Host: The Japanese Society of Toxicology
Name : The 49th Annual Meeting of the Japanese Society of Toxicology
Date : June 30, 2022 - July 02, 2022
Reactive carbonyl species (RCS) are compounds with highly reactive carbonyl groups produced in the environment and in vivo. RCS covalently binds to proteins via Michael reaction. However, the target proteins and effect on physiological functions remain unknown. We selected 21 types of RCS and analyzed their effects on phosphatidylinositol-3 kinase (PI3K)–Akt signaling, which is an important pathway for maintaining intracellular homeostasis.
We found that several types of RCS suppressed the phosphorylation of Akt by treatment with epidermal growth factor (EGF) in A594 cells. We focused on methyl vinyl ketone (MVK), which showed the most significant suppression, and tried identifying the mechanism by which MVK interferes with Akt phosphorylation. MVK attenuated the phosphorylation of PI3K, but not EGF receptor (EGFR). This result suggests that MVK act in the pathway between EGFR and PI3K. To determine the modification sites in PI3K, we performed LC-MS/MS analysis. We identified that Cys656 residue in p85 subunit of PI3K was modified with MVK. Cys656 residue is in the SH2 domain that binds to receptor tyrosine kinases such as EGFR and recognizes their phosphorylation. Co-immunoprecipitation analysis revealed that MVK inhibited the interaction between EGFR and PI3K.
These results indicate that MVK modifies Cys656 of p85 subunit of PI3K and attenuates PI3K–Akt signaling by inhibiting EGFR–PI3K interaction, and the other RCS also regulates the function of PI3K by the same mechanism as MVK.
