DUSP3 modulates IRES‐dependent translation of mRNAs through dephosphorylation of the HNRNPC protein in cells under genotoxic stimulus

• Published in: Biology of the cell 2024-05, Vol.116 (5), p.e2300128-n/a
• Main Authors: Ferruzo, Pault Y. M., Boell, Viktor K., Russo, Lilian C., Oliveira, Carla C., Forti, Fabio L.
• Format: Article
• Language: English
• Subjects: DNA Damage; Dual Specificity Phosphatase 3 - genetics; Dual Specificity Phosphatase 3 - metabolism; DUSP3; genome integrity; HeLa Cells; Heterogeneous-Nuclear Ribonucleoproteins - genetics; Heterogeneous-Nuclear Ribonucleoproteins - metabolism; HNRNPC; Humans; mRNA translation; Phosphorylation; phosphorylation/dephosphorylation; Protein Biosynthesis; protein synthesis; RNA, Messenger - genetics; RNA, Messenger - metabolism
• ISSN: 0248-4900; 1768-322X
• DOI: 10.1111/boc.202300128

Background Information The dual‐specificity phosphatase 3 (DUSP3) regulates cell cycle progression, proliferation, senescence, and DNA repair pathways under genotoxic stress. This phosphatase interacts with HNRNPC protein suggesting an involvement in the regulation of HNRNPC‐ribonucleoprotein complex stability. In this work, we investigate the impact of DUSP3 depletion on functions of HNRNPC aiming to suggest new roles for this enzyme. Results The DUSP3 knockdown results in the tyrosine hyperphosphorylation state of HNRNPC increasing its RNA binding ability. HNRNPC is present in the cytoplasm where it interacts with IRES trans‐acting factors (ITAF) complex, which recruits the 40S ribosome on mRNA during protein synthesis, thus facilitating the translation of mRNAs containing IRES sequence in response to specific stimuli. In accordance with that, we found that DUSP3 is present in the 40S, monosomes and polysomes interacting with HNRNPC, just like other previously identified DUSP3 substrates/interacting partners such as PABP and NCL proteins. By downregulating DUSP3, Tyr‐phosphorylated HNRNPC preferentially binds to IRES‐containing mRNAs within ITAF complexes preferentially in synchronized or stressed cells, as evidenced by the higher levels of proteins such as c‐MYC and XIAP, but not their mRNAs such as measured by qPCR. Under DUSP3 absence, this increased phosphorylated‐HNRNPC/RNA interaction reduces HNRNPC‐p53 binding in presence of RNAs releasing p53 for specialized cellular responses. Similarly, to HNRNPC, PABP physically interacts with DUSP3 in an RNA‐dependent manner. Conclusions and Significance Overall, DUSP3 can modulate cellular responses to genotoxic stimuli at the translational level by maintaining the stability of HNRNPC‐ITAF complexes and regulating the intensity and specificity of RNA interactions with RRM‐domain proteins. DUSP3 knockdown increases tyrosine phosphorylation levels of HNRNPC. Phosphorylated HNRNPC has increased capacity for RNA recognition and binding but reduced p53 binding. DUSP3 is present in the 40S subunit of ribosome, monosomes and polysomes interacting with HNRNPC. In DUSP3‐depleted cells the phosphorylated HNRNPC preferentially binds IRES containing mRNAs such as c‐myc and xiap increasing their protein levels, but not their mRNAs.