A Role for the Autophagy Regulator Transcription Factor EB in Amiodarone-Induced Phospholipidosis

Biochem Pharmacol. 2015 Jun 1;95(3):201-9. doi: 10.1016/j.bcp.2015.03.017. Epub 2015 Apr 13.

Abstract

The antiarrhythmic agent amiodarone, a cationic amphiphilic drug, is known to induce phospholipidosis, i.e. the accumulation of phospholipids within lysosomal structures to give multi-lamellar inclusion bodies. Despite the concerns raised about phospholipidosis in the recent years, the molecular mechanisms underlying amiodarone- or other cationic amphiphilic drug-induced phospholipidosis are still under investigation. Here we demonstrated that amiodarone doses able to induce phospholiposis according to NBD-PC uptake assay (1-12 μM, 24 h) activates Transcription Factor EB (TFEB), a pivotal regulator of the autophagic pathway, in human HepG2 cells. Further evidences confirmed the effect of amiodarone on the autophagic-lysosomal system in HepG2 and BEAS-2B cells: lysosomal β-hexosaminidase isoenzymes secretion, transcriptional up-regulation of the lysosomal β-hexosaminidase α-subunit, alteration of cathepsin B, D and L intracellular maturation in a cell- and protease-specific manner. Autophagy activation was also demonstrated by increased conversion of LC3-I into LC3-II and reduced phosphorylation of the mTORC1 target S6 kinase. Besides, we provided evidence that TFEB over-expression prevents amiodarone-induced phospholipid accumulation, suggesting that this transcription factor could be a possible target to develop strategies for phospholipidosis attenuation.

Keywords: Amiodarone; Amiodarone (PubChem CID: 2157); Autophagy; Cimetidine (PubChem CID: 2756); Lysosomal enzymes; Phospholipidosis; TFEB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amiodarone / pharmacology*
  • Autophagy / physiology*
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / physiology*
  • Hep G2 Cells
  • Humans
  • Phospholipids / metabolism*
  • Polymerase Chain Reaction

Substances

  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • Phospholipids
  • TFEB protein, human
  • Amiodarone