Pro-oxidant effect of ALA is implicated in mitochondrial dysfunction of HepG2 cells

• Published in: Biochimie 2014-11, Vol.106, p.157-166
• Main Authors: Laafi, Jihane, Homedan, Chadi, Jacques, Caroline, Gueguen, Naig, Schmitt, Caroline, Puy, Hervé, Reynier, Pascal, Carmen Martinez, Maria, Malthièry, Yves
• Format: Article
• Language: English
• Subjects: 5-Aminolevulinic acid; Adenosine Triphosphate - metabolism; Aminolevulinic Acid - metabolism; Aminolevulinic Acid - pharmacology; Antioxidants - pharmacology; Biochemistry, Molecular Biology; Blotting, Western; Carcinoma, Hepatocellular - genetics; Carcinoma, Hepatocellular - metabolism; Carcinoma, Hepatocellular - pathology; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Dose-Response Relationship, Drug; Electron Transport Complex I - genetics; Electron Transport Complex I - metabolism; Energetic dysfunctions; Gene Expression - drug effects; Hep G2 Cells; Humans; Ion Channels - genetics; Ion Channels - metabolism; Life Sciences; Liver Neoplasms - genetics; Liver Neoplasms - metabolism; Liver Neoplasms - pathology; Metalloporphyrins - pharmacology; Microscopy, Confocal; Mitochondria; Mitochondria - drug effects; Mitochondria - genetics; Mitochondria - metabolism; Mitochondrial Proteins - genetics; Mitochondrial Proteins - metabolism; Oxidants - metabolism; Oxidants - pharmacology; Oxidative phosphorylation; Oxidative stress; Oxygen Consumption - drug effects; Protoporphyrins - metabolism; Reactive Oxygen Species - metabolism; Respiratory chain; Reverse Transcriptase Polymerase Chain Reaction; Superoxide Dismutase - genetics; Superoxide Dismutase - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Uncoupling Protein 2
• ISSN: 0300-9084; 1638-6183
• DOI: 10.1016/j.biochi.2014.08.014

Heme biosynthesis begins in the mitochondrion with the formation of delta-aminolevulinic acid (ALA). In acute intermittent porphyria, hereditary tyrosinemia type I and lead poisoning patients, ALA is accumulated in plasma and in organs, especially the liver. These diseases are also associated with neuromuscular dysfunction and increased incidence of hepatocellular carcinoma. Many studies suggest that this damage may originate from ALA-induced oxidative stress following its accumulation. Using the MnSOD as an oxidative stress marker, we showed here that ALA treatment of cultured cells induced ROS production, increasing with ALA concentration. The mitochondrial energetic function of ALA-treated HepG2 cells was further explored. Mitochondrial respiration and ATP content were reduced compared to control cells. For the 300 μM treatment, ALA induced a mitochondrial mass decrease and a mitochondrial network imbalance although neither necrosis nor apoptosis were observed. The up regulation of PGC-1, Tfam and ND5 genes was also found; these genes encode mitochondrial proteins involved in mitochondrial biogenesis activation and OXPHOS function. We propose that ALA may constitute an internal bioenergetic signal, which initiates a coordinated upregulation of respiratory genes, which ultimately drives mitochondrial metabolic adaptation within cells. The addition of an antioxidant, Manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP), resulted in improvement of maximal respiratory chain capacity with 300 μM ALA. Our results suggest that mitochondria, an ALA-production site, are more sensitive to pro-oxidant effect of ALA, and may be directly involved in pathophysiology of patients with inherited or acquired porphyria. •Heme biosynthesis pathway and energetic metabolism share location and regulations.•ALA accumulation induced cellular poisoning in pathologies such acute porphyria (AIP).•We show a toxic effect dose-dependant of ALA on mitochondrial function of HepG2 cells.•Production of ROS induced decrease of OXPHOS and increase of mitochondrial biogenesis.•Pro-oxidant effect of ALA may be directly involved in pathophysiology of porphyria.