Ferroptosis and glutarylation of glutamate dehydrogenase are involved in neurological impairment in glutaric acidemia type I

Abstract Background Glutaric acidemia type 1 (GA-1) is a rare autosomal-recessive inherited metabolic disorder caused by mutations in the gene encoding glutaryl-CoA dehydrogenase (GCDH). The loss of GCDH enzyme activity leads to glutaric acid (GA) and glutaryl-CoA accumulation, causing a spectrum of neurological impairments. Elevated glutaryl-CoA levels increase protein lysine glutarylation, a novel post-translational modification. However, the molecular mechanisms underlying GA-1-associated neurological damage remain poorly understood. Methods In this study, we investigated the role of ferroptosis and glutamate dehydrogenase (GDH) glutarylation in GA-1-related neurological impairment. We established in vivo and in vitro models of GA-1 using Gcdh knockout (KO) mice and H4 cells, respectively. Results Proteomics, coupled with bioinformatics analysis, suggested the important role of ferroptosis in neurological impairment of Gcdh KO mice. In vitro experiments showed that ferroptosis induced oxidative damage in H4 cells following GA treatment. Key ferroptosis-related proteins GPX4, FSP1, and FTH1, were significantly downregulated in H4 cells following GA treatment. Glutarylation levels were significantly higher in brain tissues from Gcdh KO mice, owing to elevated glutaryl-CoA levels rather than expression changes in the deglutarylation enzyme, SIRT5. We confirmed that GDH glutarylation was significantly higher in Gcdh KO mice brain tissues by performing co-immunoprecipitation assays. The activity of glutarylated GDH was significantly inhibited, accompanied by disrupted brain amino-acid metabolism in Gcdh KO mice. Conclusions Our findings reveal the importance of ferroptosis and the underlying mechanism of post-translational glutarylation in GA-1, which may provide valuable insights for developing preventive and clinical therapeutic strategies for GA-1.