Related Experiment Video
Updated: Mar 16, 2026
Author Spotlight: Preservation of Bioenergetic Parameters in Peripheral Blood Mononuclear Cells After Cryopreservation
Published on: October 20, 2023
Oxidative stress-induced apoptosis in peripheral blood lymphocytes from patients with POLG-related disorders
Patrizia Formichi1, Elena Radi1, Chiara Branca1
1Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy.
Background:
POLG-related disorders are a group of heterogeneous diseases characterized by an overlapping clinical presentations and associated with mutations in the POLG gene. POLG codes for the catalytic subunit of mitochondrial polymerase gamma (POLG), essential for mitochondrial DNA (mtDNA) replication and repair. Studies on mutator POLG mice showed an increase in oxidative stress and apoptosis. In this regard we analysed the involvement of POLG mutations in the apoptotic regulation, evaluating apoptosis in peripheral blood lymphocytes (PBLs) from patients with POLG-related diseases.
Methods:
Cells were cultured under basal conditions and with 2-deoxy-d-ribose (dRib), a reducing sugar that induces apoptosis by oxidative stress. Apoptosis rate was assessed by flow cytometry. Phosphatidylserine translocation, mitochondrial membrane depolarization and caspase 3 activation were also analysed.
Results:
Our data showed higher percentages of apoptosis after dRib treatment in patients with POLG mutations than in controls, while under basal culture conditions, apoptosis levels were similar in the two groups.
Conclusions:
Cells with POLG mutations are more sensitive than control cells to oxidative stress-induced apoptosis, confirming that mtDNA mutations may have a role in mitochondrial apoptosis pathway. We also suggest that redox state homeostasis may play a crucial role in phenotypic expression of POLG-related diseases.
Insights
Mutations in the POLG gene increase sensitivity to oxidative stress-induced apoptosis in peripheral blood lymphocytes. This suggests mitochondrial DNA mutations impact apoptosis and disease presentation.
Area of Science:
- Genetics
- Cell Biology
- Biochemistry
Background:
- POLG-related disorders stem from mutations in the POLG gene, crucial for mitochondrial DNA (mtDNA) replication and repair.
- POLG encodes the catalytic subunit of mitochondrial polymerase gamma.
- Mutator POLG mouse models exhibit increased oxidative stress and apoptosis.
Purpose of the Study:
- To investigate the role of POLG mutations in apoptotic regulation.
- To evaluate apoptosis in peripheral blood lymphocytes (PBLs) from patients with POLG-related diseases.
Main Methods:
- Peripheral blood lymphocytes (PBLs) from patients and controls were cultured under basal conditions and with 2-deoxy-d-ribose (dRib).
- dRib was used to induce apoptosis via oxidative stress.
- Apoptosis rate was measured using flow cytometry, assessing phosphatidylserine translocation, mitochondrial membrane depolarization, and caspase 3 activation.
Main Results:
- PBLs from patients with POLG mutations showed significantly higher apoptosis rates after dRib treatment compared to controls.
- Apoptosis levels were comparable between patient and control groups under basal culture conditions.
Conclusions:
- Cells with POLG mutations exhibit heightened sensitivity to oxidative stress-induced apoptosis.
- mtDNA mutations are implicated in the mitochondrial apoptosis pathway.
- Redox state homeostasis may be critical in determining the phenotypic expression of POLG-related disorders.
