Fosgonimeton, a Small‐Molecule Positive Modulator of the HGF/MET System, Attenuates Amyloid‐β – Mediated Toxicity in Primary Neuron Culture

Background Positive modulation of the hepatocyte growth factor (HGF)/MET system may represent a promising therapeutic strategy for Alzheimer’s disease (AD). Downstream effectors of HGF/MET, such as AKT or ERK, have been shown to activate pro‐survival signaling cascades that counteract pathological components of AD including excitotoxicity, mitochondrial dysfunction, oxidative stress, and protein aggregation. We have previously that fosgonimeton, a small molecule positive modulator of the HGF/MET system, elicits broad neuroprotective effects (Johnston et. al, 2022). Herein, we investigate the mechanism of action by which fosgonimeton induces neuroprotective effects in beta‐amyloid and glutamate‐challenged primary cortical neurons. Method Primary rat cortical neurons were treated with the active metabolite of fosgonimeton (fosgo‐AM), challenged with beta‐amyloid (Aβ1‐42; 15 µM) for 24 hours, and co‐immunostained for microtubule‐associated protein‐2 (MAP‐2) and phospho‐tau (AT100). Immunofluorescence analyses were used to determine neuronal survival, neurite network integrity (total neurite length), and phospho‐tau levels. In a separate model, rat cortical neurons were treated with fosgo‐AM and challenged with glutamate (20 µM) for 24 hours, and immunostained for MAP‐2 to determine neuronal survival and neurite network. To elucidate the mechanism of neuroprotection, protein analyses via western blot and homogenous time‐resolved fluorescence were conducted to assay HGF/MET downstream signaling pathways. In addition, the effect of fosgo‐AM on mitochondrial membrane potential (MMP) was assessed in primary cortical neuron culture via fluorescent MMP dye. Result Fosgo‐AM treatment significantly improved survival of cortical neurons, protected neurite networks, and reduced tau hyperphosphorylation after injury with Aβ1‐42. Additionally, fosgo‐AM reduced glutamate‐mediated cortical neuron death and neurite degeneration. Analyses of downstream signaling effects indicate that the neuroprotective effects of fosgo‐AM treatment may, in part, be the result of activation of AKT signaling and subsequent rescue of mitochondrial membrane potential, thereby reducing protein pathology and oxidative stress. Conclusion Our in vitro data demonstrate the address pathological of AD reduce tau . neuroprotective effects of fosgonimeton, in addition to its neurotrophic and pro‐cognitive effects in preclinical models, highlight its therapeutic potential to interrupt disease progression