Phosphonate Inhibitors of Pyruvate Dehydrogenase Perturb Homeostasis of Amino Acids and Protein Succinylation in the Brain

Abstract

Mitochondrial pyruvate dehydrogenase complex (PDHC) is essential for brain glucose and neurotransmitter metabolism, which is dysregulated in many pathologies. Using specific inhibitors of PDHC in vivo, we determine biochemical and physiological responses to PDHC dysfunction. Dose dependence of the responses to membrane-permeable dimethyl acetylphosphonate (AcPMe2) is non-monotonous. Primary decreases in glutathione and its redox potential, methionine, and ethanolamine are alleviated with increasing PDHC inhibition, the alleviation accompanied by physiological changes. A comparison of 39 brain biochemical parameters after administration of four phosphinate and phosphonate analogs of pyruvate at a fixed dose of 0.1 mmol/kg reveals no primary, but secondary changes, such as activation of 2-oxoglutarate dehydrogenase complex (OGDHC) and decreased levels of glutamate, isoleucine and leucine. The accompanying decreases in freezing time are most pronounced after administration of methyl acetylphosphinate and dimethyl acetylphosphonate. The PDHC inhibitors do not significantly change the levels of PDHA1 expression and phosphorylation, sirtuin 3 and total protein acetylation, but increase total protein succinylation and glutarylation, affecting sirtuin 5 expression. Thus, decreased production of the tricarboxylic acid cycle substrate acetyl-CoA by inhibited PDHC is compensated by increased degradation of amino acids through the activated OGDHC, increasing total protein succinylation/glutarylation. Simultaneously, parasympathetic activity and anxiety indicators decrease.

The emerging importance of the α-keto acid dehydrogenase complexes in serving as intracellular and intercellular signaling platforms for the regulation of metabolism

“…In this case, short-term inhibition was achieved with site-specific inhibitor for KGDHc, carboxyethyl succinyl phosphonate (CESP) [ 87 , 104 , 115 ]. Importantly, membrane penetrating trimethyl ester acetylphosphonate (AcPMe 2 ), triethyl succinyl phosphonate (TESP) and trimethyl or triethyl adipoyl phosphonate (TEAP or TMAP) that selectively interfere with PDHc, KGDHc, and OADHc, respectively, were recently developed to evaluate the role of KDHc in triggering oxidative eustress and distress in cells [ 36 , 116 , 117 ]. These tools, like KMV and CPI-613, can induce a robust ∼80–90 % decrease in mtO 2 •- /mtH 2 O 2 generation, making these inhibitors highly valuable in the study of KDHc enzymes in cell redox homeodynamics.…”

Dysregulation of protein succinylation and disease development

“…Additionally, succinylation of tau protein promotes its aggregation into tangles and impairs microtubule assembly (Yang Y. et al, 2022). An elevated succinylation level of pyruvate dehydrogenase complex (PDHC) in the hippocampus may downregulate mitochondrial energy metabolism, while potentially contributing to parasympathetic activity dysregulation, anxiety and depression (Artiukhov et al, 2022). Therefore, studying the mechanism and function of desuccinylation can provide a foundation for targeted therapy of nervous system diseases.…”

Enhancing Zinc Uptake through Dual-Modification of Cicer arietinum Protein

“…Tis is because the succinylation process and zinc binding do not signifcantly alter the overall protein amount. Te specifc amino acid residues targeted during succinylation and the occupancy of zinc-binding sites are already present in the nonbound protein, resulting in minimal changes to the total protein content [54]. In addition, the stability of the protein structure is not signifcantly afected by succinylation and zinc binding, leading to a nonsignifcant difference in protein content [54].…”

“…Te specifc amino acid residues targeted during succinylation and the occupancy of zinc-binding sites are already present in the nonbound protein, resulting in minimal changes to the total protein content [54]. In addition, the stability of the protein structure is not signifcantly afected by succinylation and zinc binding, leading to a nonsignifcant difference in protein content [54]. Our study is consistent with Shiplashree's study [41]," where the protein content of zinc-bound succinylated whey protein exhibits a nonsignifcant increase when compared to nonbound whey protein.…”