Functional analysis of molecular and pharmacological modulators of mitochondrial fatty acid oxidation

Abstract

fatty acid oxidation (fAo) is a key bioenergetic pathway often dysregulated in diseases. the current knowledge on fAo regulators in mammalian cells is limited and sometimes controversial. previous FAO analyses involve nonphysiological culture conditions or lack adequate quantification. We herein described a convenient and quantitative assay to monitor dynamic fAo activities of mammalian cells in physiologically relevant settings. the method enabled us to assess various molecular and pharmacological modulators of the fAo pathway in established cell lines, primary cells and mice. Surprisingly, many previously proposed fAo inhibitors such as ranolazine and trimetazidine lacked FAO-interfering activity. In comparison, etomoxir at low micromolar concentrations was sufficient to saturate its target proteins and to block cellular fAo function. oxfenicine, on the other hand, acted as a partial inhibitor of fAo. As another class of fAo inhibitors that transcriptionally repress fAo genes, antagonists of peroxisome proliferator-activated receptors (ppARs), particularly that of ppARα, significantly decreased cellular FAO activity. Our assay also had sufficient sensitivity to monitor upregulation of fAo in response to environmental glucose depletion and other energy-demanding cues. Altogether this study provided a reliable fAo assay and a clear picture of biological properties of potential fAo modulators in the mammalian system.

Re-polarization of immunosuppressive macrophages to tumor-cytotoxic macrophages by repurposed metabolic drugs

“…22,39 Yet recently it has also been demonstrated that in the cell lines MCF-7 and T47D, PerHx did not directly impair FAO. 40 Even more, the same mechanism was described for Etomoxir (another CPT-1 inhibitor), which impaired IL-4 mediated polarization independently of CPT-1 inhibition by an offtarget inhibition of the Adenine Nucleotide Translocator (ANT) and depletion of cytoplasmic CoA. 41 Further studies are needed to unravel the effect of PerHx on mitochondrial respiration and immune cells, considering that PerHx dosage may have to be adjusted per patient to prevent side effects.…”

Glycolysis and Fatty Acid Oxidation Inhibition Improves Survival in Glioblastoma

“…It is noted that the effects of Rano on the cell may not be limited to FAO inhibition. Although, noted as a partial FAO inhibitor, Rano was found to lack the FAO-interfering activity in complete media with or without serum ( 35 ), despite showing FAO-inhibiting ability in our FAO assay utilizing glucose-deprivation and a single FAO source (18C unsaturated fatty acid oleate).…”

Mitochondrial Metabolism in Astrocytes Regulates Brain Bioenergetics, Neurotransmission and Redox Balance

“…Accordingly, the impairment in FAO observed in astrocytes derived from induced pluripotent stem cells isolated from Alzheimer's disease patients is corrected by PPARβ/δ agonists (Konttinen et al, 2019). The specificity of the metabolic modifiers ranolazine (Ranexa) and trimetazidine, initially described as partial FAO inhibitors that target the HAD (or 3-KAT) activity of the trifunctional protein HADHA, has been recently questioned (Ma et al, 2020).…”