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Published on: July 9, 2016
Mitochondrial dysfunction in mouse trisomy 16 brain
1Department of Anesthesiology, University of Maryland, School of Medicine, Baltimore, MD 21201, USA. lbambric@umaryland.edu
Abstract:
Mitochondrial function in the brain of mouse trisomy 16, an animal model of Down syndrome with accelerated neuron death, was studied in isolated cortex mitochondria. Using an oxygen-sensitive Clarke electrode, a selective 16% decrease in respiration was detected with the Complex I substrates malate and glutamate but not with the Complex II substrate succinate. Western blotting revealed a 20% decrease in the 20 kDa subunit of Complex I in Ts16 brain cortex homogenates with no significant decrease in marker proteins for the other complexes of the electron transport chain. Although no differences in H(2)O(2) production or maximal calcium uptake were detected in the Ts16 mitochondria, there was an 18% decrease in pyruvate dehydrogenase levels, a change associated with oxidative stress in ischemia. These results are similar to those found in Parkinson's disease suggesting some neurodegenerative diseases may have mitochondrial pathology as a common step.
Insights
Mitochondrial dysfunction in Down syndrome models shows reduced Complex I respiration and a key subunit decrease. This suggests shared mitochondrial pathology in neurodegenerative diseases like Parkinson's.
Area of Science:
- Neuroscience
- Mitochondrial Biology
- Genetics
Background:
- Down syndrome is associated with accelerated neuron death.
- Mouse trisomy 16 (Ts16) serves as an animal model for Down syndrome.
- Mitochondrial dysfunction is implicated in neurodegenerative processes.
Purpose of the Study:
- To investigate mitochondrial function in the brain cortex of Ts16 mice.
- To identify specific defects in the electron transport chain.
- To explore potential links to other neurodegenerative conditions.
Main Methods:
- Isolated cortex mitochondria were used for functional assays.
- Oxygen consumption was measured using a Clarke electrode.
- Western blotting was employed to quantify protein levels of electron transport chain subunits and pyruvate dehydrogenase.
Main Results:
- A 16% decrease in respiration with Complex I substrates (malate, glutamate) was observed in Ts16 mitochondria.
- A 20% reduction in the 20 kDa subunit of Complex I was detected.
- Pyruvate dehydrogenase levels were decreased by 18% in Ts16 brain cortex.
Conclusions:
- Ts16 mice exhibit specific Complex I deficits in brain mitochondria.
- These mitochondrial alterations may contribute to accelerated neuron death in Down syndrome.
- Shared mitochondrial pathology could be a common factor in neurodegenerative diseases, including Parkinson's disease.
