion diseases, which involve the alteration of cellular prion protein into a misfolded isoform, disrupt the central nervous systems of humans and animals alike. Prior research has suggested that peroxisome proliferator‑activator receptor (PPAR)γ and autophagy provide some protection against neurodegeneration. PPARs are critical to lipid metabolism regulation and autophagy is one of the main cellular mechanisms by which cell function and homeostasis is maintained. The present study examined the effect of troglitazone, a PPARγ agonist, on autophagy flux in a prion peptide (PrP) (106‑126)‑mediated neurodegeneration model. Western blot analysis confirmed that treatment with troglitazone increased LC3‑II and p62 protein expression, whereas an excessive increase in autophagosomes was verified by transmission electron microscopy. Troglitazone weakened PrP (106‑126)‑mediated neurotoxicity via PPARγ activation and autophagy flux inhibition. A PPARγ antagonist blocked PPARγ activation as well as the neuroprotective effects induced by troglitazone treatment, indicating that PPARγ deactivation impaired troglitazone‑mediated protective effects. In conclusion, the present study demonstrated that troglitazone protected primary neuronal cells against PrP (106‑126)‑induced neuronal cell death by inhibiting autophagic flux and activating PPARγ signals. These results suggested that troglitazone may be a useful therapeutic agent for the treatment of neurodegenerative disorders and prion diseases.

Keywords: troglitazone; prion protein; autophagy flux; PPARγ; neurotoxicity.

MeSH terms

  • Animals
  • Autophagy / drug effects*
  • Autophagy-Related Protein 5 / genetics
  • Cell Line
  • Humans
  • Hypoglycemic Agents / pharmacology*
  • Mice
  • Mice, Inbred ICR
  • Neurons / drug effects
  • Neurons / metabolism*
  • Neuroprotective Agents / pharmacology
  • PPAR gamma / agonists
  • PPAR gamma / metabolism*
  • Peptide Fragments / adverse effects*
  • Prion Proteins
  • Prions / adverse effects*
  • Troglitazone / pharmacology*

Substances

  • Atg5 protein, mouse
  • Autophagy-Related Protein 5
  • Hypoglycemic Agents
  • Neuroprotective Agents
  • PPAR gamma
  • Peptide Fragments
  • Prion Proteins
  • Prions
  • prion protein (106-126)
  • Troglitazone

Grants and funding

This study was supported by a Korean Grant from the National Research Foundation (NRF) funded by the Ministry of Education (grant no. 2019R1A2B5B02069765) and ‘Research Base Construction Fund Support Program’ funded by Jeonbuk National University in 2020.