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Accumulation of somatic mutation in mitochondrial DNA extracted from peripheral blood cells in diabetic patients
T Nomiyama1, Y Tanaka, N Hattori
1Department of Medicine, Metabolism and Endocrinology, School of Medicine, Juntendo University, Tokyo, Japan.
Aims/Hypothesis:
A point mutation of mitochondrial DNA at nucleotide number 3243 A to G is responsible for both the major genetic aetiologies of the MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) and mitochondrial diabetes. Otherwise, this mutation is also reported to occur as an acquired somatic mutation, possibly due to oxidative stress. Since diabetes can cause severe oxidative stress, we hypothesize that the accumulation of the somatic 3243 A to G mutation in mitochondrial DNA can be accelerated by diabetes.
Methods:
DNA was extracted from blood samples of 290 non-diabetic healthy subjects (age 20-60) including 98 newborn infants and from 383 patients with Type II (non-insulin-dependent) diabetes mellitus (age 18-80). The extent of somatic 3243 A to G mutation to total mitochondrial DNA was detected by real-time PCR using the TaqMan Probe.
Results:
Whereas the level of the 3243 A to G mutation was negligible in the newborn group, it was increased in healthy subjects who were 20 to 29 and 41 to 60 years of age, suggesting that this mutation was somatic. In the diabetic patients the mutation rate increased along with age and the duration of diabetes. In the middle-aged group (age 41-60), the 3243 A to G mutation accumulates fourfold higher in the diabetic patients than the healthy subjects. Moreover, multiple regression analysis showed that the most critical factor associated with this mutation in diabetic patients was the duration of diabetes.
Conclusion/Interpretation:
Diabetes accelerates the accumulation of the somatic 3243 A to G mutation in mitochondrial DNA, which can accelerate the ageing process. This somatic mutation could possibly be a new marker for estimating the duration of diabetes.
Insights
Diabetes accelerates the accumulation of the mitochondrial DNA 3243 A to G mutation. This somatic mutation may serve as a marker for diabetes duration and potentially impact the aging process.
Area of Science:
- Mitochondrial genetics
- Molecular biology
- Endocrinology
Background:
- The mitochondrial DNA 3243 A to G mutation is linked to MELAS and mitochondrial diabetes.
- This mutation can also occur somatically, potentially due to oxidative stress.
- Diabetes itself can induce significant oxidative stress.
Purpose of the Study:
- To investigate if diabetes accelerates the accumulation of the somatic 3243 A to G mitochondrial DNA mutation.
- To explore the relationship between diabetes duration and this specific mitochondrial DNA mutation.
Main Methods:
- DNA extraction from blood samples of healthy subjects (n=290) and Type II diabetes patients (n=383).
- Quantification of the 3243 A to G mutation load using real-time PCR with TaqMan Probe.
- Analysis of mutation levels in relation to age and diabetes duration.
Main Results:
- The 3243 A to G mutation was negligible in newborns but increased with age in healthy adults.
- Diabetic patients showed a higher mutation rate compared to healthy individuals, particularly in the 41-60 age group (fourfold higher).
- Diabetes duration was identified as the most critical factor associated with the mutation in diabetic patients.
Conclusions:
- Diabetes accelerates the accumulation of the somatic 3243 A to G mitochondrial DNA mutation.
- This accelerated accumulation may contribute to the aging process.
- The somatic mutation could potentially serve as a novel biomarker for estimating diabetes duration.
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