Proteomic Analysis Identifies ATE1-Dependent Arginylation Dysregulation across Meningioma Grades.

Meningiomas are the most common primary brain tumors, yet the molecular pathways that distinguish grade 1 from grade 2 lesions remain insufficiently understood. Among post-translational modifications, N-terminal arginylation─catalyzed by ATE1─regulates protein stability and cellular stress responses, but its role in meningioma biology has not been explored. Here, we integrated mass-spectrometry-based proteomics, immunoblotting, and transcriptomic reanalysis to investigate pathway regulation across tumor grades. Grade 1 meningiomas displayed higher ATE1 expression and increased arginylation of key chaperones, accompanied by activation of the PERK branch of the unfolded protein response (UPR), enhanced autophagy, and greater engagement of apoptotics pathways. In contrast, grade 2 tumors showed reduced ATE1 levels, diminished BIP arginylation, attenuated UPR-PERK signaling, impaired autophagy, and increased proliferative signaling. Proteins predicted to be substrates of ATE1-mediated degradation were upregulated in grade 2 tumors, suggesting that loss of arginylation may stabilize pro-oncogenic factors. Together, these findings reveal grade-specific remodeling of the N-degron/arginylation axis and highlight protein arginylation as a previously unrecognized modulator of meningioma progression, with potential therapeutic relevance.