Ca²⁺-activated K⁺ channels modulate microglia affecting motor neuron survival in hSOD1^G93A mice

Area of Science:

• Neuroscience
• Immunology
• Pharmacology

Background:

• Microglia play a crucial role in amyotrophic lateral sclerosis (ALS) by promoting a pro-inflammatory environment that leads to motor neuron degeneration.
• Identifying molecular pathways that control microglia activation is essential for developing targeted therapies to slow ALS progression.

Purpose of the Study:

• To investigate the role of the intermediate-conductance calcium-activated potassium channel KCa3.1 in microglia activation in the context of ALS.
• To evaluate the therapeutic potential of inhibiting KCa3.1 using a selective inhibitor (TRAM-34) in a mouse model of ALS.

Main Methods:

• Utilized the hSOD1^G93A mouse model, which mimics key features of human ALS.
• Administered a selective KCa3.1 inhibitor, TRAM-34, to hSOD1^G93A mice.
• Assessed microglia phenotype, motor neuron survival, disease onset, survival rates, muscle denervation, acetylcholine receptor expression, and neuromuscular junction integrity.

Main Results:

• Treatment with TRAM-34 significantly attenuated the pro-inflammatory phenotype of microglia in the spinal cord of hSOD1^G93A mice.
• KCa3.1 inhibition led to reduced motor neuron death, delayed onset of muscle weakness, and increased overall survival.
• Specific effects included slowed muscle denervation, decreased fetal acetylcholine receptor γ subunit expression, and reduced neuromuscular junction damage.

Conclusions:

• KCa3.1 channels play a critical role in mediating the pro-inflammatory activation of microglia in ALS.
• Inhibition of KCa3.1 channels represents a promising therapeutic strategy for ALS, offering neuroprotection and disease modification.