An anaplerotic approach to correct the mitochondrial dysfunction in ataxia-telangiectasia (A-T)
Autor: | Robert G. Parton, Martin F. Lavin, Magtouf Gatei, David Coman, Kok Leong Chong, Abrey J. Yeo, G.N. Subramanian |
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Jazyk: | angličtina |
Rok vydání: | 2021 |
Předmět: |
Mitochondrion
medicine.disease_cause Endoplasmic Reticulum Ataxia-telangiectasia chemistry.chemical_compound Ataxia Telangiectasia Endoplasmic reticulum–mitochondrial interaction Mitophagy medicine Humans Glycolysis Heptanoate (C7) Molecular Biology Internal medicine Cells Cultured Nutrient deprivation Chemistry Endoplasmic reticulum Cell Biology medicine.disease RC31-1245 Triheptanoin Cell biology Mitochondria Anaerobic glycolysis ATM Original Article Mitochondrial dysfunction Oxidative stress |
Zdroj: | Molecular Metabolism, Vol 54, Iss, Pp 101354-(2021) Molecular Metabolism |
ISSN: | 2212-8778 |
Popis: | Background ATM, the protein defective in the human genetic disorder, ataxia-telangiectasia (A-T) plays a central role in response to DNA double-strand breaks (DSBs) and in protecting the cell against oxidative stress. We showed that A-T cells are hypersensitive to metabolic stress which can be accounted for by a failure to exhibit efficient endoplasmic reticulum (ER)-mitochondrial signalling and Ca2+ transfer in response to nutrient deprivation resulting in mitochondrial dysfunction. The objective of the current study is to use an anaplerotic approach using the fatty acid, heptanoate (C7), a metabolic product of the triglyceride, triheptanoin to correct the defect in ER-mitochondrial signalling and enhance cell survival of A-T cells in response to metabolic stress. Methods We treated control cells and A-T cells with the anaplerotic agent, heptanoate to determine their sensitivity to metabolic stress induced by inhibition of glycolysis with 2- deoxyglucose (2DG) using live-cell imaging to monitor cell survival for 72 h using the Incucyte system. We examined ER-mitochondrial signalling in A-T cells exposed to metabolic stress using a suite of techniques including immunofluorescence staining of Grp75, ER-mitochondrial Ca2+ channel, the VAPB-PTPIP51 ER-mitochondrial tether complexes as well as proximity ligation assays between Grp75-IP3R1 and VAPB1-PTPIP51 to establish a functional interaction between ER and mitochondria. Finally, we also performed metabolomic analysis using LC-MS/MS assay to determine altered levels of TCA intermediates A-T cells compared to healthy control cells. Results We demonstrate that heptanoate corrects all aspects of the defective ER-mitochondrial signalling observed in A-T cells. Heptanoate enhances ER-mitochondrial contacts; increases the flow of calcium from the ER to the mitochondrion; restores normal mitochondrial function and mitophagy and increases the resistance of ATM-deficient cells and cells from A-T patients to metabolic stress-induced killing. The defect in mitochondrial function in ATM-deficient cells was accompanied by more reliance on aerobic glycolysis as shown by increased lactate dehydrogenase A (LDHA), accumulation of lactate, and reduced levels of both acetyl CoA and ATP which are all restored by heptanoate. Conclusions We conclude that heptanoate corrects metabolic stress in A-T cells by restoring ER-mitochondria signalling and mitochondrial function and suggest that the parent compound, triheptanoin, has immense potential as a novel therapeutic agent for patients with A-T. Highlights • The fatty acid heptanoate rescues cell killing after nutrient deprivation in A-T cells. • Heptanoate enhances endoplasmic reticulum (ER)-mitochondrial contacts. • Normal mitochondrial function and mitophagy are restored in A-T cells by heptanoate. • Heptanoate shifts A-T cells to more reliance on oxidative phosphorylation. |
Databáze: | OpenAIRE |
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