Related Experiment Videos
Hypoxemia is associated with mitochondrial DNA damage and gene induction. Implications for cardiac disease
M Corral-Debrinski1, G Stepien, J M Shoffner
1Department of Genetics, Emory University School of Medicine, Atlanta, GA 30322.
Objective:
--Oxidative phosphorylation (OXPHOS) deficiency due to hypoxemia or other causes was hypothesized to increase oxygen radical generation, damage mitochondrial DNA (mtDNA), and reduce adenosine triphosphate synthesis, resulting in compensatory OXPHOS gene induction. Therefore, we investigated the levels of mtDNA damage and OXPHOS transcripts in normal and ischemic hearts, and then in other forms of heart disease.
Design:
--DNA was extracted from the heart and the levels of the common 4977 base pair mtDNA deletion were quantitated as an index for mtDNA damage. Total RNA was extracted from hearts and analyzed for OXPHOS transcript levels.
Results:
--In control hearts, the 4977 base pair mtDNA deletion appeared at age 40 years and reached a maximum deletion of 0.0035%. Much higher levels were found in ischemic hearts (0.02% to 0.85%), as well as in three of 10 cases with other types of heart disease (0.017% to 0.16%). The OXPHOS transcripts were increased in all diseased hearts.
Conclusion:
--Ischemic hearts have increased mtDNA damage and OXPHOS gene expression, suggesting that mtDNA damage is associated with OXPHOS deficiency. Oxidative phosphorylation defects may also play a role in some other forms of cardiac disease.
Insights
Mitochondrial DNA damage and oxidative phosphorylation (OXPHOS) gene expression increase in ischemic hearts. This suggests OXPHOS deficiency contributes to cardiac disease, highlighting the role of mitochondrial dysfunction in heart conditions.
Area of Science:
- Cardiology
- Mitochondrial Biology
- Molecular Medicine
Background:
- Oxidative phosphorylation (OXPHOS) is crucial for cellular energy production.
- Defects in OXPHOS can lead to mitochondrial dysfunction and disease.
- Mitochondrial DNA (mtDNA) damage is implicated in various pathologies.
Purpose of the Study:
- To investigate the relationship between mtDNA damage and OXPHOS gene expression in normal and diseased hearts.
- To quantify mtDNA damage and OXPHOS transcript levels in ischemic and other cardiac conditions.
- To explore the role of OXPHOS deficiency in the pathogenesis of heart disease.
Main Methods:
- Quantification of the common 4977 base pair mtDNA deletion as an index of mtDNA damage.
- Analysis of total RNA for OXPHOS transcript levels in heart tissue.
- Comparison of mtDNA damage and gene expression between control, ischemic, and other heart disease groups.
Main Results:
- Significant increases in mtDNA damage (4977 bp deletion) were observed in ischemic hearts compared to controls.
- Elevated levels of mtDNA damage were also found in a subset of other heart disease cases.
- OXPHOS transcripts were upregulated in all examined diseased hearts, correlating with mtDNA damage.
Conclusions:
- Ischemic heart disease is characterized by increased mtDNA damage and OXPHOS gene expression.
- mtDNA damage is strongly associated with OXPHOS deficiency in the heart.
- OXPHOS defects may contribute to the pathophysiology of various cardiac diseases.