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Slow progressive degeneration of nigral dopaminergic neurons in postnatal Engrailed mutant mice
Paola Sgadò1, Lavinia Albéri, Daniel Gherbassi
1Interdisciplinary Center for Neuroscience, Department of Neuroanatomy, Ruprecht-Karls Universität Heidelberg, 69120 Heidelberg, Germany.
Abstract:
The homeobox transcription factors Engrailed-1 and Engrailed-2 are required for the survival of mesencephalic dopaminergic neurons in a cell-autonomous and gene-dose-dependent manner. Because of this requirement, the cells die by apoptosis when all four alleles of the Engrailed genes are genetically ablated (En1-/-;En2-/-). In the present study, we show that viable and fertile mice, heterozygous null for Engrailed-1 and homozygous null for Engrailed-2 (En1+/-;En2-/-), have an adult phenotype that resembles key pathological features of Parkinson's disease. Specifically, postnatal mutant mice exhibit a progressive degeneration of dopaminergic neurons in the substantia nigra during the first 3 mo of their lives, leading to diminished storage and release of dopamine in the caudate putamen, motor deficits similar to akinesia and bradykinesia, and a lower body weight. This genetic model may provide access to the molecular etiology for Parkinson's disease and could assist in the development of novel treatments for this neurodegenerative disorder.
Insights
Engrailed genes are crucial for dopaminergic neuron survival. Genetic ablation in mice causes Parkinson's-like symptoms, offering a new model for neurodegenerative disease research.
Area of Science:
- Neuroscience
- Genetics
- Developmental Biology
Background:
- Homeobox transcription factors Engrailed-1 and Engrailed-2 (En1, En2) are vital for mesencephalic dopaminergic neuron survival.
- Complete genetic ablation of all four Engrailed alleles (En1-/-;En2-/-) leads to cell death via apoptosis.
Purpose of the Study:
- To investigate the phenotype of mice with partial genetic ablation of Engrailed genes.
- To determine if this genetic model exhibits features relevant to Parkinson's disease.
Main Methods:
- Generation of mice heterozygous null for Engrailed-1 and homozygous null for Engrailed-2 (En1+/-;En2-/-).
- Observation and analysis of postnatal phenotypes, including dopaminergic neuron degeneration, dopamine levels, motor function, and body weight.
Main Results:
- Viable and fertile En1+/-;En2-/- mice display progressive degeneration of dopaminergic neurons in the substantia nigra within 3 months.
- Mutant mice exhibit reduced dopamine storage and release in the caudate putamen.
- Characteristic motor deficits (akinesia, bradykinesia) and lower body weight were observed.
Conclusions:
- Partial genetic deficiency in Engrailed genes recapitulates key pathological and clinical features of Parkinson's disease.
- This En1+/-;En2-/- mouse model offers a valuable tool for studying the molecular etiology of Parkinson's disease.
- The model may facilitate the development of novel therapeutic strategies for this neurodegenerative disorder.
