Synergistic Neuroprotection of MFSD2A Overexpression and DHA Supplementation in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive motor neuron loss, with limited effective therapies. Docosahexaenoic acid (DHA) exhibits neuroprotective effects, but its limited transport across the blood-brain barrier (BBB) restricts clinical utility. Major facilitator superfamily domain-containing protein 2A (MFSD2A) is the primary transporter of DHA into the central nervous system, yet its role in ALS remains unclear. This study investigated the therapeutic potential and mechanisms of MFSD2A overexpression combined with DHA supplementation in male SOD1^G93A ALS mice. We found that MFSD2A expression was markedly reduced in ALS mice and correlated with impaired motor function and neuronal damage. DHA supplementation or MFSD2A overexpression partially improved behavioral deficits, while their combination produced synergistic benefits. Histological analyses revealed attenuated neuronal degeneration and reduced muscle fibrosis following combined treatment. Furthermore, MFSD2A physically interacted with the E3 ubiquitin ligase TRIM21, regulating glycolytic metabolism by modulating key enzymes (GLUT1, HK2, LDHA, PDK1) and products (lactate/pyruvate and NADH/NADPH ratio). TRIM21 knockdown reversed MFSD2A-mediated neuroprotection and impaired glycolytic metabolism, indicating its critical role in this pathway. The combined intervention also suppressed systemic inflammation and oxidative stress by decreasing pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) and restoring antioxidant enzyme activities (GSH-Px), while reducing lipid peroxidation (MDA). These findings suggest that MFSD2A facilitates DHA's neuroprotective effects by enhancing glycolytic metabolism and mitigating neuroinflammation. This study highlights MFSD2A and DHA as promising therapeutic targets in ALS and provides novel insights into overcoming BBB transport limitations for neurodegenerative disease treatment.