Protein Stability of Pyruvate Kinase Isozyme M2 Is Mediated by HAUSP

Abstract

The ubiquitin–proteasome system (UPS) is responsible for proteasomal degradation, regulating the half-life of the protein. Deubiquitinating enzymes (DUBs) are components of the UPS and inhibit degradation by removing ubiquitins from protein substrates. Herpesvirus-associated ubiquitin-specific protease (HAUSP) is one such deubiquitinating enzyme and has been closely associated with tumor development. In a previous study, we isolated putative HAUSP binding substrates by two-dimensional electrophoresis (2-DE) and identified them by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF/MS) analysis. The analysis showed that pyruvate kinase isoenzyme M2 (PKM2) was likely to be one of the substrates for HAUSP. Further study revealed that PKM2 binds to HAUSP, confirming the interaction between these proteins, and that PKM2 possesses the putative HAUSP binding motif, E or P/AXXS. Therefore, we generated mutant forms of PKM2 S57A, S97A, and S346A, and found that S57A had less binding affinity. In a previous study, we demonstrated that PKM2 is regulated by the UPS, and that HAUSP- as a DUB-acted on PKM2, thus siRNA for HAUSP increases PKM2 ubiquitination. Our present study newly highlights the direct interaction between HAUSP and PKM2.

The role of ubiquitination and deubiquitination in cancer metabolism

“…E3 ligase PARKIN modifies PKM2 by ubiquitination to decrease its enzymatic activity without affecting its stability [258]. PKM2 deubiquitinated by USP7 can strengthen the protein stability of PKM2 [259]. USP20 can also hydrolyze the ubiquitin chain on PKM2, but the detailed function of this deubiquitination is unclear [260].…”

Multiple functions of pyruvate kinase M2 in various cell types

“…In addition to E3 ubiquitin ligases, PKM2 also binds to the deubiquitinylating enzyme ubiquitin‐specific protease (HAUSP). HAUSP performs the deubiquitinylation of K48 residues in PKM2 and augments PKM2 stability (Choi et al, 2020). The deubiquitinase USP20 can mediate deubiquitinylation of PKM2 and it contributes to cancer metabolism through regulation of PKM2 activity (S. R. Kim et al, 2015).…”

Deubiquitinase PSMD14 promotes ovarian cancer progression by decreasing enzymatic activity of PKM2

“…Ubiquitination is another common and essential type of post‐translational modification; however, its functions in the regulation of PKM2 oligomers are still poorly known. PKM2 was reported to interact with E3 ligases including Parkin, CHIP, TRIM58, and laforin/malin complex, as well as DUBs including HAUSP and USP20 [ 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. CHIP and HAUSP participate in the regulation of ubiquitination and stability of PKM2 protein [ 35 , 38 ].…”

“…PKM2 was reported to interact with E3 ligases including Parkin, CHIP, TRIM58, and laforin/malin complex, as well as DUBs including HAUSP and USP20 [ 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. CHIP and HAUSP participate in the regulation of ubiquitination and stability of PKM2 protein [ 35 , 38 ]. USP20 can deubiquitinate PKM2 without affecting PKM2 expression [ 36 ].…”