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In Vivo Electrophysiological Measurement of Compound Muscle Action Potential from the Forelimbs in Mouse Models of Motor Neuron Degeneration
Published on: June 15, 2018
Mutant HSPB8 causes motor neuron-specific neurite degeneration
Joy Irobi1, Leonardo Almeida-Souza, Bob Asselbergh
1Peripheral Neuropathy, VIB Department of Molecular Genetics, University of Antwerp, Antwerp, Belgium.
Human Molecular Genetics
|June 12, 2010
Summary
Missense mutations in HSPB8 cause motor neuron disease by damaging neurites without cell death. Only motor neurons are affected, explaining the specific disease phenotype in distal HMN and CMT2L.
Area of Science:
- Neuroscience
- Genetics
- Cell Biology
Background:
- Missense mutations in the small heat shock protein HSPB8 (HSP22) alpha-crystallin domain lead to distal hereditary motor neuropathy (distal HMN) and Charcot-Marie-Tooth neuropathy type 2L (CMT2L).
- The precise mechanism by which mutant HSPB8 causes these specific motor neuron diseases remains unclear.
Purpose of the Study:
- To investigate the cellular mechanisms underlying mutant HSPB8-induced neurodegeneration.
- To determine the cell-type specificity of HSPB8 mutations' effects.
Main Methods:
- Primary neuronal and glial cell cultures were utilized to compare the effects of mutant HSPB8 expression.
- Expression of HSPB8 K141N and K141E mutations was analyzed in motor neurons, sensory neurons, cortical neurons, and glial cells.
Main Results:
- Expression of mutant HSPB8 (K141N and K141E) induced significant neurite degeneration in motor neurons, characterized by reduced neurite number and length.
- The K141E mutation, and to a lesser extent K141N, caused spheroid formation in motor neuron neurites.
- Neurite degeneration occurred without inducing apoptosis in motor neurons.
- Phenotypic alterations were minimal in sensory neurons and absent in cortical neurons and glial cells.
Conclusions:
- Mutant HSPB8 specifically affects motor neurons, leading to neurite degeneration without cell death.
- This cell-type specificity explains the predominant motor neuron involvement observed in distal HMN and CMT2L.
- HSPB8 mutations represent a targeted mechanism for motor neuron dysfunction in specific neuropathies.
