Activation of the neurotrophic HGF system has been reported to have beneficial effects in preclinical models of ALS through its pleiotropic actions that can counteract various neurodegenerative mechanisms. We have previously demonstrated that ATH-1105, a small-molecule positive modulator of the HGF system, preserves neuromuscular function and promotes survival in the Prp-TDP43^A315T mouse model of ALS.

Primary rat motor neurons were treated with ATH-1105 for 15 minutes and exposed to excitotoxic glutamate for 24h. Neuroprotective activity was assessed via MAP2 immunostaining to evaluate neuronal survival and neurite length. To determine if ATH-1105 engages HGF signaling, MET (HGF receptor) phosphorylation was evaluated by immunoblotting. In a separate experiment, neurons were pre-treated with siRNA targeting MET and the neuroprotective activity of ATH-1105 was assessed as described above. To test ATH-1105 activity in human cells, iPSC-derived motor neurons carrying the homozygous SOD1-A4V mutation were co-cultured with human muscle, treated with ATH-1105 for 20 minutes, and challenged with glutamate for 48h. Neuronal survival and neurite length were quantified by MAP2 immunostaining.

Rat motor neurons treated with ATH-1105 + glutamate showed significant increases in neuronal survival and neurite length compared to those challenged with glutamate alone, and such effects were accompanied by a significant increase in MET activation (phosphorylation).  Knockdown of the MET receptor using siRNA abolished the protective effects of ATH-1105. In co-cultures of human iPSC-derived SOD1-A4V motor neurons and muscle, treatment with ATH-1105 + glutamate led to a significant increase in neuronal survival and neurite lengths compared to controls.