Related Experiment Video

Updated: Jul 3, 2026

Histological Examination of Mitochondrial Morphology in a Parkinson's Disease Model
06:07

Histological Examination of Mitochondrial Morphology in a Parkinson's Disease Model

Published on: June 23, 2023

Dopaminergic midbrain neurons are the prime target for mitochondrial DNA deletions

Andreas Bender1, Rachel-Maria Schwarzkopf, Anja McMillan

  • 1Dept. of Neurology, Mitochondrial Neurogenetics, University of Munich, Marchioninistr. 15, 81377, Munich, Germany. andreas.bender@med.uni-muenchen.de

Journal of Neurology
|July 8, 2008
PubMed

Insights

Mitochondrial DNA deletions accumulate in aging brains, particularly in substantia nigra neurons, irrespective of Alzheimer's or Parkinson's disease. This highlights a specific neuronal vulnerability to mitochondrial damage.

Area of Science:

  • Neuroscience
  • Cell Biology
  • Genetics

Background:

  • Mitochondrial dysfunction and mitochondrial DNA (mtDNA) damage are implicated in neurodegenerative diseases like Alzheimer's (AD) and Parkinson's disease (PD), as well as normal brain aging.
  • Previous studies often failed to detect significant levels of mtDNA point mutations or deletions in brain homogenates.
  • Recent single-cell analyses revealed high mtDNA deletion levels in dopaminergic substantia nigra (SN) neurons in PD patients.

Purpose of the Study:

  • To quantify mtDNA deletion levels in single cells from multiple brain regions (putamen, frontal cortex, SN) of Alzheimer's disease (AD) patients and age-matched controls.
  • To investigate potential differences in mtDNA deletion loads between AD patients and controls across different brain regions.
  • To determine if dopaminergic SN neurons exhibit a specific susceptibility to mtDNA deletion accumulation.

Main Methods:

  • Quantitative single-cell analysis was employed to measure mtDNA deletion levels.
  • Three brain regions (putamen, frontal cortex, SN) were analyzed from individuals with AD (n=9) and age-matched controls (n=8).
  • Statistical analysis (ANOVA) was used to compare deletion loads between regions and groups.

Main Results:

  • No significant differences in mtDNA deletion loads were found between AD patients and age-matched controls in any of the studied brain regions.
  • A significantly higher load of mtDNA deletions was observed in dopaminergic SN neurons compared to neurons from the putamen and frontal cortex within both AD patients and controls (p < 0.01).
  • This accumulation of mtDNA deletions in SN neurons occurred regardless of the clinical phenotype.

Conclusions:

  • Dopaminergic neurons in the substantia nigra exhibit a distinct vulnerability to accumulating substantial levels of mtDNA deletions.
  • This susceptibility is independent of the presence of Alzheimer's disease or Parkinson's disease, suggesting a fundamental aspect of aging or neuronal type.
  • The findings underscore the importance of single-cell analysis for detecting biologically relevant mtDNA damage in neurodegeneration and aging.

More Related Videos

Using Live Cell STED Imaging to Visualize Mitochondrial Inner Membrane Ultrastructure in Neuronal Cell Models08:48

Using Live Cell STED Imaging to Visualize Mitochondrial Inner Membrane Ultrastructure in Neuronal Cell Models

Published on: June 30, 2023

Analyzing Mitochondrial Transport and Morphology in Human Induced Pluripotent Stem Cell-Derived Neurons in Hereditary Spastic Paraplegia07:32

Analyzing Mitochondrial Transport and Morphology in Human Induced Pluripotent Stem Cell-Derived Neurons in Hereditary Spastic Paraplegia

Published on: February 9, 2020

Related Concept Videos

Animal Mitochondrial Genetics02:59

Animal Mitochondrial Genetics

Among all the organelles in an animal cell, only mitochondria have their own independent genomes. Animal mitochondrial DNA is a double-stranded, closed-circular molecule with around 20,000 base pairs. Mitochondrial DNA is unique in that one of its two strands, the heavy, or H, -strand is guanine rich, whereas the complementary strand is cytosine rich and called the light, or L, -strand. Compared to nuclear DNA, mitochondrial DNA has a very low percentage of non-coding regions and is marked by...
ATP Synthase: Mechanism01:48

ATP Synthase: Mechanism

In animals, the mitochondrial F1F0 ATP synthase is the key protein that synthesizes ATP molecules through a complex catalytic mechanism. While the nuclear genome encodes the majority of ATP synthase subunits, the mitochondrial genome encodes some of the enzyme's most critical components. The formation of this multi-subunit enzyme is a complex multi-step process regulated at the level of transcription, translation, and assembly. Defects in one or more of these steps can result in decreased ATP...
Export of Mitochondrial and Chloroplast Genes02:19

Export of Mitochondrial and Chloroplast Genes

A eukaryotic cell can have up to three different types of genetic systems: nuclear, mitochondrial, and chloroplast. During evolution, organelles have exported many genes to the nucleus; this transfer is still ongoing in some plant species. Approximately 18% of the Arabidopsis thaliana nuclear genome is thought to be derived from the chloroplast’s cyanobacterial ancestor, and around 75% of the yeast genome derived from the mitochondria’s bacterial ancestor. This export has occurred irrespective...
Mitochondrial Protein Sorting01:39

Mitochondrial Protein Sorting

Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death.  Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Electron Transport Chain: Complex I and II01:46

Electron Transport Chain: Complex I and II

The mitochondrial electron transport chain (ETC) is the main energy generation system in the eukaryotic cells. However, mitochondria also produce cytotoxic reactive oxygen species (ROS) due to the large electron flow during oxidative phosphorylation. While Complex I is one of the primary sources of superoxide radicals, ROS production by Complex II is uncommon and may only be observed in cancer cells with mutated complexes.
ROS generation is regulated and maintained at moderate levels necessary...
Drugs Affecting Neurotransmitter Synthesis01:29

Drugs Affecting Neurotransmitter Synthesis

Drugs affecting neurotransmitter synthesis can impact the adrenergic neuron and the synthesis of neurotransmitters. For example, α-methyltyrosine and carbidopa target specific enzymes involved in catecholamine synthesis. α-methyltyrosine inhibits the enzyme tyrosine hydroxylase, which converts tyrosine into dopamine. By blocking this enzyme, α-methyltyrosine reduces dopamine production and other catecholamines. Carbidopa, on the other hand, inhibits the enzyme dopa decarboxylase, which converts...