81 Metabolomic Analyses Show Failure of Acylcarnitine Metabolism and Increased Oxidative Stress in Liver of Gracile (BCS1LG/G) Mice

Abstract

Background and aims: BCS1L is a chaperone assembling the Rieske iron-sulphur protein into respiratory chain complex III. To study BCS1L functions and pathophysiology of GRACILE syndrome (MIM 603358), we have introduced the disease mutation (Bcs1l 232A> G) into mice, using gene targeting. The homozygous mutant mice (Bcs1lG/G) exhibit a lethal disease after 24 d of age resembling GRACILE syndrome: growth restriction, hepatopathy, tubulopathy, and progressive complex III deficiency. We aimed to assess metabolic changes in liver of Bcs1lG/G mice to characterize genotype-metabolomic phenotype correlation. Methods: Bcs1lG/G mice and littermate controls were sacrificed at age 7 (14 pairs) and 24 d (symptomless, 8 pairs), and 5±1 wk (affected, 18 pairs). Snap-frozen liver samples were stored in 80°C. Metabolomic analyses of 199 metabolites (amino acids, series of carnitines and lipids, HODE, HETE, bile acids, metabolites of the energy metabolism) were carried out at BIOCRATES Life Sciences AG. Results: Profound changes in liver metabolite levels (increase in medium and long chain acylcarnitines and decrease in short chain acylcarnitines) were found in 5±1 wk, and slight changes in 24d Bcs1lG/G animals. Markers of oxidative stress (15S-HETE, 12S-HETE, 13-HODE and methioninsulfoxide), bile acids, amino acids, biogenic amino acids, sphingolipids and phosphatidylcholines were significantly increased in affected Bcs1lG/G animals only. Hexose-phosphate, lactate, alpha – ketoglurate were decreased compared to littermates Conclusions: Affected Bcs1lG/G mice with progressive complex III deficiency have major changes in acylcarnitine metabolism, which seems to precede oxidative stress and profound changes in metabolites indicating cell injury as well as liver dysfunction.