Pharmacological inhibition of ALCAT1 mitigates amyotrophic lateral sclerosis by attenuating SOD1 protein aggregation

OBJECTIVE: Mutations in the copper-zinc superoxide dismutase (SOD1) gene cause familial amyotrophic lateral sclerosis (ALS), a progressive fatal neuromuscular disease characterized by motor neurons death and severe skeletal muscle degeneration. However, there is no effective treatment for this debilitating disease, since the underlying cause for the pathogenesis remains poorly understood. Here, we investigated a role of acyl-CoA:lysocardiolipin acyltransferase 1 (ALCAT1), an acyltransferase that promotes mitochondrial dysfunction in age-related diseases by catalyzing pathological remodeling of cardiolipin, in promoting the development of ALS in the SOD1(G93A) transgenic mice. METHODS: Using SOD1(G93A) transgenic mice with targeted deletion of the ALCAT1 gene and treated with Dafaglitapin (Dafa), a very potent and highly selective ALCAT1 inhibitor, we determined whether ablation or pharmaceutical inhibition of ALCAT1 by Dafa would mitigate ALS and the underlying pathogenesis by preventing pathological remodeling of cardiolipin, oxidative stress, and mitochondrial dysfunction by multiple approaches, including lifespan analysis, behavioral tests, morphological and functional analysis of skeletal muscle, electron microscopic and Seahorse analysis of mitochondrial morphology and respiration, western blot analysis of the SOD1(G93A) protein aggregation, and lipidomic analysis of cardiolipin content and acyl composition in mice spinal cord. RESULTS: ALCAT1 protein expression is potently upregulated in the skeletal muscle of the SOD1(G93A) mice. Consequently, ablation or pharmacological inhibition of ALCAT1 by Dafa attenuates motor neuron dysfunction, neuronal inflammation, and skeletal muscle atrophy in SOD1(G93A) mice by preventing SOD1(G93A) protein aggregation, mitochondrial dysfunction, and pathological CL remodeling, leading to moderate extension of lifespan in the SOD1(G93A) transgenic mice. CONCLUSIONS: ALCAT1 promotes the development of ALS by linking SOD1(G93A) protein aggregation to mitochondrial dysfunction, implicating Dafa as a potential treatment for this debilitating disorder.