Amyotrophic lateral sclerosis mutant TDP-43 may cause synaptic dysfunction through altered dendritic spine function.

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Amyotrophic lateral sclerosis (ALS) is characterized by altered cortical excitability and synapse dysfunction.
• Mislocalization and aggregation of TAR DNA-binding protein 43 (TDP-43) are key pathological hallmarks of ALS.
• The precise role of ALS-linked TDP-43 mutations in neuronal excitability and synaptic function remains unclear.

Purpose of the Study:

• To investigate the impact of ALS-linked mutant TDP-43 (TDP-43^A315T) on synapse formation and neuronal excitability.
• To examine the morphological, immunocytochemical, and excitability profiles of primary cortical pyramidal neurons over-expressing TDP-43^A315T.

Main Methods:

• Utilized transgenic mouse models expressing human TDP-43^A315T in primary cortical pyramidal neurons.
• Performed morphological and immunocytochemical analyses to assess synapse density and receptor localization.
• Measured action potential generation and neuronal excitability.

Main Results:

• TDP-43^A315T over-expression significantly reduced dendritic spine density.
• Increased total GluR1 levels but decreased its localization to dendritic spines.
• Reduced co-localization of presynaptic synaptophysin with dendritic spines.
• Decreased action potential generation in TDP-43^A315T pyramidal neurons.

Conclusions:

• Mutant TDP-43^A315T impairs synapse formation and synaptic GluR1 recruitment, potentially via cytoplasmic mislocalization.
• Reduced neuronal excitability and attenuated synaptic function are implicated in TDP-43-associated ALS pathogenesis.
• Further research into AMPA receptor-mediated excitability changes may reveal therapeutic targets for ALS.