α-Ketoisocaproic Acid Disrupts Mitochondrial Bioenergetics in the Brain of Neonate Rats: Molecular Modeling Studies of α-ketoglutarate Dehydrogenase Subunits Inhibition

Author(s)

Zemniacak, angela Beatris ; Ribeiro, Rafael Teixeira ; das Neves, Gustavo Machado ; Cunha, Samela de Azevedo ; Tavares, Tailine Quevedo ; Carvalho, Andrey Vinicios Soares ; Netto, Carlos Alexandre ; Castilho, Roger Frigerio ; Wajner, Moacir ; Amaral, Alexandre Umpierrez

• Document type: Journal article
• Source: Neurochemical Research; v. 50, n. 1, p. 15-pg., 2025-02-01.

Abstract

Brain accumulation of the branched-chain alpha-keto acids alpha-ketoisocaproic acid (KIC), alpha-keto-beta-methylvaleric acid (KMV), and alpha-ketoisovaleric acid (KIV) occurs in maple syrup urine disease (MSUD), an inherited intoxicating metabolic disorder caused by defects of the branched-chain alpha-keto acid dehydrogenase complex. Patients commonly suffer life-threatening acute encephalopathy in the newborn period and develop chronic neurological sequelae of still undefined pathogenesis. Therefore, this work investigated the in vitro influence of pathological concentrations of KIC (5 mM), KMV (1 mM), and KIV (1 mM) on mitochondrial bioenergetics in the cerebral cortex of neonate (one-day-old) rats. KIC, but not KMV and KIV, decreased phosphorylating (stimulated by ADP) and uncoupled (induced by CCCP) mitochondrial respiration supported by pyruvate, malate, and glutamate, indicating metabolic inhibition. These effects were less evident after supplementing the medium with succinate. KIC also mildly increased non-phosphorylating respiration (in the presence of oligomycin) using pyruvate plus malate or glutamate plus malate as substrates, suggesting an uncoupling effect. Moreover, KIC markedly inhibited the activity of alpha-ketoglutarate dehydrogenase noncompetitively and decreased ATP synthesis. Finally, docking simulations demonstrated that KIC preferentially interacts with E2 and E3 subunits of alpha-ketoglutarate dehydrogenase at the dihydrolipoamide binding site and into an allosteric site of E1. The present data strongly indicate that KIC compromises mitochondrial bioenergetics in the neonatal rat brain, supporting the hypothesis that disruption of energy homeostasis caused by brain KIC accumulation in the first days of life may be implicated in the neuropathology of MSUD. (AU)

• FAPESP's process: 23/00229-0 - Pathophysiological roles of mitochondrial NAD(P)+ transhydrogenase
• Grantee: Roger Frigério Castilho
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 17/17728-8 - Mitochondrial function and dysfunction: implications for aging and associated diseases
• Grantee: Aníbal Eugênio Vercesi
• Support Opportunities: Research Projects - Thematic Grants