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Updated: Jan 27, 2026

Measuring Single-Cell Mitochondrial DNA Copy Number and Heteroplasmy Using Digital Droplet Polymerase Chain Reaction
Published on: July 12, 2022
DNA polymerase-γ hypothesis in nucleoside reverse transcriptase-induced mitochondrial toxicity revisited: A
Mathabo Ruth Lutu1, Sanelisiwe Nzuza1, Pascale Edith Mofo Mato1
1Molecular and Clinical Pharmacology Research Laboratory, Department of Pharmacology, Discipline of Pharmaceutical, School of Health Sciences, University of KwaZulu-Natal, Westville Campus, Private Bag X5400, Durban 3629, South Africa.
Abstract:
Nucleoside reverse transcriptase inhibitors (NRTIs) form the backbone in combination antiretroviral therapy (cARVs). They halt chain elongation of the viral cDNA by acting as false substrates in counterfeit incorporation mechanism to viral RNA-dependent DNA polymerase. In the process genomic DNA polymerase as well as mitochondrial DNA (mtDNA) polymerase-γ (which has a much higher affinity for these drugs at therapeutic doses) are also impaired. This leads to mitochondrial toxicity that manifests clinically as mitochondrial myopathy, peripheral neuropathy, hyperlactatemia or lactic acidosis and lipoatrophy. This has led to the revision of clinical guidelines by World Health Organization to remove stavudine from first-line listing in the treatment of HIV infections. Recent reports have implicated oxidative stress besides mtDNA polymerase-γ hypothesis in NRTI-induced metabolic complications. Reduced plasma antioxidant concentrations have been reported in HIV positive patients on cARVs but clinical intervention with antioxidant supplements have not been successful either due to low efficacy or poor experimental designs. Citrus fruit-derived naringenin has previously been demonstrated to possess antioxidant and free radical scavenging properties which could prevent mitochondrial toxicity associated with these drugs. This review revisits the controversy surrounding mtDNA polymerase-γ hypothesis and evaluates the potential benefits of naringenin as a potent anti-oxidant and free radical scavenger which as a nutritional supplement or therapeutic adjunct could mitigate the development of mitochondrial toxicity associated with these drugs.
Insights
Nucleoside reverse transcriptase inhibitors (NRTIs) used in HIV treatment can cause mitochondrial toxicity. Naringenin, an antioxidant from citrus, may prevent this drug-induced damage.
Area of Science:
- Biochemistry
- Pharmacology
- Toxicology
Background:
- Nucleoside reverse transcriptase inhibitors (NRTIs) are crucial in combination antiretroviral therapy (cARVs) for HIV treatment.
- NRTIs can inhibit both viral and human DNA polymerases, including mitochondrial DNA polymerase-γ, leading to mitochondrial toxicity.
- Clinical manifestations of NRTI-induced mitochondrial toxicity include myopathy, neuropathy, and metabolic disturbances.
Purpose of the Study:
- To review the mechanisms of NRTI-induced mitochondrial toxicity, focusing on the role of mitochondrial DNA polymerase-γ and oxidative stress.
- To evaluate the potential of naringenin, a citrus-derived flavonoid, as a therapeutic agent to mitigate NRTI-induced mitochondrial toxicity.
Main Methods:
- Literature review of studies on NRTI mechanisms, mitochondrial toxicity, oxidative stress, and naringenin's properties.
- Analysis of existing hypotheses regarding NRTI-induced mitochondrial damage.
- Evaluation of naringenin's antioxidant and free radical scavenging capabilities.
Main Results:
- NRTIs impair mitochondrial DNA polymerase-γ, contributing to toxicity, with oxidative stress also implicated in metabolic complications.
- Previous attempts at clinical intervention with antioxidants have shown limited success.
- Naringenin exhibits significant antioxidant and free radical scavenging properties.
Conclusions:
- Naringenin shows promise as a nutritional supplement or therapeutic adjunct to prevent or reduce NRTI-induced mitochondrial toxicity.
- Further research is warranted to explore naringenin's efficacy and optimal use in managing NRTI-related side effects.
- Understanding the interplay between mtDNA polymerase-γ inhibition and oxidative stress is key to developing effective interventions.
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