Mitochondrial DNA Depletion and Respiratory Chain Activity in Primary Human Subcutaneous Adipocytes Treated with Nucleoside Analogue Reverse Transcriptase Inhibitors

Stankov, Metodi V.; Lücke, Thomas; Das, Anibh M.; Schmidt, Reinhold E.; Behrens, Georg M. N.

doi:10.1128/aac.00914-09

Cited by 54 publications

(67 citation statements)

References 35 publications

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“…Our data showing normal levels of mtDNAdependent enzyme activities and proteins unambiguously demonstrated efficient compensation of mtDNA depletion at the tissue level. They confirmed recent in vitro and animal data that have shown divergence between mtDNA content and respiratory chain activity (42,46). They do not contradict the previously reported focal histological defects of mtDNA-dependent proteins or activities (33) which indicated the presence of scattered mitochondria with altered composition, a finding also inferred in our study from the abnormal ratios of mitochondrial proteins (MT-CO2p and COX4p) and of enzymatic activities (COX and CS).…”

Section: Discussionsupporting

confidence: 78%

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Mitochondrial DNA Content, an Inaccurate Biomarker of Mitochondrial Alteration in Human Immunodeficiency Virus-Related Lipodystrophy

Kim

Jardel

Barthélémy

et al. 2008

Antimicrob Agents Chemother

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Lipoatrophy is a prevalent side effect of antiretroviral treatment of human immunodeficiency virus (HIV)infection. Its mechanisms are still disputed but include mitochondrial toxicity and, in particular, mitochondrial DNA (mtDNA) depletion induced by nucleoside reverse transcriptase inhibitors. To obtain an integrated evaluation of the mitochondrial alteration in lipoatrophy, we investigated the DNA, RNA, and protein levels in 15 samples of abdominal subcutaneous adipose tissue from HIV-infected patients with peripheral lipoatrophy and compared the results with those for 15 samples from age-and body mass index-matched controls. The DNA and RNA analyses used PCR-based techniques, while proteins were quantified with enzyme-linked immunosorbent assay and measurement of activities with spectrophotometric assays. Depletion of mtDNA and mtDNAencoded MT-CO2 mRNA was present, but normal levels of mtDNA-dependent activity (cytochrome c oxidase) and protein (MT-CO2p) showed that it was compensated for. An increase in nuclear-DNA-dependent mitochondrial activities (citrate synthase and malate dehydrogenase) and protein (COX4I1p), as well as transcriptional up-regulation of nuclear-DNA-encoded mitochondrial genes (COX4I1 and UCP2), demonstrated increased mitochondrial biogenesis. However, the expression of the known transcription factors of mitochondrial biogenesis (TFAM, NRF1, GABPA, PPARGC1A, PPARGC1B, and PPRC1) was normal or decreased. Increased amounts of activated caspase 3 and of DDIT3 mRNA showed the induction of apoptosis and oxidative stress, respectively. The mtDNA content did not correlate with any other mitochondrial parameter. In conclusion, mtDNA content does not appear to be an accurate biomarker of mitochondrial alteration in lipoatrophic adipose tissue. The preservation of mtDNA-dependent mitochondrial functions occurred despite severe mtDNA depletion. The presence of significant oxidative stress and apoptosis did not correlate with the mtDNA content.

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Section: Discussionsupporting

confidence: 78%

“…Furthermore, the mtDNA content under NRTI has been shown to possibly diverge from its transcription (12,28,32) or from respiratory chain activities (17,42,46). Another confounding parameter is the mitochon-drial proliferation that was observed in association with mtDNA depletion in HIV-infected patients' lipodystrophic adipose tissue (25,33,34,37,49).…”

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confidence: 99%

Mitochondrial DNA Content, an Inaccurate Biomarker of Mitochondrial Alteration in Human Immunodeficiency Virus-Related Lipodystrophy

Kim

Jardel

Barthélémy

et al. 2008

Antimicrob Agents Chemother

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“…As a result, compromised adipogenesis with enhanced rates of cell death was proposed as one of the pathogenic mechanisms of NRTI-mediated lipoatrophy (9). Furthermore, impaired differentiation with increased levels of apoptosis has been repeatedly confirmed in vitro as a result of AZT and d4T incubation (10)(11)(12)(13)15).…”

Section: Discussionmentioning

confidence: 99%

“…Drugrelated disturbance of adipogenesis in combination with increased cell loss was hypothesized to lead to fat tissue atrophy. Using well-characterized cell lines and primary human adipocytes, we and others repeatedly confirmed AZT's and d4T's antiadipogenic properties in vitro (10)(11)(12)(13)(14)(15), which could well have a clinical impact on adipogenesis in vivo (16).…”

