ROMO1 loss in cholinergic neurons induces mitochondrial ultrastructural damage and ALS-like neuromuscular degeneration

Mitochondrial dysfunction is strongly associated with the pathogenesis of amyotrophic lateral sclerosis (ALS), a neurodegenerative disorder characterized by progressive motor neuron degeneration. However, it remains obscure whether mitochondrial abnormities are sufficient to drive ALS development. Here, we show that selective depletion of reactive oxygen species modulator 1 (ROMO1), an inner mitochondrial membrane-delimited protein, in cholinergic neurons leads to adult-onset, progressive locomotor deficits in mice that closely resemble ALS pathology. ROMO1 ablation in cholinergic neurons induces ALS-like neuromuscular degeneration, as evidenced by age-dependent motor neuron loss, axon degeneration, disrupted cholinergic transmission, neuromuscular junction denervation, and the resultant muscle atrophy. Notably, ROMO1 loss induces early and progressive mitochondrial cristae deformation in motor neurons, preceding the onset of ALS-like syndromes. Our findings support that mitochondrial impairment in vulnerable motor neurons is a sufficient contributor to ALS etiology, positioning mitochondria as a potential therapeutic target.