Mitochondrial respiratory chain dysfunction, a non-receptor-mediated effect of synthetic PPAR-ligands: biochemical and pharmacological implications

https://doi.org/10.1016/j.bbrc.2004.05.072Get rights and content

Abstract

Peroxisome proliferator activated receptors (PPARs) are a class of nuclear receptors involved in lipid and glucidic metabolism, immune regulation, and cell differentiation. Many of their biological activities have been studied by using selective synthetic activators (mainly fibrates and thiazolidinediones) which have been already employed in therapeutic protocols. Both kinds of drugs, however, showed pharmacotoxicological profiles, which cannot be ascribed by any means to receptor activation. To better understand these non-receptorial or extrareceptorial aspects, the effect of different PPAR-ligands on the metabolic status of human HL-60 cell line has been investigated. At this regard, NMR analysis of cell culture supernatants was accomplished in order to monitor modifications at the level of cell metabolism. Cell growth and chemiluminescence assays were employed to verify cell differentiation. Results showed that all the considered PPAR-ligands, although with different potencies and independently from their PPAR binding specificity, induced a significant derangement of the mitochondrial respiratory chain consisting in a strong inhibition of NADH–cytochrome c reductase activity. This derangement has been shown to be strictly correlated to the adaptive metabolic modifications, as evidenced by the increased formation of lactate and acetate, due to the stimulation of anaerobic glycolysis and fatty acid β-oxidation. It is worthy noting that the mitochondrial dysfunction appeared also linked to the capacity of any given PPAR-ligand to induce cell differentiation. These data could afford an explanation of biochemical and toxicological aspects related to the therapeutic use of synthetic PPAR-ligands and suggest a revision of PPAR pathophysiologic mechanisms.

Section snippets

Materials and methods

Cells and treatments. The human acute promyelocytic leukemia HL-60 cell line was obtained from Interlab Cell Line Collection (CBA, Genoa, Italy). Cells were maintained at 37 °C under a humidified atmosphere of 5% CO2 in RPMI 1640 Hepes modified medium supplemented with 10% (v/v) heat inactivated fetal calf serum, 2 mM glutamine, 100 IU/ml penicillin, and 100 μg/ml streptomycin. Cell number was determined using a Neubauer hemocytometer and viability was assessed by their ability to exclude trypan

Mitochondrial respiratory chain enzyme activities

All the considered PPAR-ligands inhibited significantly the mitochondrial respiratory chain at the level of NADH–cytochrome c reductase in a dose-dependent manner in digitonin permeabilized HL-60 cells and the efficiency of mitochondrial inhibition varied from ligand to ligand (Fig. 1). In fact, considering the inhibitory activity observed at 50 μmol (the concentration at which ciglitizone attains its highest effect and that approaches usual plasma concentration of the other ligands during

Discussion

Alternative biochemical activities of PPAR synthetic ligands, apart from receptor binding and activation, were taken into consideration in order to explain contradictory aspects of PPAR pathophysiology. The investigations that were therefore performed at this purpose gave results showing that all the considered PPAR-ligands inhibited the electron transport chain of mitochondria of digitonin permeabilized HL-60 cells at the level of NADH–cytochrome c reductase in a dose-dependent manner.

To say

Acknowledgements

The authors thank Prof. Paolo Sarti (Università La Sapienza di Roma) for his support and helpful comments.

References (25)

  • A.J Scheen

    Thiazolidinediones and liver toxicity

    Diabetes Metab.

    (2001)
  • A Shek et al.

    Statin-fibrate combination therapy

    Ann. Pharmacother.

    (2001)
  • Cited by (61)

    • Treating Hepatic Steatosis and Fibrosis by Modulating Mitochondrial Pyruvate Metabolism

      2019, Cellular and Molecular Gastroenterology and Hepatology
      Citation Excerpt :

      TZD infusion into isolated rat liver increased lactate production and decreased glucose output within 10 minutes,53 and similar effects on lactate production in astrocytes were independent of gene transcription or protein translation.54 These effects initially were proposed to be owing to inhibition of mitochondrial complex I activity.55,56 However, the respiration defects subsequently were reported to be specific to pyruvate-stimulated, and not glutamate-stimulated, respiration, indicating the TZD effect to be upstream of complex I.54,57 In an attempt to identify a mitochondrial TZD target, a pioglitazone-based 125I-labeled probe was created and shown to bind mitochondrial lysates at an approximately 14- to 17-kilodalton protein.

    • Protective roles of fenofibrate against cisplatin-induced ototoxicity by the rescue of peroxisomal and mitochondrial dysfunction

      2018, Toxicology and Applied Pharmacology
      Citation Excerpt :

      PPAR-α activation is necessary to prevent cellular oxidative damage that may occur during physiological cellular metabolism or under conditions of inflammation and oxidative stress, likely by repressing NF-κB signaling and limiting inflammatory cytokine production (Me and Daynes, 1998; Toyama et al., 2004), and a recent study within PPAR-γ KO mice revealed that PPAR-γ plays a crucial protective role in cardiomyocytes and may prevent myocardial ischemia-reperfusion injury by modulating NF-κB-associated inflammatory mechanisms in the infarcted myocardium (Hobson et al., 2014). However, fenofibrate-mediated activation of PPAR-α induced increase ROS production through increased mitochondrial or peroxisomal beta-oxidation (Scatena et al., 2004; Yeldandi et al., 2000). In this study, we also detected the fenofibrate alone treatment slightly increased the NF-kB p65 expression (Fig. 4A and B) and weakly increased the expression of NOX3 and NOX4 protein (Fig. 5A and B) with the cochlea of immunohistochemistry staining and then, results partially increased the ROS production (Fig. 5C).

    • Remarks on Mitochondrial Myopathies

      2023, International Journal of Molecular Sciences
    View all citing articles on Scopus
    View full text