Novel FKBP prolyl isomerase 1A (FKBP12) ligand promotes functional improvement in SOD1G93A amyotrophic lateral sclerosis (ALS) mice.

Abstract

Background and purpose: Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease with limited treatment options. ALS pathogenesis involves intricate processes within motor neurons, characterized by dysregulated Ca²⁺ influx and buffering in early ALS-affected motor neurones. This study proposes the modulation of ryanodine receptors (RyRs), key mediators of intracellular Ca²⁺, as a therapeutic target.

Experimental approach: A novel class of novel FKBP12 ligands that show activity as cytosolic calcium modulators through stabilizing RyR channel activity, were tested in the superoxide dismutase 1 (SOD1)^G93A mouse model of ALS. Different outcomes were used to assess treatment efficacy, including electrophysiology, histopathology, neuromuscular function and survival.

Key results: Among the novel FKBP12 ligands, MP-010 was chosen for its central nervous system availability and favourable in vitro pharmaco-toxicological profile. Chronic administration of MP-010 to SOD1^G93A mice produced preservation of motor nerve conduction, with the 61-mg·kg^-1 dose significantly delaying the onset of motor impairment. This was accompanied by improved motor coordination, increased innervated endplates and significant preservation of motor neurones in the spinal cord of treated mice. Notably, MP-010 treatment significantly extended lifespan by an average of 10 days compared to vehicle.

Conclusions and implications: FKBP12 ligands, particularly MP-010, exhibit promising neuroprotective effects in ALS, highlighting their potential as novel therapeutic agents. Further investigations into the molecular mechanisms and clinical translatability of these compounds are needed for their application in ALS treatment.