title: A role for the autophagy regulator Transcription Factor EB in amiodarone-induced phospholipidosis.
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.
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, Department of Chemistry, Biology and Biotechnology, University of Perugia, via del Giochetto, I-06123 Perugia, Italy. Electronic address: sandra.buratta@unipg.it.
authors.forename: Sandra
authors.initials: S
authors.lastname: Buratta
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, Department of Chemistry, Biology and Biotechnology, University of Perugia, via del Giochetto, I-06123 Perugia, Italy. Electronic address: lorena.urbanelli@unipg.it.
authors.forename: Lorena
authors.initials: L
authors.lastname: Urbanelli
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, Department of Chemistry, Biology and Biotechnology, University of Perugia, via del Giochetto, I-06123 Perugia, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Ferrara
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, Department of Chemistry, Biology and Biotechnology, University of Perugia, via del Giochetto, I-06123 Perugia, Italy.
authors.forename: Krizia
authors.initials: K
authors.lastname: Sagini
authors.affiliation: Laboratory for Chemoinformatics and Molecular Modelling, Department of Chemistry, Biology and Biotechnology, University of Perugia, via Elce di Sotto 8, 06123 Perugia, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Goracci
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, Department of Chemistry, Biology and Biotechnology, University of Perugia, via del Giochetto, I-06123 Perugia, Italy; CEMIN-Center of Excellence for Innovative Nanostructured Material, Perugia, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Emiliani
mesh_terms: D000638:Amiodarone / Q000494:pharmacology*; D001343:Autophagy / Q000502:physiology*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000502:physiology*; D056945:Hep G2 Cells; D006801:Humans; D010743:Phospholipids / Q000378:metabolism*; D016133:Polymerase Chain Reaction
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D010743:Phospholipids; C064972:TFEB protein, human; D000638:Amiodarone
keywords: Amiodarone; Amiodarone (PubChem CID: 2157); Autophagy; Cimetidine (PubChem CID: 2756); Lysosomal enzymes; Phospholipidosis; TFEB