Evidence of K+ homeostasis disruption in cellular dysfunction triggered by 7-ketocholesterol, 24S-hydroxycholesterol, and tetracosanoic acid (C24:0) in 158N murine oligodendrocytes

Maryem Bezine (1, 2) , Meryam Debbabi (1, 2) , Thomas Nury (1) , Rym Ben-Khalifa (3) , Mohammad Samadi (4) , Mustapha Cherkaoui-Malki (1) , Anne Vejux (1) , Quentin Raas (1) , Jérôme de Sèze (5) , Thibault Moreau (6) , Mohamed El-Ayeb (3) , Gérard Lizard (1)

1 BIO-PEROXIL - Laboratoire Bio-PeroxIL. Biochimie du peroxysome, inflammation et métabolisme lipidique [Dijon]
2 UM - Université de Monastir - University of Monastir
3 LR11IPT08 - Laboratoire des Venins et Biomolécules Thérapeutiques - Laboratory of Venoms and Therapeutic Biomolecules
4 LCP-A2MC - Laboratoire de Chimie et Physique - Approche Multi-échelle des Milieux Complexes
5 Hôpital de Hautepierre [Strasbourg]
6 Service de Neurologie générale, vasculaire et dégénérative (CHU de Dijon)

Imbalance in the homeostasis of K+ ions has been reported to contribute to the pathogenesis of neurodegenerative diseases. 7-ketocholesterol (7KC), 24S-hydroxycholesterol (24S-OHC), and tetracosanoic acid (C24:0), often found at increased levels in patients with Alzheimer's disease, Multiple Sclerosis and X-ALD, are able to trigger numerous nerve cell dysfunctions. We therefore studied the impact of 7KC, 24S-OHC, and C24:0 on 158N murine oligodendrocytes, and determined their impact on K+ homeostasis. The effects of 7KC, 24S-OHC and C24:0 on lipid membrane organization and membrane potential were examined with merocyanine 540 (MC540) and bis-(1,3-diethylthiobarbituric acid) trimethine oxonol (DiSBAC2(3)), respectively. The intracellular concentration of K+ ([K+]i) was measured by flame photometry and the ratiometric approach using the PBFI-AM fluorescence indicator. To determine the relationships between [K+]i and lipotoxicity, 158N cells were pre-treated with a universal Kv channels blocker, 4-aminopyridine (4-AP), without or with 7KC, 24S-OHC or C24:0. Cell adhesion, cell growth, mitochondrial depolarization, cytoplasmic membrane integrity, the presence of SubG1 and the morphological aspect of the nuclei were determined with various microscopy, flow cytometry and biochemistry methods. 7KC, 24S-OHC and C24:0 induced changes in lipid content and polarization of the cytoplasmic membrane. These events were associated with increased [K+]i. Blocking Kv channels with 4-AP exacerbated 7KC-, 24S-OHC- and C24:0-induced cell dysfunction. 4-AP exacerbated loss of cell adhesion and cell growth inhibition, amplified mitochondrial depolarization and cytoplasmic membrane damage, and increased the percentage of SubG1 cells. The positive correlation between [K+]i and cell death supports the potential involvement of K+ in 7KC-, 24S-OHC-, and C24:0-induced cytotoxicity.

Mots clés: 158N murine oligodendrocytes; 24S-Hydroxycholesterol; 4-Aminopyridine; 7-Ketocholesterol; Potassium kv channels; Tetracosanoic acid (C24:0)

Domaines: Sciences du Vivant [q-bio]

Maryem Bezine, Meryam Debbabi, Thomas Nury, Rym Ben-Khalifa, Mohammad Samadi, et al.. Evidence of K+ homeostasis disruption in cellular dysfunction triggered by 7-ketocholesterol, 24S-hydroxycholesterol, and tetracosanoic acid (C24:0) in 158N murine oligodendrocytes. Chemistry and Physics of Lipids, 2017, 207 (Pt B), pp.135-150. ⟨10.1016/j.chemphyslip.2017.03.006⟩. ⟨pasteur-01964971⟩