mentioning

confidence: 83%

Thymidine Analogues Suppress Autophagy and Adipogenesis in Cultured Adipocytes

Stankov

Panayotova-Dimitrova

Leverkus

et al. 2013

Antimicrob Agents Chemother

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bLipoatrophy in HIV patients can result from prolonged exposure to thymidine analogues. Mitochondrial toxicity leading to dysregulated adipogenesis and increased cell death has been proposed as a leading factor in the etiology of peripheral fat loss. We hypothesized that thymidine analogues interfere with autophagy, a lysosomal degradation pathway, which is important for mitochondrial quality control, cellular survival, and adipogenesis. We assessed the effects of zidovudine (AZT), stavudine (d4T), and lamivudine (3TC) on autophagy in eukaryotic cells and adipocytes (3T3-F442A) by fluorescence microscopy and flow cytometry. The effects were compared to interventions with established genetic and pharmacological inhibitors of autophagy and correlated to assessments of cell viability, proliferation, and differentiation. AZT and d4T, but not 3TC, inhibited both constitutive and induced autophagic activity in adipocytes. This inhibition was associated with accumulation of dysfunctional mitochondria, increased reactive oxygen species (ROS) production, increased apoptosis, decreased proliferation, and impaired adipogenic conversion. Autophagy inhibition was dose and time dependent and detectable at therapeutic drug concentrations. Similar phenotypic changes were obtained when genetic or pharmacological inhibition of autophagy was employed. Our data suggest that thymidine analogues disturb adipocyte function through inhibition of autophagy. This novel mechanism potentially contributes to peripheral fat loss in HIV-infected patients.

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“…82 It is becoming clear that in obesity, changes in both nuclear and mitochondrial transcription are present and are important in the production of the observed changes in cardiac metabolism. 61 One of the key controllers of nuclear gene transcription, which regulates myocardial mitochondrial fatty acid oxidation, is the peroxisome proliferator-activated receptors (PPARs), 83 which, when activated, induce perixosome proliferation.…”

Section: Mitochondrial Metabolism and Lipotoxicity In Obesitymentioning

confidence: 99%

Myocardial substrate metabolism in obesity

et al. 2012

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Obesity is linked to a wide variety of cardiac changes, from subclinical diastolic dysfunction to end-stage systolic heart failure. Obesity causes changes in cardiac metabolism, which make ATP production and utilization less efficient, producing functional consequences that are linked to the increased rate of heart failure in this population. As a result of the increases in circulating fatty acids and insulin resistance that accompanies excess fat storage, several of the proteins and genes that are responsible for fatty acid uptake and metabolism are upregulated, and the metabolic machinery responsible for glucose utilization and oxidation are inhibited. The resultant increase in fatty acid metabolism, and the inherent alterations in the proteins of the electron transport chain used to create the gradient needed to drive mitochondrial ATP production, results in a decrease in efficiency of cardiac work and a relative increase in oxygen usage. These changes in cardiac mitochondrial metabolism are potential therapeutic targets for the treatment and prevention of obesity-related heart failure. (2013) Keywords: myocardial metabolism; review; obese INTRODUCTION Cardiac energy metabolism is essentially a four-step process involving the following: (1) myocellular substrate uptake/selection, (2) mitochondrial ATP production and (3) ATP transfer from the site of production (mitochondrion) to (4) the site of ATP utilization (cardiac myofibril; Figure 1). 1 Although glycolysis is an ATP generator, the overall ATP production is controlled largely by the rate at which the Krebs (tricarboxylic acid) cycle operates. 2 Acetyl co-enzyme A (CoA), which is produced from the oxidation of fatty acids, ketone bodies, or glucose via glycolysis, and the pyruvate dehydrogenase (PDH) enzyme complex 3 enters the Krebs cycle for complete oxidation. During oxidative phosphorylation, electrons, primarily obtained from oxidative metabolism of carbohydrates and fats, are transferred through the electron transport chain, a fourcomplex protein system embedded within the inner membrane of the mitochondria. The major function of the electron transport chain is to produce a proton electrochemical potential difference between two compartments that powers ATP synthase to generate ATP, which is used for all cardiac cellular processes. 4 ATP is the heart's only immediate source of energy for contraction, and as both systole and diastole are ATP-consuming processes, 5,6 cardiac ATP demand is very high. To keep up with this demand for continuous and efficient contraction and relaxation, the heart needs to produce around 20 times its own weight in ATP per day. 1 As a result of this large energy requirement, any impairment in ATP production, transfer or utilization can have detrimental effects on cardiac function. 7 Cardiac metabolism and ATP production is altered in obesity and has emerged as a candidate mechanism to explain the increase in heart failure in this population. 8 Indeed, it has recently been shown that obesity, in the absence of co-morbiditie...

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Mitochondrial DNA Depletion and Respiratory Chain Activity in Primary Human Subcutaneous Adipocytes Treated with Nucleoside Analogue Reverse Transcriptase Inhibitors

Cited by 54 publications

References 35 publications

Mitochondrial DNA Content, an Inaccurate Biomarker of Mitochondrial Alteration in Human Immunodeficiency Virus-Related Lipodystrophy

Mitochondrial DNA Content, an Inaccurate Biomarker of Mitochondrial Alteration in Human Immunodeficiency Virus-Related Lipodystrophy

Thymidine Analogues Suppress Autophagy and Adipogenesis in Cultured Adipocytes

Myocardial substrate metabolism in obesity

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