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Survival motor neuron protein modulates neuron-specific apoptosis
D A Kerr1, J P Nery, R J Traystman
1Departments of Neurology, Molecular Microbiology and Immunology, Anesthesiology and Critical Care Medicine, and Pharmacology and Molecular Sciences, The Johns Hopkins Schools of Medicine and Public Health, Baltimore, MD 21205, USA.
Summary
Spinal muscular atrophy (SMA) is linked to SMN1 gene mutations. The survival motor neuron (SMN) protein protects neurons from apoptosis, while SMA-associated SMN mutants promote neuronal death, contributing to disease progression.
Area of Science:
- Neuroscience
- Genetics
- Molecular Biology
Background:
- Spinal muscular atrophy (SMA) is caused by SMN1 gene mutations, leading to motor neuron loss.
- The role of survival motor neuron (SMN) protein in neuronal apoptosis is not fully understood.
Purpose of the Study:
- To investigate the function of SMN protein in regulating neuronal apoptosis.
- To determine if SMN mutations found in SMA patients contribute to neuronal death.
Main Methods:
- Utilized a neurotropic Sindbis virus vector system in primary neurons, neuron-like stem cells, and cell lines.
- Investigated SMN protein's protective effects in vivo in mice.
- Analyzed SMN mutants (SMNDelta7, SMN-Y272C) and SMN cleavage at Asp-252.
Main Results:
- SMN protein protects neurons from virus-induced apoptotic death.
- SMN mutants (SMNDelta7, SMN-Y272C) are proapoptotic, increasing neuronal apoptosis and mortality.
- SMN cleavage in apoptotic brains produces a proapoptotic form; mutating Asp-252 enhances SMN's antiapoptotic function.
Conclusions:
- Loss-of-function mutations or C-terminal deletions of SMN result in a proapoptotic protein.
- This proapoptotic SMN form may contribute to neuronal death in SMA and other neurodegenerative diseases.